Poster: Salinity

Abs # 99: Stress-inducible expression of choline oxidase confers salt tolerance in transgenic rice

Presenter:	Su, Jin , js74@cornell.edu
Authors	Su, Jin  (A) (B)  Selvaraj, Gopalan  (C)   Wu*, Ray  (A)
Affiliations:	(A): Department of Molecular Biology and Genetics, Cornell University, USA. *Corresponding author (B): Biotech Research Institute, Chinese Academy of Agricultural Sciences, PR China (C): Plant Biotech Institute, National Research Council of Canada, Canada

Constitutive overproduction of choline oxidase (COX) for synthesis of glycinebetaine has been shown to enhance salt tolerance in plants. However, constitutive overexpression of the transgene may compete for the building blocks and machinery needed for RNA and protein synthesis under conditions without stress. Thus, it seems desirable to generate plants with transgene expression driven by a stress-inducible promoter, so that the specific mRNA and proteins are not produced unless under stress conditions. We report here that stress-inducible expression of choline oxidase confers a higher level of salt tolerance in transgenic rice than that of constitutive expression. A total of 16 lines of ABA-inducible promoter-driven COX plants (ABAIP-COX) and 10 lines of maize ubiquitin promoter-directed COX plants (Ubi-COX) were generated via Agrobacterium-mediated transformation. The average level of COX enzymatic activity of ABAIP-COX plants was induced to a level similar to that of the Ubi-COX plants after treatments with 150 mM NaCl solution for 48h. After two rounds of NaCl stress/recovery treatments, the ABAIP-COX plants showed a much higher level of salt tolerance than that of Ubi-COX plants as judged by higher plant biomass production and lower extent of ion leakage from leaf cells. AcknowledgementsFinancial support from the Rockefeller Foundation is gratefully acknowledged.