ORCID Profile
0000-0001-9841-1112
Current Organisation
La Trobe University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Plant Biology | Cell Metabolism | Plant Physiology | Biochemistry and Cell Biology | Plant Cell and Molecular Biology | Crop and Pasture Production | Plant Physiology | Crop and Pasture Nutrition | Crop and Pasture Biochemistry and Physiology | Ecology | Plant Biochemistry And Physiology | Plant Nutrition | Post Harvest Technologies | Plant Protection (Pests, Diseases And Weeds) | Receptors and Membrane Biology | Terrestrial Ecology | Gene Expression | Protein Targeting And Signal Transduction | Membrane Biology | Plant Pathology | Genetic Technologies: Transformation, Site-Directed Mutagenesis, Etc. |
ANZSRC Socio-Economic Objective (SEO)
Field crops | Grain legumes | Horticultural crops | Soybeans | Environmentally Sustainable Plant Production not elsewhere classified | Primary products from plants | Grain Legumes | Land and water management | Wheat | Native Forests | Management of Water Consumption by Plant Production | Farmland, Arable Cropland and Permanent Cropland Soils | Forest and Woodlands Flora, Fauna and Biodiversity
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Publications
The Symbiosome Membrane
Publisher: Wiley
Date: 14-07-2015
AtNDB2 is the main external NADH dehydrogenase in mitochondria and is important for tolerance to environmental stress
Publisher: Oxford University Press (OUP)
Date: 13-08-2019
DOI: 10.1104/PP.19.00877
Iron transport across symbiotic membranes of nitrogen-fixing legumes
Publisher: MDPI AG
Date: 04-01-2021
DOI: 10.3390/IJMS22010432
Abstract: Iron is an essential nutrient for the legume-rhizobia symbiosis and nitrogen-fixing bacteroids within root nodules of legumes have a very high demand for the metal. Within the infected cells of nodules, the bacteroids are surrounded by a plant membrane to form an organelle-like structure called the symbiosome. In this review, we focus on how iron is transported across the symbiosome membrane and accessed by the bacteroids.
Cell-to-cell transport via the lumen of the endoplasmic reticulum
Publisher: Wiley
Date: 04-04-2011
Iron: an essential micronutrient for the legume-rhizobium symbiosis
Publisher: Frontiers Media SA
Date: 2013
The Metabolic Response of Brachypodium Roots to the Interaction with Beneficial Bacteria Is Affected by the Plant Nutritional Status
Publisher: MDPI AG
Date: 03-06-2021
Abstract: The potential of plant growth promoting (PGP) bacteria in improving the performance of plants in suboptimal environments is increasingly acknowledged, but little information is available on the mechanisms underlying this interaction, particularly when plants are subjected to a combination of stresses. In this study, we investigated the effects of the inoculation with the PGP bacteria Azospirillum brasilense (Azospirillum) on the metabolism of the model cereal Brachypodium distachyon (Brachypodium) grown at low temperatures and supplied with insufficient phosphorus. Investigating polar metabolite and lipid fluctuations during early plant development, we found that the bacteria initially elicited a defense response in Brachypodium roots, while at later stages Azospirillum reduced the stress caused by phosphorus deficiency and improved root development of inoculated plants, particularly by stimulating the growth of branch roots. We propose that the interaction of the plant with Azospirillum was influenced by its nutritional status: bacteria were sensed as pathogens while plants were still phosphorus sufficient, but the interaction became increasingly beneficial for the plants as their phosphorus levels decreased. Our results provide new insights on the dynamics of the cereal-PGP bacteria interaction, and contribute to our understanding of the role of beneficial microorganisms in the growth of cereal crops in suboptimal environments.
Characterization of narrow-leaf lupin (Lupinus angustifolius L.) recombinant major allergen IgE-binding proteins and the natural β-conglutin counterparts in sweet lupin seed species
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.FOODCHEM.2017.10.015
Abstract: β-conglutin has been identified as a major allergen for Lupinus angustifolius seeds. The aim of this study was to evaluate the binding of IgE to five recombinant β-conglutin isoforms (rβ) that we overexpressed and purified and to their natural counterparts in different lupin species and cultivars. Western blotting suggested β-conglutins were the main proteins responsible for the IgE reactivity of the lupin species and cultivars. Newly identified polypeptides from "sweet lupin" may constitute a potential new source of primary or cross-reactive sensitization to lupin, particularly to L. albus and L. angustifolius seed proteins. Several of them exhibited qualitative and quantitative differences in IgE-binding among these species and cultivars, mainly in sera from atopic patients that react to lupin rather than peanut. IgE-binding was more consistent to recombinant β2 than to any of the other isoforms, making this protein a potential candidate for diagnosis and immunotherapy.
Medicago truncatula Yellow Stripe‐Like7 encodes a peptide transporter participating in symbiotic nitrogen fixation
Publisher: Wiley
Date: 13-04-2021
DOI: 10.1111/PCE.14059
GmVTL1 is an iron transporter on the symbiosome membrane of soybean with an important role in nitrogen fixation
Publisher: Cold Spring Harbor Laboratory
Date: 05-03-2020
DOI: 10.1101/2020.03.03.975805
Abstract: Legumes establish symbiotic relationships with soil bacteria (rhizobia), housed in nodules on plant roots. The plant supplies carbon substrates and other nutrients to the bacteria in exchange for fixed nitrogen. The exchange occurs across a plant-derived symbiosome membrane (SM), which encloses rhizobia to form a symbiosome. Iron supplied by the plant is crucial for the rhizobial enzyme nitrogenase that catalyses N 2 fixation, but the SM iron transporter has not been identified. We use complementation of yeast and plant mutants, real-time PCR, hairy root transformation, microscopy and proteomics to demonstrate the role of soybean GmVTL1 and 2. Both are members of the vacuolar iron transporter family and homologous to Lotus japonicus SEN1 (LjSEN1), previously shown to be essential for N 2 fixation. GmVTL1 expression is enhanced in nodule infected cells and both proteins are localised to the SM. GmVTL1 and 2 transport iron in yeast and GmVTL1 restores N 2 fixation when expressed in the Ljsen1 mutant. Three GmVTL1 amino acid substitutions that reduce iron transport in yeast also block N 2 fixation in Ljsen1 plants. We conclude GmVTL1 is responsible for transport of iron across the SM to bacteroids and plays a crucial role in the N 2 -fixing symbiosis.
Transformation of a grain legume (Lupinus angustifolius L.) via Agrobacterium tumefaciens-mediated gene transfer to shoot apices
Publisher: Springer Science and Business Media LLC
Date: 1997
Soybean Yellow Stripe-like 7 is a symbiosome membrane peptide transporter important for nitrogen fixation
Publisher: Oxford University Press (OUP)
Date: 05-02-2021
Abstract: Legumes form a symbiosis with rhizobia that convert atmospheric nitrogen (N2) to ammonia and provide it to the plant in return for a carbon and nutrient supply. Nodules, developed as part of the symbiosis, harbor rhizobia that are enclosed in a plant-derived symbiosome membrane (SM) to form an organelle-like structure called the symbiosome. In mature nodules exchanges between the symbionts occur across the SM. Here we characterize Yellow Stripe-like 7 (GmYSL7), a Yellow stripe-like family member localized on the SM in soybean (Glycine max) nodules. It is expressed specifically in infected cells with expression peaking soon after nitrogenase becomes active. Unlike most YSL family members, GmYSL7 does not transport metals complexed with phytosiderophores. Rather, it transports oligopeptides of between four and 12 amino acids. Silencing GmYSL7 reduces nitrogenase activity and blocks infected cell development so that symbiosomes contain only a single bacteroid. This indicates the substrate of YSL7 is required for proper nodule development, either by promoting symbiosome development directly or by preventing inhibition of development by the plant. RNAseq of nodules where GmYSL7 was silenced suggests that the plant initiates a defense response against rhizobia with genes encoding proteins involved in amino acid export downregulated and some transcripts associated with metal homeostasis altered. These changes may result from the decrease in nitrogen fixation upon GmYSL7 silencing and suggest that the peptide(s) transported by GmYSL7 monitor the functional state of the bacteroids and regulate nodule metabolism and transport processes accordingly. Further work to identify the physiological substrate for GmYSL7 will allow clarification of this role.
