ORCID Profile
0000-0002-7618-3814
Current Organisations
CSIRO A&F
,
Australian National University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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.
Microbial Ecology | Ecosystem Function | Microbiology | Plant Physiology | Terrestrial Ecology | Plant Biology | Plant Improvement (Selection, Breeding And Genetic Engineering) | Condensed Matter Physics not elsewhere classified
Renewable Energy not elsewhere classified | Primary products from plants | Expanding Knowledge in the Environmental Sciences | Expanding Knowledge in the Biological Sciences | Biological sciences | Integrated (ecosystem) assessment and management |
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: Wiley
Date: 08-1998
Publisher: Wiley
Date: 05-05-2022
DOI: 10.1111/PCE.14337
Abstract: Canola varieties exhibit variation in drought avoidance and drought escape traits, reflecting adaptation to water‐deficit environments. Our understanding of underlying genes and their interaction across environments in improving crop productivity is limited. A doubled haploid population was analysed to identify quantitative trait loci (QTL) associated with water‐use efficiency (WUE) related traits. High WUE in the vegetative phase was associated with low seed yield. Based on the resequenced parental genome data, we developed sequence‐capture‐based markers and validated their linkage with carbon isotope discrimination (Δ 13 C) in an F 2 population. RNA sequencing was performed to determine the expression of candidate genes underlying Δ 13 C QTL. QTL contributing to main and QTL × environment interaction effects for Δ 13 C and yield were identified. One multiple‐trait QTL for Δ 13 C, days to flower, plant height, and seed yield was identified on chromosome A09. Interestingly, this QTL region overlapped with a homoeologous exchange (HE) event, suggesting its association with the multiple traits. Transcriptome analysis revealed 121 significantly differentially expressed genes underlying Δ 13 C QTL on A09 and C09, including in HE regions. Sorting out the negative relationship between vegetative WUE and seed yield is a priority. Genetic and genomic resources and knowledge so developed could improve canola WUE and yield.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Wiley
Date: 05-2006
DOI: 10.1111/J.1462-2920.2005.00973.X
Abstract: Native bacteria, Pseudomonas and filamentous bacteria were quantified and localized on wheat roots grown in the field using fluorescence in situ hybridization (FISH). Seminal roots were s led through the season from unploughed soil in a conservation farming system. Such soils are spatially heterogeneous, and many roots grow slowly through hard soil with cracks and pores containing dead roots remnant from previous crops. Root and rhizosphere morphology, and contact with soil particles were preserved, and autofluorescence was avoided by observing sections in the far-red with Cy5 and Cy5.5 fluorochromes. Spatial analyses showed that bacteria were embedded in a stable matrix (biofilm) within 11 microm of the root surface (range 2-30 microm) and were clustered on 40% of roots. Half the clusters co-located with axial grooves between epidermal cells, soil particles, cap cells or root hairs the other half were not associated with visible features. Across all wheat roots, although variable, bacteria averaged 15.4 x 10(5) cells per mm(3) rhizosphere, and of these, Pseudomonas and filaments comprised 10% and 4%, respectively, with minor effects of s le time, and no effect of plant age. Root caps were most heavily colonized by bacteria along roots, and elongation zones least heavily colonized. Pseudomonas varied little with root development and were 17% of bacteria on the elongation zone. Filamentous bacteria were not found on the elongation zone. The most significant factor to rhizosphere populations along a wheat root, however, was contact with dead root remnants, where Pseudomonas were reduced but filaments increased to 57% of bacteria (P < 0.001). This corresponded with analyses of root remnants showing they were heavily colonized by bacteria, with 48% filaments (P < 0.001) and 1.4%Pseudomonas (P = 0.014). Efforts to manage rhizosphere bacteria for sustainable agricultural systems should continue to focus on root cap and mucilage chemistry, and remnant roots as sources of beneficial bacteria.
Publisher: Springer Science and Business Media LLC
Date: 2008
Publisher: Oxford University Press (OUP)
Date: 02-03-2012
Abstract: Mixed-linkage glucan (MLG) is a cell wall polysaccharide containing a backbone of unbranched (1,3)- and (1,4)-linked β-glucosyl residues. Based on its occurrence in plants and chemical characteristics, MLG has primarily been associated with the regulation of cell wall expansion due to its high and transient accumulation in young, expanding tissues. The Cellulose synthase-like F (CslF) subfamily of glycosyltransferases has previously been implicated in mediating the biosynthesis of this polymer. We confirmed that the rice (Oryza sativa) CslF6 gene mediates the biosynthesis of MLG by overexpressing it in Nicotiana benthamiana. Rice cslf6 knockout mutants show a slight decrease in height and stem diameter but otherwise grew normally during vegetative development. However, cslf6 mutants display a drastic decrease in MLG content (97% reduction in coleoptiles and virtually undetectable in other tissues). Immunodetection with an anti-MLG monoclonal antibody revealed that the coleoptiles and leaves retain trace amounts of MLG only in specific cell types such as sclerenchyma fibers. These results correlate with the absence of endogenous MLG synthase activity in mutant seedlings and 4-week-old sheaths. Mutant cell walls are weaker in mature stems but not seedlings, and more brittle in both stems and seedlings, compared to wild type. Mutants also display lesion mimic phenotypes in leaves, which correlates with enhanced defense-related gene expression and enhanced disease resistance. Taken together, our results underline a weaker role of MLG in cell expansion than previously thought, and highlight a structural role for MLG in nonexpanding, mature stem tissues in rice.
Publisher: Frontiers Media SA
Date: 08-01-2019
Publisher: Scientific Scholar
Date: 13-04-2021
Publisher: Proceedings of the National Academy of Sciences
Date: 23-11-2022
Abstract: Semidwarfing genes have greatly increased wheat yields globally, yet the widely used gibberellin (GA)-insensitive genes Rht-B1b and Rht-D1b have disadvantages for seedling emergence. Use of the GA-sensitive semidwarfing gene Rht13 avoids this pleiotropic effect. Here, we show that Rht13 encodes a nucleotide-binding site/leucine-rich repeat ( NB-LRR ) gene. A point mutation in the semidwarf Rht-B13b allele autoactivates the NB-LRR gene and causes a height reduction comparable with Rht-B1b and Rht-D1b in erse genetic backgrounds. The autoactive Rht-B13b allele leads to transcriptional up-regulation of pathogenesis-related genes including class III peroxidases associated with cell wall remodeling. Rht13 represents a new class of reduced height ( Rht ) gene, unlike other Rht genes, which encode components of the GA signaling or metabolic pathways. This discovery opens avenues to use autoactive NB-LRR genes as semidwarfing genes in a range of crop species, and to apply Rht13 in wheat breeding programs using a perfect genetic marker.
