Biochemical Changes Associated with Zygotic Pine Embryo Development

Johnson, M. A., Carlson, J. A., Conkey, J. H. and Noland, T. L. 1987. Biochemical changes associated with zygotic pine embryo development.—J. exp. Bot. 38: 518-524. At intervals during the period from pre-fertilization to near maturation, pine (Pinus resinosa Ait. and Pinus strobus L.) ovules were analysed for several biochemical constituents, and the results were expressed on a fresh weight basis. Lipid accumulated in parallel with the growth of the developing seeds. Soluble protein also accumulated but only in the initial stages of development. ATP content peaked approximately 2 weeks after fertilization, followed about one week later by the energy charge; these peaks were associated with maximal growth stages of the developing embryos. Likewise, peaks of glutathione (GSH) and ascorbic acid (AA), two water-soluble reductants, preceded or coincided with the ATP maximum. At late stages of seed development, dissection of the more mature ovules into embryos and gametophytes for analysis revealed that the ATP, GSH, and AA were more concentrated in the embryonic tissue. On the other hand, this segregation showed that virtually no proanthocyanidin was located in the developing embryos proper, although they contained other reductants, some of which were probably phenolics. Also, general staining with reagents for phenolics and thiols indicated that the former occurred primarily in non-embryonic tissue, whereas GSH was in the embryo per se. These findings are consistent with roles for ATP, GSH, and AA in the growth and development of zygotic pine embryos; however, it would appear that lipid and protein are being stored for subsequent germination events and that much of the phenolic component is segregated from the developing embryo.