ORCID Profile
0000-0002-9751-8433
Current Organisation
University of Tasmania
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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 | Plant Physiology | Plant Cell and Molecular Biology | Plant Developmental and Reproductive Biology | Intellectual Property Law | Agricultural marine biotechnology | Plant biology | Population, Ecological and Evolutionary Genetics | Biological Mathematics | Plant Physiology | Genetic Development (Incl. Sex Determination) | Plant biochemistry | Plant physiology
ANZSRC Socio-Economic Objective (SEO)
Grain Legumes | Environmentally Sustainable Plant Production not elsewhere classified | Grain legumes | Plant Production and Plant Primary Products not elsewhere classified | Field crops | Horticultural crops | Expanding Knowledge in Law and Legal Studies | Expanding Knowledge in the Agricultural and Veterinary Sciences | Vegetables | Expanding Knowledge in the Mathematical Sciences |
Related Links
Publications
Something old, something new: Auxin and strigolactone interact in the ancient mycorrhizal symbiosis
Publisher: Informa UK Limited
Date: 04-2013
DOI: 10.4161/PSB.23656
The Role of Gibberellins and Brassinosteroids in Nodulation and Arbuscular Mycorrhizal Associations
Publisher: Frontiers Media SA
Date: 15-03-2019
Rht18 Semidwarfism in Wheat Is Due to Increased GA 2-oxidaseA9 Expression and Reduced GA Content
Publisher: Oxford University Press (OUP)
Date: 15-03-2018
DOI: 10.1104/PP.18.00023
The role of strigolactones in photomorphogenesis of pea is limited to adventitious rooting
Publisher: Wiley
Date: 04-08-2014
DOI: 10.1111/PPL.12246
Abstract: The recently discovered group of plant hormones, the strigolactones, have been implicated in regulating photomorphogenesis. We examined this extensively in our strigolactone synthesis and response mutants and could find no evidence to support a major role for strigolactone signaling in classic seedling photomorphogenesis (e.g. elongation and leaf expansion) in pea (Pisum sativum), consistent with two recent independent reports in Arabidopsis. However, we did find a novel effect of strigolactones on adventitious rooting in darkness. Strigolactone-deficient mutants, Psccd8 and Psccd7, produced significantly fewer adventitious roots than comparable wild-type seedlings when grown in the dark, but not when grown in the light. This observation in dark-grown plants did not appear to be due to indirect effects of other factors (e.g. humidity) as the constitutively de-etiolated mutant, lip1, also displayed reduced rooting in the dark. This role for strigolactones did not involve the MAX2 F-Box strigolactone response pathway as Psmax2 f-box mutants did not show a reduction in adventitious rooting in the dark compared with wild-type plants. The auxin-deficient mutant bushy also reduced adventitious rooting in the dark, as did decapitation of wild-type plants. Rooting was restored by the application of indole-3-acetic acid (IAA) to decapitated plants, suggesting a role for auxin in the rooting response. However, auxin measurements showed no accumulation of IAA in the epicotyls of wild-type plants compared with the strigolactone synthesis mutant Psccd8, suggesting that changes in the gross auxin level in the epicotyl are not mediating this response to strigolactone deficiency.
The role of CLAVATA signalling in the negative regulation of mycorrhizal colonization and nitrogen response of tomato
Publisher: Oxford University Press (OUP)
Date: 13-11-2020
DOI: 10.1093/JXB/ERAA539
Abstract: Plants form mutualistic nutrient-acquiring symbioses with microbes, including arbuscular mycorrhizal fungi. The formation of these symbioses is costly, and plants employ a negative feedback loop termed autoregulation of mycorrhizae (AOM) to limit formation of arbuscular mycorrhizae (AM). We provide evidence for the role of one leucine-rich repeat receptor-like kinase (FAB), a hydroxyproline O-arabinosyltransferase enzyme (FIN), and additional evidence for one receptor-like protein (SlCLV2) in the negative regulation of AM formation in tomato. Reciprocal grafting experiments suggest that the FAB gene acts locally in the root, while the SlCLV2 gene may act in both the root and the shoot. External nutrients including phosphate and nitrate can also strongly suppress AM formation. We found that FAB and FIN are required for nitrate suppression of AM but are not required for the powerful suppression of AM colonization by phosphate. This parallels some of the roles of legume homologues in the autoregulation of the more recently evolved symbioses with nitrogen-fixing bacteria leading to nodulation. This deep homology in the symbiotic role of these genes suggests that in addition to the early signalling events that lead to the establishment of AM and nodulation, the autoregulation pathway might also be considered part of the common symbiotic toolkit that enabled plants to form beneficial symbioses.
