Genome-wide identification of papain-like cysteine protease family genes in cultivated peanut (Arachis hypogaea L.) and functional characterization of AhRD21B in response to chilling stress

Papain-like cysteine proteases (PLCPs) play essential roles in plant growth, senescence, and stress responses. However, researches on the PLCP genes are limited in cultivated peanut (Arachis hypogaea L.). Here, we identified and analyzed AhPLCP genes in cultivated peanut using bioinformatic approaches and verified the involvement of AhRD21B in response to chilling tolerance using an experimental test. We identified 52 AhPLCP genes in peanut genome and categorized them into eight subfamilies. Six tandem duplicated genes were identified in cultivated peanut. The promoters of AhPLCP genes contained many stress responsive elements. AhPLCP genes were generally expressed constitutively, and many AhPLCP genes were cold-responsive. Among these genes, heterologous expression of AhRD21B significantly increased the tolerance of transgenic Arabidopsis to cold compared with the wild-type plants. In addation, AhRD21B can regulate cold-related genes that participate in enhancing chilling tolerance in transgenic Arabidopsis. These findings provide valuable insights into the functions of AhPLCP genes in plant stress tolerance.