Comparative Analysis of Phospholipase D (PLD) Gene Family in Camelina sativa and Brassica napus and Its Responses in Camelina Seedlings under Salt Stress

Phospholipases are among the important elements involved in lipid-dependent cell signaling that lead to the induction of downstream pathways. In the current study, phospholipases D (PLDs) gene family was characterized and compared in two important oilseed crops, Brassica napus and Camelina sativa. The results revealed that PLD has 33 members in Camelina sativa (CsPLD) and 41 members in Brassica napus (BnPLD). All studied PLDs showed a negative GRAVY value, indicating that PLDs are probably hydrophilic proteins. Phylogenetic analysis classified PLDs into five main subfamilies, including gamma, delta, beta, alpha, and zeta. According to evolution analysis, a different evolution process was observed between CsPLD and BnPLD. In addition, the results disclosed that most of the PLD genes have been segmentally duplicated under purifying selection. Cis-regulatory elements related to ABA and auxin responsiveness were found more in the upstream region of CsPLDs, while elements linked with MeJA responsiveness were observed more in the promoter region of BnPLDs. Analysis of the expression data showed that PLD alpha genes have a wide expression in most tissues. Quantitative expression analysis (qPCR) of CsPLD genes under salt stress, 200 mM of NaCl, was conducted in different time series. The results revealed that the CsPLD genes are involved in the response to salinity stress and their expression levels enhance with increasing salinity stress period. The outcomes of this research will be useful for future molecular works related to lipid signaling in oilseed plants.