Genome Wide Identification Of HSFs And HSPs Gene Family In Eggplant(solanum Melongema L.) And Analysis Of Their Expression Pattern Under High Temperature

Heat shock transcription factors(Hsfs)and heat shock proteins(Hsps) are widely distributed among plant species, and they play crucial roles in plant development and defence processes. The production and quality of eggplant(Solanum melongema L.), an economically important vegetable crop, are severely reduced by adverse environmental stress, such as heat, salt and osmotic stress. Although the eggplant genome has been sequenced, but the related research of the Hsf and Hsp gene family have not been reported until now, so it is important to study molecular biology of Hsf and Hsp genes and reveal their biological function in eggplant. In our study, Hsfs and Hsps genes were identified from eggplant genome by bioinformatics approaches, meanwhile classification, phylogenetic, protein motifs and exon/intron structure of Hsfs and Hsps genes were also analysed. Nine candidate genes to be used as reference gene for Q-PCR were evaluated according to the statistical analysis by ge Norm, Norm Finder, and Best Keeper softwares. Real-time fluorescence quantitative technique was used to study the part eggplant Hsfs and Hsps genes expression pattern under high temperature stress(42℃ 6h). This main results obtained were as follows:1. A total of 24 Hsf members and 174 Hsp were identified in the eggplant genome. Based on analysisof bioinformatics and phylogenetic, Hsf were grouped into three classes, s Hsp were grouped into ten classes, Hsp40 were grouped into three classes, Hsp60, Hsp70, Hsp90 and Hsp100, respectively, were grouped into four classes.2. Phylogenetic analysis of eggplant Hsf and Hsp genes along with arabidopsis and tomato counterparts indicated that Hsf and Hsp genes in eggplant were more closer to those of tomato than those of Arabidopsis, which demonstrated that eggplant and tomato diverged more recently from a common ancestor. In addition, we also found 84 pairs of orthologous genes and 17 pairs of the homologous genes among the three species.3. Protein motifs analysis demonstrated that eggplant Hsf and Hsp genes of almost all the family members were involved in structure domain lost. The analysis exon/intron structure indicated that, there were a larger difference in the numbers of exon/intron of eggplant Hsf and Hsp gene familys, the difference in intron length may be result in diversity of gene family function.4. By RNA-Seq, the seedling transcriptome of heat susceptible 05-1 and heat tolerant 05-4 under the heat stress was examined, and differentially expressed genes(DEGs) were identified simultaneously. Gene ontology and Pathway analyses showed that the identified DEGs were enriched in pathways, including metabolic, plant hormone signal transduction and protein processing in endoplasmic reticulum, especially many heat shock proteins, such as s Hsp, Hsp40, Hsp70 and Hsp90 invovled in the pathway of protein processing in endoplasmic reticulum. The expression of Hsf and Hsp gene were comprehensively analysed based on the transcriptome sequencing before and after high temperature stress(42℃ 6 h), the results indicated that Hsf and Hsp had similar expression patterns in the two lines, majority of the Hsf and Hsp to participated in high temperature response of eggplant seedling.5. To determine the optimal reference gene for Q-PCR analysis under heat stress, We analyzed nine candidate reference genes and found that, after 42℃treatment, Sm EF1 a was the best choice for normalization in different time treatments, and the second was Sm UCP. Sm EF1 a and Sm60 s RNA were the most stable genes in different tissues.6. Using Q-PCR technology, we analysised the expression of Sm Hsf A1 b, Sm17.9B-s Hsp, Sm26.4-s Hsp, Smcp Hsc70-2, Sm Hsp90-7.2 genes under high temperature, the results showed that heat treatment could rapidly upregulate the expression of Sm Hsf A1 b, Sm17.9B-s Hsp, Sm26.4-s Hsp, Smcp Hsc70-2 and Sm Hsp90 7.2 genes in susceptible 05-1 and heat tolerant 05-4, while the genes expressing quantity in heat tolerant line were ususlly higher than those in susceptible line, that means they may play important role in eggplant thermotolerance response. In addition, these genes showed variable expression levels in root, stem, leaf and its function also to the regulation of the parts. We draw a conclusion that, a total of 5 genes were associated with eggplant heat resistance.