Genome-wide characterization of phospholipase D family genes in allotetraploid peanut and its diploid progenitors revealed their crucial roles in growth and abiotic stress responses.

Abiotic stresses such as cold, drought and salinity are the key environmental factors that limit the yield and quality of oil crop peanut. Phospholipase Ds (PLDs) are crucial hydrolyzing enzymes involved in lipid mediated signaling and have valuable functions in plant growth, development and stress tolerance. Here, 22, 22 and 46 genes were identified in , and , respectively, and divided into α, β, γ, δ, ε, ζ and φ isoforms. Phylogenetic relationships, structural domains and molecular evolution proved the conservation of s between allotetraploid peanut and its diploid progenitors. Almost each except for had a corresponding homolog in and genomes. The expansion of gene families were mainly attributed to segmental and tandem duplications under strong purifying selection. Functionally, the most proteins interacting with AhPLDs were crucial components of lipid metabolic pathways, in which ahy-miR3510, ahy-miR3513-3p and ahy-miR3516 might be hub regulators. Furthermore, plenty of -regulatory elements involved in plant growth and development, hormones and stress responses were identified. The tissue-specific transcription profiling revealed the broad and unique expression patterns of s in various developmental stages. The qRT-PCR analysis indicated that most s could be induced by specific or multiple abiotic stresses. Especially, , , , and were highly up-regulated under all three abiotic stresses, whereas was neither expressed in 22 peanut tissues nor induced by any abiotic stresses. This genome-wide study provides a systematic analysis of the gene families and valuable information for further functional study of candidate s in peanut growth and abiotic stress responses.