Comparison of Kernel Starch Accumulation and Related Enzyme Activities among Six Maize Cultivars of Different Yield Types

Abstract

Six maize cultivars were used to compare the difference of the related enzyme activities in kernel starch accumulation and starch synthesis among different yield cultivars.Sucrose synthase(SS),UDPG pyrophosphorylase(UGPase)and starch branching enzyme(SBE)were the key enzymes in maize starch synthesis.High activities of SS,UGPase and SBE were beneficial to the accumulation of starch and the improvement of kernel weight.The time of amylose accumulation in low yield cultivars(LYV)(30 d)was shorter than that in middle yield cultivars(MYV)(40 d)and high yield cultivars(HYV)(50 d).Amylopectin accumulation was slower in LYV than in MYV and HYV during the earlier stage of kernel-filling,but the difference among them became smaller during the later stage.SS activity in LYV kernel was higher than that in MYV and HYV during 10-30 days after pollination,but decreased rapidly at 30 days later after pollination and had larger decreasing range than that in HYV.The peak of UGPase activity appeared on the 20th day after pollination in LYV,while on the 40th day after pollination in MYV and HYV,and the activity in LYV was obviously lower than that in MYV and HYV during the later stage of kernel-filling stage.The SBE activity during the later stage of kernel-filling(30-50 days after pollination)was HYVMYVLYV,and the decreasing range was 72.44%(LYV),44.54%(MYV),and 30.21%(HYV).The activity of soluble starch synthase(SSS)in MYV and HYV showed"N" type curve changes with the first peak on the 30th day after pollination,while it showed single peak curve in LYV.The activity of ADPG pyrophosphorylase(ADPGPPase)in LYV was higher than that in MYV and HYV.The activity of starch debranching enzyme(DBE)in the three yield types of cultivar all decreased rapidly during the whole process of kernel-filling,and the difference among different types was not obvious.