Genome-wide identification and characterization of potato NRL gene family and functional analysis of StNRL-6 in response to Phytophthora infestans.

Abstract

NPH3/RPT2-Like (NRL) proteins, as blue light receptor phototropin-interacting modules, regulate various aspects of physiological responses in light signaling. However, little information is available on NRL family members regulating plant immunity, especially concerning plants' late blight resistance to Phytophthora infestans. In this study, a systematical analysis of the potato NRL family was performed. In total, 35 StNRL genes were identified and phylogenetically classified into six subfamilies. Twelve StNRL genes were defined as seven pairs of segmental duplication, which was the major evolutionary driving force for StNRL expansion. Synteny analysis between the genomes of potato and Arabidopsis thaliana, tomato, and rice provided insights into evolutionary characteristics. Two StNRL family members, StNRL-6 and StNRL-7, interacted with the blue light photoreceptor Stphot1 and negatively regulated potato and Nicotiana benthamiana resistance against P. infestans. Moreover, the key motif RxSxS identified in the NRL family member is essential for StNRL-6 to interact with Stphot1 and enhance plant susceptibility to P. infestans. This comprehensive analysis of the StNRL family provides valuable information to elucidate key molecular mechanisms on how blue light regulates plant immunity.