Strigolactones promote nodulation in pea
Publisher: Springer Science and Business Media LLC
Date: 17-09-2011
DOI: 10.1007/S00425-011-1516-7
Abstract: Strigolactones are recently defined plant hormones with roles in mycorrhizal symbiosis and shoot and root architecture. Their potential role in controlling nodulation, the related symbiosis between legumes and Rhizobium bacteria, was explored using the strigolactone-deficient rms1 mutant in pea (Pisum sativum L.). This work indicates that endogenous strigolactones are positive regulators of nodulation in pea, required for optimal nodule number but not for nodule formation per se. rms1 mutant root exudates and root tissue are almost completely deficient in strigolactones, and rms1 mutant plants have approximately 40% fewer nodules than wild-type plants. Treatment with the synthetic strigolactone GR24 elevated nodule number in wild-type pea plants and also elevated nodule number in rms1 mutant plants to a level similar to that seen in untreated wild-type plants. Grafting studies revealed that nodule number and strigolactone levels in root tissue of rms1 roots were unaffected by grafting to wild-type scions indicating that strigolactones in the root, but not shoot-derived factors, regulate nodule number and provide the first direct evidence that the shoot does not make a major contribution to root strigolactone levels.
Cell layer specific roles for hormones in root development: Gibberellins suppress infection thread progression, promote nodule and lateral root development in the endodermis and interact with auxin an
Publisher: Cold Spring Harbor Laboratory
Date: 05-09-2023
Common and divergent roles of plant hormones in nodulation and arbuscular mycorrhizal symbioses
Publisher: Informa UK Limited
Date: 18-06-2014
DOI: 10.4161/PSB.29593
GOLDEN TANGERINE TOMATO ROOTS SHOW INCREASED ACCUMULATION OF ACYCLIC CAROTENOIDS, LESS ABSCISIC ACID, DROUGHT SENSITIVITY, AND IMPAIRED ENDOMYCORRHIZAL COLONIZATION
Publisher: Cold Spring Harbor Laboratory
Date: 09-12-2021
DOI: 10.1101/2021.12.07.471680
Abstract: Heirloom golden tomato fruit varieties are highly nutritious as they accumulate tetra- cis -lycopene, which has a higher bioavailability and recognised health benefits in treating anti-inflammatory diseases compared to all- trans -lycopene isomers found in red tomatoes. We investigated if photoisomerization of tetra- cis -lycopene occurs in roots of the golden tangerine Micro-Tom variety ( tang mic ), and how this affects root to shoot biomass, mycorrhizal colonization, abscisic acid accumulation, and responses to drought. tang mic plants grown in soil under glasshouse conditions displayed a reduction in height, number of flowers, fruit yield, and root length compared to wild type (WT). Soil inoculation with Rhizophagus irregularis revealed fewer arbuscules and other fungal structures in the endodermal cells of roots in tang mic relative to WT. The roots of tang mic hyperaccumulated acyclic cis -carotenes, while only trace levels of xanthophylls and abscisic acid were detected. In response to a water deficit, leaves from the tang mic plants displayed a rapid decline in maximum quantum yield of photosystem II compared to WT, indicating a defective root to shoot signalling response to drought. The lack of xanthophylls biosynthesis in tang mic roots reduced abscisic acid levels, thereby likely impairing endomycorrhiza colonisation and drought-induced root to shoot signalling. Photoisomerization of prolycopene to lycopene is limited in root plastids. Roots of tangerine reveal an important tissue sink to store micronutrients such as prolycopene. Roots of tangerine lack ABA and show impaired mycorrhizal colonization. The tangerine plant is drought sensitive and has a smaller biomass as well as reduced yield.
