PSY4-mediated carotenoid biosynthesis confers yellow anther and enhances heat tolerance in cotton

Carotenoids are lipophilic isoprenoid pigments with essential roles in plants. While the cultivated allotetraploid cottons exhibit distinct mature anther coloration — yellow in Gossypium barbadense versus predominantly white in G. hirsutum — the genetic basis of this divergence remains unclear. The purpose of this study was to identify the genetic basis of anther-color variation in cotton (Gossypium) species. We firstly identified carotenoids as the primary pigments underlying yellow-anthers coloration. Comparative transcriptomics of anthers revealed that the carotenoid biosynthesis gene GbPSY4 was expressed as a key regulator in G. barbadense. Functional validation via tissue-specific expression, subcellular localization, in vivo enzymatic assays, and virus-induced gene silencing confirmed its role in carotenoid biosynthesis and yellow pigmentation. Genome-wide association studies in a G. hirsutum population revealed GhPSY4_At, an ortholog of GbPSY4, as the causal gene of anther-color variation. We conclude that PSY4-regulated carotenoid biosynthesis governs yellow pigmentation. Furthermore, a finding that G. hirsutum accessions with yellow anthers showed greater pollen viability under high-temperature stress than those with white anthers suggests that the same pathway that governs yellow pigmentation influences heat tolerance. PSY4 is a promising target for breeding stress-tolerant cotton varieties.