Accumulation and leakage of abscisic acid during embryo development and seed dormancy in wheat

摘要

Seed dormancy develops late in embryogenesis after a period of potential premature germination and has been associated with levels of abscisic acid (ABA) in, and sensitivity to, ABA of embryos. In wheat (Triticum aestivum L.) embryos, there are two peaks in levels of ABA during development: the first occurs 25 days after pollination (DAP) and the second from 35 to 40 DAP. The first peak of ABA appears to be associated with the development of the embryo's sensitivity to ABA since such sensitivity was altered in seeds on ears that were incubated in a solution of ABA from 15 and 20 DAP. In the embryos of Kitakei wheat, a line that exhibits dormancy, the second peak, at around 35 DAP, was more prolonged in comparison to Chihoku, a non-dormant line. The results support the proposed involvement of ABA in the formation and maintenance of seed dormancy during middle and late embryogenesis. When developing embryos were incubated in water, embryonic ABA leaked out from the embryos, in particular between 30 and 40 DAP. Premature germination observed between 30 and 40 DAP might be related to such leakage of ABA from embryos. [References: 26]