Difference of Starch Physiochemical Properties and Its Biosynthesis in Grain among Wheat Cultivars with Different Noodle Quality

In order to provide reference to genetic improvement of wheat noodle quality,the activities of starch biosynthetic enzymes at grain-filling stage were investigated in grains of 4 wheat cultivars carrying all 3 Wx proteins subunits,which controlling the synthesis of amylose,starch physiochemical properties and noodle quality.Results showed that the activity of granule-bound starch synthase(GBSS) in developing endosperm from Jimai19 and Jimai20 was significantly lower than that of Lumai14 and Lumai21,while the activities of other key enzymes involved in amylopectin biosynthesis were similar,such as ADP-glucose pyrophosphorylase(AGPase),soluble starch synthase(SSS),and starch branching enzyme(SBE).Therefore,Jimai19 and Jimai20 exhibited lower amylose content in grain,and higher flour swelling power,pasting peak viscosity and breakdown,as well as better noodle quality.Activities of starch biosynthetic enzymes were correlated significantly with accumulating rate of amylose and amylopectin during grain filling,which suggested wheat cultivars were different in starch biosynthesis and processing quality mainly due to genotype.The activities of enzymes involved in starch biosynthesis were correlated significantly in developing endosperm,which indicated that they interacted in starch biosynthesis,the same was as accumulation of amylose and amylopectin.It is possible to breed wheat cultivars for preferred noodle quality from wild common wheat without Wx protein deficiency,and modification in activity or expression of one and several enzymes might not improve starch properties greatly.