Publisher: Wiley
Date: 21-06-2022
DOI: 10.1111/PCE.14375
Abstract: Inter‐tissue communication is instrumental to coordinating the whole‐body level behaviour for complex multicellular organisms. However, little is known about the regulation of inter‐tissue information exchange. Here we carried out genetic screens for root‐to‐shoot mobile silencing in Arabidopsis plants with a compromised small RNA‐mediated gene silencing movement rate and identified radical‐induced cell death 1 (RCD1) as a critical regulator of root–shoot communication. RCD1 belongs to a family of poly (ADP‐ribose) polymerase proteins, which are highly conserved across land plants. We found that RCD1 coordinates symplastic and apoplastic movement by modulating the sterol level of lipid rafts. The higher superoxide production in rcd1 ‐knockout plants resulted in lower plasmodesmata (PD) frequency and altered PD structure in the symplasm of the hypocotyl cortex. Furthermore, the mutants showed increased lateral area of tracheary pits, which reduced axial movement. Our study highlights a novel mechanism through which root‐to‐shoot long‐distance signalling can be modulated both symplastically and apoplastically.
Publisher: Oxford University Press (OUP)
Date: 10-08-2010
Abstract: The microRNA159 (miR159) family represses the conserved GAMYB-like genes that encode R2R3 MYB domain transcription factors that have been implicated in gibberellin (GA) signaling in anthers and germinating seeds. In Arabidopsis (Arabidopsis thaliana), the two major miR159 family members, miR159a and miR159b, are functionally specific for two GAMYB-like genes, MYB33 and MYB65. These transcription factors have been shown to be involved in anther development, but there are differing reports about their role in the promotion of flowering and little is known about their function in seed germination. To understand the function of this pathway, we identified the genes and processes controlled by these GAMYB-like genes. First, we demonstrate that miR159 completely represses MYB33 and MYB65 in vegetative tissues. We show that GA does not release this repression and that these transcription factors are not required for flowering or growth. By contrast, in the absence of miR159, the deregulation of MYB33 and MYB65 in vegetative tissues up-regulates genes that are highly expressed in the aleurone and GA induced during seed germination. Confirming that these genes are GAMYB-like regulated, their expression was reduced in myb33.myb65.myb101 seeds. Aleurone vacuolation, a GA-mediated programmed cell death process required for germination, was impaired in these seeds. Finally, the deregulation of MYB33 and MYB65 in vegetative tissues inhibits growth by reducing cell proliferation. Therefore, we conclude that miR159 acts as a molecular switch, only permitting the expression of GAMYB-like genes in anthers and seeds. In seeds, these transcription factors participate in GA-induced pathways required for aleurone development and death.
Publisher: Wiley
Date: 11-07-2016
DOI: 10.1111/PBI.12590
Publisher: Springer Science and Business Media LLC
Date: 27-11-2011
Publisher: Springer Science and Business Media LLC
Date: 11-11-2022
DOI: 10.1186/S13007-022-00953-4
Abstract: Cytokinins are a class of phytohormone that play a crucial role in the development of plants. They are involved in the regulation of nearly every aspect of plant growth, from germination to senescence. The role of cytokinins in many developmental programs is complex and varies both spatially and temporally. Current techniques used to investigate the functions of cytokinins in plant development lack this spatial and temporal resolution required to observe cell-type specific effects. To this end, we present a method of activating a caged cytokinin in single cells. A caged benzyladenine was synthesized, along with caged adenine as a negative control. In vitro testing confirmed ultraviolet light-mediated uncaging, and subsequent root growth assays demonstrated that uncaging produced a cytokinin phenotype. This uncaging was confined to single cells using multiphoton confocal microscopy. Using an Arabidopsis thaliana cytokinin reporter line expressing TCSn::GFP , the resulting GFP expression was confined to the uncaging region, including in single cells. This study presents a novel cell-targeted method of cytokinin delivery, which has the potential to elucidate a broad range of processes in plant development. We combined multiphoton confocal microscopy and a caged cytokinin treatment, allowing cell type-specific uncaging of a cytokinin in Arabidopsis roots.
Publisher: Cold Spring Harbor Laboratory
Date: 29-05-2022
DOI: 10.1101/2022.05.28.493833
Abstract: Semidwarfing genes have greatly increased wheat yields globally, yet the widely used gibberellin (GA) insensitive genes Rht-B1b and Rht-D1b have disadvantages for seedling emergence. Use of the GA sensitive semidwarfing gene Rht13 avoids this pleiotropic effect. Here we show that Rht13 encodes a nucleotide-binding site/leucine-rich repeat (NB-LRR) gene. A point mutation in the semidwarf Rht-B13b allele autoactivates the NB-LRR gene and causes a height reduction comparable to Rht-B1b and Rht-D1b in erse genetic backgrounds. The autoactive Rht-B13b allele leads to transcriptional upregulation of pathogenesis-related genes including class III peroxidases associated with cell wall remodelling. Rht13 represents a new class of reduced height ( Rht ) gene, unlike other Rht genes which encode components of the GA signalling or metabolic pathways. This discovery opens new avenues to use autoactive NB-LRR genes as semidwarfing genes in a range of crop species, and to apply Rht13 in wheat breeding programmes using a perfect genetic marker.
