水稻种子次生休眠特性的遗传多样性与诱发机制

In the rice production areas，once the conditions are suitable the underground seeds derived from a large number of shattered seeds and the soil seed bank persistence during the harvest season will germinate and may become volunteer rice. The volunteer rice can affect rice yield and grain quality because it do not only compete with cultivated rice for resources, but also are the intermediate host of crop pathogens and pests, as well as may pollute the purity of the seed. Secondary dormancy may be the important reason for led to volunteer rice reproduction. At present, a loss of awareness with regard to secondary dormancy characteristic in rice seed has become a major bottleneck which has seriously affected the quality of Chinese rice production. In order to explore the induced mechanisms of secondary dormancy in rice seed, we firstly analyzed the secondary dormancy characteristic and genetic diversity of different rice varieties, and defined the role of four environmental factors including light, temperature, water, and atmosphere in reducing secondary dormancy, using 200 cultivated varieties in China as experimental materials. And then, we further investigated possible relationship among secondary dormancy, endogenous hormones and gene expression. These studies are of great theoretical and practical significance to regulate seed dormancy and control the hazard of volunteer rice, as well as to provide scientific evidence for rice breeding and production management.

在水稻产区，由于收获期间种子落粒以及地下种子库持续存在，地下种子一旦条件适宜便萌发形成自生苗。水稻自生苗不仅与栽培稻竞争生长资源，又是作物病原菌及害虫的中间寄主，同时还会污染制种田种子纯度，对水稻产量和品质造成严重影响。种子的次生休眠性可能是导致这些落粒种子成为自生苗的重要原因。当前，缺乏对水稻种子次生休眠特性的认识已经成为影响我国水稻生产质量的一个重要障碍。本项目以具有代表性的200个我国水稻主栽品种为材料，考察不同水稻品种次生休眠特性的程度和遗传多样性，明确光、温、水、气四种环境因子在诱发种子次生休眠中的作用，探讨次生休眠与内源激素以及基因表达的关系，进而从环境、生理和遗传三个方面综合分析水稻种子次生休眠特性发生的原因与规律，揭示水稻种子次生休眠的诱发机制。研究结果对于调控水稻种子休眠，控制自生苗危害具有重要的理论意义与现实意义，同时也将为我国水稻育种和生产管理提供科学依据。

在水稻产区，由于收获期间种子落粒以及地下种子库持续存在，地下种子一旦条件适宜便萌发形成自生苗。水稻自生苗不仅与栽培稻竞争生长资源，又是作物病原菌及害虫的中间寄主，同时还会污染制种田种子纯度，对水稻产量和品质造成严重影响。种子的次生休眠性可能是导致这些落粒种子成为自生苗的重要原因。当前，缺乏对水稻种子次生休眠特性的认识已经成为影响我国水稻生产质量的一个重要障碍。本项目以我国不同地区水稻主栽品种为材料，考察不同水稻品种次生休眠特性的程度和遗传多样性，明确光、温、水、气四种环境因子在诱发种子次生休眠中的作用，探讨次生休眠与内源激素以及基因表达的关系，进而从环境、生理和遗传三个方面综合分析水稻种子次生休眠特性发生的原因与规律。.通过项目实施，已成功解决“我国水稻品种次生休眠的遗传多样性”这一关键科学问题，筛选出次生休眠性显著差异的水稻品种。研究发现，温度（低温）是诱导水稻种子次生休眠的主要环境因子。通过对不同休眠性的水稻品种研究发现，休眠状态的水稻种子中贮存的淀粉、可溶性总糖含量显著高于非休眠种子，而可溶性蛋白含量则相反。种子休眠性越强，籽粒中淀粉、可溶性总糖含量越高，可溶性蛋白含量则越低。内源激素含量的测定结果表明，水稻休眠性越强，籽粒中ABA含量越高，GA3含量越低。但休眠种子中的激素含量都显著低于非休眠种子。前期的研究结果也发现ABA和GA合成和信号转导基因在诱导前后表达水平出现明显差异，且总体上表现为ABA合成基因转录本趋向上调，ABA代谢基因转录本趋向下调。.本研究已申请国家发明专利1 项。相关研究结果对于调控水稻种子休眠，控制自生苗危害具有重要的理论意义与现实意义，同时可为我国水稻育种和生产管理提供科学依据。