A myelocytomatosis transcription factor from Hevea brasiliensis positively regulates the expression of the small rubber particle protein gene

Abstract

Small rubber particle protein (SRPP) is a major rubber particle-associated protein in latex from rubber tree (Hevea brasiliensis Muell. Arg.), and it implicated in the natural rubber biosynthesis. However, the regulatory mechanism of H. brasiliensis SRPP gene (HbSRPP) is incompletely understood. In this study, a myelocytomatosis (MYC) transcription factor (designated as HbMYC2b) regulating the HbSRPP expression was identified. HbMYC2b possesses a 2037 bp open reading frame that encodes 681 amino acids. The HbMYC2b protein has a basic helix-loop-helix (bHLH)-leucine zipper domain, and a bHLH-MYC-N domain. The highest expression of HbMYC2b is observed in the bark followed by the latex, flowers, and leaves. HbMYC2b significantly increases the activity of the HbSRPP promoter, suggesting that HbMYC2b activates this promoter. HbMYC2b may be a positive regulator of HbSRPP in rubber tree.