Joint International Conference on Long-term Experiments ...

THE EFFECT OF THE GENOTYPE AND EXPLANT UPON THE SOMATIC
EMBRYO INDUCTION IN THREE QUERCUS SPECIES
AI. Timofte*, M. Palada-Nicolau**, M. Ardelean***, D. Pamfil***
*University of Oradea, Romania
**Forest Research and Management Institute, Research Center Simeria, Romania
***University of Agriculture and Veterinary Medicine Cluj-Napoca, Romania
ABSTRACT
The somatic embryogenesis is an advanced method for clonal propagation and a useful
tool for ex situ conservation of genetic resources.
Three oak species were tested for the somatic embryogenesis ability: Quercus robur
(three provenances), Q.petraea (one provenance), Q.frainetto (two provenances).
The most important factor affecting the efficiency of somatic embryogenesis was
found to be the developmental stage of the zygotic embryos used as juvenile explants.
The high embryogenic ability of young zygotic embryos and low embryogenic ability of
maturing zygotic ones showed the strong positive relationship between somatic embryo
induction and accumulation of reserve nutrients in cotyledons.
Two nutritive culture media and two growth hormone combinations were tested.
The effect nutritive media was insignificant, but the effect of hormone combination was
either week, or masked by the effect of explant type or that of the genotype. As for
genotype, some differences were found among species, as well as among the
provenances of the same species, regardless the explants type. These differences were
analysed statistically and some week correlations were found.
The subsequent phases of the somatic embryogenesis process (multiplication,
germination and plant regeneration) were not related to the initial embryo efficiency,
but only to the quality of stabilized embryogenic lines.
Key words: oak species, somatic embryogenesis, explants, genotype, statistics.
INTRODUCTION
The in vitro clonal propagation in oaks is an important step in the breeding activity
using clonal strategies, and in the same time a tool for the application of somaclonal
selection procedures in the improvement of adaptability traits.
The use of somatic embryogenesis in oak clonal micropropagation is preferable in
the applications concerning somaclonal variation and selection, because the plants
regenerated from somatic embryos usually have monocellular origin and consist in
clones of long-term culture, submitted of in vitro selection procedures.
Generally, the somatic embryogenesis can be considered an efficient mean of
clonal propagation, when the following conditions are accomplished:
• the stable embryogenic cultures constantly produce a big amount of somatic
embryos
• the embryogenic ability of such cultures can be maintained for long time by serial
adventitious embryogenesis
• the somatic embryos can be efficiently converted into acclimatable plants.
• Starting with the first successful embryogenic inductions (Chalupa, 1987, 1990,
441