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Determining the site of action of strigolactones during nodulation


McAdam, EL and Hugill, C and Fort, S and Samian, E and Cottaz, S and Davies, NW and Reid, JB and Foo, E, Determining the site of action of strigolactones during nodulation, Plant Physiology, 174, (3) pp. 1-16. ISSN 0032-0889 (2017) [Refereed Article]


Copyright Statement

Copyright 2017 American Society of Plant Biologists

DOI: doi:10.1104/pp.17.00741


Strigolactones (SLs) influence the ability of legumes to associate with nitrogen-fixing bacteria. In this study we determine the precise stage at which SLs influence nodulation. We show that SLs promote infection thread formation, as a null SL-deficient pea (Pisum sativum) mutant forms significantly less infection threads than wild type plants and this reduction can be overcome by the application of the synthetic SL GR24. We found no evidence that SLs influence physical events in the plant before or after infection thread formation, since SL-deficient plants displayed a similar ability to induce root hair curling in response to rhizobia or lipochito-oligosaccharides (LCOs) and SL-deficient nodules appear to fix nitrogen at a similar rate to wild type plants. In contrast, a SL receptor mutant displayed no decrease in infection thread formation or nodule number, suggesting SL-deficiency may influence the bacterial partner. We found this influence of SL-deficiency was not due to altered flavonoid exudation or ability of root exudates to stimulate bacterial growth. The influence of SL-deficiency on infection thread formation was accompanied by reduced expression of some early nodulation (ENOD) genes. Importantly, SL synthesis is down-regulated by mutations in genes of the Nod LCO signalling pathway and this requires the downstream transcription factor NSP2 but not NIN. This, together with the fact that the expression of certain SL biosynthesis genes can be elevated in response to rhizobia/Nod factors suggests that Nod LCOs may induce SL biosynthesis. SLs appear to influence nodulation independently of ethylene action, as SL-deficient and ethylene insensitive double mutant plants display essentially additive phenotypes and we found no evidence that SLs influence ethylene synthesis or vice versa.

Item Details

Item Type:Refereed Article
Keywords:strigolactone, nodulation, infection thread, pea, hormone
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant physiology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Environmentally sustainable plant production
Objective Field:Environmentally sustainable plant production not elsewhere classified
UTAS Author:McAdam, EL (Dr Erin McAdam)
UTAS Author:Hugill, C (Miss Cassandra Hugill)
UTAS Author:Davies, NW (Associate Professor Noel Davies)
UTAS Author:Reid, JB (Professor Jim Reid)
UTAS Author:Foo, E (Associate Professor Eloise Foo)
ID Code:119322
Year Published:2017
Funding Support:Australian Research Council (FT140100770)
Web of Science® Times Cited:34
Deposited By:Plant Science
Deposited On:2017-07-31
Last Modified:2018-05-07
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