OsbZIP01 Affects Plant Growth and Development by Regulating OsSD1 in Rice

As the‘Green Revolution’gene,SD1(encoding GA20ox2),has been widely applied to improve yield in rice breeding.However,research on its transcriptional regulation is limited.Here,we identified a transcription factor OsbZIP01,which can suppress the expression of SD1 and regulate gibberellin(GA)biosynthesis in rice.Knockout mutants of OsbZIP01 exhibited increased plant height,while the overexpression lines showed a semi-dwarf phenotype and diminished germination rate.Furthermore,the semi-dwarf phenotype of OE-bZIP01,was caused by the reduced internode length,which was accompanied by a thin stem width.The predominant expression of OsbZIP01 was observed in leaves and sheaths.OsbZIP01 protein was localized in the nucleus and showed transcriptional repression activity.In addition,OsbZIP01 could directly bind to the promoter of the OsSD1 gene,and inhibit its transcription.The semi-dwarf phenotype of OE-bZIP01 could be rescued by exogenous GA_(3).Meanwhile,the bzip01 sd1 double mutant showed a shorter shoot length compared with the wild type,indicating that OsbZIP01 regulated plant growth mainly through the GA biosynthesis pathway.Collectively,OsbZIP01 negatively regulates GA biosynthesis by restraining SD1 transcription,thereby affecting plant growth and development.

一个新的黄瓜叶色突变体的光合特性分析

叶色突变体是研究植物光合系统结构与功能、叶绿素生物合成与代谢以及叶绿体发育的理想材料。该研究以黄瓜黄绿叶突变体C777及其野生型CCMC为试材,对其苗期叶片的光合色素质量分数、光合特性、叶绿素荧光参数等进行测定。结果表明,突变体叶绿素a、叶绿素b、类胡萝卜素以及总叶绿素质量分数均显著低于野生型;光合特性方面,突变体净光合速率显著低于野生型,而胞间CO_2浓度显著高于野生型,表明突变体对CO2的利用率较野生型低;叶绿素荧光动力学参数的测定结果表明,突变体的F_o、F_m、F_v/F_m、F′_v/F′_m、Φ_(PSⅡ)、qP、ETR和NPQ均显著降低,说明光合色素质量分数的降低导致PSⅡ反应中心捕光能力较弱和光化学转化效率较低,使得突变体光合速率降低。试验为进一步阐明该黄瓜黄绿叶突变体的叶色突变机制和该种质的合理利用提供相关基础资料。