Investigation of biochemical changes in barley inoculated with Trichoderma harzianum T-22 under salt stress [PREPRINT OR COMPARABLE]
Publisher: Cold Spring Harbor Laboratory
Date: 19-10-2020
DOI: 10.1101/2020.10.19.346056
Abstract: Increases in soil salinity impacts growth and yield of agricultural plants by inhibiting plant functions. Soil salinization is increasing because of the pressure of a growing population on food supply. Genetically modified crops and plant breeding techniques are being used to produce plants tolerant to salt stress. However, interactions of fungal endophytes with crop plants can also improve tolerance and is a less expensive approach. Here, the role of Trichoderma harzianum T-22 in alleviating NaCl-induced stress in two barley genotypes (cv. Vlamingh and cv. Gairdner) has been investigated. Metabolomics using GC-MS for polar metabolites and LC-MS for lipids was employed to provide insights into the biochemical changes in barley roots inoculated with fungus during the early stages of interaction. T. harzianum increased the root length of both genotypes under controlled and saline conditions. The fungus reduced the relative concentration of sugars in both genotypes and caused no change in organic acids under saline conditions. Amino acids decreased only in cv. Gairdner in fungus-inoculated roots under saline conditions. Lipid analyses suggest that salt stress causes large changes in the lipid profile of roots but that inoculation with fungus greatly reduces the extent of these changes. By studying a tolerant and a sensitive genotype and their responses to salt and inoculation we have been able to develop hypotheses about what lipid species and metabolites may be involved in the tolerant genotype for its tolerance to salt and how fungal inoculation changes the response of the sensitive genotype to improve its tolerance.
Long-distance movement of phosphate starvation-responsive microRNAs in Arabidopsis.
Publisher: Wiley
Date: 12-04-2017
DOI: 10.1111/PLB.12568
Abstract: Plant microRNAs are small RNAs that are important for genetic regulation of processes such as plant development or environmental responses. Specific microRNAs accumulate in the phloem during phosphate starvation, and may act as long-distance signalling molecules. We performed quantitative PCR on Arabidopsis hypocotyl micrograft tissues of wild-type and hen1-6 mutants to assess the mobility of several phosphate starvation-responsive microRNA species. In addition to the previously confirmed mobile species miR399d, the corresponding microRNA* (miR399d*) was identified for the first time as mobile between shoots and roots. Translocation by phosphate-responsive microRNAs miR827 and miR2111a between shoots and roots during phosphate starvation was evident, while their respective microRNA*s were not mobile. The results suggest that long-distance mobility of microRNA species is selective and can occur without the corresponding duplex strand. Movement of miR399d* and root-localised accumulation of miR2111a* opens the potential for persisting microRNA*s to be mobile and functional in novel pathways during phosphate starvation responses.
Proteomic Analysis of the Soybean Symbiosome Identifies New Symbiotic Proteins
Publisher: Elsevier BV
Date: 05-2015
Identification and characterisation of seed storage protein transcripts from Lupinus angustifolius
Publisher: Springer Science and Business Media LLC
Date: 04-04-2011
Abstract: In legumes, seed storage proteins are important for the developing seedling and are an important source of protein for humans and animals. Lupinus angustifolius (L.), also known as narrow-leaf lupin (NLL) is a grain legume crop that is gaining recognition as a potential human health food as the grain is high in protein and dietary fibre, gluten-free and low in fat and starch. Genes encoding the seed storage proteins of NLL were characterised by sequencing cDNA clones derived from developing seeds. Four families of seed storage proteins were identified and comprised three unique α, seven β, two γ and four δ conglutins. This study added eleven new expressed storage protein genes for the species. A comparison of the deduced amino acid sequences of NLL conglutins with those available for the storage proteins of Lupinus albus (L.), Pisum sativum (L.), Medicago truncatula (L.), Arachis hypogaea (L.) and Glycine max (L.) permitted the analysis of a phylogenetic relationships between proteins and demonstrated, in general, that the strongest conservation occurred within species. In the case of 7S globulin (β conglutins) and 2S sulphur-rich albumin (δ conglutins), the analysis suggests that gene duplication occurred after legume speciation. This contrasted with 11S globulin (α conglutin) and basic 7S (γ conglutin) sequences where some of these sequences appear to have erged prior to speciation. The most abundant NLL conglutin family was β (56%), followed by α (24%), δ (15%) and γ (6%) and the transcript levels of these genes increased 10 3 to 10 6 fold during seed development. We used the 16 NLL conglutin sequences identified here to determine that for in iduals specifically allergic to lupin, all seven members of the β conglutin family were potential allergens. This study has characterised 16 seed storage protein genes in NLL including 11 newly-identified members. It has helped lay the foundation for efforts to use molecular breeding approaches to improve lupins, for ex le by reducing allergens or increasing the expression of specific seed storage protein(s) with desirable nutritional properties.
Cloning sequencing of Lol pI, the major allergenic protein of rye‐grass pollen
Publisher: Wiley
Date: 25-02-1991
DOI: 10.1016/0014-5793(91)80151-R
Abstract: We have isolated a full length cDNA clone encoding the major glycoprotein allergen Lol pI. The clone was selected using a combination of immunological screening of a cDNA expression library and PCR lification of Lol pI-specific transcripts. Lol pI expressed in bacteria as a fusion protein shows recognition by specific IgE antibodies present in sera of grass pollen-allergic subjects. Northern analysis has shown that the Lol pI transcripts are expressed only in pollen of rye-grass. Molecular cloning of Lol pI provides a molecular genetic approach to study the structure-function relationship of allergens.
Type II NAD(P)H dehydrogenases are targeted to mitochondria and chloroplasts or peroxisomes in Arabidopsis thaliana
Publisher: Wiley
Date: 12-08-2008
DOI: 10.1016/J.FEBSLET.2008.07.061
Abstract: We found that four type II NAD(P)H dehydrogenases (ND) in Arabidopsis are targeted to two locations in the cell NDC1 was targeted to mitochondria and chloroplasts, while NDA1, NDA2 and NDB1 were targeted to mitochondria and peroxisomes. Targeting of NDC1 to chloroplasts as well as mitochondria was shown using in vitro and in vivo uptake assays and dual targeting of NDC1 to plastids relies on regions in the mature part of the protein. Accumulation of NDA type dehydrogenases to peroxisomes and mitochondria was confirmed using Western blot analysis on highly purified organelle fractions. Targeting of ND proteins to mitochondria and peroxisomes is achieved by two separate signals, a C-terminal signal for peroxisomes and an N-terminal signal for mitochondria.
