Genome-wide analysis and Stress-Responsive Expression Profiling of the LEA (late embryogenesis abundant) Gene Family in Wild Peanut

Abstract Late embryogenesis abundant (LEA) proteins generally accumulate in seeds during the later stages of maturation. However, LEA proteins also accumulate in response to abiotic stressors, particularly those involving cellular dehydration. LEA genes have been well-characterized in many plant species, but not in peanut. Here we studied the LEA genes in two wild peanut species (Arachis duranensis and Arachis ipaensis) in an effort to create a genetic resource for peanut crop improvement. Specifically, we examined AdLEA and AiLEA sequence characteristics, gene structure, evolutionary relationships, chromosomal localization, promoter cis-acting elements, and expression patterns in different tissues under low temperature, salinity, drought, and ABA stress. In all, we identified 65 AdLEA and 69 AiLEA genes representing all 8 LEA subfamilies, which were unevenly distributed across all 10 peanut chromosomes. The majority of LEA proteins were found to be highly hydrophilic. MEME analysis indicated that LEA gene motifs were conserved within groups, but not between groups. The LEA genes contained a diverse array of stress- and phytohormone-responsive cis-acting elements, with the AdLEA2-20 and AiLEA2-20 genes containing the greatest number of elements. Both AdLEA2-20 and AiLEA2-20 were upregulated in response to cold temperatures, drought, salinity, and ABA-exposure, although the dynamics were tissue-dependent. This study lays the foundation for future studies on the LEA gene family and abiotic stress in peanut, and our results will be invaluable for the genetic improvement of peanut by characterizing the genetic resources of wild peanut species.