Physiological Traits Of Transgenic Indica Rice (Oryza Sativa L.) With Over-expressed OsSUT2/OsSUT5 During Grain Filling Period

Effective earring tillers, seed-setting percentage, thousand kernel weight and filled-grain percentage are key factors to influence the yield of rice. These factors have also related to the transportation and metabolism of sucrose. The insufficiency in grain filling is the major reason for low seed-setting percentage and others traits closely related to bad grain quality, especially in hybrids between indica and japonica rice or other new type.Sucrose transportation is a bridge in sink and source. Sucrose transporter has been demonstrated to have the function of transferring sucrose through cytoplasm membrane.In this study, based on two transgenic indica rice with OsSUT2 and OsSUT5, ratio of source to sink increment, photosynthesis rate of flag leave, and other quality-related traits were measured and determined, to study the impact of the over-expression of the two genes on the relationship among sink, source and path, and to analyze the changes in the increment, transportation and distribution of photosynthetic products. The results were as follows:1. The over-expression of the transgenic lines with OsSUT2 and OsSUT5 showed significant difference with the control group,which the change of OsSUT2 lines in the ration of source to sink was significantly higher than the control in 20-25 days, and to OsSUT5, in 30 days. It could be inferred that OsSUT2 and OsSUT5 play the role in the forward reglution. The two genes behaved different role during grain filling period. OsSUT2 focused on the role of filling in the middle and late period, and to OsSUT5,in the late period.2. The result of the measurement of transportation rate of photosynthetic products showed that the transgenic lines with OsSUT2 were significant different with the control, with their higher seed-setting percentage.3. It could be inferred that the over-expression of the transgenic rice with OsSUT2 effectily enhanced photosynthesis during grain filling period, but to the transgenic rice with OsSUT5 had not similar performance. It could be inferred that the over-expression of the transgenic rice with OsSUT2 effectily enhanced photosynthesis during grain filling period. 4. The content of the soluble sugar in the flag leaves of the transgenic rice with 0sSUT2 and OsSUT5 was significantly higher than that of the control after twelver days of budding; the contents of the soluble sugar in the reverse fourth leaves of the transgenic rice were significantly higher than that in the control after eighteen days of budding. It could be inferred that the over-expression of OsSUT2 enhanced the the transportation and metabolism of sucrose.5. The ripened grain rate, average individual panicle weight of the transgenic rice with OsSUT2 was significantly higher than the control. The chalkiness rate, chalky white and grain length of the transgenic rice with OsSUT2 was lower than that of the control, and the brown rice rate, milled rice rate, head milled rice rate increase than the control. The over-expression of OsSUT2 improved the economic character and performed an important role in sink and source. Transgenic line SJD230 with OsSUT5 to the average individual panicle weigh, the degree of grain filling was significantly higher than the control. The over-expression of OsSUT2 also had a certain contribution.To sum up: OsSUT2 and OsSUT5 behaved different control functions during grain filling period. OsSUT2 was significantly higher than the control in the ration of source to sink, the measurement of transportation rate of photosynthetic products, photosynthetic rates of the flag and the content of the soluble sugar in the flag leaves and the reverse fourth leaves. It could be inferred that OsSUT2 was an important regulatory gene during grain filling period, and OsSUT5, its main functions will be further studied.