HD-Zip III和木质素在柠条叶脉响应干旱向木质部分化及促导管成熟作用解析

HD-Zip III是主导叶脉维管原形成层向木质部前体细胞分化的转录因子，其上游SHR/SCR通过下调表达介导miRNA165/166对HD-Zip III的转录后负调控，可与蛋白互作调控基因表达产生逆境响应。我们前期通过对叶脉解剖结构的观察并挖掘非模式木本植物柠条RNA-seq数据，预测干旱胁迫诱导叶脉HD-Zip III加强向木质部分化，并刺激木质素合成促进导管成熟，提高水分利用效率和抵御水分胁迫能力。然而干旱所致的柠条发达叶脉网络建成受到的以HD-Zip III为核心的转录调控以及木质素合成促进导管成熟的内在机制尚不明确。本项目拟在比较正常与干旱胁迫柠条叶脉网络特征的基础上，借助柠条CkHD-Zip III基因过表达和沉默表达、蛋白互作以及抗旱性分析，解析柠条叶脉由HD-Zip III表达水平决定的粗脉向木质部分化而细脉全面发生发育的调控机制，以及木质素对导管成熟的促进作用。

HD-Zip III is a transcription factor leading to vascular procambium to xylem precursor cell in leaf vein. The SHR/SCR negatively regulated the HD-Zip III through miRNA165/166 and mediated downstream gene expression and improve the response to abiotic stress. Our previous RNA-seq data analysis and anatomy observation for non-pattern woody plants Caragana korshinskii predicted that drought induced HD-Zip III to strengthen the xylem differentiation of leaf vein, and induced lignin synthesis to promote vessel maturation, therefore formed developed vein network to improve the water use efficiency and the resist water stress capacity. However, the transcriptional regulation mechanism of HD-Zip III governing vein differentiation and lignin synthesis promoting the vessel maturation in the formation of developed vein network induced by drought is still unclear, need to be verified. How does HD-Zip III work as the centre of the transcriptional regulation and lignin biosynthesis play promotional role? In this project, objective comparison of leaf vein development in normal and drought stress of C. korshinskii will be carried out through indoor drought treatment. The depth analysis of expression pattern of HD-Zip III gene and lignin synthase gene responding to drought will be done with the help of over expression and silence expression of CkHD-Zip III in tobacco as well as protein interaction and physiological response resist drought. The regulation mechanism of developed leaf vein network then will be interpreted clearly. This helps us further expand understanding on the reason of drought promote developed leaf conducting tissue.