Candidate Genes for Brown Fiber in Cotton Revealed Among the R2R3-Myb and bHLH-Myc Gene Families

Abstract

Naturally colored cotton varieties attract investigators due to their eco-friendly and hypoallergenic properties. Genetic mechanisms, determining control of pigment biosynthesis pathway in cotton fiber, are being intensively studied nowadays. However, the knowledge, explaining control of proanthocyanidins accumulation in cotton fiber by the MBW complex (R2R3-Myb, bHLH-Myc and WD40), is insufficient. In this connection, we focused on the regulatory genes from a number of the most likely ones involved in proanthocyanidins biosynthesis. We used the Sanger sequencing approach to reveal the allelic diversity of the R2R3-Myb and bHLH-Myc genes among contrast genotype accessions including various fiber shades and hypocotyl color. Having used the number of bioinformatics tools, we concluded that the replacement of conserved tryptophan residue abolished the DNA-binding activity of the GhMYB10-A transcription factor and this, probably, can be associated with the light brown fiber phenotype. Deeper studies are required to definitely establish the GhMYB10-A function. However, our achievements can be practically applied in marker-assisted breeding of cotton varieties with naturally colored fiber.

Keywords

• R2R3-Myb
• bHLH-Myc
• MBW complex
• flavonoids
• proanthocyanidins
• naturally colored cotton