Valsa mali secretes an effector protein VmEP1 to target a K homology domain‐containing protein for virulence in apple

Abstract

The K homology (KH) repeat is an RNA‐binding motif that exists in various proteins, some of which participate in plant growth. However, the function of KH domain‐containing proteins in plant defence is still unclear. In this study, we found that a KH domain‐containing protein in apple ( Malus domestica ), HEN4‐like (MdKRBP4), is involved in the plant immune response. Silencing of MdKRBP4 compromised reactive oxygen species (ROS) production and enhanced the susceptibility of apple to Valsa mali , whereas transient overexpression of MdKRBP4 stimulated ROS accumulation in apple leaves, indicating that MdKRBP4 is a positive immune regulator. Additionally, MdKRBP4 was proven to interact with the VmEP1 effector secreted by V. mali , which led to decreased accumulation of MdKRBP4. Coexpression of MdKRBP4 with VmEP1 inhibited cell death and ROS production induced by MdKRBP4 in Nicotiana benthamiana . These results indicate that MdKRBP4 functions as a novel positive regulatory factor in plant immunity in M. domestica and is a virulence target of the V. mali effector VmEP1.

An efficient screening system of disease-resistant genes from wild apple, Malus sieversii in response to Valsa mali pathogenic fungus

“…Inoculating leaves and twigs with mycelium plugs (M1) is a common method of introducing V. mali due to its uniformity [ 29 , 55 ]. Irrespective of its simplicity, fixing mycelial plugs to leaves and stems is a lengthy and time-consuming process.…”

Nucleic acid-binding KH domain proteins influence a spectrum of biological pathways including as part of membrane-localized complexes

“…Under long-night and short-day growing conditions a fly1 knockout mutant, and a FLY artificial microRNA knockdown line, flowered earlier than the wild type ( Dai et al, 2020 ). Yet another study demonstrated that HEN4-like (MdKRBP4), a KH domain-containing protein in apple, is involved in the plant’s immune response ( Wang et al, 2022 ).…”

Multi-Omics Approaches Provide New Insights into the Identification of Putative Fungal Effectors from Valsa mali

“…Previous studies have shown that the effector protein of V. mali plays a very important role in the process of infecting its host, and several effector proteins have been reported [16,17]. For example, the effector protein VmEP1 interacts with host MdPR10 protein, ultimately inhibiting the resistance mediated by MdPR10 against V. mali [18]. Another effector, Vm1G-1794, protects the aggregated MdEF-Tu from autophagic degradation to promote infection in apple [19].…”