Mycosphaerella graminicola LysM Effector-Mediated Stealth Pathogenesis Subverts Recognition Through Both CERK1 and CEBiP Homologues in Wheat

Abstract

Fungal cell-wall chitin is a well-recognized pathogen-associated molecular pattern. Recognition of chitin in plants by pattern recognition receptors activates pathogen-triggered immunity (PTI). In Arabidopsis, this process is mediated by a plasma membrane receptor kinase, CERK1, whereas in rice, a receptor-like protein, CEBiP, in addition to CERK1 is required. Secreted chitin-binding lysin motif (LysM) containing fungal effector proteins, such as Ecp6 from the biotrophic fungus Cladosporium fulvum, have been reported to interfere with PTI. Here, we identified wheat homologues of CERK1 and CEBiP and investigated their role in the interaction with the nonbiotrophic pathogen of wheat Mycosphaerella graminicola (synonym Zymoseptoria tritici). We show that silencing of either CERK1 or CEBiP in wheat, using Barley stripe mosaic virus-mediated virus-induced gene silencing, is sufficient in allowing leaf colonization by the normally nonpathogenic M. graminicola Mg3LysM (homologue of Ecp6) deletion mutant, while the Mg1LysM deletion mutant was fully pathogenic toward both silenced and wild-type wheat leaves. These data indicate that Mg3LysM is important for fungal evasion of PTI in wheat leaf tissue and that both CERK1 and CEBiP are required for activation of chitin-induced defenses, a feature conserved between rice and wheat, and perhaps, also in other cereal species.

Genome expansion and lineage-specific genetic innovations in the forest pathogenic fungi Armillaria

“…1a, Supplementary Table 5). In other plant pathogens, these are involved in modifying fungal cell wall composition and/or capturing chitin residues to mask chitin-triggered immune signals and evade detection by the host plants [21][22][23][24][25] , suggesting similar roles in Armillaria.…”

Transcriptome and Metabolite Profiling of the Infection Cycle of Zymoseptoria tritici on Wheat Reveals a Biphasic Interaction with Plant Immunity Involving Differential Pathogen Chromosomal Contributions and a Variation on the Hemibiotrophic Lifestyle Definition

“…For Z. tritici to still require these pathways as long as 4 dpi suggests that it remains in a nutrient-limiting environment within the wheat leaf, which may be (at least in part) responsible for the limited increase in biomass seen during symptomless colonization. Fungus-secreted proteins are also prevalent among the up-regulated genes during this period, including previously characterized LysM effectors that function to suppress PAMP-triggered immunity (Marshall et al, 2011;Lee et al, 2014). Consequently, at 1 dpi, plant transcriptome analysis identified many defense-associated processes to be suppressed, possibly as a result of the functions of putative fungal-secreted protein effectors.…”

“…This growth is so slow that it has often proven difficult/impossible to detect significant increases in fungal biomass in infected tissue during this period (Kema et al, 1996;Pnini-Cohen et al, 2000;Keon et al, 2007). It was demonstrated recently that the function of a secreted LysM domain-containing Z. tritici effector protein, Mg3LysM, plays an important role in establishing this initial symptomless colonization through the suppression of chitin (PAMP) recognition by the wheat chitin elicitor binding protein (TaCEBiP) and chitin elicitor receptor kinase1 (TaCERK1; Marshall et al, 2011;Lee et al, 2014). However, at some point after 7 to 10 d post infection (dpi), and for reasons that are currently unclear, wheat cells then suddenly begin to die.…”

A Metabolic Gene Cluster in the Wheat W1 and the Barley Cer-cqu Loci Determines β-Diketone Biosynthesis and Glaucousness

“…BSMV:mcs4D, which contains noncoding sequence, was included in all VIGS experiments as a nonsilencing virus control. Transformation of the BSMV binary plasmids into Agrobacterium tumefaciens strain GV3101 and agroinfiltration into 3-to 4-week-old N. benthamiana plants were performed as described previously (Lee et al, 2014). Sap from the infiltrated N. benthamiana leaves was used to mechanically inoculate the third fully expanded leaf of 28-d-old wheat plants at the four-leaf stage.…”