Effect On Carbohydrate And Grain Weight By Over-expressing OsSUT1Gene After The Heading Stage

Abstract:Grain weight is the highest heritability factor in the constituent elements of rice production. It is a most important way to improve rice production by increasing grain weight. Grain weight is regulated by the source, sink and flow. In the flow level, the capacity of photoassimilates transport is the main constraints to the grain weight. The transport capacity of sucrose, which is the main form of assimilate transport and temporary storage in the plant, impact on the grain filling and enrichment directly. Sucrose transporter OsSUTl of rice has a function of sucrose long-distance transport. And it also plays a key role in the photoassimilate transport and distribution. To verify the effect of over-expression OsSUTl gene for carbohydrates and grain weight,we analysised the expression amount of OsSUTl and its influence to the photo rate,sugar content in nutrition organ,grain weight and the other yield characters,using the pure lines promoted by senescence-associated promoter PSAG12。The main results are as follows:(1)We successfully transport the senescence-associated promoter PsSAG12promoted OsSUT1gene into super hybrid parent R299, using Agrobacterium mediated transformation method. And obtained102plants from independent transformation in the last.(2)We identified61positive plants by PCR and Southern Blot detection. Qualitative and quantitative analysis by RT-PCR and RT-qPCR showed that:OsSUT1gene low expression in transgenic plants in the early growth stage, with the growth process to continue its expression level gradually increased, showing high expression characters in the late growth stage. The expression amount of OsSUT1has reached a high level in7DAF in each of the tissues, and continues to21DAF. High expression behavior of target gene in filling stage is very important to meet the nutrients supply to the grain filling, and it also laid a basis of mobilization substances to improve grain plumpness.(3) Over-expression of OsSUT1gene does not affect the photosynthetic rate, reduce the soluble sugar content (reduce10.9%, average) in the leaf blade, increase sucrose content(increase of3.5%and8.5%, respectively) and soluble sugar content(increase of6.5%and14.5%, respectively) in stem and leaf sheath. And it also improved the capacity of grain filling material supply.(4)Over-expression OsSUT1gene performance increases the total number of spikelets per plant,unchanged seed setting rate,as well as the improvement of1000-grain weight and theoretical yield per plant,with an average increase of4.75%and26.31%,in seed setting characteristics. Correlation coefficient between OsSUT1gene expression amount and grain weight is0.511, indicating that reasonable use OsSUT1can improve the yield potential of rice effectively.