Zhang_2022_Int.J.Mol.Sci_23_4911

Phospholipase Dalpha (PLDalpha), which produces signaling molecules phosphatidic acid (PA), has been shown to play a critical role in plants adapting to salt environments. However, it is unclear whether phospholipase Ddelta (PLDdelta) can mediate the salt response in higher plants. PePLDdelta was isolated from salt-resistant Populus euphratica and transferred to Arabidopsis thaliana to testify the salt tolerance of transgenic plants. The NaCl treatment (130 mM) reduced the root growth and whole-plant fresh weight of wild-type (WT) A. thaliana, vector controls (VC) and PePLDdelta-overexpressed lines, although a less pronounced effect was observed in transgenic plants. Under salt treatment, PePLDdelta-transgenic Arabidopsis exhibited lower electrolyte leakage, malondialdehyde content and H(2)O(2) levels than WT and VC, resulting from the activated antioxidant enzymes and upregulated transcripts of genes encoding superoxide dismutase, ascorbic acid peroxidase and peroxidase. In addition, PePLDdelta-overexpressed plants increased the transcription of genes encoding the plasma membrane Na(+)/H(+) antiporter (AtSOS1) and H(+)-ATPase (AtAHA2), which enabled transgenic plants to proceed with Na(+) extrusion and reduce K(+) loss under salinity. The capacity to regulate reactive oxygen species (ROS) and K(+)/Na(+) homeostasis was associated with the abundance of specific PA species in plants overexpressing PePLDdelta. PePLDdelta-transgenic plants retained a typically higher abundance of PA species, 34:2 (16:0-18:2), 34:3 (16:0-18:3), 36:4 (18:2-18:2), 36:5 (18:2-18:3) and 36:6 (18:3-18:3), under control and saline conditions. It is noteworthy that PA species 34:2 (16:0-18:2), 34:3 (16:0-18:3), 36:4 (18:2-18:2) and 36:5 (18:2-18:3) markedly increased in response to NaCl in transgenic plants. In conclusion, we suppose that PePLDdelta-derived PA enhanced the salinity tolerance by regulating ROS and K(+)/Na(+) homeostasis in Arabidopsis.