Effects of Gibberellins on Nectar Production in Arabidopsis thaliana

Abstract

Gibberellins (GA) are well known for their roles in regulating stem elongation and seed germination, but less understood is the role of GA in regulating floral maturation. We recently identified GA 2-OXIDASE 6 (GA2OX6, At1g02400) as being highly expressed in the actively secreting nectaries of Arabidopsis thaliana, but at low levels in other tissues. GA2OX6 was previously demonstrated to inactivate bioactive GA. Multiple independent ga2ox6 mutants displayed decreased nectar production, which suggests that elevated levels of active GA negatively regulate nectar production. Similarly, spindly (spy) mutants, which also have an increased GA signaling response, displayed decreased nectar production, further supporting the hypothesis that GA negatively regulates nectar production. Wild-type flowers also displayed an intense auxin response in actively secreting nectaries, whereas ga2ox6 and spy mutants had strongly reduced DR5-dependent signal in nectaries. This suggests significant crosstalk occurs between GA and auxin signaling pathways in the regulation of nectar production.