Gibberellins and seed development in maize. I. Evidence that gibberellin/abscisic acid balance governs germination versus maturation pathways.

摘要

Because gibberellins (GAs) and abscisic acid (ABA) act antagonistically in many aspects of plant development, it was hypothesized that ABA antagonizes a positive GA signal for precocious germination in maize. It was shown that a GA deficiency earlyin seed development, induced genetically or via biosynthesis inhibitors, suppressed vivipary in ABA-deficient developing kernels. The resulting seeds had both desiccation tolerance and storage longevity. Temporal analysis of GA accumulation in wild-typekernels revealed the accumulation of bioactive GA1 and GA3 prior to the peak in ABA content. It is suggested that these GAs stimulate development leading to vivipary in the absence of normal amounts of ABA, and that a reduction in GA content reestablishes an ABA/GA ratio appropriate for suppression of germination and induction of maturation. In contrast, the induction of a GA deficiency did not suppress vivipary in viviparous-1 mutant kernels, suggesting that VP1 acts downstream of both GA and ABA in programming seed development.