Molecular Clonging And Functional Analysis Of Heat Shock Transcriptional Factor CarHSFB2 In Chickpea (Cicer Arietinum L.)

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. The plant has an elaborate system to adapt to extreme environments. Heat shock transcription factor (HSF) is a big transcriptional factor family in plant. 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 heat shock transcription factors (HSFs). 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 none of research on the chickpea HSFs. In our study, we isolated an identified one chickpea HSF gene named CarHSFB2. Furthermore, espression patterns of the CarHSFB2 were globally investigated in various developmental processes and under diverse stresses. And function of the CarHSFB2 was analyzed using transgenic Arabidopsis. Main results of this study are as follows.The CarHSFB2 encodes an HSF family protein which has 267 amino acids, and contains an intron with 87bp. Based on phylogenetic analysis, CarHSFB2 protein is one of class B-HSF proteins. Comparing the putative amino acid sequence of CarHSFB2 with that of other HSF proteins, CarHSFB2 has conserved functional regions and intron harboring site. Subcellular localization analysis shows that CarHSFB2 protein is localized in the nucleus. CarHSFB2 is investigated a single or low copy genes in chickpea by southern blot analysis.Expression patterns of CarHSFB2 were investigated in various developmental processes and under diverse stress and chemical treatments by RT-PCR. The tanscript of CarHSFB2 was up-regulated in leaf senescence, germination and seed development. Meanwhile, CarHSFB2 was induced in heat stress, H2O2 treatment, salt stress and drought stress. Under IAA treatment, CarHSFB2 was up-regulated, too. However, it was down-regulated under the GA3 and 6-BA chemical treatment. These findings suggested that function of CarHSFB2 was involved in plant growth and development regulation as well as environmental stress responses.In the function research, the CarHSFB2 transgenic Arabidopsis was grown under the heat and drought conditions, and the CarHSFB2 is constitutive expression in transgenic Arabidopsis. It showed that the expression of CarHSFB2 enhance the thermotolerance and resistance to drought. These results show that CarHSFB2 was an transcriptional activitor in heat and drought stress, furthermore, it is another evidence for class B-HSFs as a coactivator.