衰老是叶片发育的最后阶段，伴随着大分子物质降解与营养元素回收，影响着作物的产量和品质。已有研究表明叶片衰老是一个受到遗传调控的发育过程，但分子调控机制还不清楚。我们在前期研究中，通过激活标签法获得一个拟南芥叶片早衰、茎秆粗度与木质素含量显著增加的基因功能获得型突变体—HTB9-1D，该基因编码H2B组蛋白变体。转录组分析发现，调控叶片衰老的重要激素茉莉酸信号通路及木质素生物合成的苯丙烷类代谢途径在HTB9过表达植株中显著富集。但是，HTB9如何调控叶片衰老和木质素合成以及木质素合成和叶片衰老之间是否有关联还不清楚。本项目拟利用CRISPR等方法构建HTB9功能缺失突变体及H2B家族组蛋白变体多重突变体，通过分子遗传学、生物化学和高通量测序等方法研究HTB9调控叶片衰老和木质素合成的分子机制，为定向改良叶片衰老进程及细胞壁木质素合成、进而培育生物能源植物提供理论依据和技术支持。

Senescence is the last stage of leaf development, accompanied with macromolecular degradation and nutrient recycling during this process, which affects the yield and quality of crops. Previous studies have shown that leaf senescence is a genetically regulated developmental process, but the molecular regulatory mechanisms are still unclear. In this project, we obtained a functionally acquired mutant HTB9-1D, which encodes a H2B histone variant HTB9, with premature senescence of leaves and increased stalk thickness and lignin content in Arabidopsis thaliana by constructing and screening activation tagging mutant libraries. Transcriptome analysis revealed that the jasmonic acid signaling pathway involved in the regulation of leaf senescence and the phenylpropanoid pathway involved in lignin synthesis were significantly enriched in HTB9 overexpressing plants. However, it is unclear how HTB9 regulates leaf senescence and lignin synthesis and whether there is a correlation between leaf senescence and lignin synthesis. This project intends to generate HTB9 loss-of-function mutant and H2B histone variant multiplex mutants by using the CRISPR method, and to study the molecular regulatory mechanisms of the histone variant HTB9 on leaf senescence and lignin synthesis by molecular genetics, biochemistry and high-throughput sequencing. The implementation of this project should be able to provide theoretical basis and technical support for cultivation of bioenergy plant through directional improvement of leaf senescence process and cell wall lignin biosynthesis.