Thermoinhibition of Arabidopsis seeds and induction of abscisic acid biosynthesis and signaling gene expression by high temperature

Abstract

Temperature is one of the critical environmental cues for seed germination. Germination of Arabidopsis seeds is inhibited by high temperature and induced by low temperature. We showed alleviation of thermoinhibition by abscisic acid (ABA) biosynthesis inhibitor and enhancement of ABA sensitivity at high temperature, and suggested that regulations of both ABA biosynthesis and signaling are involved in thermoinhibition. To see the effect of temperature on expression of ABA-related genes, we adopted quantitative PCR method. Expression of ABA biosynthesis genes, ZEP, NCED, ABA2 and AAO3 was induced remarkably after 12 h at 34^oC, but decreased to low levels at 22^oC. Expression of ABA signaling genes, ABI3 and ABI5, was induced at 34^oC but diminished at 22^oC. These results suggest that the induction of ABA biosynthesis and signaling genes by high temperature is responsible for the enhancement of ABA content and the sensitivity in Arabidopsis seeds.