| Xinjiang is the main producing area of cotton.Drought and water shortage directly affect cotton production and quality.At present,the molecular mechanism of drought resistance in cotton is not clear enough,and the understanding of major drought-responsive genes is not comprehensive.Therefore,it is necessary to thoroughly study the molecular mechanism of cotton response to drought and find the key genes for cotton drought resistance.The analysis of cotton gene expression and metabolic pathway changes under drought stress at the overall level by transcriptome sequencing will help to analyze the main ways of drought resistance in cotton and provide theoretical basis for future research on molecular mechanisms of drought resistance in cotton.It has an important guiding role in digging potential genes for improving drought resistance in cotton.1.In this study,44.92 Gb Clean Data was obtained by RNA-Seq sequencing.The percentage of the sample bases(Q30)was greater than 93%,and compared to the Reads on the upland cotton reference genome,it was more than 86%,indicating that the data coverage was good.A total of 2509 differentially expressed genes were obtained in RNA-Seq data,of which Nr library could annotate 2479 differential genes,and the NR database annotation rate was 98.8%.The GO functional annotation classification showed that differential genes can be enriched into 3 categories and 44 subcategories,with a higher proportion in cell processes,single organism processes,and metabolic processes.The KEGG annotation of differentially expressed genes indicated that differential genes were mainly accumulated in plant hormone signal transduction,carbon metabolism,photosynthesis related pathways and other metabolic pathways,indicating that these processes may play an important role in the growth and development of cotton and its resistance to drought stress.2.To further explore the stress-resistance mechanism and major stress-resistance related genes of cotton drought,we analyzed photosynthetic pathways,DNA damage repair systems,osmotic adjustment systems,reactive oxygen species scavenging systems,and differentially expressed transcription factors under cotton drought stress.The results showed that 58 photosynthetic related genes were screened out in photosynthesis pathways,and most of themwere down-regulated genes,indicating that drought inhibited cotton photosynthesis.The DNA damage repair system was analyzed and a total of 51 genes involved in DNA damage repair were screened out,of which slightly more down-regulated genes than up-regulated genes showed that drought had some damage to DNA damage repair pathways.The osmotic adjustment system was used to analyze the results.The results showed that under drought stress,cotton penetrates the small molecular substances to reduce the damage to the cells and increase the resilience of the cells.Galactose plays an important role.The active oxygen scavenging system was analyzed.The results showed that under drought stress,cotton synthesizes a large amount of ROS to scavenge related enzymes to reduce the oxidative damage.Differential transcription factors were analyzed and the results showed that the bHLH family transcription factors had the largest number of changes under drought stress,followed by WRKY family and MYB family transcription factors.Combined with transcriptome data analysis,a molecular network map of cotton response to drought was initially drawn.3.qRT-PCR was used to detect the relative expression of the GhOleosin1,which was highly expressed in cotton.qRT-PCR results showed that drought stress induced the expression of GhOleosin 1.Further cloning and induced expression in prokaryotic system provide ideas for studying the function of Gh Oleosin 1. |
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