Dual intracellular localization and targeting of aminoimidazole ribonucleotide synthetase in cowpea
Publisher: Oxford University Press (OUP)
Date: 03-2003
Abstract: De novo purine biosynthesis is localized to both mitochondria and plastids isolated from Bradyrhizobium sp.-infected cells of cowpea (Vigna unguiculata L. Walp) nodules, but several of the pathway enzymes, including aminoimidazole ribonucleotide synthetase (AIRS [EC 6.3.3.1], encoded by Vupur5), are encoded by single genes. Immunolocalization confirmed the presence of AIRS protein in both organelles. Enzymatically active AIRS was purified separately from nodule mitochondria and plastids. N-terminal sequencing showed that these two isoforms matched the Vupur5 cDNA sequence but were processed at different sites following import the mitochondrial isoform was five amino acids longer than the plastid isoform. Electrospray tandem mass spectrometry of a trypsin digest of mitochondrial AIRS identified two internal peptides identical with the amino acid sequence deduced from Vupur5 cDNA. Western blots of proteins from mitochondria and plastids isolated from root tips showed a single AIRS protein present at low levels in both organelles. 35S-AIRS protein translated from aVupur5 cDNA was imported into isolated pea (Pisum sativum) leaf chloroplasts in vitro by an ATP-dependent process but not into import-competent mitochondria from several plant and non-plant sources. Components of the mature protein are likely to be important for import because the N-terminal targeting sequence was unable to target green fluorescent protein to either chloroplasts or mitochondria in Arabidopsis leaves. The data confirm localization of the protein translated from the AIRS gene in cowpea to both plastids and mitochondria and that it is cotargeted to both organelles, but the mechanism underlying import into mitochondria has features that are yet to be identified.
Consequences of transforming narrow leafed lupin (Lupinus angustifolius L. ) with an IPT gene under control of a flower-specific promoter
Publisher: Springer Science and Business Media LLC
Date: 23-02-2011
DOI: 10.1007/S11248-011-9497-7
Abstract: Phenotypes of five transgenic lines of narrow-leafed lupin (Lupinus angustifolius [L] cv Merrit) stably transformed with the isopentenyl pyrophosphate transferase (ipt) gene from Agrobacterium tumefaciens coupled to a flower-specific promoter (TP12) from Nicotiana tabacum [L.] are described. Expression of the transgene was detected in floral tissues and in shoot apical meristems on all orders of inflorescence. In each transgenic line there was significant axillary bud outgrowth at all nodes on the main stem with pronounced branch development from the more basal nodes in three of the lines. The lowest basal branches developed in a manner similar to the upper stem axillary branches on cv Merrit and bore fruits, which, in two lines, contained a significant yield of filled seeds at maturity. Senescence of the cotyledons was delayed in all lines with green cotyledons persisting beyond anthesis in one case. IPT expression increased cytokinin (CK) levels in flowers, meristem tissues and phloem exudates in a form specific manner, which was suggestive of localized flower and meristem production with significant long-distance re-distribution in phloem. The total number of fruits formed (pod set) on some transgenic lines was increased compared to cv Merrit. Grain size compared to cv Merrit was not significantly altered in transgenic lines.
Time-resolution of the shoot and root growth of the model cereal Brachypodium in response to inoculation with Azospirillum bacteria at low phosphorus and temperature
Publisher: Springer Science and Business Media LLC
Date: 11-2021
DOI: 10.1007/S10725-020-00675-4
Abstract: A non-invasive plant phenotyping platform, GrowScreen-PaGe , was used to resolve the dynamics of shoot and root growth of the model cereal Brachypodium ( Brachypodium distachyon Bd21-3) in response to the plant growth promoting (PGP) bacteria Azospirillum ( Azospirillum brasilense Sp245). Inoculated Brachypodium plants had greater early vigor and higher P use efficiency than non-inoculated Brachypodium at low P and low temperature conditions. Root systems were imaged non-invasively at eight time points and data combined with leaf area, shoot biomass and nutrient content from destructive subs les at 7, 14 and 21 days after inoculation (DAI). Azospirillum colonisation of roots improved Brachypodium shoot and, to a greater degree, root growth in three independent experiments. Inoculation promoted P use efficiency in shoots but not P concentration or uptake, despite increased total root length. Longer roots in inoculated plants arose from twofold faster branch root growth but slower axile root growth, detected at 11 DAI. Analysis of the spatio-temporal phenotypes indicated that the effects of Azospirillum inoculation increased as shoot P concentration declined, but the magnitude depended on the time after inoculation and growth rate of branch roots compared to axile roots. High throughput plant phenotyping platforms allow the details of plant-microorganism symbioses to be resolved, offering insights into the timing of changes in different tissues to allow molecular mechanisms to be determined.
Inoculation of barley with Trichoderma harzianum T-22 modifies lipids and metabolites to improve salt tolerance
Publisher: Oxford University Press (OUP)
Date: 19-07-2021
DOI: 10.1093/JXB/ERAB335
Abstract: Soil salinity has a serious impact on plant growth and agricultural yield. Inoculation of crop plants with fungal endophytes is a cost-effective way to improve salt tolerance. We used metabolomics to study how Trichoderma harzianum T-22 alleviates NaCl-induced stress in two barley (Hordeum vulgare L.) cultivars, Gairdner and Vlamingh, with contrasting salinity tolerance. GC-MS was used to analyse polar metabolites and LC-MS to analyse lipids in roots during the early stages of interaction with Trichoderma. Inoculation reversed the severe effects of salt on root length in sensitive cv. Gairdner and, to a lesser extent, improved root growth in more tolerance cv. Vlamingh. Biochemical changes showed a similar pattern in inoculated roots after salt treatment. Sugars increased in both cultivars, with ribulose, ribose, and rhamnose specifically increased by inoculation. Salt stress caused large changes in lipids in roots but inoculation with fungus greatly reduced the extent of these changes. Many of the metabolic changes in inoculated cv. Gairdner after salt treatment mirror the response of uninoculated cv. Vlamingh, but there are some metabolites that changed in both cultivars only after fungal inoculation. Further study is required to determine how these metabolic changes are induced by fungal inoculation.
Analysis of Crude Protein and Allergen Abundance in Peanuts (Arachis hypogaea cv. Walter) from Three Growing Regions in Australia
Publisher: American Chemical Society (ACS)
Date: 08-04-2013
DOI: 10.1021/JF305347R
Abstract: The effects of plant growth conditions on concentrations of proteins, including allergens, in peanut ( Arachis hypogaea L.) kernels are largely unknown. Peanuts (cv. Walter) were grown at five sites (Taabinga, Redvale, Childers, Bundaberg, and Kairi) covering three commercial growing regions in Queensland, Australia. Differences in temperature, rainfall, and solar radiation during the growing season were evaluated. Kernel yield varied from 2.3 t/ha (Kairi) to 3.9 t/ha (Childers), probably due to differences in solar radiation. Crude protein appeared to vary only between Kairi and Childers, whereas Ara h 1 and 2 concentrations were similar in all locations. 2D-DIGE revealed significant differences in spot volumes for only two minor protein spots from peanuts grown in the five locations. Western blotting using peanut-allergic serum revealed no qualitative differences in recognition of antigens. It was concluded that peanuts grown in different growing regions in Queensland, Australia, had similar protein compositions and therefore were unlikely to show differences in allergenicity.
Localization of carbonic anhydrase in legume nodules
Publisher: Wiley
Date: 03-2001
Air synthetase in cowpea nodules: A single gene product targeted to two organelles?
