The Arabidopsis LYSIN MOTIF-CONTAINING RECEPTOR-LIKE KINASE3 Regulates the Cross Talk between Immunity and Abscisic Acid Responses    

Abstract

Transmembrane receptor-like kinases characterized by the presence of one or more lysin motif (LysM) domains in the extracytoplasmic portion (LysM-containing receptor-like kinases [LYKs]) mediate recognition of symbiotic and pathogenic microorganisms in plants. The Arabidopsis (Arabidopsis thaliana) genome encodes five putative LYKs; among them, AtLYK1/ CHITIN ELICITOR RECEPTOR KINASE1 is required for response to chitin and peptidoglycan, and AtLYK4 contributes to chitin perception. More recently, AtLYK3 has been shown to be required for full repression, mediated by Nod factors, of Arabidopsis innate immune responses. In this work, we show that AtLYK3 also negatively regulates basal expression of defense genes and resistance to Botrytis cinerea and Pectobacterium carotovorum infection. Enhanced resistance of atlyk3 mutants requires PHYTOALEXIN-DEFICIENT3, which is crucial for camalexin biosynthesis. The expression of AtLYK3 is strongly repressed by elicitors and fungal infection and is induced by the hormone abscisic acid (ABA), which has a negative impact on resistance against B. cinerea and P. carotovorum. Plants lacking a functional AtLYK3 also show reduced physiological responses to ABA and are partially resistant to ABA-induced inhibition of PHYTOALEXIN-DEFICIENT3 expression. These results indicate that AtLYK3 is important for the cross talk between signaling pathways activated by ABA and pathogens.

Plant cell wall‐mediated immunity: cell wall changes trigger disease resistance responses

“…In contrast, LYK3 seems to negatively regulate resistance to B. cinerea and P. carotovorum by controlling the balance between ABA‐dependent responses and pathogen resistance (Paparella et al ., ). Interestingly, LYK3 expression was repressed upon plant infection with these pathogens and upon treatment with OGs, chitin or flg22 (Paparella et al ., ). In contrast, LYK3 is the only LYK member whose expression is induced in response to A. brassicicola that is consistent with its positive function in the resistance of Arabidopsis to this fungus (Paparella et al ., ).…”

“…Interestingly, LYK3 expression was repressed upon plant infection with these pathogens and upon treatment with OGs, chitin or flg22 (Paparella et al ., ). In contrast, LYK3 is the only LYK member whose expression is induced in response to A. brassicicola that is consistent with its positive function in the resistance of Arabidopsis to this fungus (Paparella et al ., ).…”

Lipochitooligosaccharide recognition: an ancient story

“…l), ultimately leading to a suppression of innate immunity. Consistent with the negative role of AtLYK3 in plant innate immunity, Atlyk3 mutant plants are more resistant to the fungal pathogens Botrytis cinerea and Pectobacterium carotovorum (Paparella et al ., ). Although not directly tested, it is interesting to speculate that fungal pathogens may seek to counter chitin MTI by further hydrolyzing chitooligosacharides to produce short‐chain molecules that can suppress innate immunity.…”

Sustained exposure to abscisic acid enhances the colonization potential of the mutualist fungus Piriformospora indica on Arabidopsis thaliana roots

“…Furthermore, it is possible that ABA-responsive proteins interfere with the immune response. Recently, lysin motif-containing receptor-like kinase3 (AtLYK3), which represses PTI in A. thaliana, has been shown to mediate ABA-related responses and might play a crucial role in ABA-mediated repression of immunity (Liang et al, 2013;Paparella et al, 2014).…”