Effects Of Overexpression Rice GS5 Gene And Maize ZmMRP-1 Gene On Maize Yield

Maize is one of the most important food crops.Because of the decrease of cultivated land and environmental problems such as global warming,Increasing maize yield is of great significance to alleviate the growing food demand.The grain yield of maize is composed of ear number per unit area,grain number per ear and grain weight,and the grain weight plays a decisive role in the formation of yield.On the basis of the Zm MRP-1 and GS5 trangenic maize by using Agrobacterium tumefaciens-mediated callus transformation,the molecular identification and yield-related character identification confirmed that the introduction of exogenous gene and the enhancement of endogenous gene expression in maize could improve maize grain weight.The main findings results are as follows:1.Molecular identification for GS5 gene of transgenic T3 generation plants.The positive rate of different lines was between 22.50% and 91.36% by PCR amplification.The Southern blot results showed that the GS5 gene was integrated into maize genome with low copy.RTPCR showed that exogenous GS5 gene could be overexpressed in maize.2.Agronomic characterization of GS5 transgenic maize twice a year during two years.The yield-related traits of some lines were improved significantly,OE-34 the most obvious change,grain width increased significantly by 8.99%,10.96%,respectively.100-seed weight increased by 14.10%,10.82%,respectively.Ear weight increased by 13.96%,15.71%,respectively.While Other agronomic traits such as plant height,ear height,grain length,kernel number per ear,ear rows and ear length are slightly change.In addition,GS5 gene could increase grain filling rate.3.Effects of overexpression GS5 gene on maize grain starch synthesis.OE-25,OE-34,OE-57 grain starch content increased by 10.30%,7.39%,6.39%,respectively.Scanning electron microscopy to observe the change of starch particle size,the starch particle diameter of transgenic materials decreased significantly.RT-PCR to detect the expression of related genes in starch synthesis,Overall,these gene expression were up-regulated.It is speculated that exogenous GS5 genes can increase starch content by regulating the expression of related genes in starch synthesis pathway.4.GS5 gene utilizing value for breeding.the OE-34,WT were hybridized with Zheng58,Chang7-2,Ye478,Huangzao4,respectively.Positive plants compared to negative plants,the GS5 gene can be stably expressed,the grain width,100-seed weight and ear weight are significantly increased.5.Molecular identification of Zm MRP-1 transgenic plants,the positive rate of each line was 13.63%-66.83%;Southern blot results showed that the Zm MRP-1 gene had been integrated into the maize genome and with single copy.OE-8 and OE-19 Zm MRP-1 genes were overexpressed compared to wild-type,and they were significantly up-regulated 3 days after pollination,and the expression intensity reached the highest 12 days after pollination,then the expression decreased,and basically RNA only expressed within 30 days after pollination.6.Agronomic characterization of Zm MRP-1 T2 generation transgenic maize.The yieldrelated traits of some line were improved significantly.The grain length increased from 0.85 cm to 0.90-0.93 cm,by 5.88%-9.41%;The grain width increased from 0.73 cm to 0.77-0.80 cm,by 5.48%-9.59%;and the 100-seed weight increased from 17.26 g to 18.67-19.02 g,by 8.17%-10.20%.