Publisher: Springer Science and Business Media LLC
Date: 1998
Abstract: A cDNA (VUpur5) encoding phosphoribosyl aminoimidazole (AIR) synthetase, the fifth enzyme of the de novo purine biosynthesis pathway has been isolated from a cowpea nodule cDNA library. It encodes a 388 amino acid protein with a predicted molecular mass of 40.4 kDa. The deduced amino acid sequence has significant homology with AIR synthetase from other organisms. AIR synthetase is present in both mitochondria and plastids of cowpea nodules. A signal sequence encoded by the VUpur5 cDNA has properties associated with plastid transit sequences but there is no consensus cleavage site as would be expected for a plastid targeted protein. Although the signal sequence does not have the structural features of a mitochondrial targeted protein, it has a mitochondrial cleavage site motif (RX/XS) close to the predicted N-terminus of the mature protein. Southern analysis suggests that AIR synthetase is encoded by a single gene raising questions as to how the product of this gene is targeted to the two organelles. VUpur5 is expressed at much higher levels in nodules compared to other cowpea tissues and the gene is active before nitrogen fixation begins. These results suggest that products of nitrogen fixation do not play a role in the initial induction of gene expression. VUpur5 was expressed in Escherichia coli and the recombinant protein used to raise antibodies. These antibodies recognize two forms of AIR synthetase which differ in molecular size. Both forms are present in mitochondria, although the larger protein is more abundant. Only the smaller protein was detected in plastids.
Reexamination of the intracellular localization of de novo purine synthesis in cowpea nodules
Publisher: Oxford University Press (OUP)
Date: 1997
DOI: 10.1104/PP.113.1.127
Abstract: Sucrose and Percoll density gradient centrifugation were used to separate organelles from the central zone tissue of cowpea (Vigna unguiculata L. Walp. cv Vita 3: Bradyrhizobium strain CB 756) nodules. Enzyme activity analysis has shown that both plastids and mitochondria have a full complement of enzymes for de novo purine synthesis. In vitro activities of in idual component enzymes (glycinamide ribonucleotide synthetase, EC 6.3.4.13 glycinamide ribonucleotide transformylase, EC 2.1.2.2 aminoimidazole ribonucleotide synthetase, EC 6.3.3.1 aminoimidazole carboxamide ribonucleotide transformylase, EC 6.3.2.6 and adenylosuccinate-AMP lyase, EC 4.3.2.2) as well as of the whole purine pathway (from ribose-5-phosphate to inosine monophosphate) were similar in the two organelles. No significant cytosolic or bacteroidal activity of any of the purine pathway enzymes was detected on assay. These findings are contrary to earlier studies (M.J. Boland, K.R. Schubert [1983] Arch Biochem Biophys 220: 179–187 B.J. Shelp C.A. Atkins, P.J. Storer, D.T. Canvin [1983] Arch Biochem Biophys 224: 429–441) that concluded that enhanced expression of purine synthesis in nodules of ureide-forming species is localized to plastids. Significantly increased recovery of activity of key pathway enzymes (particularly of labile aminoimidazole ribonucleotide synthetase) coupled with improved assay methods and the use of Percoll in addition to sucrose for gradient centrifugation have together contributed to much higher reaction rates and more definitive analyses of particulate fractions.
Proteomic analysis of lupin seed proteins to identify conglutin beta as an allergen, Lup an 1
Publisher: American Chemical Society (ACS)
Date: 12-07-2008
DOI: 10.1021/JF800840U
Abstract: Lupin products may be valuable as human foods because of their high protein content and potential anticholesterolemic properties. However, a small percentage of the population is allergic to lupin. In this study, we use in vitro IgE binding and mass spectrometry to identify conglutin beta, a major storage protein, as an allergen in seeds of Lupinus angustifolius and Lupinus albus. Purification of conglutin beta from L. angustifolius flour confirmed that serum IgE binds to this protein. Where IgE in sera recognized lupin proteins on Western blots, it recognized conglutin beta, suggesting this protein is a major allergen for lupin. The L. angustifolius conglutin beta allergen has been designated Lup an 1 by the International Union of Immunological Societies (IUIS) allergen nomenclature subcommittee.
Reflection across plant cell boundaries in confocal laser scanning microscopy
Publisher: Wiley
Date: 31-07-2008
DOI: 10.1111/J.1365-2818.2008.02068.X
Abstract: The fluorescence patterns of proteins tagged with the green fluorescent protein (GFP) and its derivatives are routinely used in conjunction with confocal laser scanning microscopy to identify their sub-cellular localization in plant cells. GFP-tagged proteins localized to plasmodesmata, the intercellular junctions of plants, are often identified by single or paired punctate labelling across the cell wall. The observation of paired puncta, or 'doublets', across cell boundaries in tissues that have been transformed through biolistic bombardment is unexpected if there is no intercellular movement of the GFP-tagged protein, since bombardment usually leads to the transformation of single, isolated cells. We expressed a putative plasmodesmal protein tagged with GFP by bombarding Allium porrum epidermal cells and assessed the nature of the doublets observed at the cell boundaries. Doublets were formed when fluorescent spots were abutting a cell boundary and were only observable at certain focal planes. Fluorescence emitted from the half of a doublet lying outside the transformed cells was polarized. Optical simulations performed using finite-difference time-domain computations showed a dramatic distortion of the confocal microscope's point spread function when imaging voxels close to the plant cell wall due to refractive index differences between the wall and the cytosol. Consequently, axially and radially out-of-focus light could be detected. A model of this phenomenon suggests how a doublet may form when imaging only a single real fluorescent body in the vicinity of a plant cell wall using confocal microscopy. We suggest, therefore, that the appearance of doublets across cell boundaries is insufficient evidence for plasmodesmal localization due to the effects of the cell wall on the reflection and scattering of light.
Macromolecules in phloem exudates-a review
Publisher: Springer Science and Business Media LLC
Date: 05-11-2011
DOI: 10.1007/S00709-010-0236-3
Abstract: Proteomic and transcriptomic analyses using the growing resources of genomic information have been applied to identification of macromolecules in exudates collected from phloem. Most of the analyses rely on collection of exudate following incisions made to the vasculature, but some limited data are available for exudates collected from excised aphid stylets. Species examined, to date, include a number of cereals (rice, barley, and wheat), a number of cucurbits, castor bean, members of the genus Lupinus, brassicas, and Arabidopsis. As many as 1,100 proteins, some hundreds of transcripts, and a growing number of small ribonucleic acids (RNAs), including micro-RNAs, have been identified across the species with a high degree of commonality. Questions relating to the nature and extent of contamination of sieve element contents with those of surrounding companion cells and nonvascular cells are addressed together with likely functions of identified macromolecules. The review considers likely translocation and systemic signaling functions among the macromolecular inventory of phloem exudates.