Publisher: Springer Science and Business Media LLC
Date: 07-03-2021
DOI: 10.1186/S13007-021-00725-6
Abstract: The formation of infection threads in the symbiotic infection of rhizobacteria in legumes is a unique, fascinating, and poorly understood process. Infection threads are tubes of cell wall material that transport rhizobacteria from root hair cells to developing nodules in host roots. They form in a type of reverse tip-growth from an inversion of the root hair cell wall, but the mechanism driving this growth is unknown, and the composition of the thread wall remains unclear. High resolution, 3-dimensional imaging of infection threads, and cell wall component specific labelling, would greatly aid in our understanding of the nature and development of these structures. To date, such imaging has not been done, with infection threads typically imaged by GFP-tagged rhizobia within them, or histochemically in thin sections. We have developed new methods of imaging infection threads using novel and traditional cell wall fluorescent labels, and laser confocal scanning microscopy. We applied a new Periodic Acid Schiff (PAS) stain using rhodamine-123 to the labelling of whole cleared infected roots of Medicago truncatula which allowed for imaging of infection threads in greater 3D detail than had previously been achieved. By the combination of the above method and a calcofluor-white counter-stain, we also succeeded in labelling infection threads and plant cell walls separately, and have potentially discovered a way in which the infection thread matrix can be visualized. Our methods have made the imaging and study of infection threads more effective and informative, and present exciting new opportunities for future research in the area.
Publisher: Wiley
Date: 22-05-2019
DOI: 10.1111/PCE.13558
Abstract: Rapid metabolite diffusion across the mesophyll (M) and bundle sheath (BS) cell interface in C
Publisher: Wiley
Date: 04-07-2015
DOI: 10.1111/PPL.12234
Abstract: The barley (Hordeum vulgare) gene HvALMT1 encodes an anion channel in guard cells and in certain root tissues indicating that it may perform multiple roles. The protein localizes to the plasma membrane and facilitates malate efflux from cells when constitutively expressed in barley plants and Xenopus oocytes. This study investigated the function of HvALMT1 further by identifying its tissue-specific expression and by generating and characterizing RNAi lines with reduced HvALMT1 expression. We show that transgenic plants with 18-30% of wild-type HvALMT1 expression had impaired guard cell function. They maintained higher stomatal conductance in low light intensity and lost water more rapidly from excised leaves than the null segregant control plants. Tissue-specific expression of HvALMT1 was investigated in developing grain and during germination using transgenic barley lines expressing the green fluorescent protein (GFP) with the HvALMT1 promoter. We found that HvALMT1 is expressed in the nucellar projection, the aleurone layer and the scutellum of developing barley grain. Malate release measured from isolated aleurone layers prepared from imbibed grain was significantly lower in the RNAi barley plants compared with control plants. These data provide molecular and physiological evidence that HvALMT1 functions in guard cells, in grain development and during germination. We propose that HvALMT1 releases malate and perhaps other anions from guard cells to promote stomatal closure. The likely roles of HvALMT1 during seed development and grain germination are also discussed.
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: Frontiers Media SA
Date: 03-05-2018
Publisher: Springer Science and Business Media LLC
Date: 18-07-2007
DOI: 10.1007/S00425-007-0580-5
Abstract: Cotton (Gossypium hirsutum L.) fibre initial cells undergo a rapid cellular re-programming around anthesis to form the long cellulose fibres prized for textile manufacture. On the day of anthesis the cotton fibre initial cells balloon out from the ovule surface and so are clearly distinguished from adjacent epidermal pavement cells. To enhance our understanding of the molecular processes that determine which cells become fibres and why adjacent epidermal cells remain in a different developmental state we studied the expression profiles of the two respective cell types. Using laser-capture microdissection, coupled with an in vitro RNA lification system, we used cDNA microarray slides to profile the gene expression in expanding fibre initials compared to the non-expanding epidermal cells at an early stage just after the fibre initials are discernable. Except for a few regulatory genes, the genes that are up-regulated in the cotton fibre initials relative to epidermal cells predominantly encode proteins involved in generating the components for the extra cell membrane and primary cell wall needed for the rapid cell expansion of the initials. This includes synthesis of enzymes and cell wall proteins, carbohydrates, and lipids. An analysis of single channel fluorescence levels confirmed that these classes of genes were also the most highly expressed genes in fibre initials. Genes involved in DNA metabolism were also well represented in the expanding fibre cell, consistent with the limited endoreduplication we previously reported to occur in fibre initial cells.
Publisher: Frontiers Media SA
Date: 02-08-2017
Publisher: Scientific Societies
Date: 10-2019
DOI: 10.1094/PHYTO-03-19-0099-R
Abstract: The wheat Sr2 locus confers partial resistance to four biotrophic pathogens: wheat stem rust (Puccinia graminis f. sp. tritici), leaf rust (P. triticina), stripe rust (P. striiformis f. sp. tritici), and powdery mildew (Blumeria graminis f. sp. tritici). In addition, Sr2 is linked with a brown coloration of ears and stems, termed pseudo-black chaff (PBC). PBC, initially believed to be elicited by stem rust infection, was subsequently recognized to occur in the absence of pathogen infection. The current study demonstrates that the resistance response to stem rust is associated with the death of photosynthetic cells around rust infection sites in the inoculated leaf sheath. Similarly, Sr2-dependent resistance to powdery mildew was associated with the death of leaf mesophyll cells around mildew infection sites. We demonstrate that PBC occurring in the absence of pathogen inoculation also corresponds with death and the collapse of photosynthetic cells in the affected parts of stems and ears. In addition, Sr2-dependent necrosis was inducible in leaves by application of petroleum jelly or by heat treatments. Thus, Sr2 was found to be associated with cell death, which could be triggered by either biotic or abiotic stresses. Our results suggest a role for the Sr2 locus in controlling cell death in response to stress.
Publisher: Oxford University Press (OUP)
Date: 06-2016
DOI: 10.1105/TPC.16.00155
Publisher: Springer Science and Business Media LLC
Date: 08-07-2005
Publisher: Oxford University Press (OUP)
Date: 18-04-2011
Abstract: Drought stress at the reproductive stage causes pollen sterility and grain loss in wheat (Triticum aestivum). Drought stress induces abscisic acid (ABA) biosynthesis genes in anthers and ABA accumulation in spikes of drought-sensitive wheat varieties. In contrast, drought-tolerant wheat accumulates lower ABA levels, which correlates with lower ABA biosynthesis and higher ABA catabolic gene expression (ABA 8′-hydroxylase). Wheat TaABA8′OH1 deletion lines accumulate higher spike ABA levels and are more drought sensitive. ABA treatment of the spike mimics the effect of drought, causing high levels of sterility. ABA treatment represses the anther cell wall invertase gene TaIVR1, and drought-tolerant lines appeared to be more sensitive to the effect of ABA. Drought-induced sterility shows similarity to cold-induced sterility in rice (Oryza sativa). In cold-stressed rice, the rate of ABA accumulation was similar in cold-sensitive and cold-tolerant lines during the first 8 h of cold treatment, but in the tolerant line, ABA catabolism reduced ABA levels between 8 and 16 h of cold treatment. The ABA biosynthesis gene encoding 9-cis-epoxycarotenoid dioxygenase in anthers is mainly expressed in parenchyma cells surrounding the vascular bundle of the anther. Transgenic rice lines expressing the wheat TaABA8′OH1 gene under the control of the OsG6B tapetum-specific promoter resulted in reduced anther ABA levels under cold conditions. The transgenic lines showed that anther sink strength (OsINV4) was maintained under cold conditions and that this correlated with improved cold stress tolerance. Our data indicate that ABA and ABA 8′-hydroxylase play an important role in controlling anther ABA homeostasis and reproductive stage abiotic stress tolerance in cereals.
