水稻穗发芽遗传与分子机制的研究进展

Advances in Genetic and Molecular Mechanisms of Pre-harvest Sprouting in Rice

水稻穗发芽是指水稻在收获前如遇连续阴雨天气或高温潮湿环境条件,往往诱导籽粒在穗上发芽的现象。穗发芽导致水稻种子活力和品质下降,给水稻生产带来巨大损失。对于水稻抗穗发芽育种,除了扩大对穗发芽突变体的筛选外,挖掘和克隆一些控制穗发芽的新基因并解析其穗发芽调控机制,是水稻抗穗发芽育种的重要工作。穗发芽过程中,水稻的淀粉酶活性增强、可溶性糖含量升高,且水稻籽粒中植物激素ABA和GA的含量及二者的平衡是决定穗发芽的关键。OsVP1等一些关键基因通过ABA信号通路控制水稻种子休眠,GA则可通过激活GA相关转录因子等调控种子萌发。本文从水稻穗发芽的内部生理因素及环境条件、水稻穗发芽的遗传机制、水稻穗发芽的分子机制和水稻穗发芽的性状改良这四方面进行综述,以期阐述穗发芽的整体调控机制,为水稻抗穗发芽品种的选育提供理论参考。

Pre-harvest sprouting refers to the phenomenon that rice tends to induce seed germination on the spike if it encounters continuous cloudy and rainy weather or high-temperature and humid environmental conditions before harvest.Pre-harvest sprouting leads to decreased seed vigor and quality of rice,resulting in huge losses to rice production.In addition to expanding the screening of pre-harvest sprouting mutants,excavating and cloning some new genes controlling pre-harvest sprouting and analyzing their spike germination regulatory mechanisms are important tasks for breeding rice for pre-harvest sprouting resistance.During the process of pre-harvest sprouting,rice amylase activity is enhanced,soluble sugar content is elevated,and the content and balance of phytohormones ABA and GA in rice seeds are the key factors determining pre-harvest sprouting.Some key genes such as OsVP1 control rice seed dormancy through the ABA signaling pathway,while GA regulates seed germination through the activation of GA-associated transcription factors.The article reviews the four areas,i.e.,internal physiological factors and environmental conditions of rice pre-harvest sprouting,genetic mechanisms of rice pre-harvest sprouting,molecular mechanisms of rice pre-harvest sprouting,and trait improvement of rice pre-harvest sprouting,and thus aiming to provide theoretical references for the selection of varieties that are resistant to pre-harvest sprouting in rice.