不同脱水剂对杂交水稻制种种子质量及基因表达的影响

种子脱水干燥是杂交水稻制种过程的一个重要环节,种子自然脱水速率慢,遇雨天还易引起成熟期推后和穗发芽等问题。利用脱水剂快速降低种子水分对种子安全生产有重要意义。本研究以Y两优689杂交水稻品种为材料,比较不同脱水剂对其制种种子脱水及种子质量的影响。11种脱水剂均能加快种子成熟后期脱水,7号和9号脱水剂喷施后5 d,种子水分分别下降4.6%和3.6%,且对种子千粒重、发芽和幼苗生长无不良影响,种子可溶性蛋白、可溶性糖、ABA和GA3含量则显著高于对照。种子室温贮藏6个月后,与对照相比,7号、8号和9号脱水剂处理对种子发芽和幼苗生长无显著影响,7号和9号脱水剂处理的种子可溶性蛋白含量、α-淀粉酶活性、ABA含量与对照无显著差异。7号比9号的脱水效果好,可作为Y两优689的脱水剂。种子贮藏前,7号、8号和9号脱水剂处理能提高种子中OsNECD1和OsNCED2基因的表达,降低OsGA2ox1的表达;而种子贮藏6个月后,OsNECD1和OsNCED2表达量下降,OsCYP707A5和OsGA2ox1表达量上升。这表明经过6个月贮藏,脱水剂处理对种子ABA合成相关基因和GA3分解相关基因表达的影响减弱,同时OsCYP707A5的高表达导致种子ABA含量减少,可能是种子贮藏后萌发力提高的主要原因。

Effects of Different Dehydrating Agents on Seed Quality and Gene Expression inHybrid Rice Seed Production

In order to accelerate seed dehydration process in hybrid rice seed production, the effects of different dehydrating agents on seed dehydration and quality of cv. Y Liangyou 689 were studied. Different dehydrating agents were sprayed on rice spike at late dough stage inseed production in the field. All the eleven combination treatments could accelerate seed dehydration. Among the treatments, No.7 and No.9 dehydrating agents significantly decreased seed moisture content by 4.6% and 3.6%, respectively as compared with the control, and had no negative effects on 1000-grain weight, seed germination and seedling growth. Moreover, these two agents significantly increased the contents of soluble protein, soluble sugar, ABA and GA₃ in seeds. After storage at room temperature for sixmonths, No.7, No.8, and No.9 agents had no negative effects on seed germination and seedling growth as compared with the control. And there were no significant differences in soluble protein content, α-amylase activity and ABA content among No.7, No.9 agents and the control. In addition, No.7 agent treatment had better effect in decreasing seed moisture content than No.9 agent, suggestingthat No.7 agent was a suitable seed dehydrating agent inhybrid rice (cv. Y Liangyou 689) seed production. Further studies showed that No.7, No.8, and No.9 agents could increase the expression of OsNECD1, OsNCED2 and reduce the expression of OsGA2ox1 in the seeds. As compared with the seeds without storage, after the storage for six month the expression of OsNECD1 and OsNCED2 decreased, however the expression of OsCYP707A5 and OsGA2ox1 increased in seeds treated by the three kinds of dehydrating agents. The results showed the effect of dehydrating agents on ABA biosynthesis genes and GA₃ catabolism genes in seedswas weakenedby storage, and the high expression of OsCYP707A5 resulted in the decline of ABA content in seeds, which might be the main reason for increasing seed germination.