RNA干扰水稻SBE3基因的表达对籽粒淀粉合成及其关键酶活性的影响

Effects of RNA Interference of SBE3 Gene Expression on Starch Accumulation and Key Enzymes Activities Involved in Starch Synthesis in Transgenic Rice Grain

为探讨RNA干扰水稻SBE3基因的表达对籽粒淀粉合成及其关键酶活性的影响,以水稻品种中花11及以其为受体的转基因株系为材料,分别检测水稻SBE3基因的表达、籽粒发育各时期淀粉合成关键酶活性变化及直链、支链淀粉相对含量。结果表明,导入的SBE3基因RNA干扰结构成功地降低了目的基因的表达,并使其酶活性在籽粒发育各时期均显著降低并提前3d达高峰期,且不同株系间具有差异。同时也使不同发育时期籽粒的ADPG-PPase和SSS及DBE活性均不同程度地显著降低,尤其以SSS和ADPG-PPase活性峰值降幅最大。此外,两个转基因水稻株系各时期籽粒直链淀粉含量均显著高于对照,而其成熟籽粒千粒重却显著降低,直链淀粉含量越高,千粒重越低。

Rice cultivar ＂Zhonghua 11＂ （control） and its transgenic line were used as the experimental materials. The expression level ofSBE3 gene, some related key enzymes activities, and the contents of amylose and amylopectin at different developmental stages of rice grain were measured. Results showed that the SBE3 gene expression level and the SBE activity were distinctly reduced by RNA interference （RNAi）, but a little difference was observed between the two transgenic lines. The peak values of SBE activity reached three days earlier in transgenic rice than in non-transgenic control. RNAi of the SBE3 gene expression level also obviously reduced the enzyme activities of ADPG-PPase, SSS and DBE during different grain developmental stages, especially, the peak values of activities of ADPG-PPase and SSS decreased to the largest extent. In addition, the content of amylose was significantly higher at different developmental stages in transgenic rice grain than that in the control, while thousand-grain weight was significantly reduced in mature grain, the general trend was that the higher the amylose content, the smaller the grain weight.