Abstract
We conducted detailed quantification analysis of abscisic acid (ABA) by LC-MS/MS during Arabidopsis seed development. Determination of ABA levels in individual F2 seeds generated by crossing wild type and an ABA deficient mutant aba2 showed that ABA accumulated in seeds during mid development is derived from maternal tissues. Despite active ABA biosynthesis in maternal tissues in this stage, ABA was highly accumulated in the embryo, suggesting that ABA is transported to the embryo from other tissues. On the other hand, during later stages of seed development, ABA is mainly synthesized in the embryo and/or endosperm although the amount is much lower than that synthesized during middle stage. We identified genes whose expression was regulated by endogenous ABA during seed development by microarray analysis and compared their expression levels in mutants that exhibit different degree of ABA deficiency depend on tissues. It was shown that the expression levels of ABA-regulated genes did not always correlate with endogenous ABA levels in whole seeds, suggesting that ABA synthesized in different tissues has distinct role on downstream gene expression.
