Genome-wide analysis and expression profiling of the phospholipase D gene family in Gossypium arboreum

The plant phospholipase D (PLD) plays versatile functions in multiple aspects of plant growth, development, and stress responses. However, until now, our knowledge concerning the PLD gene family members and their expression patterns in cotton has been limited. In this study, we performed for the first time the genome-wide analysis and expression profiling of PLD gene family in Gossypium arboretum, and finally, a total of 19 non-redundant PLD genes (GaPLDs) were identified. Based on the phylogenetic analysis, they were divided into six well-supported clades (alpha, beta/gamma, delta, epsilon, zeta and (phi). Most of the GaPLD genes within the same Glade showed the similar exon-intron organization and highly conserved motif structures. Additionally, the chromosomal distribution pattern revealed that GaPLD genes were unevenly distributed across 10 of the 13 cotton chromosomes. Segmental duplication is the major contributor to the expansion of GaPLD gene family and estimated to have occurred from 19.61 to 20.44 million years ago when a recent large-scale genome duplication occurred in cotton. Moreover, the expression profiling provides the functional divergence of GaPLD genes in cotton and provides some new light on the molecular mechanisms of GaPLD alpha l and GaPLD delta 2 in fiber development.