Transgenic Arabidopsis plants expressing the type 1 inositol 5-phosphatase exhibit increased drought tolerance and altered abscisic acid signaling.

The phosphoinositide pathway and inositol-1,4,5-trisphosphate (InsP(3)) are implicated in plant responses to stress. To determine the downstream consequences of altered InsP(3)-mediated signaling, we generated transgenic Arabidopsis thaliana plants expressing the mammalian type I inositol polyphosphate 5-phosphatase (InsP 5-ptase), which specifically hydrolyzes soluble inositol phosphates and terminates the signal. Rapid transient Ca(2+) responses to a cold or salt stimulus were reduced by approximately 30% in these transgenic plants.