Constitutive expression of a chrysanthemum phospholipase Dα gene in Chrysanthemum morifolium enhances drought tolerance

Drought causes water shortage and consequent retardation of plants growth and development. Therefore, improving the drought tolerance of plants is necessary for expanding cultivation and resource promotion. Increasing evidence indicates that phospholipase is involved in the response of plants to drought stress. The objective of this study was to create new drought-tolerant chrysanthemum germplasm, which lays a foundation for the study of the molecular mechanism of phospholipase mediated stress response in chrysanthemum. CmPLDα has the closest relationship with sunflower HaPLDα, and belongs to the PLDα family. CmPLDα over-expressing plants showed a slight shrinking under 20% PEG6000 treatment. The survival rate increased significantly by 1.7−1.8 times that of the wild type. Relative water content (RWC) of CmPLDα over-expressing plants were nearly 10% higher than that of the wild type. Relative electrical conductivity and MDA content were significantly lower than those of the wild type. ABA content of the over-expression lines Z1, Z2 were 1.3 and 1.22 times that of wild type, but ABA content of antisense lines F1, F2 was approximately 0.83 and 0.81 of those of wild type. Most plants of antisense transgenic lines F1, F2 were wrinkled, with a wilting index of 5 and 6, and the survival rate was also lower than that of the wild type after recovery growth. RWC of antisense lines were lower than over-expression lines, relative electrical conductivity and MDA content were significantly higher than those of the wild type. In summary, CmPLDα could enhance tolerance of chrysanthemum to drought conditions.