Overexpression of a wheat phospholipase D gene, TaPLD?, enhances tolerance to drought and osmotic stress in Arabidopsis thaliana.
Phospholipase D (PLD) is crucial for plant responses to stress and signal transduction, however, the regulatory mechanism of PLD in abiotic stress is not completely understood; especially, in crops. In this study, we isolated a gene, TaPLD?, from common wheat (Triticum aestivum L.). Analysis of the amino acid sequence of TaPLD? revealed a highly conserved C2 domain and two characteristic HKD motifs, which is similar to other known PLD family genes. Further characterization revealed that TaPLD? expressed differentially in various organs, such as roots, stems, leaves and spikelets of wheat. After treatment with abscisic acid (ABA), methyl jasmonate, dehydration, polyethylene glycol and NaCl, the expression of TaPLD? was up-regulated in shoots. Subsequently, we generated TaPLD?-overexpressing transgenic Arabidopsis lines under the control of the dexamethasone-inducible 35S promoter. The overexpression of TaPLD? in Arabidopsis resulted in significantly enhanced tolerance to drought, as shown by reduced chlorosis and leaf water loss, higher relative water content and lower relative electrolyte leakage than the wild type. Moreover, the TaPLD?-overexpressing plants exhibited longer roots in response to mannitol treatment. In addition, the seeds of TaPLD?-overexpressing plants showed hypersensitivity to ABA and osmotic stress. Under dehydration, the expression of several stress-related genes, RD29A, RD29B, KIN1 and RAB18, was up-regulated to a higher level in TaPLD?-overexpressing plants than in wild type. Taken together, our results indicated that TaPLD? can enhance tolerance to drought and osmotic stress in Arabidopsis and represents a potential candidate gene to enhance stress tolerance in crops.