Genome-wide Identification And Transcript Profiles Of Walnut Heat Stress Transcription Factor Involved In Abiotic Stress

Walnut(Juglans regia L.)is a deciduous tree of Juglandaceae,and is one of the important economic tree species widely planted in the world.However,due to abiotic stress,the development of the walnut industry has been severely affected.Therefore,it has become an urgent task to excavate resistance genes and cultivate superior strains with high resistance through molecular breeding.Heat Shock Transcription Factors(HSFs)play an important role in stress resistance in plants.In this study,the c DNAs of ‘Qingxiang’ and ‘Xiangling’ walnuts were used as templates to clone genes and conduct bioinformatics analysis.Real-time quantitative PCR(q RT-PCR)was used to analyze the expression patterns of HSFs gene family in walnut cultivars ‘Qingxiang’ and ‘Xiangling’ under three abiotic stresses,namely,heat,salt and drought.The yeast expression vector was constructed and transformed into yeast cells to analyze the resistance of transgenic yeast to abiotic stress.The main research results are as follows:(1)29 HSF genes were identified by bioinformatics,covering 18 HSFA,9 HSFB and 2HSFC genes.The results showed that these HSFs contained 128-505 amino acids,the relative molecular weight was 14.43-65.42 k Da,and the isoelectric point was 2.12-9.28.Chromosome mapping analysis with TBtools showed that 29 members are located on 13 chromosomes of walnut,with the largest number on the 2D chromosome,including 4JrHSFs genes.(2)Using Clustal X 2.1 software to perform multiple sequence alignment,it was found that the sequence of JrHSFs gene has high similarity,and it is inferred that the domain of JrHSFs gene is very conservative.The phylogenetic tree was constructed with MEGA6.0software,and the results showed that walnut HSFs and Arabidopsis HSFs are closely related and have different evolutionary processes.(3)Analysis of the expression patterns of JrHSFs genes in different abiotic stresses found that most walnut HSFs are expressed in the ‘Qingxiang’ and ‘Xiangling’ walnut varieties,but their expression patterns are different in the two varieties.The expression of JrHSFs gene in ‘Qingxiang’ is more prominent,and the expression under heat stress was more significant than under salt stress and drought stress.In addition,under the same stress,the expression pattern of the same JrHSFs gene in different walnut varieties is different,and the expression pattern of different JrHSFs genes in the same walnut variety under the same stress is also different.(4)The JrHSF19 was cloned,and the yeast expression vector p YES2-JrHSF19 was constructed and transferred into INVSc1.The recombinant yeast INVSc1-p YES2-JrHSF19 and the control yeast INVSc1-p YES2 were subjected to stress treatment,respectively.The results showed that JrHSF19 mainly improves the acquired heat tolerance and systemic heat tolerance of yeast cells,and may have an inhibitory effect on salt stress and drought stress.It is speculated that JrHSF19 plays an important role in plant resistance to abiotic stress.