Arabidopsis Biological Resource Center

Ploidy: 2

Phenotype: Severe defect in seed germination and root growth; dwarf plants; severe root length growth phenotype similar to the ga1-3 mutant; reduced ability of seeds to germinate, in contrast to each single mutant, double mutant seeds fail to germinate in the dark and had only a 5% germination frequency in the light, this slight leakiness in germination of the double mutant is similar to the ga1-3 mutant; plants have the same number of leaves as wild type, but flowering is delayed for 7 days; no observable plant phenotype was noted in the flowers and the fertility (average number of seeds/silique on primary inflorescence stems). Although the ga3ox2 single mutant does not have any phenotype, plants are 30% smaller in leaf diameter and 37% shorter than ga3ox1; therefore, production of bioactive GA by GA3ox2 during early vegetative growth may be sufficient for transport to the stem to induce the partial stem elongation observed in the ga3ox1 mutant, the overall phenotype of the double mutant is consistent with expression patterns of these two genes. The bioactive level of GA4 is severely decreased; while the level of GA9 is drastically increased, compared to wild type plants; exogenous application of GA4, but not GA9, was able to induce seed germination in a dose-dependent manner.