Publisher: Oxford University Press (OUP)
Date: 12-2004
Abstract: Cotton fibers are single-celled hairs that elongate to several centimeters long from the seed coat epidermis of the tetraploid species (Gossypium hirsutum and Gossypium barbadense). Thus, cotton fiber is a unique system to study the mechanisms of rapid cell expansion. Previous work has shown a transient closure of plasmodesmata during fiber elongation (Y.-L. Ruan, D.J. Llewellyn, R.T. Furbank [2001] Plant Cell 13: 47–60). To examine the importance of this closure in fiber elongation, we compared the duration of the plasmodesmata closure among different cotton genotypes differing in fiber length. Confocal imaging of the membrane-impermeant fluorescent molecule carboxyfluorescein revealed a genotypic difference in the duration of the plasmodesmata closure that positively correlates with fiber length among three tetraploid genotypes and two diploid progenitors. In all cases, the closure occurred at the rapid phase of elongation. Aniline blue staining and immunolocalization studies showed that callose deposition and degradation at the fiber base correlates with the timing of plasmodesmata closure and reopening, respectively. Northern analyses showed that the expression of a fiber-specific β-1,3-glucanase gene, GhGluc1, was undetectable when callose was deposited at the fiber base but became evident at the time of callose degradation. Genotypically, the level of GhGluc1 expression was high in the short fiber genotype and weak in the intermediate and long fiber genotypes. The data provide genotypic and developmental evidence that (1) plasmodesmata closure appears to play an important role in elongating cotton fibers, (2) callose deposition and degradation may be involved in the plasmodesmata closure and reopening, respectively, and (3) the expression of GhGluc1 could play a role in this process by degrading callose, thus opening the plasmodesmata.
Publisher: Oxford University Press (OUP)
Date: 16-07-2004
DOI: 10.1093/JXB/ERH190
Publisher: Scientific Societies
Date: 10-2011
Abstract: Rice is atypical in that it is an agricultural cereal that is immune to fungal rust diseases. This report demonstrates that several cereal rust species (Puccinia graminis f. sp tritici, P. triticina, P. striiformis, and P. hordei) can infect rice and produce all the infection structures necessary for plant colonization, including specialized feeding cells (haustoria). Some rust infection sites are remarkably large and many plant cells are colonized, suggesting that nutrient uptake occurs to support this growth. Rice responds with an active, nonhost resistance (NHR) response that prevents fungal sporulation and that involves callose deposition, production of reactive oxygen species, and, occasionally, cell death. Genetic variation for the efficacy of NHR to wheat stem rust and wheat leaf rust was observed. Unlike cereal rusts, the rust pathogen (Mel sora lini) of the dicotyledenous plant flax (Linum usitatissimum) rarely successfully infects rice due to an apparent inability to recognize host-derived signals. Morphologically abnormal infection structures are produced and appressorial-like structures often don't coincide with stomata. These data suggest that basic compatibility is an important determinate of nonhost infection outcomes of rust diseases on cereals, with cereal rusts being more capable of infecting a cereal nonhost species compared with rust species that are adapted for dicot hosts.
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.JHAZMAT.2006.08.077
Abstract: This study investigated the performance of a combined ozone and zeolite system in eliminating gaseous toluene which is a major contaminant in many industrial and indoor environments. The hypothesis that the removal of toluene by ozone can be substantially affected by confining the oxidation reaction in a zeolite structure was evaluated. The degradation of toluene seemed to be contributed by the active oxygen atom generated from the decomposition of ozone at the Lewis acid sites in the zeolite 13X. Air containing toluene levels at 1.5, 2 and 3 ppm was injected with ozone in the range of 0-6 ppm before being vented into a fixed amount of 3600 g zeolite 13X with 90 mm bed-length. The experimental results showed that the elimination rate of toluene was significantly enhanced when compared to using zeolite or ozone alone. In particular, over 90% of the 1.5 ppm toluene was removed when 6 ppm ozone was used at 40% relative humidity level. Deactivation of the zeolite 13X after a few hours of reactions under the current experimental conditions was probably due to the adsorbed water, carbon dioxide and the reaction by-products. The residue species left in the zeolite and the intermediate species in the exhaust gas stream were characterized by FT-IR, GC-MS and HP-LC methods, respectively. A distinctive peak of O atom attached to the Lewis acid site at 1380 cm(-1) was found in the FT-IR spectrum and trace amount of aldehydes was found to be the reaction by-products.
Publisher: Oxford University Press (OUP)
Date: 05-2002
DOI: 10.1104/PP.010918
Abstract: We have previously identified GAMYB, a gibberellin (GA)-regulated transcriptional activator of α-amylase gene expression, in aleurone cells of barley (Hordeum vulgare). To examine the regulation of GAMYB expression, we describe the use of nuclear run-on experiments to show that GA causes a 2-fold increase in the rate of GAMYB transcription and that the effect of GA can be blocked by abscisic acid (ABA). To identify GA-signaling components that regulate GAMYB expression, we examined the role of SLN1, a negative regulator of GA signaling in barley. SLN1, which is the product of the Sln1(Slender1) locus, is necessary for repression of GAMYB in barley aleurone cells. The activity of SLN1 in aleurone cells is regulated posttranslationally. SLN1 protein levels decline rapidly in response to GA before any increase in GAMYB levels. Green fluorescent protein-SLN1 fusion protein was targeted to the nucleus of aleurone protoplasts and disappeared in response to GA. Evidence from a dominant dwarf mutant at Sln1, and from thegse1 mutant (that affects GA “sensitivity”), indicates that GA acts by regulating SLN1 degradation and not translation. Mutation of the DELLA region of SLN1 results in increased protein stability in GA-treated layers, indicating that the DELLA region plays an important role in GA-induced degradation of SLN1. Unlike GA, ABA had no effect on SLN1 stability, confirming that ABA acts downstream of SLN1 to block GA signaling.