Arbuscular-Mycorrhizal Symbiosis in Medicago Regulated by the Transcription Factor MtbHLHm1;1 and the Ammonium Facilitator Protein MtAMF1;3
Publisher: MDPI AG
Date: 19-09-2023
Biochemical Changes in Two Barley Genotypes Inoculated With a Beneficial Fungus Trichoderma harzianum Rifai T-22 Grown in Saline Soil
Publisher: Frontiers Media SA
Date: 02-08-2022
Abstract: One of the most important environmental factors impacting crop plant productivity is soil salinity. Fungal endophytes have been characterised as biocontrol agents that help in plant productivity and induce resistance responses to several abiotic stresses, including salinity. In the salt-tolerant cereal crop barley ( Hordeum vulgare L.), there is limited information about the metabolites and lipids that change in response to inoculation with fungal endophytes in saline conditions. In this study, gas chromatography coupled to mass spectrometry (GC–MS) and LC–electrospray ionisation (ESI)–quadrupole–quadrupole time of flight (QqTOF)-MS were used to determine the metabolite and lipid changes in two fungal inoculated barley genotypes with differing tolerance levels to saline conditions. The more salt-tolerant cultivar was Vlamingh and less salt tolerant was Gairdner. Trichoderma harzianum strain T-22 was used to treat these plants grown in soil under control and saline (200 mM NaCl) conditions. For both genotypes, fungus-colonised plants exposed to NaCl had greater root and shoot biomass, and better chlorophyll content than non-colonised plants, with colonised-Vlamingh performing better than uninoculated control plants. The metabolome dataset using GC–MS consisted of a total of 93 metabolites of which 74 were identified in roots of both barley genotypes as organic acids, sugars, sugar acids, sugar alcohols, amino acids, amines, and a small number of fatty acids. LC-QqTOF-MS analysis resulted in the detection of 186 lipid molecular species, classified into three major lipid classes—glycerophospholipids, glycerolipids, and sphingolipids, from roots of both genotypes. In Cultivar Vlamingh both metabolites and lipids increased with fungus and salt treatment while in Gairdner they decreased. The results from this study suggest that the metabolic pathways by which the fungus imparts salt tolerance is different for the different genotypes.
Detection of brassinosteroids in pollen of Lolium perenne L. by immunocytochemistry
Publisher: Springer Science and Business Media LLC
Date: 1993
DOI: 10.1007/BF00201349
Spatio-Temporal Metabolite and Elemental Profiling of Salt Stressed Barley Seeds During Initial Stages of Germination by MALDI-MSI and µ-XRF Spectrometry
Publisher: Frontiers Media SA
Date: 25-09-2019
Isolation of cDNA-encoding a newly identified major allergenic protein of rye-grass pollen - intracellular targeting to the amyloplast
Publisher: Proceedings of the National Academy of Sciences
Date: 15-02-1991
Abstract: We have identified a major allergenic protein from rye-grass pollen, tentatively designated Lol pIb of 31kDa and with pI 9.0. A cDNA clone encoding Lol pIb has been isolated, sequenced, and characterized. Lol pIb is located mainly in the starch granules. This is a distinct allergen from Lol pI, which is located in the cytosol. Lol pIb is synthesized in pollen as a pre-allergen with a transit peptide targeting the allergen to amyloplasts. Epitope mapping of the fusion protein localized the IgE binding determinant in the C-terminal domain.
Development of molecular markers using MFLP linked to a gene conferring resistance to Diaporthe toxica in narrow-leafed lupin ( Lupinus angustifolius L.)
Publisher: Springer Science and Business Media LLC
Date: 08-2002
DOI: 10.1007/S00122-002-0925-1
Abstract: Phomopsis stem blight (PSB) caused by Diaporthe toxica is a major disease in narrow-leafed lupin ( Lupinus angustifolius L.). The F(2) progeny and the parental plants from a cross between a breeding line 75A:258 (containing a single dominant resistance gene Phr1 against the disease) and a commercial cultivar Unicrop (susceptible to the disease) were used for development of molecular markers linked to the disease resistance gene. Two pairs of co-dominant DNA polymorphisms were detected using the microsatellite-anchored fragment length polymorphism (MFLP) technique. Both pairs of polymorphisms were isolated from the MFLP gels, re- lified by PCR, sequenced, and converted into co-dominant, sequence-specific and PCR-based markers. Linkage analysis by MAPMAKER suggested that one marker (Ph258M2) was 5.7 centiMorgans (cM) from Phr1, and the other marker (Ph258M1) was 2.1 cM from Ph258M2 but further away from Phr1. These markers are suitable for marker-assisted selection (MAS) in lupin breeding.
Immunological relationships among group I and group V allergens from grass pollen
Publisher: Elsevier BV
Date: 04-1994
DOI: 10.1016/0161-5890(94)90068-X
Abstract: Specific IgE antibodies have been affinity-purified from recombinant grass pollen allergens, and used to identify isoforms of the two major allergens of rye-grass pollen, Lol p I and Lol p V and cross-reactive allergens in other grasses. Lol p I-specific IgE (affinity-purified from the recombinant protein expressed by clone 13R which encodes amino acids 96-240 of Lol p I) identified four isoforms of the allergen. The same probe recognized cross-reactive epitopes in pollen proteins from 14 out of 16 grasses. The allergens identified by Lol p V-specific IgE (affinity-purified from the recombinant protein expressed by clones 12R or 19R which encode the full Lol p V protein) varied more in their physicochemical characteristics than the Group I isoforms. At least eight isoforms of Lol p V were identified by the Lol p V-specific IgE. The same probe recognized cross-reactive epitopes in pollen protein from 13 out of 16 grasses. Group I proteins were identified in grasses from two sub-families of the Poaceae, while the Group V allergens were only identified in pollen of grasses from one sub-family, the Pooideae.
DNA fingerprinting based on microsatellite-anchored fragment length polymorphisms, and isolation of sequence-specific PCR markers in lupin (lupinus angustifolius L.)
Publisher: Springer Science and Business Media LLC
Date: 2001
Translocation in legumes: Assimilates, nutrients, and signaling molecules
Publisher: Oxford University Press (OUP)
Date: 06-2007
Dynamic changes in the mitochondrial electron transport chain underpinning cold acclimation of leaf respiration
Publisher: Wiley
Date: 09-07-2008
DOI: 10.1111/J.1365-3040.2008.01830.X
Abstract: We examined the effect of short- and long-term changes in temperature on gene expression, protein abundance, and the activity of the alternative oxidase and cytochrome oxidase pathways (AOP and COP, respectively) in Arabidopsis thaliana. The AOP was more sensitive to short-term changes in temperature than the COP, with partitioning to the AOP decreasing significantly below a threshold temperature of 20 degrees C. AOP activity was increased in leaves, which had been shifted to the cold for several days, but this response was transient, with AOP activity subsiding (and COP activity increasing) following the development of leaves in the cold. The transient increase in AOP activity in 10-d cold-shifted leaves was not associated with an increase in alternative oxidase (AOX) protein or AOX1a transcript abundance. By contrast, the amount of uncoupling protein was significantly increased in cold-developed leaves. In conjunction with this, transcript levels of the uncoupling protein-encoding gene UCP1 and the external NAD(P)H dehydrogenase-encoding gene NDB2 exhibited sustained increases following growth in the cold. The data suggest a role for each of these alternative non-phosphorylating bypasses of mitochondrial electron transport at different points in time following exposure to cold, with increased AOP activity being important only in the early stages of cold treatment.
Identification and characterisation of microRNAs and their target genes in phosphate-starved Nicotiana benthamiana by small RNA deep sequencing and 5'RACE analysis.
Publisher: Springer Science and Business Media LLC
Date: 12-2018
Cellular localization of water soluble, allergenic proteins in rye-grass (Lolium perenne) pollen using monoclonal and specific IgE antibodies with immunogold probes
Publisher: Springer Science and Business Media LLC
Date: 05-1990
DOI: 10.1007/BF01387183
Abstract: 1. Complete lipid patterns of specific precipitates from horse and rabbit Type I antipneumococcus sera, as well as of the sera themselves, have been determined by gasometric micro methods. 2. The lipid patterns of horse and rabbit antisera are very similar, and as regards the phosphatide fractions are relatively identical. 3. The lipid patterns of specific precipitates from horse and rabbit antisera show one outstanding qualitative difference. The specific precipitate from horse antiserum contains an amino phosphatide, which is probably cephalin, while that from rabbit antiserum contains a non-amino phosphatide, which is thought to be lecithin.
