Figure 1.

The regulatory model controlling brown coloration by the MYB113 transcription factor. Light-responsive factor PIF4 binds to the G-Box region in the promoter of MYB113 to drive its expression. Afterward, MYB113 forms a protein complex with TT8 and activates the expression of anthocyanin biosynthesis genes, leading to the accumulation of anthocyanin and PA. The increased pigmentation produces red foliated cotton and brown fiber. Coding genes are depicted as bars with line and arrow showing promoter and transcription direction, respectively. Proteins are represented with circles.