Phenotype Study Of A High Silicon Accumulation Mutant Hsi1 In Rice

Rice is the most important food crop in China.Obtaining high-yield and high-quality rice varieties has an important role in solving the food shortage problem in China.Silicon(Si)is the second most abundant element,both in terms of weight and number of atoms,in the earth’s crust.Rice(Oryza sativa)is the most effective Si accumulating plant known,and accumulates Si to levels up to 10.0% of shoot dry weight.Silicon plays an important role in vegetative growth,reproductive growth,and biological and abiotic stress in rice.In this study,a mutant line(Line3)with early flowering and low pollen fertility was found in transgenic rd29A::At NCED3 rice.Compared with wild-type WT,the mutant plants had higher silicon content in their organs.This mutant was tentatively named a high-silicon accumulation mutant(hsi1).PCR detection showed that the mutant still carried the transgene At NCED3.The phenotype observation,physiological detection,optical microscope observation、transmission electron microscope observation、scanning electron microscope observation,the estimation of the copy number of the exogenous gene of the mutant(hsi1)were carried out.The main results were as follows:1.Phenotype characteristics of growth and development of mutants:compared with wild type(WT)plants,mutant hsi1 plants grew faster in the early stage,slower in late growth stage.The leaves were wider and the stem was thicker comparing with wild type plant.Besides,the flowering period of the mutant was earlier than that of the wild type.The pollen fertility of the mutant is lower than that of the wild type.The width and length of mutant seed grains were longer than the wild type.The seed-setting percentage of mutant hsi1 declined comparing with the wild type.In addition,the plant height of the mutants after maturity is shorter than that of the wild type.2.The results of physiological experiments show that the water loss rate of leaves of mutant hsi1 plants was lower than that of wild type plants.Moreover,the relative water content of the mutant hsi1 leaves increased,and the chlorophyll permeability of the leaves decreased.The silicon content of each organ of the mature rice was measured.It was found that the content of silicon in the mutants hsi1 was higher than that of the wild type,and the silicon content in the rice husk was the highest.3.The results of leaf scanning electron microscopy showed that the silicon cells in the leaves of the mutant hsi1 rice were larger than those of the wild type.Transmission electron microscopy revealed that there was a thicker and denser silicon layer in the epidermal cells of the mutant hsi1 than in the wild type.4.The copy number analysis experiment of exogenous gene showed that the copy number of At NCED3 gene in mutant hsi1 was 1.