This paper provides results of somatic embryogenesis study in our laboratory. General description of somatic embryogenesis (SE) induction, maturation of somatic embryos and plantlets regeneration of the Abies species, followed by a comparisons of some characteristics of zygotic and somatic embryos, seedlings and emblings (somatic seedlings). Own results are supplemented with some literature data. Also aplication of SE for improving of plantlet regeneration of elite fir trees from Dobroč primeval is described as well as initiation of the SE from seeds of incompatible crossings of firs where zygotic embryos abort usually several weeks after pollination
Pollen viability was tested in two hybrid swarm populations of Pinus mugo and P. sylvestris in northern Slovakia and in control populations of the parental species. It was significantly reduced in hybrid populations, as evidenced by average germination percentages ranging from 49.0% and 61.53% and by pollen tube length averaging 74.54-86.47 µm. The corresponding values in the control populations were 78.38-88.5% and 102.92-152.84 µm, respectively. The frequency of microsporogenesis disturbances at the tetrad and mature pollen stages was higher in hybrid swarms than in the control population of P. sylvestris. Based on in vitro germination data, the amount of sterile pollen was estimated at 40-41% in hybrid swarm populations, 12% in P. sylvestris, and 21% in P. mugo.
The paper reports a comparative study of storage protein synthesis and enzyme activity during zygotic and somatic embryogenesis of silver fir. The SDS-PAGE profiles of storage proteins in zygotic and somatic embryos were similar but not identical. Six storage protein fractions were detected in zygotic embryos, as compared with eleven fractions in somatic embryos. The principal storage protein of zygotic embryos was represented by the 43 kDa fraction, and in somatic embryos by the 53 kDa fraction. Peroxidase activity was lower in the precotyledonary and cotyledonary stages of somatic embryos than in the corresponding developmental stages of zygotic embryos. However, following desiccation, the mature somatic embryos possessed three times higher peroxidase activity than the mature zygotic embryos. The reverse was true of the specific activity of esterase, which was higher in zygotic embryos than in somatic embryos in all stages of development.
Anther culture is currently the most successful method for production of doubled haploid lines in flax. Recently, ovary culture was also described as a good source of doubled haploids. In this contribution we investigated the incorporation of enzyme polymorphism of acid phosphatase and peroxidase as molecular markers for the gametic origin of flax plants derived from anther and ovary cultures.
Artificial hybridization experiments revealed a relatively high degree of crossability between Pinus sylvestris and P. mugo, ranging between 0.15 and 0.98. Differences between P. sylvestris x P. mugo and reciprocal hybrids of the species were observed. Hybrid seeds of P. sylvestris x P. mugo shared higher germination potential than seeds from selling, controlled intraspecific crossing, and open pollination. The corresponding value in reciprocal combination was slightly lower. The hybrid nature of the seeds obtained was shown by restriction analysis of chloroplast DNA (cp DNA) using the trnV-trnH/Hinf I primer-enzyme combination.
The height growth dynamics of three interspecific crosses with Greek fir (Abies cephalonica Loud.) acting as mother and a control variant from self-pollination were followed throughout a period of 30 years. The hybrid combination A. cephalonica × A. nordmanniana exhibited enhanced growth relative to the selfed control at stage of 4-year old seedlings already, whereas the hybrid A. cephalonica × A. alba only at stage of 9-year old saplings. At age of 30, the heterotic growth persisted only in the latter, the hybrid A. cephalonica × A.nordmanniana was comparable in height growth parameters with a selfed control. The interspecific cross A. cephalonica × A. numidica was remarkable by its accelerated growth during early stages of the development. At age of 4 years it has surpassed in height growth both A. cephalonica × A. alba and control but has declined profoundly during subsequent stages of its development. A conspicuous feature of the hybrid needle anatomy were abundant resin canals and reduced size of some anatomical traits of its needles. In spite of variable growth potentials, all the three interspecific hybrids are recommended for planting in Slovakia, especially at densely polluted areas where domestic silver fir cannot withstand emission pressure.
We used artificial hybridization to study the crossability of the noble fir (Abies procera) with Manchurian fir (A. holophylla) and Caucasian fir (A. nordmanniana), and found compatibility between A. procera of North American origin and the Asian species A. holophylla as evidenced by the 14% fraction of filled seeds obtained in A. procera × A. holophylla crossing. Crossing of A. procera with the Mediterranean species A. nordmanniana failed completely, producing only empty seeds.