水稻种子成熟后期高湿环境下种子休眠相关基因的表达

为探讨水稻种子成熟后期持续阴雨天气影响种子休眠的分子机制,将成熟后期水稻放置于人工气候室（12 h光照/28 ℃,12 h黑暗/22 ℃,相对湿度为60%,光量子通量密度为600 μmol∙m^-2∙s^-1）并定时喷水（每3 h喷水1次,每桶水稻每次喷水500 mL,共处理5 d）模拟持续阴雨条件来处理开花后26、28、30、32 d的粳稻,检测其穗上发芽的情况。用同样处理条件对开花后30 d的水稻种子进行高湿处理,检测高湿处理后不同时间点的种子中ABA和GA生物合成和代谢,以及α-淀粉水解酶等相关基因的动态表达情况。结果显示,种子成熟度是受高湿诱导的穗发芽的一个重要影响因素,粳稻Dongjin开花后26 d与28 d的种子经高湿处理后少有萌发,开花后30 d及以上的种子高湿处理后大多数能萌发;高湿处理能够快速诱导脱落酸（abscisic acid,ABA）降解途径基因OsABA8ox1、OsABA8ox3和赤霉素（gibberellin,GA）合成基因OsGA3ox2和OsGA20ox1的表达,同时抑制ABA合成关键基因OsNECD1、OsNECD2和OsNECD3的表达;喷水处理72 h后,α-淀粉水解酶基因OsAmy1A、OsAmy3B、OsAmy3C和OsAmy3D的表达量快速上调,促进淀粉水解,为种子萌发提供物质和能量。该研究结果将为解析成熟期水稻在多雨高湿环境下诱发穗发芽的分子机制提供基础。

Dynamic profile of genes related to seed dormancy under high humidity condition during late stage of rice grain filling

To investigate the effect of high humidity on pre-harvest sprouting in the late stage of rice grain filling, milky stage rice plants, at 26, 28, 30, 32 DAP (day after pollination) respectively, were undergo high humidity treatment in the artificial climate chamber (28 ℃/22 ℃, 12 h light/12 h dark cycle, relative humidity were 60%, photosynthetic photon flux density were 600 μmol·m^-2·s^-1). Spikelet was sprayed periodically by water (spray 500 mL water once every 3 h per bots, 5 d in total) to mimic continuous rainy conditions, and the viviparity of mature seeds were then investigated. Then, developing seeds at DAP30 were undergo same treatment and the dynamic expression of ABA and GA synthesis and metabolism and α-starch hydrolase and other related genes were investigated at different time under high humidity treatment. The results indicated that seed maturity was an important factor affecting viviparity induced by high humidity. Few seeds were sprouted at DAP26 and DAP28 but most of seeds could be sprouted after DAP30 under high humidity treatments. The results showed that high humidity treatment could rapidly induce the expression of abscisic acid (ABA) degradation related genes, such as OsABA8ox1 and OsABA8ox3, and gibberellin (GA) synthesis genes such as OsGA3ox2 and OsGA20ox1, and simultaneously inhibited the expression of key ABA synthesis genes OsNECD1, OsNECD2 and OsNECD3. Many α-starch hydrolase genes, such as OsAmy1A, OsAmy3B, OsAmy3C and OsAmy3D were activated after 72 h water-spraying treatment and provided material and energy for seed germination. The results of this study would help us to understand the molecular mechanism of pre-harvest sprouting under rainy climate.