Plant Stress

Frying Up a New Stress Regulator

Science's STKE  14 Aug 2001:
Vol. 2001, Issue 95, pp. tw2
DOI: 10.1126/stke.2001.95.tw2

Using a screen to identify Arabidopsis mutants that have abnormal responses to abscisic acid (ABA) or stress conditions, Xiong et al. identified a mutant, called fiery (fry), that has higher-than-normal, nonadaptive responses to stressful stimuli. Under cold temperature conditions, high salt, or ABA treatment, fry1 plants harboring a combination stress-responsive and ABA-responsive reporter gene exhibited greater-than-normal levels of reporter gene expression. Even at temperatures slightly below that of normal room temperature, expression from the gene reporter in fry1 plants was greater than normal, suggesting that fry1 reduced the threshold of stress-dependent gene expression. fry1 plants were defective for stress tolerance as measured by ion leakage under cold or drought-mimicking conditions, and increased plant death was exhibited under high salt concentrations. The fry1 mutation was mapped and the gene isolated, the sequence of which predicted an inositol polyphosphate 1-phosphatase. Chimeric GST-Fry1 (wild-type) proteins dephosphorylated substrates in vitro, whereas mutant Fry1 chimeric proteins were devoid of catalytic activity. Under stress conditions, fry1 plants produced and accumulated large amounts of inositol trisphosphate (IP3), suggesting that impaired turnover of the second messenger IP3 may result in hypersensitivity to stress and ABA stimuli.

L. Xiong, B.-h. Lee, M. Ishitani, H. Lee, C. Zhang, J.-K. Zhu, FIERY1 encoding an inositol polyphosphate 1-phosphatase is a negative regulator of abscisic acid and stress signaling in Arabidopsis. Genes Dev. 15, 1971-1984 (2001). [Abstract] [Full Text]