Transcriptome Analysis of Wild Arachis Under Water Deficit

Wild peanut relatives (Arachis spp.) are genetically diverse and were adapted, throughout the evolution course, to a range of environments. Therefore, they constitute an important source of allelic diversity for resistance to biotic and abiotic stresses. In particular, A. duranensis and A. stenosperma, parentals of the reference A-genome genetic map, have contrasting responses to limited water conditions. The objective of the present study was to identify genes in these wild species that are differentially expressed during drought stress by conducting a comprehensive transcriptome analysis using Illumina HI-SEQ technology. For that, 15 days-old seedlings of accessions of A. duranensis and A. stenosperma were grown in hydroponic system and submitted to water deficit through nutrient solution withdrawal. These accessions showed contrasting physiological responses throughout the treatment, as measured with Licor6400. Roots were collected at six points (at each 25 minutes after stress induction) and used to construct four cDNA pair-ended libraries. More than 8.4 MB of sequencing data was produced with an average read size of 200 bp. De novo assembly resulted on 42,075 contigs for A. duranensis and 60,000 for A. stenosperma with an average length of 949 and 730 pb, respectively. This data generated more than 200,000 SNPs between the two species which will be used for saturation of the A-genome genetic map. In silicoanalysis revealed significant differential expression of some genes related to drought tolerance, including transcription factors, cell wall-modifying and hormone responsive proteins, and their expression profiles will be validated by qRT-PCR.

Financial support: Embrapa, CNPq and Generation Challenge Program.