植物细胞次生壁为细胞提供保护和支撑、保障水分和营养物质的运输，与“株高”、“抗倒伏”等作物重要性状密切相关。微管细胞骨架在植物次生壁形成过程中发挥重要作用，但目前对参与这一过程的调控因子及其调控分子机制尚不完全清楚。本项目前期工作中发现拟南芥ARM-TPR蛋白SAV4和微管切割蛋白KTN1协同调控导管和纤维细胞次生壁形成。SAV4和KTN1基因双突变体中，导管和纤维细胞次生壁加厚几乎完全缺失。在蛋白水平上，发现SAV4与KTN1存在物理互作。本项目将通过SAV4协同KTN1调控次生壁形成的表型刻画，SAV4与KTN1互作促进次生壁形成的细胞学机理研究，以及SAV4介导的次生壁形成调控蛋白互作网络的构建三方面的工作，揭示SAV4和KTN1协同调控植物次生壁形成的分子机制，丰富和完善次生壁形成调控的基因和蛋白互作网络，为利用现代生物技术人工改造次生壁提供理论支撑和基因资源。

Plant secondary cell wall (SCW) provides protection and support for plant cells, and ensures efficient transportation of water and nutrients. The properties of SCW are critical determinants of agricultural traits including “crop height” and “lodging resistance”. Microtubule cytoskeleton is intimately involved in the regulation of SCW formation, but the molecular mechanisms and factors involved in this process are not fully understood. In our preliminary work, we found that Arabidopsis ARM-TPR protein SAV4 and microtubule severing enzyme KTN1 synergistically regulate the formation of vessel and fibre cell SCW. When SAV4 and KTN1 were simultaneously mutated in the sav4 ktn1 double mutant, the thickening of vessel and fibre cell SCW was almost completely abolished. Moreover, we discovered a direct physical interaction between SAV4 and KTN1. Based on these findings, we propose to perform detailed phenotypic characterizations of SAV4 and KTN1 loss-of-function mutants to understand their SCW defects at cellular and molecular level, unravel the cellular basis of how SAV4 and KTN1 coordinate to promote SCW formation, and identify new interaction partners of SAV4 in the context of SCW development. Together, our work will uncover the molecular mechanism of SCW formation mediated by the SAV4-KTN1 interaction, build the SAV4-centered protein-protein interaction network underlying SCW biogenesis, and provide new knowledge and gene resources for artificial modifications of SCW through modern biotechnology.