Promoter of Vegetable Pea PsPIP2-4 Responds to Abiotic Stresses in Transgenic Tobacco

Plasma membrane intrinsic proteins (PIPs), one sub-family of aquaporins (AQPs), are responsible for plant abiotic stress responses. However, little information is currently available about the stress responsiveness of the PIP promoter in vegetable pea. In the present study, one novel promoter of PsPIP2-4 which shared high similarity to the PIP2-type AQPs from other plants, was isolated. Quantitative real-time PCR (qRT-PCR) assays suggested that PsPIP2-4 was predominantly expressed in leaves and abundantly induced by abiotic stress treatments (polyethylene glycol (PEG) 6000, NaCl, and methyl jasmonate (MeJA)). Further, the promoter activity of PsPIP2-4 was verified in transgenic tobacco plants. Beta-glucuronidase (GUS) staining driven by the PsPIP2-4 promoter confirmed that it was mainly detected in the leaves of transgenic seedlings, especially in the guard cells. Exposure of transgenic seedlings to various environmental stimuli proved that the promoter activity of PsPIP2-4 was abundantly strengthened by osmotic, salt, and MeJA stresses. This research provides one stress-inducible promoter enabling targeted gene expression under abiotic stresses and demonstrates its usefulness in the genetic improvement of plant stress resistance.