Abstract
Peanut (Arachis hypogaea L.) is an important legume cultivated mostly in drought-prone areas where its productivity can be limited by water scarcity. The development of more drought-tolerant varieties is, therefore, a priority for peanut breeding programs worldwide. In contrast to cultivated peanut, wild relatives have a broader genetic diversity and constitute a rich source of resistance/tolerance alleles to biotic and abiotic stresses. The present study takes advantage of this diversity to identify drought-responsive genes by analyzing the expression profile of two wild species, Arachis duranensis and Arachis magna (AA and BB genomes, respectively), in response to progressive water deficit in soil. Data analysis from leaves and roots of A. duranensis (454 sequencing) and A. magna (suppression subtractive hybridization (SSH)) stressed and control complementary DNA (cDNA) libraries revealed several differentially expressed genes in silico, and 44 of them were selected for further validation by quantitative RT-PCR (qRT-PCR). This allowed the identification of drought-responsive candidate genes, such as Expansin, Nitrilase, NAC, and bZIP transcription factors, displaying significant levels of differential expression during stress imposition in both species. This is the first report on identification of differentially expressed genes under drought stress and recovery in wild Arachis species. The generated transcriptome data, besides being a valuable resource for gene discovery, will allow the characterization of new alleles and development of molecular markers associated with drought responses in peanut. These together constitute important tools for the peanut breeding program and also contribute to a better comprehension of gene modulation in response to water deficit and rehydration.Electronic supplementary materialThe online version of this article (doi:10.1007/s11105-015-0882-x) contains supplementary material, which is available to authorized users.
Highlights
Peanut (Arachis hypogaea L.) is an oilseed crop cultivated worldwide and one of the major grain legumes in tropical and subtropical regions
To better capture gene expression modulations associated with the variations in transpiration profile, samples from both species were collected at three time points in an attempt to provide representative stages of limited water stress, as described by Sinclair and Ludlow (1986)
In order to better address the multiplicity of biological processes involved in drought perception and responses, the transcriptome profile of these two wild species was analyzed at different stages of a gradual water deficit, followed by rehydration
Summary
Peanut (Arachis hypogaea L.) is an oilseed crop cultivated worldwide and one of the major grain legumes in tropical and subtropical regions. Considering the highly complex aspects of drought tolerance in plants, the understanding of response mechanisms to waterlimited conditions and identification of the pathways and genes involved in these responses are strategic for the development of new varieties (Hu and Xiong 2014; Juenger 2013). In this respect, transcriptome approaches have the potential to aid the understanding of tolerance mechanisms and to orientate gene discovery. Large transcriptome surveys have been undertaken in recent years for many crop plants, including peanut (Chen et al 2013; Wu et al 2013; Yin et al 2013; Zhang et al 2012)
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