Microbe‐derived non‐necrotic glycoside hydrolase family 12 proteins act as immunogenic signatures triggering plant defenses

Abstract

Plant pattern recognition receptors (PRRs) are sentinels at the cell surface sensing microbial invasion and activating innate immune responses. During infection, certain microbial apoplastic effectors can be recognized by plant PRRs, culminating in immune responses accompanied by cell death. However, the intricated relationships between the activation of immune responses and cell death are unclear. Here, we studied the glycoside hydrolase family 12 (GH12) protein, Ps109281, secreted by Phytophthora sojae into the plant apoplast during infection. Ps109281 exhibits xyloglucanase activity, and promotes P. sojae infection in a manner dependent on the enzyme activity. Ps109281 is recognized by the membrane‐localized receptor‐like protein RXEG1 and triggers immune responses in various plant species. Unlike other characterized GH12 members, Ps109281 fails to trigger cell death in plants. The loss of cell death induction activity is closely linked to a sequence polymorphism at the N‐terminus. This sequence polymorphism does not affect the in planta interaction of Ps109281 with the recognition receptor RXEG1, indicating that cell death and immune response activation are determined using different regions of the GH12 proteins. Such GH12 protein also exists in other Phytophthora and fungal pathogens. Taken together, these results unravel the evolution of effector sequences underpinning different immune outputs.

Host-pathogen interaction between pitaya and Neoscytalidium dimidiatum reveals the mechanisms of immune response associated with defense regulators and metabolic pathways

“…Pectinases ( EVM000744 , EVM003060 ), keratinases ( EVM001395 ), glycoside hydrolases ( EVM004934 ), and necrotic and ethylene-inducible proteins ( EVM008162 ) appeared to be up-regulated in expression. These proteins are typical virulence factors that have already been demonstrated in U. virens and Phytophthora [ 43 , 44 ]. Our next step will be to investigate the function of these individual genes in the infestation of pitaya by N. dimidiatum .…”

Tilletia horrida glycoside hydrolase family 128 protein, designated ThGhd_7, modulates plant immunity by blocking reactive oxygen species production

“…According to genomic annotation, the genome of T. horrida encodes five GH proteins (Wang et al, 2018), but their functions in T. horrida –host interactions have not been identified. Several studies have shown that GH family proteins are secreted proteins that play crucial roles in the interactions between pathogens and plants (Liu et al, 2023; Wang et al, 2022a; Yuan et al, 2022). However, there were few studies on GH128 family proteins in pathogenic fungi, especially in Tilletia fungi.…”

“…For example, the EIX‐like protein from V. dahliae is recognised as a PAMP by N. benthamiana NbEIX2 (Yin et al, 2021), and the GH12 protein PsXEG1 from P. sojae is recognised as a PAMP by the N. benthamiana leucine‐rich repeat receptor‐like protein (LRR‐RLP) RXEG1 and induces an immune response (which can be inhibited by pathogen RXLR effectors). Additionally, the GH12 protein Ps109281 from P. sojae is recognised as a PAMP by RXEG1 and induces immune responses in plants, though it fails to cause cell death in plants (Wang et al, 2022a), thereby differing from the other GH12 proteins mentioned above. Recently, the GH42 protein UvGHF1 from Ustilaginoidea virens was found to be an essential virulence factor and is recognised ad a PAMP in N. benthamiana and rice (Zou et al, 2023).…”

The elicitor VP2 from Verticillium dahliae triggers defence response in cotton

“…The coevolution between host plants and their pathogens is a dynamic process (Woolhouse et al ., 2002 ). This competitive evolution drives frequent changes in the gene sequence and promoter, such as single‐nucleotide polymorphisms (SNPs), insertion, and deletion, making these genes highly polymorphic (Guttman et al ., 2014 ; Wang et al ., 2022b ). For example, the serine substitution of glycine in Phytophthora avirulence effector PsAvr3c leads to evasion of Rps3c‐mediated soybean immunity (Huang et al ., 2018 ).…”

“…For example, the serine substitution of glycine in Phytophthora avirulence effector PsAvr3c leads to evasion of Rps3c‐mediated soybean immunity (Huang et al ., 2018 ). The secreted protein Ps109281 of Phytophthora sojae , due to its N‐terminal sequence polymorphism, cannot trigger plant cell death like other GH12 members (Wang et al ., 2022b ). In addition, the resistance‐breaking isolates carrying unexpressed alleles evades being recognized by RPP4‐containing Arabidopsis (Asai et al ., 2018 ).…”