Qpe9-1 Gene Regulation Mechanism Research Of Rice Grain Filling

Populations of panicle erectness (PE) varieties show higher photosynthetic rates and material production capacity, but lower filled grain percentage, and lower numbers of spikelets on the main panicle, and exhibit negative effects on individual plant yield. Recently researchers identified and characterized qPE9-1, a major quantitative trait loci on chromosome9responsible for the erect panicle trait.A deletion in qPE9-1leads to PE in rice.Researchers transferred qPE9-1into wuyunjing7(PE type) and the transgenic rice showed higher numbers of spikelets on the main panicle, higher grain yield per plant and higher thousand seed weight. This gene was found to be a key regulator of plant architecture, but how did it regulate starch synthesis is unclear. Our research focused on clarifying the mechanism of qPE9-1regulating the filling stage of rice. The research is divided into four parts:the endosperm cells size and numbers, the changes of starch content, activities of enzymes which catalyses sucrose and starch metabolism, endogenous hormone contents. The materials which were used in our experiment are wuyunjing7(non-transgenic rice) and transgenic rice(qPE9-1).The research is based on field experiment and pot experiment which is utilized to illustrate the function of exogenous hormones IAA and ABA. The following is my major work:1. The endosperm cells size of transgenic rice were larger than non-transgenic rice, and numbers and starch content of endosperm cells of transgenic rice were higher, which suggests the gene can promote endosperm cell division, growth and regulats the process of starch synthesis and facilitates starch synthesis.2. Sucrose synthase(SUS), alkaline invertase (ALI), acid invertase (ACI)which are involved in unloading assimilate were obviously higher than non-transgnic rice, moreover, ADP Glucose Pyrophosphorylase (AGP) activity in transgenic rice were higher than non-transgenic rice. So qPE9-1may improve the efficiency of starch synthesis through promoting the assimilation synthesis and assimilation transport in leaf and stem, promoting synthesising ADPG.3. Analyzing the endogenous hormone contents, CTK, IAA and ABA in transgenic rice were higher than non-transgenic type. We speculate that transgenic type with high content of ABA and IAA can promote transporting assimilates, while high content CTK and IAA, can promote endosperm cell division, promote cell growth.4. Analysizing pot experiment, we found that, exogenous hormones made endosperm cells size larger and numbers of endosperm cells higher of these rice.so are the results of starch content. Activities of enzymes after various hormone treatmentm show that activities of SUS and AGP increase both in transgenic rice and non-transgenic rice.So we can speculate, qPE9-1, by influencing endogenous hormone concentration, control the size and numbers of endosperm cells, and promote transfer of assimilation, promote unloading assimilate and synthesising the substrat for starch and further regulate the activities of enzymes which is inferred in starch synthesis.