Biological Effects And Mechanisms Of Overexpression Of ZmSUS1 On Starch Content And Composition Of Endosperm Of Maize (Zea Mays L.)

Cereal crops accumulate starch in seeds as an energy reserve.Sucrose Synthase(Su Sy)plays an important role in grain starch synthesis.In this study,sucrose synthase gene ZmSUS1 was transformed into maize inbred line KN5585,transgenic plants identified by PCR、RTPCR、Southern blot and Western blot were obtained.Compared with the non-transgenic negative control,the content and activity of sucrose synthase were significantly increased,the amylose content in mature seeds of transgenic maize increased by 41.1-69.2%,the total starch content increased by 5.0-13.5%,the 100-grain weight increased by 19.0-26.2% and the average diameter of starch granules increased by 10.8-17.2%.These results indicated that overexpression of ZmSUS1 can significantly improve the traits of maize seeds and obtain new lines with high amylose content.It was also found that the overexpression of ZmSUS1 may increase the amylose content by altering the expression of endosperm ADP-glucose pyrophosphorylase(AGPase)subunits Shrunken2(Sh2)and Brittle2(Bt2).Moreover,the ectopic expression of ZmSUS1 also affected the expression of Granule bound starch synthase1(GBSS1)and Starch synthase1(SS1)which encode starch synthase.This study proved the important role of ZmSUS1 in maize starch synthesis,and provided a new technology strategy for improving maize starch content and yield.