Unraveling GhMYB102: A Dual-Function of the Gh_A01G069800 Gene in Promoting Anthocyanin Biosynthesis Inhibition, and Drought Tolerance in Cotton

Background Cotton plants display significant genetic diversity in petal color, which is essential for resilience against pests and diseases, UV radiation mitigation, and pollinator attraction. The MYB gene family regulates anthocyanin biosynthesis, but the specific functions of the 4th subfamily remain poorly understood in floral color formation. Methods This study focuses on the MYB gene Gh_A01G069800, evaluating its impact on floral pigmentation using virus-induced gene silencing (VIGS). Results The results showed that VIGS plants exhibited higher pigment intensity across four cotton varieties, with the highest anthocyanin levels recorded in Zhongyihong (5.5 nmol/g) and Y52 (5.7 nmol/g), surpassing their wild types. In contrast, overexpression (OE) of Gh_A01G069800 resulted in lower pigmentation (3.0 nmol/g) compared to wild types and mutants, which had anthocyanin levels of 4.0 and 7.5 nmol/g, respectively. Gene expression analysis revealed that while chalcone synthase (CHS) and flavonoid glycosyltransferase (UFGT) were highly upregulated in wild types, genes like chalcone isomerase (CHI), flavonoid-3-hydroxylase (F3H), dihydroflavonol-4-reductase (DFR), and anthocyanin synthase (ANS) showed elevated expression in VIGS plants, suggesting Gh_A01G069800's inhibitory role in anthocyanin biosynthesis. Furthermore, GhMYB102 was shown to directly inhibit CHI, ANS, and F3'5'H expression, affecting anthocyanin synthesis. Overall, Gh_A01G069800 appears to play a crucial role in regulating floral color and enhancing drought stress tolerance in cotton plants.