ABSTRACT
Anthocyanin biosynthesis is regulated by regulatory genes encoding transcription factors which control expression of several structural genes in the anthocyanin pathway. The OSB2 gene encoding a Myc-type basic-helix-loop-helix (bHLH) transcription factor which regulates anthocyanin biosynthesis was previously cloned from a Thai black rice variety Khum. In this study, the cloned OSB2 gene was transformed into two white rice varieties Nipponbare and Taichung 65 using Agrobacterium to study the regulation of anthocyanin biosynthesis in rice. The semi-quantitative RT-PCR analysis revealed that transgenic rice plants overexpressing the OSB2 gene up-regulated the expression of some structural genes in anthocyanin biosynthesis including early biosynthesis gene (EBG) i.e. F3H (flavanone 3-hydroxylase) and also late biosynthesis genes (LBGs) i.e. DFR (dihydroflavonol 4-reductase) and ANS (anthocyanidin synthase). The present results support the other evidences that the regulatory mechanism of anthocyanin biosynthesis in rice may be different from other plants in which EBGs and LBGs were regulated separately. The results provide the understanding of functions of OSB2 gene in regulation of anthocyanin biosynthesis pathway in rice and will be useful to apply this gene as a marker gene for the improvement of rice varieties.
KEYWORDS
Anthocyanin biosynthesis; OSB2 gene; Oryza sativa; Transformation; Agrobacterium