Tomato LysM Receptor-Like Kinase SlLYK12 Is Involved in Arbuscular Mycorrhizal Symbiosis

Abstract

Arbuscular mycorrhiza (AM) is a widespread symbiotic relationship between plants and fungi (Glomeromycota), which improves the supply of water and nutrients to host plants. AM symbiosis is set in motion by fungal chitooligosaccharides and lipochitooligosaccharides, which are perceived by plant-specific LysM-type receptor kinases (LYK). In rice this involves OsCERK1, a LYK also essential for chitin triggered innate immunity. In contrast in legumes, the CERK1 homologous gene experienced duplication events resulting in subfunctionalization. However, it remains unknown whether this subfunctionalization is legume-specific, or has occurred also in other dicot plant species. We identified four CERK1 homologs in tomato (SlLYK1, SlLYK11, SlLYK12, and SlLYK13) and investigated their roles in chitin signaling and AM symbiosis. We found that knockdown of SlLYK12 in tomato significantly reduced AM colonization, whereas chitin-induced responses were unaffected. In contrast, knockdown of SlLYK1 resulted in reduced responses to chitin, but did not alter responses to AM fungi. Moreover, ectopic overexpression of SlLYK1 and SlLYK13 in Nicotiana benthamiana induced cell death, whereas SlLYK12 overexpression did not. Based on our results and comparison with rice OsCERK1, we hypothesize that OsCERK1 orthologs in tomato underwent gene duplication, leading to the subfunctionalization of immunity and symbiosis.

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

“…Therefore, knockdown of SlLYK12 led to reduced AM colonisation, but CO-induced responses are not affected. Inversely, knock-down of SlLYK1 leads to reduced CO responses, but no AM phenotype (Liao et al, 2018). Therefore, CO-triggered immunity is also apparently not required for mycorrhization in tomato.…”

Diversity, Function and Regulation of Cell Surface and Intracellular Immune Receptors in Solanaceae

“…These ligands could be proteinaceous, as in the case of pathogen-derived flagellin epitopes (flg22 and flgII-28) or host-derived systemin [6][7][8]. They could be carbohydrate-based or lipid-based, as in the case of pathogen-derived chitin and lipopolysaccharide [9,10]. Finally, although they have not been demonstrated in solanaceous plants yet, these ligands could also be nucleotide-based, as in the case of pathogen-derived RNAs or host-derived ATP [11,12].…”

“…Homodimerization has been demonstrated during the perception of chitin by Arabidopsis CERK1, which is a member of the LysM family of RLKs [13]. One of the tomato CERK1 homologs is SlLYK1, which is involved in chitin-induced responses [9]. Two other tomato CERK1 homologs Bti9 and SlLyk13 are known to be targets of the bacterial virulence effector AvrPtoB and play a role in plant immunity [14].…”

The LYSIN MOTIF‐CONTAINING RECEPTOR‐LIKE KINASE 1 protein of banana is required for perception of pathogenic and symbiotic signals

“…Indeed, the LCO receptor proteins MtNFP in M. truncatula and LjNFR1 in L. japonicus are required for Myc-LCO-induced Ca spiking and subsequent transcriptional changes (Maillet et al, 2011;Czaja et al, 2012;Sun et al, 2015;Zhang et al, 2015). Similarly, orthologs of MtNFP/LjNFR5 and OsCERK1 in tomato (SILYK10 and SlLYK12) are required for successful AM colonization (Buendia et al, 2016;Liao et al, 2018). However, Myc-COs activate AM-specific nuclear Ca spiking in legume and nonlegume roots independently of the NFP/NFR5 receptor proteins (Genre et al, 2013;Sun et al, 2015;Carotenuto et al, 2017).…”