下胚轴生长的调控对于种子萌发后植物快速进入自营养生长具有重要的生物学意义。植物激素乙烯和微管骨架在调控下胚轴生长的过程中均发挥着重要的作用。但是乙烯信号途径与微管系统二者间的功能关系以及作用机制目前仍不清楚。申请人前期在拟南芥中鉴定到一个新的微管结合蛋白MAP60，其参与了下胚轴的生长调控；进一步的分析表明MAP60可能是乙烯信号通路中重要的转录因子EIN3的一个新的靶基因。在此基础上，本项目拟着重探讨乙烯通过EIN3调控MAP60的表达，进而改变微管的组织和动态，最终调控下胚轴生长的途径和机制。通过细胞生物学等手段对MAP60调控微管组织和动态的特征，参与下胚轴细胞生长的机理，特别是MAP60受乙烯调控的分子机制等进行研究。本项目将着重解决乙烯作为植物生长发育的信号分子调节微管骨架介导下胚轴细胞生长的分子机制，为深入认识植物激素在调节植物形态建成过程中的作用机理提供重要的理论依据。

The regulation of hypocotyl growth has great significance for the seedling photosynthetic growth process after postgermination.The plant hormone ethylene and the microtubule cytoskeleton both play crucial roles in regulating hypocotyl cell elongation. However, it is unclear if ethylene regulation of hypocotyl elongation involves the microtubule cytoskeleton. Our previous analysis identified a novel Arabidopsis MICROTUBULE-ASSOCIATED PROTEIN60 (MAP60) as a positive regulator of hypocotyl cell elongation. The expression level of MAP60 was regulated by ethylene. EIN3, a key transcription factor in the ethylene signal pathway, directly targeted MAP60. Based on these preliminary results, we propose this investigation to dissect the physiological function and the mechanism of MAP60 involved in ethylene regulating hypocotyl growth. The molecular mechanisms of MAP60 that regulate microtubules and further promote hypocotyl growth will be investigated. We will also study how ethylene signaling regulates MAP60 to mediate hypocotyl elongation. This investigation will derive a mechanism of how ethylene regulates microtubules to mediate hypocotyl cell growth, providing new knowledge to understand how plant hormones regulate plant morphogenesis.