Abstract
The seeds of Arabidopsis germinate in autumn since the germination is suppressed by supra-optimal high temperature during summer. We have reported that high temperature increases abscisic acid (ABA) level in seeds through up-regulation of ABA biosynthesis genes (e.g. NCED), and ABA suppresses gibberellin biosynthesis genes (e.g. GA3ox). To dissect early heat induced and late ABA induced change, we analyzed gene expression in wild type and ABA deficient mutant (aba2-2) seeds imbibed at 22 and 34 oC by microarray. The genes were classified into 17 groups by their expression patterns using K-means clustering method. Their expressions were temperature dependent, ABA and temperature dependent, imbibition induced, germination induced, genotype specific, or others. The seeds of a T-DNA insertion mutant of a high temperature induced and ABA independent gene showed high temperature resistant germination phenotype. Such early heat induced genes may have a role in the process from temperature perception to NCED gene expression.
