| With the deteriorating global environment, extreme growth environment affect quantity and quality of crop product. Chickpea (Cicer arietinum) is the third important legume crop in terms of cultivation area. It is an annual plant with a short period of duration, a small genome size and strong resistance to biotic and abiotic stresses. And chickpea has been suggested as a model plant for investigation of physiological mechanisms of plant development and responses to stresses. However, chickpea is scarcely studied in the molecular biology, especially in China. As molecular chaperones, heat shock proteins (HSPs) play important roles in protecting cells from environmental stresses and assisting protein folding and assembly. Expression of HSPs is controlled by heal shock transcription factors (HSFs) which are a big transcriptional factor family in plant. HSFs are the terminal components of the signal transduction chain mediating the activation of genes responsive to both heat stress (hs) and a large number of chemical stressors. There are much more reports about HSFs in Arabidopsis, rice and tomato, and anything of research on the chickpea HSFs. Master of Cheng in our lab isolated and characterized an identified one chickpea HSF gene named CarHSFB2. Subcellular localization analysis showed that CurHSFB2protein was localized in the nucleus. CarHSFB2was investigated a single or low copy genes in chickpea by southern blot analysis. Meanwhile, The tanscript of CarHSFB2was up-regulated in leaf senescence, germination and seed development. CarHSFB2was also induced in heat stress, H2O2treatment, salt stress and drought stress. Under IAA treatment, CarHSFB2was up-regulated, too. However, it was down-regulated under the GA3and6-BA chemical treatment. But experts suspected the multiple sequence alignment of CarHSFB2and other HSFB protein, and then they predicted that the conserved C-terminus was lacking due to a sequencing mistake. In our study, we resequenced the chickpea heat shock transcription factor. CarHSFB2. And CarHSFB2protein had been predicted with the application of Bioinformatics. At last function of the CarHSFB2was analyzed using transgenic Arabidopsis. Main results of this study were as follows.The full cDNA sequence of CarHSFB2was804bp and encoded a30076.1Da protein with267amino acids. and contained an intron with87bp. The analysis of information biology indicated that the hydrophilicity of CarHSFB2protein had no signal peptide and transmembrane sites, also CarHSFB2protein might have localized in the nucleus. Based on phylogenetic analysis, CarHSFB2protein was one of class B-HSF proteins. Comparing the putative amino acid sequence of CarHSFB2with that of other HSF proteins, CarHSFB2had conserved functional regions and intron harboring site. The results proved the correctness of the sequencing of CarHSFB2.In the function research, the CarHSFB2transgenic Arabidopsis was grown under the heat, drought and salt conditions, and the CarHSFB2transgenic Arabidopsis was constitutive expression under the heat and drought conditions. It showed that the expression of CarHSFB2enhanced the thermotolerance and resistance to drought. Among four known stress-related genes, two genes (RD29A, HsfA2) were induced by overexpression of CarHSFB2gene in transgenic plants, suggesting that CarHSFB2protein can promote the transcription of these stress-related genes and then enhance tolerance to osmotic stress in transgenic plants. This study laid the foundation for the chickpeas B family of heat shock transcription factor. CarHSFB2gene also has the potential value for crop drought-resistant genetic engineering. |
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