A Study of Gibberellin Homeostasis and Cryptochrome-Mediated Blue Light Inhibition of Hypocotyl Elongation
Publisher: Oxford University Press (OUP)
Date: 20-07-2007
Abstract: Cryptochromes mediate blue light-dependent photomorphogenic responses, such as inhibition of hypocotyl elongation. To investigate the underlying mechanism, we analyzed a genetic suppressor, scc7-D (suppressors of cry1cry2), which suppressed the long-hypocotyl phenotype of the cry1cry2 (cryptochrome1/cryptochrome2) mutant in a light-dependent but wavelength-independent manner. scc7-D is a gain-of-expression allele of the GA2ox8 gene encoding a gibberellin (GA)-inactivating enzyme, GA 2-oxidase. Although scc7-D is hypersensitive to light, transgenic seedlings expressing GA2ox at a level higher than scc7-D showed a constitutive photomorphogenic phenotype, confirming a general role of GA2ox and GA in the suppression of hypocotyl elongation. Prompted by this result, we investigated blue light regulation of mRNA expression of the GA metabolic and catabolic genes. We demonstrated that cryptochromes are required for the blue light regulation of GA2ox1, GA20ox1, and GA3ox1 expression in transient induction, continuous illumination, and photoperiodic conditions. The kinetics of cryptochrome induction of GA2ox1 expression and cryptochrome suppression of GA20ox1 or GA3ox1 expression correlate with the cryptochrome-dependent transient reduction of GA4 in etiolated wild-type seedlings exposed to blue light. Therefore we propose that in deetiolating seedlings, cryptochromes mediate blue light regulation of GA catabolic/metabolic genes, which affect GA levels and hypocotyl elongation. Surprisingly, no significant change in the GA4 content was detected in the whole shoot s les of the wild-type or cry1cry2 seedlings grown in the dark or continuous blue light, suggesting that cryptochromes may also regulate GA responsiveness and/or trigger cell- or tissue-specific changes of the level of bioactive GAs.
The role of strigolactones during plant interactions with the pathogenic fungus Fusarium oxysporum
Publisher: Springer Science and Business Media LLC
Date: 02-01-2016
DOI: 10.1007/S00425-015-2449-3
Abstract: Strigolactones (SLs) do not influence spore germination or hyphal growth of Fusarium oxysporum. Mutant studies revealed no role for SLs but a role for ethylene signalling in defence against this pathogen in pea. Strigolactones (SLs) play important roles both inside the plant as a hormone and outside the plant as a rhizosphere signal in interactions with mycorrhizal fungi and parasitic weeds. What is less well understood is any potential role SLs may play in interactions with disease causing microbes such as pathogenic fungi. In this paper we investigate the influence of SLs on the hemibiotrophic pathogen Fusarium oxysporum f.sp. pisi both directly via their effects on fungal growth and inside the plant through the use of a mutant deficient in SL. Given that various stereoisomers of synthetic and naturally occuring SLs can display different biological activities, we used (+)-GR24, (-)-GR24 and the naturally occurring SL, (+)-strigol, as well as a racemic mixture of 5-deoxystrigol. As a positive control, we examined the influence of a plant mutant with altered ethylene signalling, ein2, on disease development. We found no evidence that SLs influence spore germination or hyphal growth of Fusarium oxysporum and that, while ethylene signalling influences pea susceptibility to this pathogen, SLs do not.