Inorganic Nitrogen Uptake and Transport in Beneficial Plant Root-Microbe Interactions
Publisher: Informa UK Limited
Date: 24-10-2014
Characterisation of Arabidopsis calnexin 1 and calnexin 2 in the endoplasmic reticulum and at plasmodesmata
Publisher: Springer Science and Business Media LLC
Date: 17-12-2017
DOI: 10.1007/S00709-015-0921-3
Abstract: Calnexin (CNX) is a highly conserved endoplasmic reticulum (ER) chaperone protein. Both calnexin and the homologous ER-lumenal protein, calreticulin, bind calcium ions and participate in protein folding. There are two calnexins in Arabidopsis thaliana, CNX1 and CNX2. GUS expression demonstrated that these are expressed in most Arabidopsis tissues throughout development. Calnexin transfer DNA (T-DNA) mutant lines exhibited increased transcript abundances of a number of other ER chaperones, including calreticulins, suggesting a degree of redundancy. CNX1 and CNX2 localised to the ER membrane including that within plasmodesmata, the intercellular channels connecting plant cells. This is comparable with the previous localisations of calreticulin in the ER lumen and at plasmodesmata. However, from green fluorescent protein (GFP) diffusion studies in single and double T-DNA insertion mutant lines, as well as overexpression lines, we found no evidence that CNX1 or CNX2 play a role in intercellular transport through plasmodesmata. In addition, calnexin T-DNA mutant lines showed no change in transcript abundance of a number of plasmodesmata-related proteins. CNX1 and CNX2 do not appear to have a specific localisation or function at plasmodesmata-rather the association of calnexin with the ER is simply maintained as the ER passes through plasmodesmata.
GmVTL1a is an iron transporter on the symbiosome membrane of soybean with an important role in nitrogen fixation
Publisher: Wiley
Date: 12-07-2020
DOI: 10.1111/NPH.16734
Abstract: Legumes establish symbiotic relationships with soil bacteria (rhizobia), housed in nodules on roots. The plant supplies carbon substrates and other nutrients to the bacteria in exchange for fixed nitrogen. The exchange occurs across a plant‐derived symbiosome membrane (SM), which encloses rhizobia to form a symbiosome. Iron supplied by the plant is crucial for rhizobial enzyme nitrogenase that catalyses nitrogen fixation, but the SM iron transporter has not been identified. We use yeast complementation, real‐time PCR and proteomics to study putative soybean ( Glycine max ) iron transporters GmVTL1a and GmVTL1b and have characterized the role of GmVTL1a using complementation in plant mutants, hairy root transformation and microscopy. GmVTL1a and GmVTL1b are members of the vacuolar iron transporter family and homologous to Lotus japonicus SEN1 (LjSEN1), which is essential for nitrogen fixation. GmVTL1a expression is enhanced in nodule infected cells and both proteins are localized to the SM. GmVTL1a transports iron in yeast and restores nitrogen fixation when expressed in the Ljsen1 mutant. Three GmVTL1a amino acid substitutions that block nitrogen fixation in Ljsen1 plants reduce iron transport in yeast. We conclude GmVTL1a is responsible for transport of iron across the SM to bacteroids and plays a crucial role in the nitrogen‐fixing symbiosis.
Spectral properties of bacteriophytochrome AM1_5894 in the chlorophyll dcontaining cyanobacterium Acaryochloris marina.
Publisher: Springer Science and Business Media LLC
Date: 10-06-2016
DOI: 10.1038/SREP27547
Abstract: Acaryochloris marina , a unicellular oxygenic photosynthetic cyanobacterium, has uniquely adapted to far-red light-enriched environments using red-shifted chlorophyll d . To understand red-light use in Acaryochloris , the genome of this cyanobacterium was searched for red/far-red light photoreceptors from the phytochrome family, resulting in identification of a putative bacteriophytochrome AM1_5894 . AM1_5894 contains three standard domains of photosensory components as well as a putative C-terminal signal transduction component consisting of a histidine kinase and receiver domain. The photosensory domains of AM1_5894 autocatalytically assemble with biliverdin in a covalent fashion. This assembled AM1_5894 shows the typical photoreversible conversion of bacterial phytochromes with a ground-state red-light absorbing (Pr) form with λ BV max [Pr] 705 nm, and a red-light inducible far-red light absorbing (Pfr) form with λ BV max [Pfr] 758 nm. Surprisingly, AM1_5894 also autocatalytically assembles with phycocyanobilin, involving photoreversible conversion of λ PCB max [Pr] 682 nm and λ PCB max [Pfr] 734 nm, respectively. Our results suggest phycocyanobilin is also covalently bound to AM1_5894, while mutation of a cysteine residue (Cys11Ser) abolishes this covalent binding. The physiological function of AM1_5894 in cyanobacteria containing red-shifted chlorophylls is discussed.
Cloning and expression in yeast Pichia pastoris of a biologically active form of Cyn d 1, the major allergen of Bermuda grass pollen
Publisher: Elsevier BV
Date: 08-1996
DOI: 10.1016/S0091-6749(96)70158-6
Abstract: Pollen of grasses, such as Bermuda grass (Cynodon dactylon), represent a major cause of type I allergy. In this report we attempted to clone and express a biologically active form of recombinant Cyn d 1, the major allergen of Bermuda grass pollen, in the yeast Pichia pastoris. Clones encoding Cyn d 1 were isolated by screening a Bermuda grass pollen complementary DNA library with specific monoclonal antibodies and by polymerase chain reaction lification. Recombinant Cyn d 1 was expressed in Escherichia coli and yeast. The expressed proteins were analyzed by Western blotting to assess binding to Cyn d 1-specific monoclonal antibodies and IgE from sera of patients allergic to Bermuda grass pollen. Two isoforms of Cyn d 1 were cloned. Recombinant Cyn d 1 expressed in bacteria bound two monoclonal antibodies raised against Cyn d 1 but was not recognized by IgE from sera of patients allergic to Bermuda grass pollen. Cyn d 1 expressed in yeast bound both the monoclonal antibodies and human IgE. An IgE-reactive Cyn d 1 was expressed in yeast but not in bacteria, suggesting that posttranslational modifications (e.g., glycosylation), which occur in eukaryotic cells such as yeast, are necessary for the production of a biologically active allergen.
Macromolecular composition of phloem exudate from white lupin (Lupinus albus L.)
Publisher: Springer Science and Business Media LLC
Date: 22-02-2011
Abstract: Members of the legume genus Lupinus exude phloem 'spontaneously' from incisions made to the vasculature. This feature was exploited to document macromolecules present in exudate of white lupin ( Lupinus albus [L.] cv Kiev mutant), in particular to identify proteins and RNA molecules, including microRNA (miRNA). Proteomic analysis tentatively identified 86 proteins from 130 spots collected from 2D gels analysed by partial amino acid sequence determination using MS/MS. Analysis of a cDNA library constructed from exudate identified 609 unique transcripts. Both proteins and transcripts were classified into functional groups. The largest group of proteins comprised those involved in metabolism (24%), followed by protein modification/turnover (9%), redox regulation (8%), cell structural components (6%), stress and defence response (6%) with fewer in other groups. More prominent proteins were cyclophilin, ubiquitin, a glycine-rich RNA-binding protein, a group of proteins that comprise a glutathione/ascorbate-based mechanism to scavenge oxygen radicals, enzymes of glycolysis and other metabolism including methionine and ethylene synthesis. Potential signalling macromolecules such as transcripts encoding proteins mediating calcium level and the Flowering locus T (FT) protein were also identified. From around 330 small RNA clones (18-25 nt) 12 were identified as probable miRNAs by homology with those from other species. miRNA composition of exudate varied with site of collection (e.g. upward versus downward translocation streams) and nutrition (e.g. phosphorus level). This is the first inventory of macromolecule composition of phloem exudate from a species in the Fabaceae, providing a basis to identify systemic signalling macromolecules with potential roles in regulating development, growth and stress response of legumes.
