环境因子调控异叶水蓑衣异形叶形态建成的机制研究

植物叶形受环境调控产生显著差异的现象叫“异形叶”，它是研究植物生态适应性的理想模型。我们前期研究发现异叶水蓑衣叶形对环境敏感，培养、扩繁和转化简易，是异形叶研究的理想材料。同时发现调控叶形的基因-KNOTTED1-LIKE HOMEOBOX （KNOX1）易受环境调控，其表达与叶形显著相关，受KNOX1基因调控的赤霉素（GA）和细胞分裂素（CK）也与叶形显著相关，可能存在一个“环境调控KONX1的表达，进而调控GA和CK含量并最终决定叶形”的机制。为验证这一机制，本项目拟以异叶水蓑衣为材料，在研究环境因素调控叶形规律基础上，通过内源激素检测、qRT-PCR、原位杂交、报告基因检测和凝胶迁移实验，研究环境变化对KNOX1、GA和CK生物合成的调控关系，还将通过过量表达和敲除KNOX1、施加外源激素和抑制剂研究KNOX1基因对GA和CK生物合成以及叶形的调控作用，以期揭示异形叶发生的机制。

Plants show morphological differences in leaf form in response to changes in the surrounding environment, a phenomenon called heterophylly. Heterophylly provides an ideal process to understand mechanisms by which plants adapt their growth to withstand ecological changes. We found that the aquatic plant Hygrophila difformis is an ideal model for heterophylly study due to its obvious leaf features, sensitivity to environment, and convenience in culture, propagation and gene transformation.Further studies show that expression of KNOTTED1-LIKE HOMEOBOX (KNOX1) orthologs, the genes that regulate leaf morphogenesis and development, are correlated with environmental changes as well as with different leaf forms. Gibberellin (GA) and cytokinin (CK) signaling, regulated by KNOX1, is also correlated with leaf forms. We propose a mechnism that environmental factors regulate KNOX1 orthologs expression thereby modulating gibberellin (GA) and cytokinin (CK) content, and determining leaf form. We aim to elucidate this mechanism through this study. We will use Hygrophila difformis to investigate variations in leaf form in response to environmental factors. We will analyse endogenous hormone levels, and assess the regulationary relationships through qRT-PCR, in situ hybridization, reporter gene assays and EMSA to reveal the regulatory mechanisms of environment, KNOX1, GA and CK biosynthesis. We will also silence and over-express KNOX1 genes, apply exogenous hormones and inhibitors in plants to confirm the role of the KNOX1 genes in altering GA and CK biosynthesis and leaf form.