Blue and red photoselective shadecloths modify pea height through altered blue irradiance perceived by the cry1 photoreceptor
Publisher: Informa UK Limited
Date: 2008
Brassinosteroids play multiple roles in nodulation of pea via interactions with ethylene and auxin
Publisher: Springer Science and Business Media LLC
Date: 30-09-2020
DOI: 10.1007/S00425-020-03478-Z
Abstract: A comprehensive analysis of the role of brassinosteroids in nodulation, including their interactions with auxin and ethylene revealed that brassinosteroids inhibit infection, promote nodule initiation but do not influence nodule organogenesis or function. Nodulation, the symbiosis between legumes and rhizobial bacteria, is regulated by a suite of hormones including brassinosteroids. Previous studies have found that brassinosteroids promote nodule number by inhibiting ethylene biosynthesis. In this study, we examined the influence of brassinosteroids on the various stages of infection and nodule development. We utilise pea mutants, including brassinosteroid mutants lk, lka and lkb, the ethylene insensitive ein2 mutant and the lk ein2 double mutant, along with transgenic lines expressing the DR5::GUS auxin activity marker to investigate how brassinosteroids interact with ethylene and auxin during nodulation. We show that brassinosteroids inhibit the early stages of nodulation, including auxin accumulation, root hair deformation and infection thread formation, and demonstrate that infection thread formation is regulated by brassinosteroids in an ethylene independent manner. In contrast, brassinosteroids appear to act as promoters of nodule initiation through both an ethylene dependent and independent pathway. Although brassinosteroids positively influence the ultimate number of nodules formed, we found that brassinosteroid-deficiency did not influence nodule structure including the vascular pattern of auxin activity or nitrogen-fixation capacity. These findings suggest that brassinosteroids are negative regulators of infection but positive regulators of nodule initiation. Furthermore, brassinosteroids do not appear to be essential for nodule organogenesis or function. Given the influence of brassinosteroids on discreet stages of nodulation but not nodule function, manipulation of brassinosteroids may be an interesting avenue for future research on the optimisation of nodulation.
Auxin transport and stem vascular reconnection – has our thinking become canalized?
Publisher: Oxford University Press (OUP)
Date: 31-10-2018
DOI: 10.1093/AOB/MCY180
A role for ethylene in the phytochrome‐mediated control of vegetative development
Publisher: Wiley
Date: 25-05-2006
Strigolactones in Plant Interactions with Beneficial and Detrimental Organisms: The Yin and Yang
Publisher: Elsevier BV
Date: 06-2017
DOI: 10.1016/J.TPLANTS.2017.03.011
Abstract: Strigolactones (SLs) are plant hormones that have important roles as modulators of plant development. They were originally described as ex planta signaling molecules in the rhizosphere that induce the germination of parasitic plants, a role that was later linked to encouraging the beneficial symbiosis with arbuscular mycorrhizal (AM) fungi. Recently, the focus has shifted to examining the role of SLs in plant-microbe interactions, and has revealed roles for SLs in the association of legumes with nitrogen-fixing rhizobacteria and in interactions with disease-causing pathogens. Here, we examine the role of SLs in plant interactions with beneficial and detrimental organisms, and propose possible future biotechnological applications.
Farnesylation mediates brassinosteroid biosynthesis to regulate abscisic acid responses
Publisher: Springer Science and Business Media LLC
Date: 25-07-2016
Abstract: Protein farnesylation is a post-translational modification involving the addition of a 15-carbon farnesyl isoprenoid to the carboxy terminus of select proteins(1-3). Although the roles of this lipid modification are clear in both fungal and animal signalling, many of the mechanistic functions of farnesylation in plant signalling are still unknown. Here, we show that CYP85A2, the cytochrome P450 enzyme that performs the last step in brassinosteroid biosynthesis (conversion of castasterone to brassinolide)(4), must be farnesylated to function in Arabidopsis. Loss of either CYP85A2 or CYP85A2 farnesylation results in reduced brassinolide accumulation and increased plant responsiveness to the hormone abscisic acid (ABA) and overall drought tolerance, explaining previous observations(5). This result not only directly links farnesylation to brassinosteroid biosynthesis but also suggests new strategies to maintain crop yield under challenging climatic conditions.
