Functional Analysis Of Transcription Factor HST In Response To High Temperature Heat Damage In Rice

With the continuous development of the global industrialization,the earth's surface atmosphere temperature is increasing year by year.High temperature stress has seriously affected the growth and development of rice,posing great risk to the security of China food production.Therefore,the selection of heat resistant varieties is an effective means to alleviate the heat stress of crops.Cloning,characterization and functional analysis of high temperature resistance genes will lay a solid foundation for the development of genetic engineering.The research material of this paper were hst mutant?with the background of Zhonghua 11?,complementary transgenic plants HST-hst and wild-type ZH11.The phenotypic,physiological and biochemical characteristics of rice during the seedling stage and the flowering stage under high temperature stress were studied.The main results were as follows:1.High temperature stress resulted in the increase of transcription factor HST expression level in spikelets of ZH11.The results showed that HST could respond to high temperature,and was closely related to heat tolerance of rice.2.There was no significant difference in plant height,root length and maximum leaf width between HST-hst and ZH11,while there was a significant difference between HST-hst and hst,which indicated that HST-hst restored part morphological characteristics of ZH11.Under high temperature?42??treatment,The seedlings of HST-hst and ZH11 had higher water losing rate,lower relative water content and survival rate than hst mutant.The stronger ability of leaf water retention was the physiological factor of heat tolerance of hst during the seedling stage.3.Under high temperature treatment?40?,7 d?during anthesis,the fertilization rate,grain number per panicle,seed setting rate and yield per plant of HST-hst and ZH11 were lower than hst mutant,and there was no significant difference between HST-hst and ZH11.The higher pollen viability and the number of pollen grains on the stigma were the main reasons for heat tolerance of hst mutant.4.Under high temperature treatment?40?,7 d?during anthesis,the contents ofsoluble protein and soluble sugar in spikelet of ZH11 were significantly decreased,while the contents of MDA,H₂O₂ and free proline in spikelets of ZH11 were significantly increased.However,hst mutant had more osmotic adjustment substances and lower MDA and H₂O₂ contents than ZH11.Thus hst mutant had stronger osmotic adjustment ability and biological membrane protection ability,which might be the physiological basis of high temperature tolerance of hst mutant.