Publisher: Springer Science and Business Media LLC
Date: 2005
DOI: 10.1071/AP05031
Publisher: Springer Science and Business Media LLC
Date: 28-10-2010
Abstract: A current challenge of microRNA (miRNA) research is the identification of biologically relevant miRNA:target gene relationships. In plants, high miRNA:target gene complementarity has enabled accurate target predictions, and slicing of target mRNAs has facilitated target validation through rapid lification of 5' cDNA ends (5'-RACE) analysis. Together, these approaches have identified more than 20 targets potentially regulated by the deeply conserved miR159 family in Arabidopsis , including eight MYB genes with highly conserved miR159 target sites. However, genetic analysis has revealed the functional specificity of the major family members, miR159a and miR159b is limited to only two targets, MYB33 and MYB65 . Here, we examine the functional role of miR159 regulation for the other potential MYB target genes. For these target genes, functional analysis failed to identify miR159 regulation that resulted in any major phenotypic impact, either at the morphological or molecular level. This appears to be mainly due to the quiescent nature of the remaining family member, MIR159c . Although its expression overlaps in a temporal and spatial cell-specific manner with a subset of these targets in anthers, the abundance of miR159c is extremely low and concomitantly a mir159c mutant displays no anther defects. Examination of potential miR159c targets with conserved miR159 binding sites found neither their spatial or temporal expression domains appeared miR159 regulated, despite the detection of miR159-guided cleavage products by 5'-RACE. Moreover, expression of a miR159-resistant target ( mMYB101 ) resulted predominantly in plants that are indistinguishable from wild type. Plants that displayed altered morphological phenotypes were found to be ectopically expressing the mMYB101 transgene, and hence were misrepresentative of the in vivo functional role of miR159. This study presents a novel explanation for a paradox common to plant and animal miRNA systems, where among many potential miRNA-target relationships usually only a few appear physiologically relevant. The identification of a quiescent miR159c:target gene regulatory module in anthers provides a likely rationale for the presence of conserved miR159 binding sites in many targets for which miR159 regulation has no obvious functional role. Remnants from the demise of such modules may lead to an overestimation of miRNA regulatory complexity when investigated using bioinformatic, 5'-RACE or transgenic approaches.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/FP15252
Abstract: Plant adaptive potential is critically dependent upon efficient communication and co-ordination of resource allocation and signalling between above- and below-ground plant parts. Plant roots act as gatekeepers that sense and encode information about soil physical, chemical and biological factors, converting them into a sophisticated network of signals propagated both within the root itself, and also between the root and shoot, to optimise plant performance for a specific set of conditions. In return, plant roots receive and decode reciprocal information coming from the shoot. The communication modes are highly erse and include a broad range of physical (electric and hydraulic signals, propagating Ca2+ and ROS waves), chemical (assimilates, hormones, peptides and nutrients), and molecular (proteins and RNA) signals. Further, different signalling systems operate at very different timescales. It remains unclear whether some of these signalling systems operate in a priming mode(s), whereas others deliver more specific information about the nature of the signal, or whether they carry the same ‘weight’. This review summarises the current knowledge of the above signalling mechanisms, and reveals their hierarchy, and highlights the importance of integration of these signalling components, to enable optimal plant functioning in a dynamic environment.
Publisher: Elsevier BV
Date: 07-2006
Publisher: Oxford University Press (OUP)
Date: 23-08-2011
DOI: 10.1093/JXB/ERR227
Publisher: Oxford University Press (OUP)
Date: 17-09-2012
DOI: 10.1093/AOB/MCS206
Publisher: Scientific Societies
Date: 12-2008
Abstract: Fusarium graminearum causes head blight (FHB) and crown rot (CR) diseases in wheat. Compared with FHB, CR symptom development occurs slowly, usually taking 4 to 8 weeks to become visible. To characterize CR development, we used histological and real-time quantitative polymerase chain reaction analyses to assess fungal colonization during a timecourse of infection. Three distinct phases of infection were identified: i) initial spore germination with formation of a superficial hyphal mat at the inoculation point, ii) colonization of the adaxial epidermis of the outer leaf sheath and mycelial growth from the inoculation point to the crown, concomitant with a drop in fungal biomass, and iii) extensive colonization of the internal crown tissue. Fungal gene expression was examined during each phase using Affymetrix GeneChips. In total, 1,839 F. graminearum genes were significantly upregulated, including some known FHB virulence genes (e.g., TRI5 and TRI14), and 2,649 genes were significantly downregulated in planta compared with axenically cultured mycelia. Global comparisons of fungal gene expression with published data for FHB showed significant similarities between early stages of FHB and CR. These results indicate that CR disease development involves distinct phases of colonization, each of which is associated with a different fungal gene expression program.
Publisher: Cold Spring Harbor Laboratory
Date: 02-12-2020
DOI: 10.1101/2020.12.01.397034
Abstract: The scale of root quantification in research is often limited by the time required for s ling, measurement and processing s les. Recent developments in Convolutional Neural Networks (CNN) have made faster and more accurate plant image analysis possible which may significantly reduce the time required for root measurement, but challenges remain in making these methods accessible to researchers without an in-depth knowledge of Machine Learning. We analyzed root images acquired from three destructive root s lings using the RootPainter CNN-software that features an interface for corrective annotation for easier use. Root scans with and without non-root debris were used to test if training a model, i.e., learning from labeled ex les, can effectively exclude the debris by comparing the end-results with measurements from clean images. Root images acquired from soil profile walls and the cross-section of soil cores were also used for training and the derived measurements were compared with manual measurements. After 200 minutes of training on each dataset, significant relationships between manual measurements and RootPainter-derived data were noted for monolith (R 2 =0.99), profile wall (R 2 =0.76) and core-break (R 2 =0.57). The rooting density derived from images with debris was not significantly different from that derived from clean images after processing with RootPainter. Rooting density was also successfully calculated from both profile wall and soil core images, and in each case the gradient of root density with depth was not significantly different from manual counts. Our results demonstrate that the proposed approach using CNN can lead to substantial reductions in root s le processing workloads, increasing the potential scale of future root investigations.
