Abstract
Cultivated peanut (Arachis hypogaea) is one of the most widely grown food legumes in the world, being valued for its high protein and unsaturated oil contents. Drought stress is one of the major constraints that limit peanut production. This study’s objective was to identify the drought-responsive genes preferentially expressed under drought stress in different peanut genotypes. To accomplish this, four genotypes (drought tolerant: C76-16 and 587; drought susceptible: Tifrunner and 506) subjected to drought stress in a rainout shelter experiment were examined. Transcriptome sequencing analysis identified that all four genotypes shared a total of 2,457 differentially expressed genes (DEGs). A total of 139 enriched gene ontology terms consisting of 86 biological processes and 53 molecular functions, with defense response, reproductive process, and signaling pathways, were significantly enriched in the common DEGs. In addition, 3,576 DEGs were identified only in drought-tolerant lines in which a total of 74 gene ontology terms were identified, including 55 biological processes and 19 molecular functions, mainly related to protein modification process, pollination, and metabolic process. These terms were also found in shared genes in four genotypes, indicating that tolerant lines adjusted more related genes to respond to drought. Forty-three significantly enriched Kyoto Encyclopedia of Genes and Genomes pathways were also identified, and the most enriched pathways were those processes involved in metabolic pathways, biosynthesis of secondary metabolites, plant circadian rhythm, phenylpropanoid biosynthesis, and starch and sucrose metabolism. This research expands our current understanding of the mechanisms that facilitate peanut drought tolerance and shed light on breeding advanced peanut lines to combat drought stress.
Highlights
Large-scale screening of peanut had identified some drought-related candidate genes such as basic leucine zipper transcription factor genes that were observed from the wild relative of cultivated peanut, Arachis duranensis, when the plant was subjected to drought with 18% soil water content (Guimarães et al, 2012)
More than 4,000 genes were identified to be associated with drought stress, in which 224 transcription factors and genes were involved in photosynthesisantenna proteins, carbon metabolism, and the citrate cycle (Zhao et al, 2018)
There are significant differences found among the four genotypes under drought stress vs. non-differences under
Summary
Cultivated peanut (Arachis hypogaea L.) is an important legume that is grown mainly on arid and semiarid regions where peanut productivity is usually limited by water deficit (Pimratch et al, 2008, 2009; Songsri et al, 2008; Balota et al, 2012; Dinh et al, 2013; Brasileiro et al, 2015). RNAsequencing (RNA-Seq), a technique for genome-wide gene expression analysis, provides a powerful alternative to facilitate the development of drought-tolerant genotypes (Li et al, 2014; Lu et al, 2014; Zhao et al, 2018). Candidate genes and expression profiles in many crops, including wheat, corn, soybean, and peanut, evaluating plant response to environmental stress conditions were determined with RNA-Seq technology (Mathioni et al, 2011; Petre et al, 2012; Chen et al, 2013; Li et al, 2014; Brasileiro et al, 2015; Ruan et al, 2018; Zhao et al, 2018; Long et al, 2019).
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