Triglycerides in embryogenic conifer calli: a comparison with zygotic embryos

Abstract

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.

Morphogenic Aspects of Somatic Embryogenesis

“…White spruce embryos contained five times the triglyceride levels on a per embryo basis as compared to zygotic embryos [227]. In contrast to these reports, somatic embryos of Norway spruce [228] and white spruce [210] contained significantly less triglycerides than zygotic embryos, while in soybean, total neutral lipid levels (containing triglycerides) were significantly lower than mature zygotic embryos [229]. Again, differences in lipid and fatty acid compositions between zygotic and somatic embryos probably reflect the type of maturation protocols used.…”

“…Both ABA and osmoticum promoted fatty acid accumulation in cultured zygotic embryos [230], while ABA in combination with proline stimulated fatty acid accumulation in celery somatic embryos [226]. Application of ABA promoted triglyceride accumulation in spruce somatic embryos [228] and increasing sucrose levels promoted triglyceride accumulation in Brassica somatic embryos [218], with somatic embryos cultured on 20% sucrose accumulating triglyceride levels higher than those found in mature seed [218]. The ability to obtain somatic embryos with similar lipid and fatty acid compositions to those of zygotic embryos probably requires culture modifications that help to prolong the embryo maturation phase, and prevent precocious germination, a process which leads to the induction of enzymes associated with triglyceride degradation [219].…”

Effect of abscisic acid and cytokinins on the development of somatic embryos in Hevea brasiliensis

“…Moreover abscisic acid increased the frequency of normal embryos in different species (Ammirato 1977;Attree & Fowke 1991). This growth regulator had a promotive effect on the accumulation of storage lipids and proteins in conifer somatic embryos (Feirer et al 1989;Roberts et al 1990). In Hevea brasiliensis, Etienne et al (1993) reported that the decrease of 3,4-D and BA and the addition of ABA in solid medium stimulated induction of embryogenic cells.…”

Influence of exogenous abscisic acid on germination and plantlet conversion frequencies of hybrid larch somatic embryos (Larix � leptoeuropaea)

“…ABA is known to suppress abnormal somatic embryo development in carrot [2], interior spruce [23] and hybrid larch [14] . ABA also greatly improves the efficiency of maturation, a fact reported for norway spruce [6], interior spruce [23] and hybrid larch [14] . In a previous report dealing with interior spruce somatic embryos, the highest germination frequency was obtained when full maturation was reached and there was no (±)ABA concentration effect on root emergence [23] .…”