Identification And Analysis Of HSF Family Genes In Chinese Cabbage

Chinese cabbage(Brassica rapa L. ssp pekinensis) originated from China, and it is the most widely distributed and the largest plant areas crop. But the Chinese cabbage is sensitive to high temperature, their yield and quality will be declined seriously when suffering from heat stress in summer. So, the main measure to achieve the annual supply of Chinese cabbage is to improve their ability of resistance to heat stress. HSF(Heat shock transcription factor, HSF) is present in cell, and it can activate the expression of heat shock genes to improve the resistance to heat stress. However, The function that can be resistant to heat stress of HSF gene family from Chinese cabbage has not been characterized. So, it is important theoretical and practical value to studying Cabbage HSF gene of heat resistance. And it has provided theoretical molecular assisted breeding for Chinese cabbage. The results of this study are as follows: 1 Identification and expression pattern analysis of HSF genes in Chinese cabbageIn this study, a total of 31 HSF genes were identified and described in Chinese cabbage. The expression pattern of BrHSF genes were analyzed using real-time PCR method. Except for BrHSF3 and BrHSF4 was not detected transcript expression, the other 29 numbers have shown different response to low or high temperatures. Additionally,BrHSF13 and BrHSF14 have the most response to 35 ℃ temperature treatment, and the level of transcription were 3500 and 2000-fold to controlled, respectively. 2 BrHSF14 gene clone and transform Arabidopsis thalianaThe CDS sequence of BrHSF14 was cloned through RT-PCR method. Use pCAMBIA-35s-OCS as vector backbone, the CDS sequence of BrHSF14 was cloned into it, and construct BrHSF14 gene overexpression vector. Then the overexpression vector was transform Arabidopsis use floral dipping method mediated by Agrobacterium. By the means of semi-quantitative PCR and quantitative PCR to detect Kanamycin-resistant plants, and found that all of transgenic plants can transcript and express of the target gene normaly. 3 Analysis of transgenic Arabidopsis thermotoleranceAfter 38 ℃ 2h, 22 ℃ 2d, 44 ℃ 4h, then 22 ℃ 4d treated, most of the wild-type and Vector-control plants died. However, only a small part of 35S:BrHSF14 plants were dead. So, the survival rate of seedlings was significantly higher than wild-type and Vector-control. In addition, through detecting the chlorophyll fluorescence parameters of different genotypes plants under the heat stress conditions and found that the structure and function index(SFI) and performance index(PI) of the BrHSF14 overexpression transgenic lines were significantly higher than wild-type and Vector-control. The results suggest that overexpression of BrHSF14 gene in Arabidopsis can significantly increase the resistance to heat. 4 The heat Mechanism of transgenic ArabidopsisIn this study, the transcription expression levels of APX2, Gosl1, HSFA2, HSP17.7, HSP 18.1, HSP 25.3, HSP70, HSP101, RPS and RPS17 genes were detected by the method of quantitative PCR. The results showed that overexpression BrHSF14 gene in Arabidopsis increased the mRNA levels for these heat resistance related genes. So we speculated that the BrHSF14 improving the resistance to heat stress may be associated with the expression of up-regulated genes above-mentioned.