# Genome-Wide Characterization of WRKY Gene Family in Camellia chekiangoleosa Identifies Potential Regulatory Components in Pigment Biosynthesis Pathways

## TL;DR

This study identifies WRKY genes in Camellia chekiangoleosa that may regulate pigment production, offering new insights into fruit coloration mechanisms.

## Contribution

The study is the first to characterize WRKY genes in C. chekiangoleosa and link them to pigment biosynthesis pathways.

## Key findings

- 87 WRKY genes were identified and classified into six subgroups in C. chekiangoleosa.
- Five WRKY transcription factors were shown to bind to key pigment biosynthesis gene promoters.
- Three WRKY genes showed strong positive correlations with flavonoid accumulation.

## Abstract

The WRKY gene family is essential for controlling a variety of plant physiological functions, yet the involvement of specific WRKY members in pigment biosynthesis and accumulation in Camellia chekiangoleosa remains unexplored, particularly in anthocyanins and carotenoids, which play crucial roles in the pigmentation of C. chekiangoleosa. This study systematically identified 87 WRKY genes across 15 chromosomes in C. chekiangoleosa through bioinformatic approaches. Further structural and phylogenetic analyses of these TFs enabled their classification into six different subgroups. WRKY family expansion was shown to be mostly driven by tandem duplication. W-box elements, which can be binding sites for WRKY transcription factors, were present in a number of biosynthetic genes in the pigment production pathway. Yeast one-hybrid assay confirmed that five WRKY transcription factors (CchWRKY15/24/33/47/76) directly bind to the promoter regions of two key biosynthetic genes, CchPSY1 and Cch4CL1. Intriguingly, among the five WRKYs tested, the expression levels of CchWRKY15, CchWRKY33, and CchWRKY47 showed the strongest positive associations with flavonoid accumulation (p < 0.05, Pearson correlation analysis).These findings provide novel insights into the evolutionary patterns, transcriptional regulation, and functional characteristics of CchWRKYs, while elucidating their possible regulatory mechanisms in the fruit coloration of C. chekiangoleosa.