A MYB transcription factor containing fragment introgressed from Gossypium bickii confers pink flower on Gossypium hirsutum L.

Cotton is one of the most important multiple-usage crops, including fiber, oil, protein, and even ornament. Anthocyanins are the main chromogenic substances in plants, giving the floral organs of ornamental plants their bright colors. Here, we characterized a cotton accession (Gossypium hirsutum L.) showing pink petals with red spot at the base of petal. The pink flower (PF) accession is thought to be derived from interspecific cross between G. hirsutum and a diploid wild cotton species G. bickii native to Australia. We mapped the genetic region underlying the PF trait using bulked segregant RNA sequencing (BSR-Seq) and demonstrated introgression of a genomic region from G. bickii based on re-sequencing of the PF accession and comparative genomic analyses. The introgression fragment contains an R2R3-MYB gene (GH_A07G0851 or GhPF) homologous to GbBM regulating the formation of the red spots at the base of petals in G. barbadense. The coding region of GH_A07G0851 from the PF accession has a 15-bp deletion found only in Australian diploid wild cotton species, G. bickii, and G. australe, which possess light pink flowers with red spots at the base of petals. The temporal expression pattern of GH_A07G0851 tightly correlates with coloration of pink flowers during their development. The results demonstrate the importance of MYB gene in regulation of biosynthesis and accumulation of anthocyanins in cotton flowers and provide candidate gene for manipulating flower color, an important attribute that can facilitate the production of hybrid seeds through attracting pollinators for efficient pollen transfer so to enhance utilization of heterosis in cotton.