Screening And Identification Of Mutants For Starch Accumulating In Vascular Bundle Sheath Cells In Rice

Rice,as a kind of C₃ crops,has lower photosynthetic efficiency than that of C₄,such as millet,resulting in limiting the increase of yield.The Calvin cycle of C₄ crops mainly occurs in the bundle sheath cells.It is of great significant to screen the mutants of starch accumulation in the vascular bundles of vascular bundles and carry out relevant identification for the selection of high light efficiency rice resources.In this study,we selected 8600 T-DNA rice mutants as the material,picked up the leaves of the three-leaf stage and screened the mutants with the accumulation of starch in the vascular sheath cells.In the end,five mutants named as a128-5,a1564-7,a1701-2,a2964-3,and a3004-8,were selected and studied on the photosynthetic physiological characteristics and the activity of some C₄ photosynthetic enzymes.The main results from our research are summarized as the following:1)The net photosynthetic rate,transpiration rate and stomatal conductance of a2964-3 and a3004-8 were higher than the wild type rice.A3004-8's were the highest,significantly higher than that of wild type and A2964-3's were slightly higer than that of wild type.The results of intercellular CO2 concentration showed that the intercellular CO2 concentration of a128-5 and a3004-8 was higher than that of wild type,and the intercellular CO2 concentration of a128-5 was higher than that of a3004-8.The intercellular CO2 concentrations of a1564-7,a1701-2 and a2964-3 were lower than that of wild type,but the difference was not significant.Survey and statistics of the main agronomic traits showed that mutant's plant height,panicle length,seed setting rate,1000-grain weight were higher than the wild type.2)Determination of chlorophyll content indicated that the chlorophyll content of the mutant plants was higher than that of wild type,and the chlorophyll content of a1701-2was the highest and significantly higher than that of wild type.In addition,a1564-7,a2964-3,a3004-8,and a128-5 plants had no significant difference in chlorophyll content.The observation of the number of stomata in the far axis of the leaves of wild type and mutant plants showed that the stomatal arrangement of each row of wild type plants was more than that of the mutant plants.The stomatal length of the leaves of wild type plants and mutant plants showed that the stomatal length of the leaves of wild type plants was smaller than that of the mutant plants.3)The measure of enzyme activity showed that the activity of PPDK and NADP-ME of a128-5 was higher than that of wild type plants,and the enzyme activity of PPDK of a1564-7 was higher than wild type.The activities of PEPC,PPDK and NADP-ME of a1701-2 and a2964-3 were higher than those in wild type,and the activity of NADP-ME of a1701-2 was significantly higher than that in wild type and other mutant plants.The PEPC activity of a3004-8 was higher than that of wild type,and the PEPC activity was the highest in all mutants,which was significantly higher than that of other mutant plants.