Triglycerides in developing zygotic embryos of Norway spruce and loblolly pine were found to accumulate continuously during the course of development, comprising nearly 50% of the fresh weight of a mature embryo. Embryogenic calli of these two species contained dramatically lower levels of triglycerides. Abscisic acid treatments promoted both embryo production and triglyceride accumulation in Norway spruce cultures. A method used to determine triglyceride levels in human serum, commercially available in kit form, was adapted for use with plant tissues. Low levels of triglycerides in the cultured tissues may be related to difficulties in the development and germination of conifer somatic embryos.
Periodically from prefertilization to near maturation, pine (Pinus resinosa Ait. and Pinus strobus L.) ovules were analyzed 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 two weeks after fertilization, followed about oneweek 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 most of the ATP, GSH, and AA was associated with 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 -2the developing seed coat, 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.
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