Genome and Transcriptome Analysis of the Torreya grandis WRKY Gene Family during Seed Development

Abstract

Torreya grandis, an economically significant evergreen tree species exclusive to subtropical China, is highly valued for its seeds. However, the seed development process of T. grandis remains relatively unexplored. Given the pivotal role WRKY transcription factors (TFs) play in coordinating diverse cellular and biological activities, as well as crucial signaling pathways essential for plant growth and development, and the lack of comprehensive investigation into their specific functions in T. grandis, our study investigated its genome and successfully isolated 78 WRKY genes and categorized them into three distinct clades. A conserved motif analysis unveiled the presence of the characteristic WRKY domain in each identified TgWRKY protein. The examination of gene structures revealed variable numbers of introns (ranging from zero to eight) and exons (ranging from one to nine) among TgWRKY genes. A chromosomal distribution analysis demonstrated the presence of TgWRKY across eight chromosomes in T. grandis. Tissue-specific expression profiling unveiled distinctive patterns of these 78 TgWRKY genes across various tissues. Remarkably, a co-expression analysis integrating RNA-seq data and morphological assessments pinpointed the pronounced expression of TgWRKY25 during the developmental stages of T. grandis seeds. Moreover, a KEGG enrichment analysis, focusing on genes correlated with TgWRKY25 expression, suggested its potential involvement in processes such as protein processing in the endoplasmic reticulum, starch, and sucrose metabolism, thereby modulating seed development in T. grandis. These findings not only underscore the pivotal role of WRKY genes in T. grandis seed development but also pave the way for innovative breeding strategies.