LysM Receptor-Like Kinase LYK9 of Pisum Sativum L. May Regulate Plant Responses to Chitooligosaccharides Differing in Structure.

Irina V Leppyanen,Maria A Vashurina,Elena A Dolgikh,Oksana Y Shtark,Vyacheslav V Dolgikh,Andrey D Bovin,Igor V Sendersky,Olga A Pavlova,Igor A Tikhonovich,Alexandra V Dolgikh

doi:10.3390/ijms22020711

Abstract

This study focused on the interactions of pea (Pisum sativum L.) plants with phytopathogenic and beneficial fungi. Here, we examined whether the lysin-motif (LysM) receptor-like kinase PsLYK9 is directly involved in the perception of long- and short-chain chitooligosaccharides (COs) released after hydrolysis of the cell walls of phytopathogenic fungi and identified in arbuscular mycorrhizal (AM) fungal exudates. The identification and analysis of pea mutants impaired in the lyk9 gene confirmed the involvement of PsLYK9 in symbiosis development with AM fungi. Additionally, PsLYK9 regulated the immune response and resistance to phytopathogenic fungi, suggesting its bifunctional role. The existence of co-receptors may provide explanations for the potential dual role of PsLYK9 in the regulation of interactions with pathogenic and AM fungi. Co-immunoprecipitation assay revealed that PsLYK9 and two proposed co-receptors, PsLYR4 and PsLYR3, can form complexes. Analysis of binding capacity showed that PsLYK9 and PsLYR4, synthesized as extracellular domains in insect cells, were able to bind the deacetylated (DA) oligomers CO5-DA–CO8-DA. Our results suggest that the receptor complex consisting of PsLYK9 and PsLYR4 can trigger a signal pathway that stimulates the immune response in peas. However, PsLYR3 seems not to be involved in the perception of CO4-5, as a possible co-receptor of PsLYK9.

Highlights

To develop new approaches to regulating plant resistance or susceptibility to various microorganisms, their influence onto plants needs to be comprehensively investigated
This allowed us to verify the role of pea LysM-RLK PsLYK9 in interactions with phytopathogenic fungi and arbuscular mycorrhizal (AM) fungi
Chitin and chitosan derivatives such as their oligomers play an essential role in plant interactions with phytopathogenic and AM fungi

Summary

Introduction

To develop new approaches to regulating plant resistance or susceptibility to various microorganisms, their influence onto plants needs to be comprehensively investigated. Resistance to pathogens is determined by the plant’s capacity to recognize the surface components or secreted molecules of microorganisms, such as fungal chitin and chitooligosaccharides (COs), bacterial peptidoglycans, flagellins, the Tu elongation factor (EF-Tu), lipopolysaccharides (LPSs) and others. Such molecules are so-called microbeassociated molecular patterns (MAMPs) that are perceived by pattern recognition receptors (PRRs) [1,2]. The short-chain CO4–5 may stimulate the defense reactions in plants, albeit at an insignificant level [11] This finding demonstrates that the mechanisms by which the plants can distinguish such structurally related compounds are still not well understood. How these compounds are perceived by plants requires further investigation

Methods

Results

Conclusion