[Identification of the HaWRI1 gene family in sunflower and functional characterization of HaWRI1-28 in oil biosynthesis].

Sunflower (Helianthus annuus L.) is one of the four major oilseed crops worldwide. Its oil has important applications in the food industry and other industrial sectors, and its production and quality are receiving growing attention. WRINKLED1 (WRI1) is an important transcription factor that regulates plant oil production. However, no research on the WRI1 gene family in sunflower has been conducted to date. Therefore, this study aimed to systematically identify members of the WRI1 gene family in sunflower, analyze their phylogenetic characteristics and expression patterns, and further clarify the roles of key genes in seed oil accumulation, thereby providing a theoretical basis and candidate gene resources for the molecular breeding of high-oil sunflower varieties. This study identified 28 HaWRI1 genes in the sunflower genome. These genes were classified into four subfamilies based on phylogenetic relationships, conserved motifs, and gene structure analysis. Intra- and inter-specific collinearity analysis revealed that gene duplication events may have contributed to the functional divergence within this gene family. Further transcriptomic data revealed that HaWRI1 genes were dynamically expressed at different stages of sunflower seed development. Among them, the expression pattern of HaWRI1-28 was highly consistent with the trend of seed oil accumulation. Transient expression assays in tobacco showed that HaWRI1-28 was localized in the nucleus. Heterologous overexpression of HaWRI1-28 in Arabidopsis thaliana significantly increased seed oil content (by 6.96%-13.04%) and seed weight (by 32.2%), while also upregulating the expression of multiple genes associated with fatty acid biosynthesis. Taken together, these results indicate that HaWRI1-28 is a crucial regulator of oil synthesis in sunflower seeds, and these findings provide valuable candidate gene resources for improving oil yield in oilseed crops.