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Title: The Medicago truncatula LysM receptor‐like kinase LYK9 plays a dual role in immunity and the arbuscular mycorrhizal symbiosis

Plant ‐specific lysin‐motif receptor‐like kinases (LysM‐RLKs) are implicated in the perception ofN‐acetyl glucosamine‐containing compounds, some of which are important signal molecules in plant−microbe interactions. Among these, both lipo‐chitooligosaccharides (LCOs) and chitooligosaccharides (COs) are proposed as arbuscular mycorrhizal (AM) fungal symbiotic signals. COs can also activate plant defence, although there are scarce data about CO production by pathogens, especially nonfungal pathogens.

We testedMedicago truncatulamutants in the LysM‐RLK MtLYK9 for their abilities to interact with the AM fungusRhizophagus irregularisand the oomycete pathogenAphanomyces euteiches. This prompted us to analyse whetherA. euteichescan produce COs.

Compared with wild‐type plants,Mtlyk9mutants had fewer infection events and were less colonised by the AM fungus. By contrast,Mtlyk9mutants were more heavily infected byA. euteichesand showed more disease symptoms.Aphanomyces euteicheswas also shown to produce short COs, mainly CO II, but also CO III and CO IV, and traces of CO V, bothex plantaandin planta.

MtLYK9 thus has a dual role in plant immunity and the AM symbiosis, which raises questions about the functioning and the ancestral origins of such a receptor protein.

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Author(s) / Creator(s):
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Date Published:
Journal Name:
New Phytologist
Page Range / eLocation ID:
p. 1516-1529
Medium: X
Sponsoring Org:
National Science Foundation
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