ISHS Acta Horticulturae 560: IV International Symposium on In Vitro Culture and Horticultural Breeding
THE DISADVANTAGED EMBRYO |
| Authors: | C.H. Bornman, O.S.P. Dickens, A.M. Botha |
| Keywords: | conifer, gymnosperm, megagametophyte, Norway spruce, Picea abies, somatic embryogenesis |
| Abstract:
Somatic embryo technology will have its greatest impact and perhaps justify its high cost when it becomes possible to initiate embryos from the tissues of mature trees. Compared with its zygotic counterpart, the somatic embryo lacks a lipid- and protein-rich megagametophyte, from which amino acids and sugars can be mobilised continually during germination, as is known from a number of studies on gymnospermous seeds. In Picea abies, somatic embryos of similar dry mass contain significantly less lipid and protein compared with the zygotic embryo-megagametophyte complex. While not differing significantly in cell number, somatic embryos may have up to twice the volume of their zygotic counterparts, and transverse sections of the hypocotyl and cotyledon show larger, more vacuolate, cells and a greater relative volume of intercellular space. Lack of a gametophytic nutrient source is the somatic embryo’s greatest disadvantage. | |
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