Poster: Water Relations

Abs # 219: Ectopic overexpression in tomato of the Arabidopsis AVP1 gene results in drought tolerance

Presenter:	Gaxiola, Roberto A, roberto.gaxiola@uconn.edu
Authors	Gaxiola, Roberto A (A)   Sunghun, Park  (B)   Pittman, Jon  (C)   Berkowitz, Gerald  (A)   Li, Jisheng  (A)   Morris, Jay  (B)   Undurraga, Soledad  (A)   Yang, Haibing  (A)   Hirschi, Kendal D (C)
Affiliations:	(A): University of Connecticut (B): Texas A&M University (C): Baylor College of Medicine

Arabidopsis thaliana plants engineered to overexpress the vacuolar H+-pyrophosphatase AVP1 have enhanced tolerance to salinity and drought stress. The enhanced tolerance is most easily explained by an enhanced uptake of ions into their vacuoles. Presumably, the greater AVP1 activity in vacuolar membranes provides increased H+ to drive the secondary active uptake of cations into the vacuole. A compensatory transport of anions is expected in order to maintain electroneutrality. The resulting elevated vacuolar solute content would allow for greater osmotic adjustment capacity permitting plants to survive under conditions of low soil water potentials. To further document these observations we have generated transgenic tomato plants using a construct with the E229D gain-of-function mutant of the AVP1 gene (AVP1-D) downstream of a tandem repeat of 35S promoter of Cauliflower mosaic virus. The AVP1-D mutation results in a coordinated increase of both PPi hydrolitic activity and PPi-dependent H+-translocation. Transgenic AVP1-D Lycopersicon esculentum (cv Moneymaker) tolerate extended soil water deficit stress. Results will be presented regarding the physiological, biochemical and genetic characterization of these drought tolerant AVP1-D transgenic tomato lines. Applications of this technology should have a considerable impact in modern agriculture.