粳稻杂种后代胚乳可溶性淀粉合成酶及同工型基因表达特性分析

以籽粒直链淀粉含量为选择指标,从东农423×藤系180F2代起连续定向选择培育成的籽粒直链淀粉含量有显著差异的F10后代东农1006(直链淀粉含量为18.82%)、东农1012(直链淀粉含量为7.70%),同样,从系选1号×通769后代中选出东农1001(直链淀粉含量为17.51%)、东农1024(直链淀粉含量为7.40%)比较分析了灌浆过程中籽粒直链淀粉含量和可溶性淀粉合成酶活性及同工型基因表达量等变化特征。结果表明,灌浆不同时期籽粒直链淀粉含量低的后代及亲本直链淀粉量始终低于直链淀粉含量高的后代及亲本;成熟期籽粒直链淀粉含量低的亲本和后代籽粒支链淀粉含量均显著高于籽粒直链淀粉含量高的亲本和后代,抽穗后10d、17d、24d的籽粒直链淀粉含量与支链淀粉含量间均呈负相关,但相关未达显著水平;抽穗后10d、17d、24d的可溶性淀粉合成酶活性与籽粒直链淀粉含量的相关系数分别为0.8115**,-0.7554*,-0.5957,与支链淀粉含量的相关系数分别为-0.0694,0.5453,-0.0207;在灌浆过程中亲本及后代的胚乳OsSSSⅠ、OsSSSⅡ-1、OsSSSⅡ-3、OsSSSⅢ-1和OsSSSⅢ-2基因随籽粒灌浆进程其mRNA转录表达量逐渐增加,达到峰值后又逐渐下降,呈单峰曲线变化;而OsSSSⅢ-2和OsSSSⅣ-2基因mRNA转录表达量在灌浆各时期都比其他基因大;灌浆不同时期直链淀粉含量高的后代与高亲相比、直链淀粉含量低的后代与低亲相比,既有转录表达量增加的基因,也有降低的基因;可溶性淀粉合成酶活性与OsSSSⅠ、OsSSSⅡ-3、OsSSSⅢ-2的mRNA转录表达量正相关,相关达显著水平;与OsSSSⅡ-1、OsSSSⅣ-2的mRNA转录表达量正相关,但相关未达显著水平,与OsSSSⅢ-1的mRNA转录表达量呈负相关,但相关未达显著水平。

Analysis of Expression Characters of Soluble Starch Synthase and Isoform Genes Involved in japonica Hybrid Progeny

Using  amylose  content as the selection indicator, we chose the progenies with significantly different amylose content in grains by continuous and unidirectional orthoselection from F2 to F10 generations, compared the progeny of Dongnong 1006（Its grain amylose content was 18.82%）and Dongnong 1012（7.70%）with their parent Dongnong 423（18.33%）and Toukei 180（11.05%）, respectively. And we also compared the progeny of Dongnong 1006（18.82%）and Dongnong 1012（7.70%）with their parent Xixuan 1（18.74%）and Tong 769（17.05%）. Moreover, all groups above were chosen to analyze amylose accumulation and soluble starch synthase(SSS) activity and the expression levels of isoform genes during the grain filling. The results showed that the accumulated amount of amylose in parents and hybrid progeny with high amylose contents were always higher than that in the low amylose content progenies in different periods of grain filling, but for the amylopectin content, there were opposite results in the maturity stage. There were no significant negative correlations between the grain amylose content and amylopectin content 10, 17, 24 days after heading, and the correlation coefficients between SSS activity and the grain amylose content were 0.8115**, -07554*, -0.5957, respectively. In addition, the correlation coefficients between SSS activity and amylopectin content were -0.0694, 0.5453, -0.0207, respectively. The expression levels of the OsSSSⅠ,OsSSSⅡ 1, OsSSSⅡ 3, OsSSSⅢ 1 and  OsSSSⅢ 2genes in endosperm of parents and hybrid progenies gradually peaked and then gradually declined, following a single peak curve along with the process of grain filling, while the expression levels of the OsSSSⅣ 2  gene just showed a downdraft. However, the expression levels of the OsSSSⅢ 2  and  OsSSSⅣ 2  genes were higher than others in various periods of grain filling. Compared with their parents, hybrid progeny with high amylose content have the expression of increased genes and reducing genes during the different period of filling, as well as the hybrid progeny with low amylose content compared with their parents. Moreover, there was significantly positive correlation between SSS activity and the expression levels of the OsSSSⅠ,OsSSSⅡ 3,OsSSSⅢ 2,and no significant positive correlation between SSS activity and the expression of the OsSSSⅡ 1  and  OsSSSⅣ 2, and no significant negative correlation between SSS activity and the expression of the  OsSSSⅢ 1.