Strigolactones: New Physiological Roles for an Ancient Signal
Publisher: Springer Science and Business Media LLC
Date: 11-11-2012
The DELLA Proteins Influence the Expression of Cytokinin Biosynthesis and Response Genes During Nodulation
Publisher: Frontiers Media SA
Date: 09-04-2019
The potential roles of strigolactones and brassinosteroids in the autoregulation of nodulation pathway
Publisher: Oxford University Press (OUP)
Date: 02-04-2014
DOI: 10.1093/AOB/MCU030
Plant hormones in arbuscular mycorrhizal symbioses: an emerging role for gibberellins
Publisher: Oxford University Press (OUP)
Date: 18-03-2013
DOI: 10.1093/AOB/MCT041
Auxin influences strigolactones in pea mycorrhizal symbiosis
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.JPLPH.2012.11.002
Abstract: Hormone interactions are essential for the control of many developmental processes, including intracellular symbioses. The interaction between auxin and the new plant hormone strigolactone in the regulation of arbuscular mycorrhizal symbiosis was examined in one of the few auxin deficient mutants available in a mycorrhizal species, the auxin-deficient bsh mutant of pea (Pisum sativum). Mycorrhizal colonisation with the fungus Glomus intraradices was significantly reduced in the low auxin bsh mutant. The bsh mutant also exhibited a reduction in strigolactone exudation and the expression of a key strigolactone biosynthesis gene (PsCCD8). Strigolactone exudation was also reduced in wild type plants when the auxin content was reduced by stem girdling. Low strigolactone levels appear to be at least partially responsible for the reduced colonisation of the bsh mutant, as application of the synthetic strigolactone GR24 could partially rescue the mycorrhizal phenotype of bsh mutants. Data presented here indicates root auxin content was correlated with strigolactone exudation in both mutant and wild type plants. Mutant studies suggest that auxin may regulate early events in the formation of arbuscular mycorrhizal symbiosis by controlling strigolactone levels, both in the rhizosphere and possibly during early root colonisation.
Cytokinins and the CRE1 receptor influence endogenous gibberellin levels in Medicago truncatula
Publisher: Informa UK Limited
Date: 02-2018
Long-distance signaling and the control of branching in the rms1 mutant of pea
Publisher: Oxford University Press (OUP)
Date: 05-2001
DOI: 10.1104/PP.126.1.203
Abstract: The ramosus (rms) mutation (rms1) of pea (Pisum sativum) causes increased branching through modification of graft-transmissible signal(s) produced in rootstock and shoot. Additional grafting techniques have led us to propose that the novel signal regulated byRms1 moves acropetally in shoots and acts as a branching inhibitor. Epicotyl interstock grafts showed that wild-type (WT) epicotyls grafted between rms1 scions and rootstocks can revert mutant scions to a WT non-branching phenotype. Mutant scions grafted together with mutant and WT rootstocks did not branch despite a contiguous mutant root-shoot system. The primary action ofRms1 is, therefore, unlikely to be to block transport of a branching stimulus from root to shoot. Rather, Rms1may influence a long-distance signal that functions, directly or indirectly, as a branching inhibitor. It can be deduced that this signal moves acropetally in shoots because WT rootstocks inhibit branching in rms1 shoots, and although WT scions do not branch when grafted to mutant rootstocks, they do not inhibit branching in rms1 cotyledonary shoots growing from the same rootstocks. The acropetal direction of transport of theRms1 signal supports previous evidence that therms1 lesion is not in an auxin biosynthesis or transport pathway. The different branching phenotypes of WT andrms1 shoots growing from the same rms1rootstock provides further evidence that the shoot has a major role in the regulation of branching and, moreover, that root-exported cytokinin is not the only graft-transmissible signal regulating branching in intact pea plants.
Determining the Site of Action of Strigolactones during Nodulation
Publisher: Oxford University Press (OUP)
Date: 27-07-2017
DOI: 10.1104/PP.17.00741
MAX4 and RMS1 are ortholosgous dioxygenase-like genes that regulate shoot branching in Arabidopsis and pea
Publisher: Cold Spring Harbor Laboratory
Date: 15-06-2003
DOI: 10.1101/GAD.256603
Abstract: Shoot branching is inhibited by auxin transported down the stem from the shoot apex. Auxin does not accumulate in inhibited buds and so must act indirectly. We show that mutations in the MAX4 gene of Arabidopsis result in increased and auxin-resistant bud growth. Increased branching in max4 shoots is restored to wild type by grafting to wild-type rootstocks, suggesting that MAX4 is required to produce a mobile branch-inhibiting signal, acting downstream of auxin. A similar role has been proposed for the pea gene, RMS1 . Accordingly, MAX4 and RMS1 were found to encode orthologous, auxin-inducible members of the polyene dioxygenase family.
