Transgenic rice plants that over-express the oat arginine decarboxylase cDNA constitutively show enhanced tolerance to drought stress

The potential role of polyamines in protection against drought stress was examined in transgenic rice plants. Oryza sativa L. cv ITA 212 was transformed with the oat arginine decarboxylase cDNA driven by the CaMV 35S constitutive promoter (1). Each independent transformant showed different levels of putrescine accumulation in leaf and root tissues. A transgenic plant line, E-24, which accumulated ca. 2-fold higher putrescine levels compared to controls, exhibited a visible phenotype when exposed to drought stress for 48 hours. Progeny were exposed to drought stress for 48 h. Preliminary results indicate that recovery of the drought tolerant phenotype is linked to transgene expression and concomitant accumulation of putrescine.