Comparative Transcriptome Analysis Reveals Molecular Defensive Mechanism of Arachis hypogaea in Response to Salt Stress

Abstract

Abiotic stresses comprise all nonliving factors, such as soil salinity, drought, extreme temperatures, and metal toxicity, posing a serious threat to agriculture and affecting the plant production around the world. Peanut (Arachis hypogaea L.) is one of the most important crops for vegetable oil, proteins, minerals, and vitamins in the world. Therefore, it is of importance to understand the molecular mechanism of peanut against salt stress. Six transcriptome sequencing libraries including 24-hour salt treatments and control samples were constructed from the young leaves of peanut. A comprehensive analysis between two groups detected 3,425 differentially expressed genes (DEGs) including 2,013 upregulated genes and 1,412 downregulated genes. Of these DEGs, 141 transcription factors (TFs) mainly consisting of MYB, AP2/ERF, WRKY, bHLH, and HSF were identified in response to salinity stress. Further, GO categories of the DEGs highly related to regulation of cell growth, cell periphery, sustained external encapsulating structure, cell wall organization or biogenesis, antioxidant activity, and peroxidase activity were significantly enriched for upregulated DEGs. The function of downregulated DEGs was mainly enriched in regulation of metabolic processes, oxidoreductase activity, and catalytic activity. Fourteen DEGs with response to salt tolerance were validated by real-time PCR. Taken together, the identification of DEGs' response to salt tolerance of cultivated peanut will provide a solid foundation for improving salt-tolerant peanut genetic manipulation in the future.

Comprehensive genomic characterization of NAC transcription factor family and their response to salt and drought stress in peanut

“…We analysed their phylogenetic relationships, structural characteristics, chromosomal locations and gene orthologous gene pairs. We also determined their expression characteristics in different tissues and in response to salt and drought stresses on the basis of RNA-seq data [36,37,39]. Seventeen genes were identified as being involved in the response to both salt and drought stresses in cultivated peanut, and these results were confirmed by quantitative reverse transcription PCR (RT-qPCR).…”

“…Many NAC genes are considered to be abiotic stresseresponsive genes. To explore NAC genes involved in the response to salt and/or drought stresses, we analysed the published transcriptome sequencing results of cultivated peanut under salt [39] and drought [37] treatments. Under salt treatment, the expression level of 28 genes was upregulated by 2-fold, whereas the expression of 15 genes was downregulated more than 2-fold.…”

“…To investigate the expression patterns of NAC genes under salt and drought stress treatments, the average FPKM values of each gene under salt [37] and drought [39] treatments were obtained from our previous work. The average FPKM values of these NAC genes whose expression changed by more than twofold were compared via Excel software, log2 transformed and displayed in the form of heatmaps using HemI [55].…”

“…With the decreasing cost of RNA sequencing (RNA-seq), transcriptome sequencing has become a powerful high-throughput sensitive technique for the analyses of differentially expressed genes. Several peanut RNA-seq datasets containing information on different tissues or responses to different treatments have been published [36][37][38][39]. For example, RNA-seq data generated from 22 different tissues and from the development stage of the diploid peanut species A. duranensis and A. ipaensis have made it convenient to analyse peanut NAC homologue expression profiles [36].…”

“…For example, RNA-seq data generated from 22 different tissues and from the development stage of the diploid peanut species A. duranensis and A. ipaensis have made it convenient to analyse peanut NAC homologue expression profiles [36]. Differential gene expression in response to salt and drought stress has also been analysed, which can help in the identification of NAC genes involved in salt and drought responses [37,39].…”