The Function Of Rice Zinc Finger Transcription Factor HST In Response To High-Temperature Stress

With global warming,rice production is frequently limited by high temperature,bringing the crisis to the food safety all over the world.To cope with the reduction in grain yield caused by global warming,it is important to develop heat-tolerant rice varieties,explore the physiological and molecular mechanisms of rice in response to high-temperature stress,clone high-temperature related genes and carry out functional studies.A zinc finger transcription factor gene,HST was cloned from a hst?heat stress tolerance?mutant in our previous studies.To clarify its detail mechanism in response to high-temperature stress in rice,we used wild-type ZH11,hst mutant,complementary transgenic plants HST-hst and HST-GUS-hst transgenic plants for materails.The results were as follows:1.Bioinformatics prediction results showed that HST protein had a signal peptide,and it was mainly located on the cell membrane.The three-dimensional structure analysis found that the HST protein belonged to the C2H2 zinc finger protein.GUS staining was performed on serval organs of HST-GUS-hst transgenic plants.The results indicated that HST gene was expressed in rice roots,leaves,nodes and anthers.The subcellular localization of HST and GFP fusion proteins revealed that HST was mainly localized in the nucleus of rice cells.2.Compared with the wild-type ZH11 and the complement-transgenic plants HST-hst,hst mutant had less wilting,lower water loss rate,higher relative water content and higher survival rate under high-temperature?42�C?stress.Further physiological measurements revealed that the activities of POD and SOD in the hst mutant decreased,H₂O₂ content increased and MDA content decreased.We found that due to the loss function of HST transcription factor,the H₂O₂ content in the hst mutant increased,and the stomata closure was induced,so that the rice maintained a higher water content,thus enhancing the heat resistance of the hst mutant.3.Compared with the wild-type ZH11,the expression of PRX24?encoding an H₂O₂ scavenger?gene was decreased in the hst mutant under high-temperature stress,which was consistent with the higher H₂O₂ content in the hst mutant leaves under high-temperature treatment.Compared with the wild-type ZH11,the expression of Hsps gene in the hst mutant was higher and the expression increased rapidly under high-temperature?42�C?stress.It was shown that the expression of Hsp17.0,Hsp24.1,Hsp26.7,Hsp58.7,Hsp74.8 and Hsp80.2 increased in hst mutant due to the high accumulation of H₂O₂.Hsps as a receptor for H₂O₂,played an important role in the heat resistance of the hst mutant.4.The wild-type ZH11,hst mutant and the complement transgenic rice HST-hst were treated with the H₂O₂ production inhibitor DPI in this paper.Under high-temperature?42�C?stress,wild-type ZH11,hst mutant and the complement transgenic rice HST-hst were wilted after DPI-treated.Moreover,the H₂O₂ content of wild-type ZH11 and hst mutant was significantly lower than that of the control group,and the expression of PRX24 and Hsps in rice were all lower than those of the control group.These results further confirmed that H₂O₂,as a signal molecular,induced the rapid expression of Hsps gene and played an important role in the heat resistance of the hst mutant.