胚在花生果针向地性生长中的导向作用研究

The gravitropism response of gynophores is the reason of "aerial flowering but subterranean fructification" in peanut. The subterranean fructification, distinguished from most other plants, is the most salient feature of seed production in peanut. The mechanism of gravitropism response of gynophores is still unclear. Few studies reported the amyloplasts is responsible for the gravitropism response. However, we found when embryo was knocked out or unfertilized,the gynophores lost their gravitropism response and grew upward,and amyloplasts did not sedimentate due to gravitropism. In this study,thus, we give a new hypothesis that embryo guides gravitropism response of gynophores in peanut.The guidance of embryo to gravitropism response of gynophores will be proved by several in vitro culture experiment of gynophores with or without embryo. To confirm the mechanism of embryo guiding the gravitropism response of gynophores ,we will study the cell and subcellular constructure, tream of ions, distribution and content of plant hormone, and the differential expression profiles of genes and proteins between embryo culture on MS medium with different gravity vector and between the part of gravitropic growth in gynophores with or without embryo. Our study will provide a new complementary knowledge for the existing gravitropism theories of plants.In addition, it will facilitate to increase the number of pods of each individual plant.

果针向地生长是导致花生"地上开花地下结果"的原因，其向地性机制尚缺乏深入研究，仅少量文献报道果针向地性机理符合淀粉粒-平衡石假说。本课题组前期研究中发现胚败育或剔除时果针均失去向地性，且淀粉粒分布不符合淀粉粒-平衡石假说。基于前期研究，本课题提出"胚在果针向地生长中具有十分重要的作用，可能是果针中重力感应器"的大胆假设。本研究将以胚经过不同处理的果针为材料，通过离体培养验证胚在果针向地性中的重要作用；并通过激光消融实验探明胚中决定向地性的具体部位；通过研究重力胁迫下胚及果针弯曲部位的细胞-亚细胞形态、离子流动态、植物激素分布极性、基因及蛋白质的表达差异，探讨胚感受重力信号并引致果针向地生长的机理。本研究将是对现有的植物向重性研究理论的一个新的补充，而且将为在生产上进行调控促进果针有效入土，增加花生单株荚果数提供理论基础。

果针向地生长是导致花生“地上开花地下结果”的原因，其向地性机制尚缺乏深入研究，仅少量文献报道果针向地性机理符合淀粉粒-平衡石假说。本课题组前期研究中发现胚败育或剔除等受损情况下，果针向地性受到影响，甚至完全表现为负向地性，这种情况下淀粉粒分布不符合淀粉粒-平衡石假说。基于前期研究，本课题提出”胚在果针向地生长中具有十分重要的作用，可能是果针中重力感应器“的大胆假设。实验中通过离体培养实验显示胚缺失（或者破坏）情况下果针失去向地性生长，组织切片电镜观察发现胚败育果针中淀粉粒排列不符合淀粉粒-平衡石假说；通过离体培养结合扫描仪定位和组织切片方法，完成了对不同离体培养时间果针向心角度的测定，并确定了距果针顶端0.4-0.9cm区段为果针弯曲发生部位；激素测定结果显示正常果针与失去向地性生长的果针间植物激素浓度差异显著，其中差异最显著的激素是果针尖端0.5cm处的GA的含量差异达到极显著水平，并通过基因芯片杂交及2-D蛋白电泳分析获得向地性相关的花生果针差异表达基因共有280个。该项目研究结果对于后续探讨花生果针向地性的作用机理研究提供了研究基础。