The branching gene RAMOSUS1 mediates interactions among two novel signals and auxin in pea
Publisher: Oxford University Press (OUP)
Date: 19-01-2005
The role of strigolactones and ethylene in disease caused by Pythium irregulare
Publisher: Wiley
Date: 11-11-2015
DOI: 10.1111/MPP.12320
The Art of Self-Control – Autoregulation of Plant–Microbe Symbioses
Publisher: Frontiers Media SA
Date: 10-07-2018
The role of CLE peptides in suppression of mycorrhizal colonisation of tomato
Publisher: Oxford University Press (OUP)
Date: 24-10-2023
DOI: 10.1093/PCP/PCAD124
Interactions between ethylene, gibberellins, and brassinosteroids in the development of rhizobial and mycorrhizal symbioses of pea
Publisher: Oxford University Press (OUP)
Date: 17-02-2016
DOI: 10.1093/JXB/ERW047
Cryptochrome 1 Contributes to Blue-Light Sensing in Pea
Publisher: Oxford University Press (OUP)
Date: 21-10-2005
Abstract: Cryptochromes are widespread in higher plants but their physiological roles as blue-light photoreceptors have been examined in relatively few species. Screening in a phyA null mutant background has identified several blue-light response mutants in pea (Pisum sativum), including one that carries a substitution of a highly conserved glycine residue in the N-terminal photolyase-homologous domain of the pea CRY1 gene. Analyses of cry1, phyA, and phyB mutants show that all three photoreceptors contribute to seedling photomorphogenesis under high-irradiance blue light, whereas phyA is the main photoreceptor active under low irradiances. Triple phyA phyB cry1 mutants grown under high-irradiance blue light are indistinguishable from dark-grown wild-type plants in length and leaf expansion but show a small residual response to higher-irradiance white light. Monogenic cry1 mutants have little discernable phenotype at the seedling stage, but later in development are more elongated than wild-type plants. In addition, the loss of cry1 moderates the short-internode phenotype of older phyA mutants, suggesting an antagonism between phyA and cry1 under some conditions. Pea cry1 has a small inhibitory effect on flowering under long and short days. However, the phyA cry1 double mutant retains a clear promotion of flowering in response to blue-light photoperiod extensions, indicating a role for one or more additional blue-light photoreceptors in the control of flowering in pea.
PhyA and cry1 act redundantly to regulate gibberellin levels during de‐etiolation in blue light
Publisher: Wiley
Date: 18-04-2006
The Cryptochrome Gene Family in Pea Includes Two Differentially Expressed CRY2 Genes
Publisher: Springer Science and Business Media LLC
Date: 11-2005
DOI: 10.1007/S11103-005-0828-Z
Abstract: The cryptochromes are a family of blue light photoreceptors that play important roles in the control of plant development. We have characterised the cryptochrome gene family in the model legume garden pea (Pisum sativum L.). Pea contains three expressed cryptochrome genes a single CRY1 orthologue, and two distinct CRY2 genes that we have termed CRY2a and CRY2b. Genomic southern blots indicate that there are unlikely to be more CRY genes in pea. Each of the three genes encodes a full-length CRY protein that contains all the major domains characteristic of other higher plant cryptochromes. Database searches have identified Medicago truncatula expressed sequence tags (ESTs) corresponding to all three genes, whereas only a single CRY2 is represented in EST collections from the more distantly related legumes soybean and Lotus japonicus. The proteins encoded by the pea and Medicago CRY2b genes are distinguished from other CRY2 proteins by their shorter C-terminus. Expression analyses have identified marked differences in the regulation of the three genes, with CRY2b expression in particular distinguished by high- litude diurnal cycling and rapid repression in seedlings transferred from darkness to blue light.
