CHO1, a putative double APETALA2 domain transcription factor, is involved in the ABA-mediated regulation of GA biosynthesis during seed imbibition in Arabidopsis thaliana

Abstract

Seed dormancy and germination is antagonistically regulated by two phytohormones, abscisic acid (ABA) and gibberellins (GA). In the previous meeting, we reported that previously identified Arabidopsis mutant, chotto1 (cho1), which is mutated in a gene encoding a putative double APETALA2 domain transcription factor, exhibits decreased levels of seed dormancy and increased germination potential relative to the wild type after short periods of dry seed storage treatment (after-ripening: AR). AR led to decreases in the endogenous ABA levels and increases in the GA₄ levels after imbibition in wild-type seeds dependent on the length. However, the levels of ABA and GA were changed in cho1 regardless of AR. In agreement with this, transcript levels of ABA catabolism gene and GA biosynthetic genes were up-regulated in cho1 imbibed seeds. In the next meeting, we will report the results of analysis of double mutants between cho1 and ABA-hyper accumulating cyp707a2-1 or GA-deficient ga1-3.