Inhibition of PbeXTH1 and PbeSEOR1 is required for the Valsa canker resistance contributed by Wall-associated kinase gene MbWAK1

Abstract

Wall-associated kinases (WAKs) were determined the role for perceiving pathogenic signals and initiation of plant immune responses. However, the roles of the family members in host resistance against Valsa canker, a serious fungal disease of apple and pear, are largely unknown. Here, we identified MbWAK1in Malus baccata, a resistant germplasm, was differentially expressed during infection by Valsa mali (Vm) and multiple stress-related signals. Over-expression MbWAK1 enhanced the Valsa canker resistance of apple and pear fruits and ‘Duli-G03’ (Pyrus betulifolia) suspension cells. A large number of phloem, cell wall and lipid metabolic process-related genes were differentially expressed during overexpressed suspension cells lines respond to Valsa pyri (Vp) signals. Among these, the expression of xyloglucan endotransglucosylase/hydrolase gene PbeXTH1 and sieve element occlusion-related gene PbeSEOR1 were significantly inhibited. Transient expression of PbeXTH1 or PbeSEOR1 obviously compromised the expressional induction of MbWAK1 and the resistance contributed by MbWAK1. In addition, MbWAK1 interacted with PbeXTH1 and PbeSEOR1, as well as several patterns recognize receptors, such as MdBAK1 and MdCERK1. Our results enriched the molecular mechanisms for MbWAK1 against Valsa canker and resistant breeding.