ABSTRACT Glomerella leaf spot (GLS) caused by Colletotrichum spp. is a new disease of apple that causes massive defoliation and fruit spot symptoms. The disease significantly impacts fruit quality and presents a considerable risk to the apple industry. BAK1 is an important immunity‐related protein in plant defence systems. Previous research has reported that BAK1 confers resistance to Colletotrichum higginsianum in Arabidopsis thaliana , but whether it can confer resistance to GLS in apple is not known. The MdBAK1 gene from GL‐3 apple was cloned and a comprehensive analysis of its gene sequence, protein structure, expression characteristics and ability to confer resistance to GLS was performed. The results indicated that the expression level of the MdBAK1 gene was upregulated in response to infection by Colletotrichum fructicola . Furthermore, overexpression of the MdBAK1 gene not only significantly enhanced resistance of apple to C. fructicola but also promoted the expression of defence‐related genes. These findings indicate that MdBAK1 plays a critical role in conferring resistance to GLS in apples.
Guo et al. (2026) studied this question.