Publisher: Oxford University Press (OUP)
Date: 14-07-2011
Abstract: Sucrose (Suc) synthase (Sus) is the major enzyme of Suc breakdown for cellulose biosynthesis in cotton (Gossypium hirsutum) fiber, an important source of fiber for the textile industry. This study examines the tissue-specific expression, relative abundance, and temporal expression of various Sus transcripts and proteins present in cotton. A novel isoform of Sus (SusC) is identified that is expressed at high levels during secondary cell wall synthesis in fiber and is present in the cell wall fraction. The phylogenetic relationships of the deduced amino acid sequences indicate two ancestral groups of Sus proteins predating the ergence of monocots and dicots and that SusC sequences form a distinct branch in the phylogeny within the dicot-specific clade. The subcellular location of the Sus isoforms is determined, and it is proposed that cell wall-localized SusC may provide UDP-glucose for cellulose and callose synthesis from extracellular sugars.
Publisher: Wiley
Date: 12-2013
DOI: 10.3732/AJB.1300034
Abstract: Solanum elaeagnifolium (silverleaf nightshade), having originated in the Americas, is now a serious summer-growing, perennial weed in many countries, including Australia. Most surfaces of the plants have a dense covering of trichomes, giving them a silvery-white appearance, hence the common name. We aimed to identify structural and functional properties of its leaves, especially the trichomes, that may affect the uptake of foliar-applied tracer dyes. The structure of leaves of Solanum elaeagnifolium was examined by light and scanning electron microscopy. The potential for transport of materials between trichomes and veins was studied with symplastic (carboxyfluorescein diacetate) and apoplastic (lucifer yellow) tracer dyes. Mature leaves had a dense covering of complex, stellate trichomes on both surfaces, particularly the abaxial. The basal cells of Solanum elaeagnifolium trichomes penetrated into the underlying palisade mesophyll layers. The innermost lobes of these basal cells sometimes contacted the bundle sheath of the veins, but were not observed to directly contact the xylem or phloem. We found that neither symplastic nor apoplastic dyes were transferred between the basal cells of the trichomes and the vascular tissues. The trichome layer repelled water-based tracer dyes, while one of four adjuvants tested facilitated entry of both symplastic and apoplastic dyes. Our results did not support a transport function for the trichomes. The trichomes may protect the mesophytic leaves from invertebrate herbivory, while also probably decreasing radiation absorbed resulting in cooler leaves in this summer-growing species.
Publisher: Springer Science and Business Media LLC
Date: 14-05-2017
DOI: 10.1007/S00709-016-0984-9
Abstract: Detection of potentially pathogenic microbes through recognition by plants and animals of both physical and chemical signals associated with the pathogens is vital for host well-being. Signal perception leads to the induction of a variety of responses that augment pre-existing, constitutive defences. The plant cell wall is a highly effective preformed barrier which becomes locally reinforced at the infection site through delivery of new wall material by the actin cytoskeleton. Although mechanical stimulation can produce a reaction, there is little understanding of the nature of physical factors capable of triggering plant defence. Neither the magnitude of forces nor the contact time required has been quantified. In the study reported here, mechanical stimulation with a tungsten microneedle has been used to quantify the response of Arabidopsis plants expressing an actin-binding protein tagged with green fluorescent protein (GFP) to reveal the organisation of the actin cytoskeleton. Using confocal microscopy, the response time for actin reorganisation in epidermal cells of Arabidopsis hypocotyls was shown to be 116 ± 49 s. Using nanoindentation and a diamond spherical tip indenter, the magnitude of the forces capable of triggering an actin response has been quantified. We show that Arabidopsis hypocotyl cells can detect a force as small as 4 μN applied for as short a time as 21.6 s to trigger reorganisation of the actin cytoskeleton. This force is an order of magnitude less than the potential invasive force determined for a range of fungal and oomycete plant pathogens. To our knowledge, this is the first quantification of the magnitude and duration of mechanical forces capable of stimulating a structural defence response in a plant cell.
Publisher: Wiley
Date: 08-06-2007
Publisher: Oxford University Press (OUP)
Date: 22-04-2009
Abstract: The decay of seed dormancy during after-ripening is not well understood, but elucidation of the mechanisms involved may be important for developing strategies for modifying dormancy in crop species and, for ex le, addressing the problem of preharvest sprouting in cereals. We have studied the germination characteristics of barley (Hordeum vulgare ‘Betzes’) embryos, including a description of anatomical changes in the coleorhiza and the enclosed seminal roots. The changes that occur correlate with abscisic acid (ABA) contents of embryo tissues. To understand the molecular mechanisms involved in dormancy loss, we compared the transcriptome of dormant and after-ripened barley embryos using a tissue-specific microarray approach. Our results indicate that in the coleorhiza, ABA catabolism is promoted and ABA sensitivity is reduced and that this is associated with differential regulation by after-ripening of ABA 8′-hydroxylase and of the LIPID PHOSPHATE PHOSPHATASE gene family and ABI3-INTERACTING PROTEIN2, respectively. We also identified other processes, including jasmonate responses, cell wall modification, nitrate and nitrite reduction, mRNA stability, and blue light sensitivity, that were affected by after-ripening in the coleorhiza that may be downstream of ABA signaling. Based on these results, we propose that the coleorhiza plays a major role in causing dormancy by acting as a barrier to root emergence and that after-ripening potentiates molecular changes related to ABA metabolism and sensitivity that ultimately lead to degradation of the coleorhiza, root emergence, and germination.
