Ethylene mediates repression of anthocyanin accumulation in black rice pericarps in the absence of light.

Affiliation

DBT-AAU Centre, Assam Agricultural University Jorhat, 785013, India. Electronic address: [Email]

Abstract

The antioxidant properties of black rice are attributed to the high anthocyanin content in the pericarp. Light-dependent regulation of anthocyanin biosynthesis and the associated regulatory genes have been extensively studied in many plant species, including rice. Light is considered indispensable for anthocyanin accumulation in plants. Here, we report that anthocyanin biosynthesis and accumulation in the dark is negatively regulated by ethylene, as the ethylene biosynthesis inhibitor aminoethoxyvinylglycine hydrochloride (AVG)-treated samples in the dark exhibited significantly higher transcript levels of biosynthesis genes, including CHI, DFR, ANS, ANR, F3H, F'3H, CHS and UGFT, compared to untreated controls. Upregulation of these biosynthesis genes was accompanied by simultaneous de-repression of the R2-R3 domain and bHLH-containing transcription factors Kala3 and Kala4 at the transcript level. Additionally, bHLH152, which shows high similarity to Arabidopsis PIF3, is involved in the regulation of anthocyanin. These findings highlight the role of ethylene in modulating tissue-specific regulation of anthocyanin biosynthesis genes in the dark.

Keywords

AVG,Black rice,Dark,Ethylene,Kala3,Kala4,