| Rice quality and yield formation mechanism has been one of hot topics in the research of rice at home and abroad.While sexual hybridization is still the main method for breeding new crop varieties, hybrids showed transgressive variation is a common phenomenon, provide important foundation for the breeding of new varieties of crops; the main storage substance in rice is starch, occupy 80%-90% of dry weight of endosperm.The components directly affect the rice cooking quality and yield.Starch is synthesized and accumulated in a series of enzymatic reactions.there were lots of enzymes involved in starch synthesis, ADPG was one of the key enzymes involved in starch synthesis. Sucrose synthase is a key enzyme involved in the synthesis and accumulation of sucrose in the precursor of starch synthesis,So,we analysis of expression characters of ADP-glucose Pyrophosphorylase isoform genes and relationship between sucrose metabolism and nitrogen nutrition involved in Japonica transgressive variation endosperm to clarify the mechanism of the formation of starch and its related genes,enzymes activity and its response mechanism to the environment. This were important to understand the molecular mechanism of starch quality and yield formation.Dong nong 423(H4)Teng xi 180(L11)(combination Ⅰ) and Xi xuan 1(H16) ×Tong 769(combinationⅡ)hybrid combinations were used in this study, From the F2 generation after generation according to the amylose content as the index, the continuous directional selection until to the F12 generation, with significant difference of amylose content in each of the two hybrid progeny with transgressive variation(H6,L12 were combinationⅠ;H1,L24 were combinationⅡ). Further purification was continued to obtain a stable genetic strain. Pot experiment was used to analysis the different filling periods of parent and transgressive progenies of amylose and total starch content and AGPase gene expression of mRNA,sucrose metabolism key enzyme activity,the above three kinds of treatment response to nitrogen regulation and the relationship between AGPase and starch and sucrose metabolism key enzyme. The results are as follows:On the starch accumulation, After heading to 10 d 25d is the rapid growth of all varieties of amylose and total starch content then growth slowly; In the filling process of high amylose content in genotype the amylose and total starch content was always higher than that of l ower amylose content of genotype, these results suggest that the effect of amylose content level and accumulation rate is a major factor in the genotype; Nitrogenous fertilizer can reduce the amylose content increased the full heading stage, but the effect is weak, no significant difference; The response of total starch content to nitrogen treatment varied with cultivars. the materials of high amylose content, the total starch content increased significantly, the material of low amylose content in the early stage of total starch difference was smaller, but the difference was significant.the material of amylose content was significantly different and the protein content in the hybrid progeny with transgressive variation also appeared to have a significant difference with the parents Fertilization or not on the impact of protein content is not due to the differences amylose content, Under the nitrogen treatment, the content of protein and the weight of 1000 grain weight increased, and reached the significant level in combinationⅠ;Cooking and eating quality: Under the nitrogen treatment, the materials of low amylose content decreased but not significantly,but the materials of high amylose content in taste value has increased, reached the significant level. Nitrogen fertilization can reduce the highest viscosity, the lowest viscosity and final viscosity, but the impact were difference, some reached to a significant level. Regardless of high protein content or low protein content, low amylose parents and hybrid progeny with transgressive the taste value and amylogram properties of viscosity, and setback and final viscosity was low, indicat ed that amylose content content was higher than protein content on the influence of cooking and eating quality.SuSy,AI activity and sucrose content in grain filling process activity showed a single peak curve, Su Sy activity in 10-15 days after heading significantly increased, the peak value appeared in 15-20 days after heading.The difference of the enzyme activities of the materials with different amylose content was large, reaching a significant level. Under nitrogen treatment, the activity of the Su Sy,AI and sucrose content were increased to a significant level, and the difference was not due to the different materials. the change of the SPS activity has two situations: in high amylose starch content of parents and progenies showed a single peak curve, the peak appeared in 15 days after heading; in low amylose content of parents and progenies its activity was decreased slowly. At the same time different amylose content material of SPS activity was different, reached a significant level; SPS activity decreased to a significant level under nitrogen treatment, The activity of Su Sy in different materials and different period was higher than that of SPS and AI.The expression of the OSAGPS2a、OSAGPS2b、Os AGPL1,Os AGPL3 genes mRNA in endosperm of parents and hybrid progenies with transgressive variation are gradually increased to the peak in 15-20 day after heading and then gradually decline, which showed a single peak curve along with the process of grain filling,Os AGPS1 gene is few expression;but Os AGPL2 gene mRNA is maximum expression and rise perpendicularly during grain filling period; Os AGPL2 、 Os AGPS2 a,Os AGPS2 b are dominate expressed genes during grain filling period;at the beginning of grain filling period,the expression of endosperm AGPase isoform mRNA genes which low amylose with transgressive variation are lower than low parents,and become complex in middle period,some are higher and some are lower than low parents. OsAGPS2a、Os AGPS1、Os AGPL1 mRNA expression were up-regulated during the grain filling period, and the later grain filling period still have a higher expression but Os AGPS2b、Os AGPL2、Os AGPL3 mRNA expression were decreased in endosperm under nitrogen treatment.Correlation analysis showed that: in addition to the expression of OsAGPS1 mRNA showed no significant negative correlation to amylose and total starch content, the other isoform genes were positively correlation. The correlation about the OsAGPS2 a mRNA gene expression with amylose and total starch content, Os AGPS2 b, Os AGPL2 gene expression with total starch were significant. The correlation analysis of the enzyme activity showed that sucrose content was negatively correlated with amylose content and total starch content, and was positively correlated with Su Sy, SPS and AI activity; Su Sy, AI activity with OsAGPS2b、OsAGPL1,Os AGPL3 showed negative correlation, which the negative correlation between the activity of AI and OsAGPL3 reached significant level. were positive correlation with the Os AGPS2a、OsAGPL1,OsAGPS1 gene expression, which in addition to the SuSy showed was not significant positive correlation with Os AGPS1, the rest are reached extremely significant positive correlation;SPS activity was negatively correlated with Os AGPS2 a,OsAGPS2b, and OsAGPL3, while positively correlated with Os AGPS1、Os AGPL1 and Os AGPL2 genes. But the overall correlation is not as good as the other two enzymes. |
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