Gibberellins promote nodule organogenesis but inhibit the infection stages of nodulation
Publisher: Oxford University Press (OUP)
Date: 08-02-2018
DOI: 10.1093/JXB/ERY046
The role of CLV1, CLV2 and HPAT homologues in the nitrogen‐regulation of root development
Publisher: Wiley
Date: 16-09-2020
DOI: 10.1111/PPL.13200
Role of Plant Hormones and Small Signalling Molecules in Nodulation Under P Stress
Publisher: Springer International Publishing
Date: 2017
Common and divergent shoot–root signalling in legume symbioses
Publisher: Wiley
Date: 11-12-2015
DOI: 10.1111/NPH.13779
Abstract: The role of shoot–root signals in the control of nodulation and arbuscular mycorrhizal ( AM ) development were examined in the ergent legume species pea and blue lupin. These species were chosen as pea can host both symbionts, whereas lupin can nodulate but has lost the ability to form AM . Intergeneric grafts between lupin and pea enabled examination of key long‐distance signals in these symbioses. The role of strigolactones, auxin and elements of the autoregulation of nodulation ( AON ) pathway were investigated. Grafting studies were combined with loss‐of‐function mutants to monitor symbioses (nodulation, AM ) and hormone effects (levels, gene expression and application studies). Lupin shoots suppress AM colonization in pea roots, in part by downregulating strigolactone exudation involving reduced expression of the strigolactone biosynthesis gene Ps CCD 8 . By contrast, lupin shoots enhance pea nodulation, independently of strigolactones, possibly due to a partial incompatibility in AON shoot–root signalling between pea and lupin. This study highlights that nodulation and AM symbioses can be regulated independently and this may be due to long‐distance signals, a phenomenon we were able to uncover by working with ergent legumes. We also identify a role for strigolactone exudation in determining the status of non‐ AM hosts.
Relationship between gibberellin, ethylene and nodulation in Pisum sativum
Publisher: Wiley
Date: 18-11-2010
DOI: 10.1111/J.1469-8137.2010.03542.X
Abstract: • Gibberellin (GA) deficiency resulting from the na mutation in pea (Pisum sativum) causes a reduction in nodulation. Nodules that do form are aberrant, having poorly developed meristems and a lack of enlarged cells. Studies using additional GA-biosynthesis double mutants indicate that this results from severe GA deficiency of the roots rather than simply dwarf shoot stature. • Double mutants isolated from crosses between na and three supernodulating pea mutants exhibit a supernodulation phenotype, but the nodule structures are aberrant. This suggests that severely reduced GA concentrations are not entirely inhibitory to nodule initiation, but that higher GA concentrations are required for proper nodule development. • na mutants evolve more than double the amount of ethylene produced by wild-type plants, indicating that low GA concentrations can promote ethylene production. The excess ethylene may contribute to the reduced nodulation of na plants, as application of an ethylene biosynthesis inhibitor increased na nodule numbers. However, these nodules were still aberrant in structure. • Constitutive GA signalling mutants also form significantly fewer nodules than wild-type plants. This suggests that there is an optimum degree of GA signalling required for nodule formation and that the GA signal, and not the concentration of bioactive GA per se, is important for nodulation.
The influence of ethylene, gibberellins and brassinosteroids on energy and nitrogen-fixation metabolites in nodule tissue
Publisher: Elsevier BV
Date: 04-2021
Ethylene Signaling Influences Light-Regulated Development in Pea
Publisher: Oxford University Press (OUP)
Date: 19-03-2015
DOI: 10.1104/PP.15.00164
Feedback Regulation of Xylem Cytokinin Content Is Conserved in Pea and Arabidopsis
Publisher: Oxford University Press (OUP)
Date: 02-02-2007
Right time, right place: The dynamic role of hormones in rhizobial infection and nodulation of legumes
Publisher: Elsevier BV
Date: 09-2022
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