Grain Filling Characteristics And Gene Expression Of Zhongyan96-3 In Wheat

Wheat grain filling is an important stage of grain formation,which is crucial to the formation of yield and quality of wheat.Choosing varieties with fast grain filling rate can help shorten the storage capacity construction period in the later growth period,promote rapid grain filling,and further increase yield in wheat.Our previous study suggested that Zhongyan96-3,a dwarf and large spike wheat variety,had a faster filling rate during the filling period.In this study,the grain weight changes,grain filling characteristics,histology and development-related gene expression of Zhongyan 96-3 during grain filling were studied.These results help to further clarify the grain filling characteristics of Zhongyan 96-3 and better use it for wheat breeding.The main results are as follows:1.The filling period of Zhongyan 96-3 is 36d,and the grain weight can reach35.60g at 25 days after flowering and 38.64g at 30 days.The fresh weight and dry weight of grain were significantly higher than those of Guinong NO.19 and China Spring.Compared with Guinong NO.19,grain length,grain width,grain thickness and thousand-grain weight at maturity increased by about 20.5%,8.6%,33.2%and28.4%,respectively,and increased by about 39.2%,18.4%,40.3%and 90.4%,respectively,compared to China Spring.Correlation analysis showed that the1000-grain weight was significantly positively correlated with grain length,grain width and grain thickness,and the correlation coefficients were 0.988,0.995 and0.904,respectively.2.The grain filling of Zhongyan96-3 showed a typical"S"curve change,showing the characteristics of"slow-fast-slow".The filling rate of Zhongyan96-3 was significantly higher than Guinong NO.19 and China Spring,especially 10-20 days after flowering.Correlation analysis between grouting parameters and 1000-grain weight showed that the 1000-grain weight was positively correlated with the average grouting rate(R_mean),the maximum grouting rate(R_max),and the grouting rate in the rapid increasing period?R₂?and the slow increasing period?R₃?,with the correlation coefficient of 1,but negatively correlated with the grouting duration?T?,with the correlation coefficient of-0.999.3.Histological observation showed that the endosperm cell size and proliferation rate of Zhongyan96-3 were significantly higher than those of Guinong NO.19 and China Spring.The seed coats of China Spring and Guinong 19 are thick and dense at10 days after flowering,which may limit the growth of endosperm cells and the expansion of storage capacity.Compared with Guinong NO.19 and China Spring,Zhongyan96-3 accumulated starch rapidly in the early stage of grain filling,and the size of A-type starch was significantly higher than Guinong 19 and China Spring,with an increase of about 16.27%and 38.83%,respectively.4.Through the q RT-PCR analysis of genes related to starch synthesis?GBSS?and AGPase1?,protein synthesis?Ta PBF-D?,negatively regulated grain weight?Ta TGW6?and grain size?Ta CYP78A5?in the process of grain filling,it was found that GBSS?and AGPase1 were high expression in the early and middle stages of grain filling.Ta PBF-D was highly expressed in the middle stage of grain filling,and Ta CYP78A5was highly expressed in the early stage of grain filling.These four genes have the highest expression in Zhongyan96-3,and the lowest in China Spring.Ta TGW6 was expressed in the middle and late stages of grouting,and the expression of China Spring and Guinong 19 was higher than that of Zhongyan 96-3.Correlation analysis between gene expression and filling rate showed that the expression of Ta CYP78A5was positively correlated with filling rate.In conclusion,Zhongyan 96-3 has high expression of genes involved in starch synthesis,protein synthesis and grain size at 5-10 days after flowering,and endosperm cells rapidly proliferate and establish a large storage capacity,so that Zhongyan 96-3 has a faster filling in the early stage of grain filling.The faster filling rate promotes the rapid synthesis and accumulation of starch and protein in the early stage.Zhongyan 96-3 therefor had a larger grain type and a higher thousand-grain weight.