复合调控Wx与SBE3基因对水稻籽粒直链淀粉含量的影响

Effects of Overexpression of Wx gene and RNA Interference of SBE3 Gene Compound Expression on Amylose Content in Rice

颗粒淀粉合成酶(GBSS)和淀粉分支酶3(SBE3)是淀粉合成过程中的两个关键酶,这两个酶主要由Wx和SBE3两个基因分别控制,它们的表达量直接影响直链淀粉和支链淀粉的含量比例。为了探讨水稻淀粉关键酶基因Wx过量与SBE3干涉复合表达对直链淀粉含量的影响,构建了Wx过量表达与SBE3干涉结合的多基因表达载体,并通过农杆菌介导的方法将其导入日本晴水稻中。经过PCR检测分析获得了65株转基因阳性植株,半定量RT-PCR检测表明转基因株系中Wx基因表达量明显增加,而SBE3基因表达量显著减少。转基因株系籽粒透明度明显降低,直链淀粉含量比野生型的平均高45%,但是千粒重变化不大,与野生型相当。遗传分析表明这些转基因株系多数可稳定遗传。

Granule-bound starch synthase（GBSS） and starch branching enzyme 3 （SBE3） are two major enzymes involved in starch biosynthesis in rice endosperm. The granule-bound starch synthase encoded by the Wx gene,and the starch branching enzyme 3 were encoded by the SBE3 gene. Their gene expression level influence the abundance ratio of amylose and amylopectin immediately. In order to study the change of the amylose content that is caused by overexpres- sion of Wx gene and RNAi of SBE3 gene expression in rice, this multiple construct was introduced into the rice variety of Oryza sativa L. by Agrobacterium-mediated transformation. Transgenic plants carrying the multiple construct were ob- tained and verified by PCR, and the expression of Wx was significantly increased in transgenic immature seeds, while the expression of RBE3 was significantly reduced in transgenic immature seeds. Grain transparency of these transgenic plants was significantly reduced. Analysed the amylase content in endosperm of these transgenic plants, the amylose content was increased. The average increase level was about 45 %. Thousand-grain weight of these transgenic plants was not change significantly. Genetic analysis showed that these genetically modified strain most can stable genetic.