Plant lysin motif extracellular proteins are required for arbuscular mycorrhizal symbiosis

Abstract

Arbuscular mycorrhizal fungi (AMF) can form a mutually beneficial symbiotic relationship with most land plants. They are known to secrete lysin motif (LysM) effectors into host root cells for successful colonization. Intriguingly, plants secrete similar types of LysM proteins; however, their role in plant–microbe interactions is unknown. Here, we show that Medicago truncatula deploys LysM extracellular (LysMe) proteins to facilitate symbiosis with AMF. Promoter analyses demonstrated that three M. truncatula LysMe genes MtLysMe1/2/3 , are expressed in arbuscule-containing cells and those adjacent to intercellular hyphae. Localization studies showed that these proteins are targeted to the periarbuscular space between the periarbuscular membrane and the fungal cell wall of the branched arbuscule. M. truncatula mutants in which MtLysMe2 was knocked out via CRISPR/Cas9-targeted mutagenesis exhibited a significant reduction in AMF colonization and arbuscule formation, whereas genetically complemented transgenic plants restored wild-type level AMF colonization. In addition, knocking out the ortholog of MtLysMe2 in tomato resulted in a similar defect in AMF colonization. In vitro binding affinity precipitation assays suggested binding of MtLysMe1/2/3 with chitin and chitosan, while microscale thermophoresis (MST) assays revealed weak binding of these proteins with chitooligosaccharides. Moreover, application of purified MtLysMe proteins to root segments could suppress chitooctaose (CO8)-induced reactive oxygen species production and expression of reporter genes of the immune response without impairing chitotetraose (CO4)-triggered symbiotic responses. Taken together, our results reveal that plants, like their fungal partners, also secrete LysM proteins to facilitate symbiosis establishment.

Genome-Wide Identification and Evolutionary Analysis of Receptor-like Kinase Family Genes Provides Insights into Anthracnose Resistance of Dioscorea alata

“…The RLK gene family represents one of the largest gene families within the plant genome and is also one of the major types of plant receptors responsible for the perception of diverse self and alien signals from abiotic and biotic stresses [19,30,31]. The comprehensive analysis of RLK genes in an increasing number of sequenced plant genomes has not only contributed to a better understanding of the origin, evolution, and functional divergence of this important gene family but has also provided invaluable resources for the identification of functional genes that are valuable for crop breeding [32][33][34][35][36][37]. In this study, the genome-wide identification and evolutionary analysis of RLK genes from D. alata provides additional insights into the evolution and functional roles of the RLK gene family, including its ancient divergence by means of considerable WGDs/SDs, rapid "birth to death" during speciation, and potential roles in disease resistance against anthracnose.…”

Wall‐associated kinase GhWAK13 mediates arbuscular mycorrhizal symbiosis and Verticillium wilt resistance in cotton

“…Yu et al . (2023) reported that chitin binds to lysM extracellular (LysMe) MtLysMe1/2/3 to impair the immune response. GhWAK7A was used to represent the immune response (Wang et al ., 2020).…”

“…Zeng et al (2020) found that the LysM domain protein, RiSLM, C. reported that OsMYR1, a receptor-like kinase involved in AM fungal recognition, negatively regulates resistance to the fungal pathogen Magnaporthe oryzae and that the resistance gene OsCEBiP also negatively affects AM symbiosis (C. . Yu et al (2023) reported that chitin binds to lysM extracellular (LysMe) MtLysMe1/2/3 to impair the immune response. GhWAK7A was used to represent the immune response (Wang et al, 2020).…”

A receptor required for chitin perception facilitates arbuscular mycorrhizal associations and distinguishes root symbiosis from immunity

“… 7 To establish a successful infection in plant roots, AMF can suppress plant immunity through LCO, short-chain CO, or secreted effectors and proteins. 7 , 40 , 46 , 47 , 48 , 49 However, how plants discriminate between the activation of immunity and symbiosis signaling remains unknown.…”