黄瓜叶形突变体的基因定位与功能分析

In crop plants, the major photosynthetic organs are leaves. The shape of leaf is closely associated with crop architecture and yields. It is of great theoretical and application values to study the mechanism of leaf development and shaping. However, it is still largely unknown about the mechanism of leaf shaping in vegetable crops. Leaf shape mutants are valuable materials to study those genes functioning in leaf development. In our previous study, a cucumber mutant with abnormal leaf shape was obtained through EMS mutagenesis. In this program, we will use next generation sequence technology and bulked segregant analysis to locate the mutation. Bulked gene pools of leaf shape mutant and normal leaves will be re-sequenced respectively and aligned to the reference genome. We will use SOAPsnp as the main tool to analyze the single-nucleotide polymorphisms (SNPs) in the mutant genome. Improved Mutmap method will be used to screen the causative SNPs. We will study SNP-index distribution along the whole-genome to find the candidate regions and use gene-function annotation and express data to further locate the candidate gene. Then the polymorphism of the candidate gene will be tested in the segregation population and the function of the candidate gene will be analyzed. The study will be a substantial aid in understanding the mechanism of leaf development in cucubitaceae and lay theoretical basis for genetic improvement of crops through molecular design.

叶片是作物光合作用的主要器官，叶片形态与作物株型和产量关系密切，探明叶片发育和形态建成机制具有重要的理论意义和应用价值。目前对蔬菜作物叶形态建成机制的了解还较缺乏。叶形突变体是研究相关基因功能的重要材料。本项目拟在前期通过人工诱变获得黄瓜叶形突变体的基础上，基于第二代测序技术和混池分组分析法分析突变体突变位点。我们将对突变叶和正常叶的混合基因池分别重测序并比对到参考基因组，利用SOAPsnp作为主要工具分析突变体基因组的单核苷酸多态性（SNP）变异，运用改进的Mutmap方法筛选SNP变异，根据SNP变异指数在全基因组上的分布情况确定候选区域，并结合基因功能注释和表达数据获得导致突变叶性状的候选基因。在此基础上对候选基因在分离群体中进行多态性验证和初步功能分析。这一研究有助于深入了解葫芦科植物叶片的发育机制，并为今后通过分子设计辅助作物遗传改良奠定理论基础。

叶片是植物主要的光合器官，叶形突变体的研究可为理解叶形态建成机制奠定重要的理论基础。在前期通过EMS诱变获得了叶形突变体的基础上，本项目利用Mutmap、设计dCAPs引物等方法对导致表型的SNP突变位点进行了筛选、检测和初步的功能分析。并对突变体植株的表型进行了调查研究，对叶片的光合性能、叶片结构等进行了测定和观察，发现叶形突变体与正常植株存在较显著的差异。将筛选的SNP在后代群体中进行检测发现，位于Chr5上的数个的突变基因位点与突变表型基因连锁。我们对与表型紧密连锁的候选基因进行了初步的结构和功能分析，在过表达的拟南芥中尚未发现明显的表型变化。本项目的研究可为后续该叶形突变基因的解析和功能确定提供了一些参考和基础。