Sorghum SbGhd7 is a major regulator of floral transition and directly represses genes crucial for flowering activation

Sorghum is multipurpose crop worldwide serving as food, feed, and feedstock for biofuels, whose floral transition and vegetative growth heavily depend on photoperiod. Although multiple sorghum maturity loci (Ma1-Ma6) have been associated with photoperiod sensitivity in previous QTL studies, the underlying molecular mechanisms remain poorly understood. By functional characterizing sorghum SbGhd7 (Ma6) and integrating RNA-seq analysis of Ghd7 overexpression sorghum, ChIP-seq analysis of SbGhd7 binding sites in protoplasts and molecular studies, we discovered that SbEhd1 and SbFT10 are the direct targets of SbGhd7. SbGhd7 is a transcriptional repressor and inhibits florigen-induced floral transition by repressing SbEhd1 and SbFT10 expression. Transient chromatin immunoprecipitation DNA-sequencing (transient ChIP-seq) for SbGhd7 in sorghum mesophyll protoplasts.

高粱（Sorghum）是一种全球多用途作物，可作为粮食、饲料及生物燃料原料，其成花转变与营养生长高度依赖光周期。此前的数量性状基因座（Quantitative Trait Locus, QTL）研究已将多个高粱成熟位点（Ma1-Ma6）与光周期敏感性相关联，但其潜在的分子机制仍不甚明晰。本研究通过对高粱SbGhd7（Ma6）开展功能鉴定，并整合过表达Ghd7的高粱的RNA测序（RNA-seq）分析、原生质体中SbGhd7结合位点的染色质免疫共沉淀测序（Chromatin Immunoprecipitation Sequencing, ChIP-seq）分析与分子生物学实验，发现SbEhd1与SbFT10是SbGhd7的直接靶基因。SbGhd7作为转录抑制因子，通过抑制SbEhd1与SbFT10的表达，阻遏成花素（florigen）所介导的成花转变。本研究同时在高粱叶肉原生质体中完成了针对SbGhd7的瞬时染色质免疫共沉淀测序（transient ChIP-seq）实验。