Putative LysM Effectors Contribute to Fungal Lifestyle

Abstract

Fungal LysM effector proteins can dampen plant host–defence responses, protecting hyphae from plant chitinases, but little is known on these effectors from nonpathogenic fungal endophytes. We found four putative LysM effectors in the genome of the endophytic nematophagous fungus Pochonia chlamydosporia (Pc123). All four genes encoding putative LysM effectors are expressed constitutively by the fungus. Additionally, the gene encoding Lys1—the smallest one—is the most expressed in banana roots colonised by the fungus. Pc123 Lys1, 2 and 4 display high homology with those of other strains of the fungus and phylogenetically close entomopathogenic fungi. However, Pc123 Lys3 displays low homology with other fungi, but some similarities are found in saprophytes. This suggests evolutionary divergence in Pc123 LysM effectors. Additionally, molecular docking shows that the NAcGl binding sites of Pc123 Lys 2, 3 and 4 are adjacent to an alpha helix. Putative LysM effectors from fungal endophytes, such as Pc123, differ from those of plant pathogenic fungi. LysM motifs from endophytic fungi show clear conservation of cysteines in Positions 13, 51 and 63, unlike those of plant pathogens. LysM effectors could therefore be associated with the lifestyle of a fungus and give us a clue of how organisms could behave in different environments.

Colletotrichum gloeosporioides Cg2LysM contributed to virulence toward rubber tree through affecting invasive structure and inhibiting chitin-triggered plant immunity

“…The LysM-containing effectors, such as Slp1 in Magnaporthe oryzae, ChELP1 and ChELP2 in Colletotrichum higginsianum, Vd2LysM in Verticillium dahliae, RsLysM in Rhizoctonia solani, Mgx1LysM in Zymoseptoria tritici, had been proved to contribute to virulence by disturbing the activation of chitin-triggered immunity (Mentlak et al, 2012;Takahara et al, 2016;Kombrink et al, 2017;Dolfors et al, 2019;Tian et al, 2021). The evolutionary study from 57 endophytes and fungi with diverse lifestyles showed that LysM effectors contributed to fungal lifestyle (Suarez-Fernandez et al, 2021). Additionally, RiSLM, a secreted LysM effector from arbuscular mycorrhiza (AM) fungal species Rhizophagus irregularis, protected fungal cell walls from chitinase by binding to chitin oligosaccharides and effectively interfere with chitin-triggered immune response to subvert chitintriggered immunity during symbiosis (Gust et al, 2012;Zeng et al, 2020).…”

Microbiota manipulation through the secretion of effector proteins is fundamental to the wealth of lifestyles in the fungal kingdom

“… 2020 , Suarez-Fernandez et al . 2021 ). Findings like these indicate that effectors are not (plant) symbiont-specific inventions to mediate (plant) host colonization, but should rather be seen as molecules that are secreted by fungi in order to manipulate their environment to their benefit.…”

Leveraging genomics to understand the broader role of fungal small secreted proteins in niche colonization and nutrition

“…Candidate effector proteins have also been found in the genomes of fungi from all lifestyles, including saprotrophic fungi [ 11 , 12 ]. Likewise, it was originally assumed that effectors were fast-evolving genes with minimal homology across species, however, the increased availability of sequenced fungal genomes has shown conservation of some of these sequences across a broader range of fungi than expected [ 5 , 11 , 13 , 14 ]. While candidate effectors are more abundant in biotrophic fungi [ 4 ], the genomic content and evolution of these effectors are more likely to be influenced by lineage than lifestyle [ 2 ].…”