Peanut protein extraction conditions strongly influence yield of allergens Ara h 1 and 2 and sensitivity of immunoassays
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.FOODCHEM.2016.10.063
Abstract: The clinical importance of peanut (Arachis hypogaea) allergies demands standardized allergen extraction protocols. We determined the effectiveness of common extraction conditions (20 buffers, defatting reagents, extraction time/temperatures, processing, extraction repeats) on crude protein and Ara h 1 and 2 yields. Despite similar 1D-gel profiles, defatting with n-hexane resulted in significantly higher yields of crude protein, Ara h 1, and Ara h 2 than with diethyl ether. The yields were affected by the composition and pH of the extraction buffers and other conditions, but crude protein yield did not always correlate with Ara h 1 and 2 yields. Denaturants, reducing agents, acidic buffers, and thermal processing of peanuts perturbed allergen quantification in ELISAs, probably via exposure of additional epitopes. Allergen detection in 2D-Western blots with PBS resulted in greater sensitivity than with TBS or Tris. We recommend that allergen extraction conditions be selected based on the research question being investigated.
Soybean Yellow Stripe-like7 is a symbiosome membrane peptide transporter essential for nitrogen fixation
Publisher: Cold Spring Harbor Laboratory
Date: 29-03-2020
DOI: 10.1101/2020.03.27.011973
Abstract: Legumes form a symbiosis with rhizobia that convert atmospheric nitrogen (N 2 ) to ammonia which they provide to the plant in return for a carbon and nutrient supply. Nodules, developed as part of the symbiosis, harbor rhizobia which are enclosed in the plant-derived symbiosome membrane (SM), to form a symbiosome. In the mature nodule all exchanges between the symbionts occur across the SM. Here we characterize GmYSL7, a member of Yellow stripe-like family which is localized to the SM in soybean nodules. It is expressed specifically in nodule infected cells with expression peaking soon after nitrogenase becomes active. Although most members of the family transport metal complexed with phytosiderophores, GmYSL7 does not. It transports oligopeptides of between four and 12 amino acids. Silencing of GmYSL7 reduces nitrogenase activity and blocks development when symbiosomes contain a single bacteroid. RNAseq of nodules in which GmYSL7 is silenced suggests that the plant initiates a defense response against the rhizobia. There is some evidence that metal transport in the nodules is dysregulated, with upregulation of genes encoding ferritin and vacuolar iron transporter family and downregulation of a gene encoding nicotianamine synthase. However, it is not clear whether the changes are a result of the reduction of nitrogen fixation and the requirement to store excess iron or an indication of a role of GmYSL7 in regulation of metal transport in the nodules. Further work to identify the physiological substrate for GmYSL7 will allow clarification of this role. GmYSL7 is a symbiosome membrane peptide transporter that is essential for symbiotic nitrogen fixation that when silenced blocks symbiosome development.
Identification of a Ca<sup>2+</sup> Binding Protein as a New Bermuda Grass Pollen Allergen Cyn d 7: IgE Cross-Reactivity with Oilseed Rape Pollen Allergen Bra r 1
Publisher: S. Karger AG
Date: 1997
DOI: 10.1159/000237678
Abstract: cDNA clones encoding two isoforms of an allergen from pollen of Bermuda grass (Cynodon dactylon) have been isolated using IgE from allergic patients. Homologous transcripts are present in pollen of 15 other grasses tested. This allergen, tentatively designated as Cyn d 7, contains two calcium binding domains and shows significant sequence similarity with other Ca2+ binding pollen allergens, namely Bet v 4 from birch and Bra r 1 from oilseed rape. Approximately 10% of allergic sera tested showed IgE reactivity to this allergen. IgE cross-reactivity was observed between this allergen and Bra r 1 of oilseed rape. IgE reactivity of this allergen requires protein-bound Ca2+. Using IgE affinity-purified from the recombinant allergen to probe Western blots of pollen extracts Cyn d 7 has been identified as a 12 kDA protein.
Isolation and Characterization of Group-I Isoallergens from Bermuda Grass Pollen
Publisher: S. Karger AG
Date: 1994
DOI: 10.1159/000236709
Abstract: Two isoallergens of Cyn d I were isolated using preparative isoelectric focussing, and were designated Cyn d Ia and b. These isoallergens differ in their pI, molecular weight (Cyn d Ia, 32 kD and Cyn d Ib, 31 kD) and their NH2-terminal sequence. Four monoclonal antibodies (Mabs) were produced using Cyn d Ia as antigen. These Mabs recognized both Cyn d Ia and b. One of the Mabs recognized four different pI forms of Cyn d I on 2D gels. The Mabs also recognized cross-reactive epitopes on proteins from eight other grasses including rye grass, timothy grass, Kentucky bluegrass and Johnson grass.
Transport processes of the legume symbiosome membrane
Publisher: Frontiers Media SA
Date: 15-12-2014
Alleviation of salinity stress in plants by endophytic plant-fungal symbiosis: Current knowledge, perspectives and future directions
Publisher: Springer Science and Business Media LLC
Date: 09-07-2020
DOI: 10.1007/S11104-020-04618-W
Abstract: Salinization of soil with sodium chloride ions inhibits plant functions, causing reduction of yield of crops. Salt tolerant microorganisms have been studied to enhance crop growth under salinity. This review describes the performance of endophytic fungi applied to crops as a supplement to plant genetics or soil management to alleviate salt stress in crops. This is achieved via inducing systemic resistance, increasing the levels of beneficial metabolites, activating antioxidant systems to scavenge ROS, and modulating plant growth phytohormones. Colonization by endophytic fungi improves nutrient uptake and maintains ionic homeostasis by modulating ion accumulation, thereby restricting the transport of Na + to leaves and ensuring a low cytosolic Na + :K + ratio in plants. Participating endophytic fungi enhance transcripts of genes encoding the high Affinity Potassium Transporter 1 (HKT1) and the inward-rectifying K + channels KAT1 and KAT2, which play key roles in regulating Na + and K + homeostasis. Endophytic-induced interplay of strigolactones play regulatory roles in salt tolerance by interacting with phytohormones. Future research requires further attention on the biochemical, molecular and genetic mechanisms crucial for salt stress resistance requires further attention for future research. Furthermore, to design strategies for sustained plant health with endophytic fungi, a new wave of exploration of plant-endophyte responses to combinations of stresses is mandatory.
