Expressed sequence tags in cultivated peanut (Arachis hypogaea): discovery of genes in seed development and response to Ralstonia solanacearum challenge.

Although an important oil crop, peanut has only 162,030 expressed sequence tags (ESTs) publicly available, 86,943 of which are from cultivated plants. More ESTs from cultivated peanuts are needed for isolation of stress-resistant, tissue-specific and developmentally important genes. Here, we generated 63,234 ESTs from our 5 constructed peanut cDNA libraries of Ralstonia solanacearum challenged roots, R. solanacearum challenged leaves, and unchallenged cultured peanut roots, leaves and developing seeds. Among these ESTs, there were 14,547 unique sequences with 7,961 tentative consensus sequences and 6,586 singletons. Putative functions for 47.8 % of the sequences were identified, including transcription factors, tissue-specific genes, genes involved in fatty acid biosynthesis and oil formation regulation, and resistance gene analogue genes. Additionally, differentially expressed genes, including those involved in ethylene and jasmonic acid signal transduction pathways, from both peanut leaves and roots, were identified in R. solanacearum challenged samples. This large expression dataset from different peanut tissues will be a valuable source for marker development and gene expression analysis. It will also be helpful for finding candidate genes for fatty acid synthesis and oil formation regulation as well as for studying mechanisms of interactions between the peanut host and R. solanacearum pathogen.