Premature Drying, Fluridone-Treatment, and Embryo Isolation During Development of Maize Kernels (Zea maysL.) Induce Germination, but the Protein Synthetic Responses are Different. Potential Regulation of Germination and Protein Synthesis by Abscisic Acid

Abstract

Freshly harvested, developing kernels of maize (Zea mays L.) do not germinate up to 77 d after pollination, but can be induced to do so by fluridone, premature desiccation, and isolation of the developing embryo. The pattern of protein synthesis in developing maize embryos is distinct from that during germination and subsequent seedling growth. Premature desiccation at 35 DAP elicits a pattern of protein synthesis upon rehydration which is similar to that in germinated embryos from mature dry kernels. Fluridone-induced viviparous germination is accompanied by changes in the synthesis of some proteins to a post-germinative pattern, but some developmental proteins continue to be synthesized. Embryos isolated from developing kernels at 35 DAP germinate when incubated on water; they also produce some developmental proteins during germination. Kernels from developing cobs at 35 DAP which are detached from the mother plant and maintained in an atmosphere of high relative humidity (moist controls) do not germinate, but neither do they continue a clearly defined pattern of either developmental or germinative protein synthesis. Drying is thus critical to effect a clear transition of protein synthesis from a developmental to a germinative mode in maize embryos. Abscisic acid within the developing embryos is reduced by fluridone, but to a lesser extent by premature drying or maturation drying. Changes in sensitivity to abscisic acid by the developing embryo may be as, or more, important in permitting germination, and the attendant synthesis of proteins, than changes in abscisic acid content.