不同脱水剂对杂交水稻制种种子质量及基因表达的影响

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

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。

Seed dehydration is very important in hybrid rice seed production.For seed production safety,dehydrating agents are used in this process because natural dehydration is slow and easily affected by rainy weather,which often results in seed late mature of and pre-harvest sprouting.In this study,the effects of different dehydrating agents on seed dehydration and quality were compared using hybrid rice variety“Y Liangyou689”.The eleven dehydrating agents tested all accelerated seed dehydration.Particularly,agents No.7and No.9resulted in seed moisture content at five days after spray decreased by4.6%and3.6%,respectively,and had no negative effects on1000-grain weight,seed germination and seedling growth.Moreover,both agents significantly increased the contents of soluble protein,soluble sugar,ABA and GA3in seeds.After storage at room temperature for six months,agents No.7,No.8,and No.9had no negative effects on seed germination and seedling growth as compared to the control.There were no significant differences in soluble protein content,α-amylase activity and ABA content among agents No.7,No.9and the control.Agent No.7was better in lowering seed moisture content than No.9,suggesting its potential use in Y Liangyou689seed production.Interestingly,agents No.7,No.8,and No.9induced OsNECD1and OsNCED2expressions and reduced OsGA2ox1expression in seeds before storage.After six-month storage,the expressions of OsNECD1and OsNCED2decreased and the expression of OsCYP707A5and OsGA2ox1increased in seeds treated with agents No.7,No.8,and No.9.This result indicate that the effects of dehydrating agents on ABA biosynthesis genes and GA3catabolism genes in seeds weakened during stor age and the high expression level of OsCYP707A5resulted in the decline of ABA content,which might be a main reason for better seed germination.