Publisher: MDPI AG
Date: 05-03-2021
DOI: 10.3390/IJMS22052642
Abstract: Black root rot (BRR) is an economically important disease of cotton and other crops, especially in cooler regions with short growing seasons. Symptoms include black discoloration of the roots, reduced number of lateral roots and stunted or slow plant growth. The cultivated tetraploid Gossypium species are susceptible to BRR. Resistance to BRR was identified in G. arboreum accession BM13H and is associated with reduced and restricted hyphal growth and less sporulation. Transcriptome analysis indicates that BM13H responds to infection at early time points 2- and 3-days post-inoculation, but by day 5, few differentially expressed genes are observed between infected and uninfected roots. Inheritance of BM13H resistance to BRR was evaluated in an F6 recombinant inbred population and shows a single semi-dominant locus conferring resistance that was fine mapped to a region on chromosome 1, containing ten genes including five putative resistance-like genes.
Publisher: Springer Science and Business Media LLC
Date: 02-09-2015
DOI: 10.1038/SREP13492
Abstract: Here we report the adaptation of the CLARITY technique to plant tissues with addition of enzymatic degradation to improve optical clearing and facilitate antibody probe penetration. P lant- E nzyme- A ssisted (PEA)-CLARITY, has allowed deep optical visualisation of stains, expressed fluorescent proteins and IgG-antibodies in Tobacco and Arabidopsis leaves. Enzyme treatment enabled penetration of antibodies into whole tissues without the need for any sectioning of the material, thus facilitating protein localisation of intact tissue in 3D whilst retaining cellular structure.
Publisher: Wiley
Date: 31-10-2011
DOI: 10.1111/J.1469-8137.2011.03938.X
Abstract: • Lack of grain dormancy in cereal crops such as barley and wheat is a common problem affecting farming areas around the world, causing losses in yield and quality because of preharvest sprouting. Control of seed or grain dormancy has been investigated extensively using various approaches in different species, including Arabidopsis and cereals. However, the use of a monocot model plant such as Brachypodium distachyon presents opportunities for the discovery of new genes related to grain dormancy that are not present in modern commercial crops. • In this work we present an anatomical description of the Brachypodium caryopsis, and we describe the dormancy behaviour of six common diploid Brachypodium inbred genotypes. We also study the effect of light quality (blue, red and far-red) on germination, and analyse changes in abscisic acid levels and gene expression between a dormant and a non-dormant Brachypodium genotype. • Our results indicate that different genotypes display high natural variability in grain dormancy and that the characteristics of dormancy and germination are similar to those found in other cereals. • We propose that Brachypodium is an ideal model for studies of grain dormancy in grasses and can be used to identify new strategies for increasing grain dormancy in crop species.
Publisher: Oxford University Press (OUP)
Date: 2006
DOI: 10.1093/PCP/PCI228
Abstract: Cotton fibres are a subset of single epidermal cells that elongate from the seed coat to produce the long cellulose strands or lint used for spinning into yarn. To identify genes that might regulate lint fibre initiation, expression profiles of 0 days post-anthesis (dpa) whole ovules from six reduced fibre or fibreless mutants were compared with wild-type linted cotton using cDNA microarrays. Numerous clones were differentially expressed, but when only those genes that are normally expressed in the ovule outer integument (where fibres develop) were considered, just 13 different cDNA clones were down-regulated in some or all of the mutants. These included: a Myb transcription factor (GhMyb25) similar to the Antirrhinum Myb AmMIXTA, a putative homeodomain protein (related to Arabidopsis ATML1), a cyclin D gene, some previously identified fibre-expressed structural and metabolic genes, such as lipid transfer protein, alpha-expansin and sucrose synthase, as well as some unknown genes. Laser capture microdissection and reverse transcription-PCR were used to show that both the GhMyb25 and the homeodomain gene were predominantly ovule specific and were up-regulated on the day of anthesis in fibre initials relative to adjacent non-fibre ovule epidermal cells. Their spatial and temporal expression pattern therefore coincided with the time and location of fibre initiation. Constitutive overexpression of GhMyb25 in transgenic tobacco resulted in an increase in branched long-stalked leaf trichomes. The involvement of cell cycle genes prompted DNA content measurements that indicated that fibre initials, like leaf trichomes, undergo DNA endoreduplication. Cotton fibre initiation therefore has some parallels with leaf trichome development, although the detailed molecular mechanisms are clearly different.
Publisher: Springer New York
Date: 11-09-2014
DOI: 10.1007/978-1-4939-1523-1_14
Abstract: To investigate plasmodesmata (PD) function, a useful technique is to monitor the effect on cell-to-cell transport of applying an inhibitor of a physiological process, protein, or other cell component of interest. Changes in PD transport can then be monitored in one of several ways, most commonly by measuring the cell-to-cell movement of fluorescent tracer dyes or of free fluorescent proteins. Effects on PD structure can be detected in thin sections of embedded tissue observed using an electron microscope, most commonly a Transmission Electron Microscope (TEM). This chapter outlines commonly used inhibitors, methods for treating different tissues, how to detect altered cell-to-cell transport and PD structure, and important caveats.
Publisher: Oxford University Press (OUP)
Date: 23-08-2005
DOI: 10.1093/JXB/ERI269
Publisher: Oxford University Press (OUP)
Date: 11-05-2012
Abstract: Upward long-distance mobile silencing has been shown to be phloem mediated in several different solanaceous species. We show that the Arabidopsis (Arabidopsis thaliana) seedling grafting system and a counterpart inducible system generate upwardly spreading long-distance silencing that travels not in the phloem but by template-dependent reiterated short-distance cell-to-cell spread through the cells of the central stele. Examining the movement of the silencing front revealed a largely unrecognized zone of tissue, below the apical meristem, that is resistant to the silencing signal and that may provide a gating or protective barrier against small RNA signals. Using a range of auxin and actin transport inhibitors revealed that, in this zone, alteration of vesicular transport together with cytoskeleton dynamics prevented or retarded the spread of the silencing signal. This suggests that small RNAs are transported from cell to cell via plasmodesmata rather than diffusing from their source in the phloem.
