Photosynthetic Carbon Assimilation Basis For High Yield Of High-quality Rice Variety Nanjing 910

Nangeng 9108（NG9108）is a new japonica rice with good taste obtained by crossing the male parent Guandong 194（GD194）and female parent Wuxianggeng 14（WXG14）in Jiangsu Academy of Agricultural Sciences.In recent years,most of the studies have focused on the analysis of fertilizer management,cultivation methods,rice quality and high yield characteristics of NG9108,while the research on its internal physiological and biochemical characteristics is rarely reported.Photosynthetic dark reaction is essential for plant dry matter accumulation.The aim of this experiment was to explore the photosynthetic carbon assimilation ability of NG9108.NG9108 was used as experimental materials.GD194 and WXG14 was used as comparision.The activity,protein content and m RNA content of Ru Bis CO,PPDK and PEPCK,the relational enzymes of photosynthetic dark reaction,were compared.The proteomic differences were also analyzed.The purpose of this study is to clarify the characteristics of photosynthetic carbon assimilation of NG9108,and to provide a theoretical basis for the breeding of high-quality and high-yield rice.The results show that:（1）NG9108 have high plant height,strong tillering and growth,and gathering and upright leaves.The good leaf and plant type of NG9108 promote the absorbtion of light.The agronomic traits showed that the plant height,flag leaf length,ear length,grain per panicle,grain density and 1000-grain weight of NG9108 were higher than those of GD194 and WXG14.The activity of Ru Bis CO,PPDK and PEPCK in Flag Leaves of NG9108 were close to GD194 and greater than WXG14 at heading and milk stages.The result indicated that the higher carbon assimilation-related enzyme activities of NG9108 can increase CO₂assimilation efficiency and boost photosynthetic product synthesis.（2）The results of Western blot and q RT-PCR showed that the protein content and m RNA transcription level of Ru Bis CO large subunit（Rbc L）,Ru Bis CO small subunit（Rbc S）,PPDK and PEPCK in the flag leaf of NG9108 were near to or a little higher than those of GD194,but significantly higher than those of WXG14 at heading stage and milk stage.It further means that the photosynthetic carbon assimilation ability of NG9108 is similar to that of GD194,but it is obviously superior to WXG14.The strong photosynthetic dark reaction ability of NG9108 promotes the synthesis and accumulation of organic matter during grain filling.Moreover,the higher activity and content of PPDK enzyme of NG9108 can promote the starch synthesis reaction and increase weight of NG9108 grain.（3）Proteomic analysis showed that the differentially expressed proteins between NG9108 and the parent were mainly involved in photosynthesis,protein metabolism,nucleic acid metabolism,signal transduction and so on.Compared with the parentthe,the expression of oxygen-releasing protein 1,cytochrome b₆f complex iron-sulfur subunit and ATP synthaseδ-chain related photoreaction were up-regulated in NG9108at milk stage.It meaned that the electron transfer efficiency,ATP synthesis rate,and photoreaction ability of NG9108 were more active and strong than the parents,which may explain why the photosynthetic carbon assimilation ability of NG9108 was slightly lower than GD194,but many yield components were higher than GD194.The trend protein synthesis anabolism of NG9108 was slower than GD194 but more active than WXG14.This may result the fact that the protein content of Ru Bis CO,PPDK and PEPCK of NG9108 is slightly lower than GD194 and higher than WXG14.The expression level of ribonuclease in NG9108 flag leaf was lower than that in parents,indicating that the degradation rate of RNA in NG9108 flag leaf was slow.