Genome-wide identification of the WRKY gene family in apricot (Prunus armeniaca L.) and functional characterization of PaWRKY57 in salt stress tolerance

Soil salinization severely restricts the growth, yield, and industrial development of apricot ( Prunus armeniaca L.). WRKY transcription factors play crucial roles in plant responses to abiotic stresses. However, the genome-wide characteristics of the WRKY family in apricot and their functional mechanisms in salt tolerance remain unclear. In this study, we identified 58 PaWRKY genes in apricot and characterized their phylogeny, chromosomal distribution, and gene structure. Based on transcriptomic and phylogenetic analyses, PaWRKY57 (homologous to AtWRKY33 ) was selected as a key salt-responsive candidate gene. Heterologous overexpression of PaWRKY57 in tobacco significantly enhanced salt tolerance; compared with the wild type, the transgenic lines exhibited a higher germination rate, better growth phenotype, lower accumulation of malondialdehyde (MDA) and reactive oxygen species (ROS), higher proline content, and stronger activities of antioxidant enzymes (SOD, POD, and APX). Protein-protein interaction prediction showed PaWRKY57 interacts with MPK3/4/6 and other stress-related proteins, and GO enrichment implicated it in osmotic stress and protein phosphorylation. This study provides preliminary genetic resources and a theoretical basis for research on the molecular mechanism of salt tolerance and stress-resistant molecular breeding in apricot.