Publisher: Oxford University Press (OUP)
Date: 05-2003
DOI: 10.1105/TPC.009134
Publisher: Oxford University Press (OUP)
Date: 02-01-2018
DOI: 10.1093/JXB/ERX456
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.YMBEN.2016.12.007
Abstract: Synthesis and accumulation of plant oils in the entire vegetative biomass offers the potential to deliver yields surpassing those of oilseed crops. However, current levels still fall well short of those typically found in oilseeds. Here we show how transcriptome and biochemical analyses pointed to a futile cycle in a previously established Nicotiana tabacum line, accumulating up to 15% (dry weight) of the storage lipid triacylglycerol in leaf tissue. To overcome this metabolic bottleneck, we either silenced the SDP1 lipase or overexpressed the Arabidopsis thaliana LEC2 transcription factor in this transgenic background. Both strategies independently resulted in the accumulation of 30-33% triacylglycerol in leaf tissues. Our results demonstrate that the combined optimization of de novo fatty acid biosynthesis, storage lipid assembly and lipid turnover in leaf tissue results in a major overhaul of the plant central carbon allocation and lipid metabolism. The resulting further step changes in oil accumulation in the entire plant biomass offers the possibility of delivering yields that outperform current oilseed crops.
Publisher: Wiley
Date: 11-01-2010
DOI: 10.1111/J.1365-3040.2009.02059.X
Abstract: We analysed the abundance, spatial distribution and soil contact of wheat roots in dense, structured subsoil to determine whether incomplete extraction of subsoil water was due to root system limitations. Intact soil cores were collected to 1.6 m below wheat crops at maturity on a red Kandosol in southern Australia. Wheat roots, remnant roots, soil pores and root-soil contact were quantified at fresh breaks in the soil cores. In surface soil layers ( 0.6 m), where 44% of roots were in pores with at least three other roots. Most pores contained no roots, with occupancy declining from 20% in surface layers to 5% in subsoil. Wheat roots clumped into pores contacted the surrounding soil via numerous root hairs, whereas roots in cracks were appressed to the soil surface and had very few root hairs. Calculations assuming good root-soil contact indicated that root density was sufficient to extract available subsoil water, suggesting that uptake is constrained at the root-soil interface. To increase extraction of subsoil water, genetic targets could include increasing root-soil contact with denser root hairs, and increasing root proliferation to utilize existing soil pores.
Publisher: PeerJ
Date: 23-12-2014
DOI: 10.7717/PEERJ.701
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/BT07003
Abstract: Yield in cultivated cotton (Gossypium spp.) is affected by the number and distribution of fibres initiated on the seed surface but, apart from simple statistical summaries, little has been done to assess this phenotype quantitatively. Here we use two types of spatial statistics to describe and quantify differences in patterning of cotton ovule fibre initials (FI). The following five different species of Gossypium were analysed: G. hirsutum L., G. barbadense L., G. arboreum, G. raimondii Ulbrich. and G. trilobum (DC.) Skovsted. Scanning electron micrographs of FIs were taken on the day of anthesis. Cell centres for fibre and epidermal cells were digitised and analysed by spatial statistics methods appropriate for marked point processes and tessellations. Results were consistent with previously published reports of fibre number and spacing. However, it was shown that the spatial distributions of FIs in all of species examined exhibit regularity, and are not completely random as previously implied. The regular arrangement indicates FIs do not appear independently of each other and we surmise there may be some form of mutual inhibition specifying fibre-initial development. It is concluded that genetic control of FIs differs from that of stomata, another well studied plant idioblast. Since spatial statistics show clear species differences in the distribution of FIs within this genus, they provide a useful method for phenotyping cotton.
Publisher: Oxford University Press (OUP)
Date: 13-06-2008
DOI: 10.1093/JXB/ERN150
Publisher: Cambridge University Press (CUP)
Date: 26-07-2019
DOI: 10.1017/S0960258519000151
Abstract: The understanding of the genetic basis of grain dormancy in wheat has rapidly improved in the last few years, and a number of genes have been identified related to that trait. We recently identified the wheat genes TaPM19-A1 and - A2 and we have now taken the first step towards understanding the role of this class of genes in seeds. By investigating the Arabidopsis homologous PM19-Like 1 ( PM19L1 ) we have found that it has a seed-specific expression pattern and, while its expression is higher in dormant than in non-dormant seeds, knock-out mutations produced seeds with increased dormancy. Not only primary dormancy, but also secondary dormancy in response to high temperature was increased by the loss-of-function. We have also examined the function of PM19L1 by localizing the PM19 protein primarily to the cotyledon cells in seeds, possibly in membranes. By investigating the co-expression network of this gene we have found that it is connected to a small group of abscisic acid (ABA)-induced seed maturation and storage-related genes. The function of PM19L1 represents a good opportunity to explore the interactions of key factors that can influence seed dormancy such as ABA, temperature and membrane properties.
Publisher: Springer Science and Business Media LLC
Date: 13-11-2016
DOI: 10.1007/S00299-015-1897-3
Abstract: A strong, stable and root-specific expression system was developed from a rice root-specific GLYCINE - RICH PROTEIN 7 promoter for use as an enabling technology for genetic manipulation of wheat root traits. Root systems play an important role in wheat productivity. Genetic manipulation of wheat root traits often requires a root-specific or root-predominant expression system as an essential enabling technology. In this study, we investigated promoters from rice root-specific or root-predominant expressed genes for development of a root expression system in bread wheat. Transient expression analysis using a GREEN FLUORESCENT PROTEIN (GFP) reporter gene driven by rice promoters identified six promoters that were strongly expressed in wheat roots. Extensive organ specificity analysis of three rice promoters in transgenic wheat revealed that the promoter of rice GLYCINE-RICH PROTEIN 7 (OsGRP7) gene conferred a root-specific expression pattern in wheat. Strong GFP fluorescence in the seminal and branch roots of wheat expressing GFP reporter driven by the OsGRP7 promoter was detected in epidermal, cortical and endodermal cells in mature parts of the root. The GFP reporter driven by the promoter of rice METALLOTHIONEIN-LIKE PROTEIN 1 (OsMTL1) gene was mainly expressed in the roots with essentially no expression in the leaf, stem or seed. However, it was also expressed in floral organs including glume, lemma, palea and awn. In contrast, strong expression of rice RCg2 promoter-driven GFP was found in many tissues. The GFP expression driven by these three rice promoters was stable in transgenic wheat plants through three generations (T1-T3) examined. These data suggest that the OsGRP7 promoter can provide a strong, stable and root-specific expression system for use as an enabling technology for genetic manipulation of wheat root traits.
Start Date: 2014
End Date: 12-2015
Amount: $1,000,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2006
End Date: 12-2007
Amount: $553,000.00
Funder: Australian Research Council
View Funded Activity