Abstract
ABA plays vital roles in the maintenance of seed dormancy. In Arabidopsis, fus3 mutant seeds fail to undergo dormancy. Several studies have shown that FUS3 positively regulates ABA biosynthesis. However, little is known about the molecular mechanisms underlying this process. To this end, we mutagenized the seeds of a transgenic line in which ectopic expression of FUS3 could be artificially induced by estrogen and screened for novel mutants defective in FUS3-imposed growth arrest and resistance to a GA biosynthesis inhibitor at seedling stages. Interestingly, several identified mutants showed organ-specific defects in FUS3-imposed growth arrest. To further investigate the regulation of ABA biosynthesis downstream of FUS3, map-based cloning of isolated mutants is being carried out. Based on these results, we will discuss possible mechanism underlying the FUS3 regulation of ABA biosynthesis during seed development.
