Genetic Analysis Of The Rice (Oryza Sativa L.)heat Tolerance Mutant During Anthesis

High temperature has heavily threatened the yield of the crops allover the world, such as the rice. It is the main reason of the reducing of therice yield that during the anthesis the rice meets with the heat stress. Becauseof the change of the world weather and the frequent happening of the extremeweather, heat stress has more and more impacted on the yield and the qualityof the rice. Therefore, it is very important to filtrate and cultivate the ricewhich is tolerant with heat stress, to clone, identify and analyze the geneswhich have heat tolerant ability, and to research the mechanism of the heattolerance in rice.The research material of this project was a mutant with the backgroundof Oryza sativa subsp. Keng Zhonghua11(ZH11), which had the ability ofthe heat tolerance during the seeding stage. The ability of the heat toleranceduring the anthesis of this mutant was identified. The anthesis of this mutantwas handled with the temperature of40℃for15days. The setting percentageof ZH11was only3.2%, while the setting percentage of the mutant was32.0%and ten times of the setting percentage of ZH11. ZH11and mutantwere cultivated in the field in2013, in which year the summer had continuedhigh temperature weather during the anthesis of the rice. In the field thesetting percentage of ZH11was only32.6%, while the setting percentage ofZH11was42.8%and10.2%more than ZH11. The results of bothexperiments indicated that the mutant had the ability of the heat toleranceduring the anthesis. For the genetic analysis of the mutant, the hybrid groupwas built with IR29and the mutant. The anthesis of the F1and F2generations was handled with the temperature of40℃for15days. F1generations were flabby. In F2generations the percentage of the seedingstrains and the strains without seeding was1:3, which indicated that the mutant gene was recessive. The molecule marks were used to roughly locatethe site of the gene on the chromosomes. As the result, one transcriptionfactor was found with the zinc finger domain. By the sequencing of the gene,it was found that4bases insert in the gene which leads to the frameshiftmutation, results in the loss of the function of HST, and indicates this zincfinger transcription factor is negative regulatory factor of the heat toleranceduring the rice anthesis, which was named to HST. HST gene was cloned andlinked to the expression vector pCAMBIA1300. By Agrobacterium mediatedmethod, the revertant genetically modified materials of the mutant wereobtained. By fluorescence quantitative PCR, the expression pattern of thegene in different tissues and organs was studied, and the results indicated thatthe expression of the leaves was far more than other tissues and organs. Byfluorescence quantitative PCR, the expression of the gene during the seedingstage handled with40℃for15days was researched, too. The results showedthat the expression of HST in the leaves was regulated by high temperature,declined firstly, up-regulating soon afterwards and recoverd the backgroundexpression after6h. In the situation of the heat stress in the seeding stage, theexpression of HST remained stable, which illuminated that it was highlypossible that HST taked part in the heat stress response passageways in therice. The status of the gene in the heat stress response passageways and thedownstream genes regulated by HST will be researched sequentially.