Peanut is frequently constrained by extreme environmental conditions such as drought. To reveal the involvement of metabolites, TAG 24 (drought-tolerant) and JL 24 (drought-sensitive) peanut genotypes were investigated under control and 20% PEG 6000-mediated water scarcity conditions at the seedling stage. Samples were analyzed by gas chromatography–mass spectrometry (GC–MS) to identify untargeted metabolites and targeted metabolites, i.e., polyamines and polyphenols by high-performance liquid chromatography (HPLC) and ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS), respectively. The principal component analysis (PCA), partial least-squares discriminant analysis (PLS-DA), heat map, and cluster analysis were applied to the metabolomics data obtained by the GC–MS technique to determine the important metabolites for drought tolerance. Among 46 resulting metabolites, pentitol, phytol, xylonic acid, d-xylopyranose, stearic acid, and d-ribose were important drought-responsive metabolites. Agmatine and cadaverine were present in TAG 24 leaves and roots, respectively, during water-deficit conditions and believed to be the potential polyamines for drought tolerance. Polyphenols such as syringic acid and vanillic acid were produced more in the leaves of TAG 24, while catechin production was high in JL 24 during stress conditions. Seven metabolic pathways, namely, galactose metabolism, starch and sucrose metabolism, fructose and mannose metabolism, pentose and glucuronate interconversion, propanoate metabolism, amino sugar and nucleotide sugar metabolism, and biosynthesis of unsaturated fatty acids were significantly affected by water-deficit conditions. This study provides valuable information about the metabolic response of peanut to drought stress and metabolites identified, which encourages further study by transcriptome and proteomics to improve drought tolerance in peanut.

Background: Peanut (Arachis hypogaeaL.) is one of the valuable oilseed crops grown in drought-prone areas worldwide. Drought seriously limits peanut production and productivitysignificantly. Method and Results: In order to decipher the drought tolerance mechanism in peanut under drought stress, RNA sequencing was performed in TAG -24 (drought tolerant genotype) and JL-24 (drought susceptible genotype). Approximately 51 million raw reads were generated from four different libraries of two genotypes subjected to drought stress exerted by 20% PEG 6000 stress and control conditions, of which ~41 million (80.87%) filtered reads were mapped to the Arachis hypogaea L. reference genome. The transcriptome analysis detected 1,629 differentially expressed genes (DEGs), 186 genes encoding transcription factors (TFs) and 30,199 SSR among the identified DEGs. The comparative analysis between the two genotypes revealed higher and integral tolerance in TAG-24 through activation of key genes involved in, plant hormone signaling pathway, ABA, LEA protein, and oxidative damage. Conclusion: This genome wide transcription map therefore provides a valuable tool for future transcript profiling under drought stress and enriches the genetic resources available for this important oilseed crop.

Background: Peanut (Arachis hypogaeaL.) is one of the valuable oilseed crops grown in drought-prone areas worldwide. Drought seriously limits peanut production and productivitysigni cantly.Method and Results: In order to decipher the drought tolerance mechanism in peanut under drought stress, RNA sequencing was performed in TAG -24 (drought tolerant genotype) and JL-24 (drought susceptible genotype). Approximately 51 million raw reads were generated from four different libraries of two genotypes subjected to drought stress exerted by 20% PEG 6000 stress and control conditions, of which ~41 million (80.87%) ltered reads were mapped to the Arachis hypogaea L. reference genome. The transcriptome analysis detected 1,629 differentially expressed genes (DEGs), 186 genes encoding transcription factors (TFs) and 30,199 SSR among the identi ed DEGs. The comparative analysis between the two genotypes revealed higher and integral tolerance in TAG-24 through activation of key genes involved in, plant hormone signaling pathway, ABA, LEA protein, and oxidative damage.Conclusion: This genome wide transcription map therefore provides a valuable tool for future transcript pro ling under drought stress and enriches the genetic resources available for this important oilseed crop.