| Rice is one of the main grain crops in the world.The traditional breeding method has hardly made any breakthroughs in raising rice yield.With the development of genomics research,many research institutes have carried out the research on transferring C4 gene into rice.Studies have shown that C4 transgenic rice also shows that the C4 gene expression products may not be activated,the specific expression of photosynthetic C4 enzyme is toxic to other cells,and plant development deformity and other limitations.In recent years,it has been found that C4 photosynthetic enzymes also exist in rice,but their activity is low.C4 photosynthesis pathway may be enriched in Hybrid Rice during rice breeding.Earlier studies in this laboratory also confirmed that there is a high abundance and active C4 cycle key enzyme in the middle vein of high yield hybrid rice "Liang You Pei Jiu".Therefore,this topic selected "Liang You Pei Jiu"(LYP9)as the research object,with its parent 9311,sorghum gene into the rice 9311 of the large spike mutant line "Gao Liang Dao"(GLD)as the control,through the study of the physiological characteristics of LYP9 C4 photosynthesis,in order to further construct the mature C4 system in rice for high photosynthetic breeding.Provide better theoretical and practical basis.(1)To investigate whether there is a C4 like photosynthetic structure in the leaves of 9311,GLD and LYP9,the ultrathin sections of rice leaves were carried out to observe the development of the vascular sheath cells and the cells of the surrounding cells.The results showed that chloroplasts existed in the edge of small amount of vascular bundle sheath cells.The vascular bundle sheath cells in GLD had large chloroplast adherence,and the starch granules were accumulated in the chloroplasts.The mesophyll cells around the vascular bundle sheath cells were arranged neatly and the chloroplasts were dense,and the intercellular plastids between the vascular bundle sheath cells and the mesophyll cells were also visible.The volume of chloroplast in vascular sheath cells of LYP9 is large,and there is a small amount of starch granules.It is confirmed that the photosynthetic structure of GLD is similar to that of LYP9,and that the development of C4 photosynthetic structure is more perfect than 931 1.(2)To investigate whether the C4 photosynthetic pathway enhances the photosynthesis of rice,we determined 9311?GLD and LYP9 by means of photosynthetic instrument and chlorophyll fluorescence analyzer at booting stage,heading stage and milk stage.The results showed that the net photosynthetic rate of LYP9 at booting stage was higher than that of 9311 and GLD,and the ABS/RC and DIo/RC in PS ? were higher than 9311 and GLD,this indicates that the balance of energy flow and heat dissipation was better in LYP9.At the stage of milk ripening,the functional leaves of LYP9 began to enter the semi senescence stage,and the function period of GLD leaves extended.At this time,the light energy efficiency was not affected by the decrease of stomatal conductance,the net photosynthetic rate was over 9311 and LYP9,and the specific performance of the PS ? reaction center was relatively small.(3)In order to further verify the photosynthetic pathway of rice by protein immunization,the abundance of C3 cycle key enzymes RuBisCO,and C4 cycle key enzymes PEPC,PEPCK,PPDK and NAD-ME in 9311,GLD and LYP9 was detected at the booting stage,heading stage and milk stage.The results showed that the content of RuBisCO in GLD and LYP9 in booting stage was lower than that of 9311.And reached milk stage.the contents of RuBisCO and PPDK increased with the senescence of functional leaves,and the abundance of RuBisCO and PEPC in GDL increased during milk stage.Compared with the three rice varieties,the changes and differences of PEPCK and NAD-ME enzymes in the three stages suggested that the CO2 decarboxylation of C4 photosynthetic pathway in rice belongs to NADP-ME type. |
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