Transcriptional Analysis Of Young Cotton (G.tomentosum) Seedlings Under Salt Stress

Cotton is an important economic and fiber crop in China.Cotton is medium salt-tolerant crop,salt stress can affect cotton growth and yield seriously,especially in the stage of seed germination and seedling growth.Salt stress is one of the most serious abiotic stresses worldwide.It influences the production of crops,using genetic engineering to improve plant salt resistance,to develop suitable plant varieties for the salinization land growth is the main method of effective utilization of salinization land.Because of Gossypium hirsutum's narrow genetic background,which take part of 90% cotton production worldwide,the current yield,quality and stress breeding for cotton are faltering.So it is necessary to explore excellent germplasm resources especially from the wild cotton to enrich the genetic diversity of cotton germplasm resources in China through many ways.Gossypium tomentosum belongs to tetraploid wild cotton,it has excellent properties such as fiber fineness and salt tolerance.But basic and applied research aiming at good qualities of Gossypium tomentosum have not been reported.This research carried out the salt stress transcriptome sequencing of Gossypium tomentosum and selected three other tetraploid cotton Gossypium hirsutum TM-1,Gossypium barbadense 3-79,half wild cotton Gossypium mariegalante85 as reference.We carried out transcriptome sequencing of Gossypium tomentosum seedlings before and after salt treatment with the method of high throughput sequencing,through the analysis of a large number of sequencing results,we found quite a few genes raised and lowered after salt stress treatment,and excavate the potential of salt resistance candidate genes.Later,we verified the results with the method of qRT-PCR.The main experimental results and conclusions were as follows:1.This study measured the PRO,SOD,POD,the soluble sugar,soluble protein content and so on physiological and biochemical indicators,PRO content of Gossypium tomentosum leaves and roots had greater than 5 ?g/g and greater than 2.5 ?g/g respectively,Gossypium tomentosum remained relatively normal form Through the PRO growth after 3 h's salt stress.Only the SOD content in the leaf of Gossypium tomentosum increased,the rest of the three materials decreased.Only the POD content in the root of Gossypium tomentosum increased,the rest of the three materials decreased.SOD is the first line of defense to clean up the ROS,SOD in Gossypium tomentosum leaf is still cleaning up excess ROS to ensure the normal form of the plant after 3 h's salt stress,and the other three cotton materials are already wilting.Only the POD content in the root of Gossypium tomentosum increased,which indicates Gossypium tomentosum roots are still cleaning ROS and the rest of the three materials decline d and wilting.Soluble sugar content of Gossypium tomentosum leaf increased 47.5 times,but it remains the same in the root after 3 h's salt treatment,the harmful ions are transported to leaves,so that soluble sugar in the root are balanced and roots are protected.Soluble protein in the Gossypium tomentosum remained unchanged after salt stress,reach the balance,and plant form keeps relatively normal,which means salt didn't affect the Gossypium tomentosum normal biochemical reactions.According to the physiological and biochemical indicators we preliminary identify Gossypium tomentosum is salt resistant.2.We received 170.5 million raw data in Treatment group and control group after a high-throughput sequencing,and 165.7 million valid data After pretreatment quality,among which 89.8 million leave Raw data,80.7 million root Raw data,After pretreatment quality we found 87.3 million valid data in leave,78.4 million in root.We compared the protein database then carried out the KEGG and GO function classification.Analyze differentially expressed genes of leaf and root respectively.There're a total of 2647 differentially expressed genes Gossypium tomentosum.Raised expressed genes(17.8%)of 473 in leaf,381(14.3%)decreased.Raised expressed genes(45.9%)of 1216 in root,577(21.7%)decreased.We found some possible participation or mediated genes in related biological ways through high abundance ratios genetic analysis.These genes are mainly playing regulating role in the original plant hormone pathways or transcription factors,Such as Gorai.009G096200.1,Gorai.007G103200.13.According to the gene expressing differences in the GO and KEGG gene clustering analysis,and combining previous regulation of transcription factors and plant hormone pathways we selected 11 genes.Using RT-PCR method to detect the relative expression of 11 genes,the results are basically identical with the sequencing results,showing that the transcriptome sequencing results are reliable.This study offers a new way for cotton salt resistance.