A putative elicitor CcHE1 from Cytospora chrysosperma enhances plant resistance to phytopathogenic fungi

Plant pathogens secrete a large number of effectors to host cells during the infection processes, which will manipulate plant immunity and promote fungal infection. Contrarily, some of the effectors can be recognized by the host plants, and then activate the immunity reactions. Therefore, unveiling the critical roles of effectors during the pathogen-plant interactions will benefit disease control.

In this study, we screened and identified a candidate effector, CcHE1, from Cytospora chrysosperma, the main agent of wood canker disease and causes serious loss annually in China. Transient expression of CcHE1 in N. benthamiana leaves showed that it triggered plant cell death in a dose-dependent manner. Subsequently, we found that infiltration injection of 5 μM CcHE1 into N. benthamiana and poplar leaves could not cause cell necrosis but triggered strong defense responses, including reactive oxygen species accumulation, callose deposition, and up-regulated expression of defense-related genes, and NbBAK1 and NbSOBIR1 are needed for plant defense response induced by CcHE1. Importantly, the CcHE1 could enhance the plant resistance to several tested pathogenic fungal species such as Botrytis cinerea, Colletotrichum gloeosporioides, C. chrysosperma, Botryosphaeria dothidea and Cryphonectria parasitica, but had no antifungal activity. Remarkably, deletion of CcHE1 did not affect the growth and pathogenicity of C. chrysosperma.

Our results found a putative elicitor CcHE1 which can induce plant immunity, and therefore improve plant broad-spectrum disease resistance. These results provide a new insight into disease control. © 2025 Society of Chemical Industry.