MaMYB4, a R2R3-MYB repressor transcription factors, negatively regulates the biosynthesis of anthocyanin in banana

Anthocyanins are spatiotemporally accumulated in certain tissues of particular species in banana plant and are major regulated by MYB transcription factors. However, this precise regulatory mechanism in banana remain to be determined. Here we reported the identification and characterization of MaMYB4, a R2R3-MYB repressor transcription factor, which possess EAR (ethylene-responsive element binding factor-associated amphiphilic repression) and TLLLFR motifs. MaMYB4 expression was induced by the accumulation of anthocyanins. Transgenic banana plants overexpressing MaMYB4 displayed a significant reduction in anthocyanin compared to wildtype. To investigate the effect of overexpression MaMYB4 on the entire transcriptome, RNA-seq profiling was performed with the leaves of wild-type and MaMYB4-overexpressors as materials.

花青素（anthocyanins）在香蕉植株特定物种的特定组织中呈时空特异性积累，其生物合成主要受MYB转录因子（MYB transcription factor）调控。然而，香蕉中这一精确的调控机制仍有待阐明。本研究报道了R2R3型MYB抑制型转录因子MaMYB4的鉴定与功能表征，该因子含有EAR（乙烯响应元件结合因子相关两亲性抑制，ethylene-responsive element binding factor-associated amphiphilic repression）基序与TLLLFR基序。MaMYB4的表达可被花青素积累所诱导。与野生型植株相比，过表达MaMYB4的转基因香蕉植株的花青素含量显著降低。为探究过表达MaMYB4对全转录组的影响，本研究以野生型和MaMYB4过表达植株的叶片为材料，开展了RNA测序（RNA-seq）转录组分析。