Genome-wide analysis of the WRKY gene family in lily and functional characterization of LdWRKY87 in response to heat stress

Abstract

WRKY genes represent a major family of transcription factors that play key roles in regulating plant responses to both biotic and abiotic stresses. While WRKY genes have been extensively studied in various plant species, their functions in lily remain largely unknown. Here, we identified 115 WRKY family genes in the lily genome through bioinformatics analyses. These genes encode proteins ranging from 72 to 708 amino acids, with predicted isoelectric points between 4.90 and 11.06. Phylogenetic analysis grouped these LdWRKY genes into clusters Ⅰ, Ⅱ, and Ⅲ, and promoter analysis identified numerous cis-acting elements related to growth, development, and hormone and stress responses. Gene expression heatmaps revealed significant variation in the expression of LdWRKY family members across different tissues, with 62 out of 115 LdWRKYs showing differential expression under heat stress conditions. Using transcriptome data, we cloned the heat stress-responsive candidate gene LdWRKY87, which encodes a nuclear-localized protein with transcriptional repression activity. Transient transformation assays confirmed the role of LdWRKY87 in regulating lily heat tolerance. Further studies suggest that LdWRKY87 may modulate heat tolerance by affecting the expression of heat tolerance-related genes, such as LdHSFA2, LdHSP70, and LdMBF1c. These findings provide a foundation for future studies on the regulatory mechanisms of WRKY transcription factors in lily heat tolerance.