Alterations in the Mitochondrial Alternative NAD(P)H Dehydrogenase NDB4 Lead to Changes in Mitochondrial Electron Transport Chain Composition, Plant Growth and Response to Oxidative Stress
Publisher: Oxford University Press (OUP)
Date: 09-06-2011
DOI: 10.1093/PCP/PCR073
Abstract: The branched respiratory electron transport chain of plants contains a non-phosphorylating alternative pathway consisting of type II NAD(P)H dehydrogenases on both sides of the inner membrane linked through the ubiquinone pool to an alternative oxidase (AOX). T-DNA and RNA interference (RNAi) were used to reduce gene expression to characterize the external NAD(P)H dehydrogenase NDB4 in Arabidopsis. The ndb4 lines showed different levels of suppression of NDB4 protein, leading to increases in NBD2 and AOX1a mRNA and protein levels in all lines. These changes were associated with lower reactive oxygen species formation and an altered phenotype, including changes in growth rate, root : shoot ratios and leaf area. The general growth pattern for the ndb4 mutants was decreased leaf area early in development (6-15 d) followed by a prompt subsequent increase in leaf area that exceeded the leaf area of the wild type by maturity (the 10-12 rosette stage). This pattern was most evident for the RNAi lines that had increased mitochondrial electron transport capacity. The RNAi lines also exhibited better tolerance to salinity stress, with better growth rates and lower shoot Na⁺ content compared with controls when grown under saline conditions. We hypothesize that these differences reflect the enhanced expression of NDB2 and AOX in the ndb4 mutant plants.
Malate Transport and Metabolism in Nitrogen-Fixing Legume Nodules
Publisher: MDPI AG
Date: 15-11-2021
DOI: 10.3390/MOLECULES26226876
Abstract: Legumes form a symbiosis with rhizobia, a soil bacterium that allows them to access atmospheric nitrogen and deliver it to the plant for growth. Biological nitrogen fixation occurs in specialized organs, termed nodules, that develop on the legume root system and house nitrogen-fixing rhizobial bacteroids in organelle-like structures termed symbiosomes. The process is highly energetic and there is a large demand for carbon by the bacteroids. This carbon is supplied to the nodule as sucrose, which is broken down in nodule cells to organic acids, principally malate, that can then be assimilated by bacteroids. Sucrose may move through apoplastic and/or symplastic routes to the uninfected cells of the nodule or be directly metabolised at the site of import within the vascular parenchyma cells. Malate must be transported to the infected cells and then across the symbiosome membrane, where it is taken up by bacteroids through a well-characterized dct system. The dicarboxylate transporters on the infected cell and symbiosome membranes have been functionally characterized but remain unidentified. Proteomic and transcriptomic studies have revealed numerous candidates, but more work is required to characterize their function and localise the proteins in planta. GABA, which is present at high concentrations in nodules, may play a regulatory role, but this remains to be explored.
Alternative splicing of the Vupur3 transcript in cowpea produces multiple mRNA species with a single protein product that is present in both plastids and mitochondria
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/FP05044
Abstract: A heterogeneous population of cDNAs (designated Vupur3) encoding phosphoribosylglycinamide formyltransferase (GART EC 2.1.2.2) was isolated from a cowpea (Vigna unguiculata L. Walp.) nodule library. Three classes of cDNA with the same ORF, but differing in their 3′-UTRs, were identified. Southern analysis and sequencing of genomic DNA confirmed that these differences result from alternative splicing of the primary transcript of a single Vupur3 gene. Alternative splicing does not appear to play a role in the production of soybean (Glycine max Merrill.) pur3 transcripts. The presence of the protein product of the Vupur3 gene, GART, in plastids and mitochondria was confirmed by immunoblotting with antibodies raised against the recombinant protein. The antibodies recognised two proteins with apparent molecular masses of 27 and 27.5 kDa in both mitochondria and plastids. All Vupur3 transcripts have two in-frame start codons that are active in wheatgerm in vitro transcription / translation experiments suggesting a mechanism by which the gene product could be targeted to two organelles. Like other genes encoding enzymes for purine synthesis, Vupur3 is expressed in nodules before nitrogen fixation begins but in contrast to these genes its expression does not increase markedly after nitrogen fixation begins.
Editorial: Legumes for Global Food Security
Publisher: Frontiers Media SA
Date: 07-07-2020
Differential expression of a novel gene during seed triacylglycerol accumulation in lupin species (Lupinus angustifolius L. and L. mutabilis L.)
Publisher: Springer Science and Business Media LLC
Date: 11-2002
DOI: 10.1007/S10142-002-0079-X
Abstract: Seed triacylglycerols (TAGs) are stored as energy reserves and extracted for various end-product uses. In lupins, seed oil content varies from 16% in Lupinus mutabilisto 8% in L. angustifolius. We have shown that TAGs rapidly accumulate during mid-stages of seed development in L. mutabilis compared to the lower seed oil species, L. angustifolius. In this study, we have targeted the key enzymes of the lipid biosynthetic pathway, acetyl-CoA carboxylase (ACCase) and diacylglycerol acyltransferase (DAGAT), to determine factors regulating TAG accumulation between two lupin species. A twofold increase in ACCase activity was observed in L. mutabilis relative to L. angustifolius and correlated with rapid TAG accumulation. No difference in DAGAT activity was detected. We have identified, cloned and partially characterised a novel gene differentially expressed during TAG accumulation between L. angustifolius and L. mutabilis. The gene has some identity to the glucose dehydrogenase family previously described in barley and bacteria and the significance of its expression levels during seed development in relation to TAG accumulation is discussed. DNA sequence analysis of the promoter in both L. angustifolius and L. mutabilis identified putative matrix attachment regions and recognition sequences for transcription binding sites similar to those found in the Adh1 gene from Arabidopsis. The identical promoter regions between species indicate that differential gene expression is controlled by alternative transcription factors, accessibility to binding sites or a combination of both.
Using genome-enabled technologies to address allergens in seeds of crop plants: Legumes as a case study
Publisher: Springer Netherlands
Date: 2012
Effect of short-term N-2 deficiency on expression of the ureide pathway in cowpea root nodules
Publisher: Oxford University Press (OUP)
Date: 07-2002
DOI: 10.1104/PP.010714
Abstract: Root systems of 28-d-old cowpea (Vigna unguiculata L. Walp cv Vita 3: Bradyrhizobiumsp. strain CB756) plants bearing nitrogen-fixing nodules in sand culture were exposed to an atmosphere of Ar:O2 (80:20, v/v) for 48 h and then returned to air. Root systems of control plants were maintained in air throughout. Nodules were harvested at the same times in control and Ar:O2-treated root systems. Activities of two enzymes of de novo purine synthesis, glycinamide ribonucleotide transformylase (GART EC 2.1.2.2), aminoimidazole ribonucleotide synthetase (AIRS EC 6.3.3.1), uricase (EC 1.7.3.3), and phosphoenolpyruvate carboxylase (PEPC EC 4.1.1.31) were measured together with the protein level of each using immune-specific polyclonal antibodies. AIRS activity and protein both declined to very low levels within 6 h in Ar:O2 together with a decline in transcript level of pur5, the encoding gene. GART activity, protein, and transcript (pur3) levels were relatively stable. Uricase activity declined in Ar:O2 as rapidly as AIRS activity but the protein was stable. PEPC activity showed evidence of increased sensitivity to inhibition by malate but the protein level was stable. The data indicate that the flux of fixed N from bacteroids (N2-fixing nodule bacteria) is in some way associated with transcriptional control over pur5and possibly also catabolism of AIRS protein. In contrast, there is limited posttranslational control over GART and PEPC and close posttranslational control over uricase activity. The significance of these different levels of regulation is discussed in relation to the overall control of enhanced expression of plant enzymes in the cowpea symbiosis.
Purine biosynthesis. Big in cell division, even bigger in nitrogen assimilation
Publisher: Oxford University Press (OUP)
Date: 03-2002
DOI: 10.1104/PP.010912
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The University Of Western Australia Faculty Of Science
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