USE OF BIOTHECHNOLOGY METHODS FOR STUDY, PRESERVATION
AND REPRODUCTION OF THE REPRESENTATIVES OF VALUABLE GENE POOL OF DECIDUOUS
SPECIES OF WOODY TREES
Mashkina O.S., Isakov Yu.N., Tabatskaya T.M.
We use biotechnology methods for preservation and
reproduction of the representatives of valuable gene pool of birch species
(including Karelian birch, Betula pendula Roth var carelica Merkl.), difficult for propagation triploid forms of white
(Populus alba L.) and gray poplar (Populus canescens Sm.), productive aspen hybrids (Populus tremula L.); in
order to receive new, valuable forms on the basis of somaclonal
variability, mutagenesis in vitro, of
anther culture; for study of reasons and mechanisms of somaclonal variability in
vitro culture and for study of genetics and plant
development. Using worked out in Research
Institute of Forest Genetics and Breeding (
It is
considered, that plant genetic status remains unchanged during vegetative
propagation. The plants have been tested for growth and development during 7-15
years. The results showed that most micropropagated
clones preserved specific for their initial genotypes growth peculiarities, habitus, cytogenetic
peculiarities. Clones showed uniformity in height and diameter of trees,
disease and pest resistance. Furthermore, the birch clones of callus origin
showed early and full display of external characters of patterned wood (since
4-5-year-old, and their 100% display by the age of 5-8). Plants grown by routine methods
(seed method), the characters of patterned texture are displayed later – at the
age of 10-12. It shows effectiveness and economical value of in vitro technology not only for
reproduction but also for preservation of valuable and unique genotypes by
establishment of collection plots and polyclonal plantations (conservation ex situ), having a wide
genetic basis and potential resistance and adaptation. Another possibility of ex situ conservation is establishment and
durably maintenance (over
10-15 years) of growing valuable genotype collection on hormone-free media and
with seldom subcultivation (Mashkina,
2005). However, during in vitro
cultivation we pointed out some cases of somaclonal
variability, breaking clone uniformity. It was especially characteristic for Karelian birch and revealed both on the level of individual
tube plants (for example, forming callus-like formations instead of roots) and
in vivo vegetating plants (appearance among clones of high-stem forms of single
dwarfs and multistem ramets).
Arising variations had differences on morphological, cytogenetic,
physiological and biochemical levels. Their appearance may be connected with
biological peculiarities of Karelian birch (presence
and realization of initial variability by the level of ploidy
and mixoploidy, the content and the balance of endogenin hormones and others), and with induction of
additional variability under the influence of phytohormones
and cultivation conditions, under genome reprogramming during the process of
dedifferentiation and callus-forming. Being the source of widening of genetic
diversity of initial material, somaclonal variability
can be used in breeding for getting of new economically valuable genotypes.
The method of tissue culture is used for the study of plant development genetics. Thus, in leafdessected form of Betula pendula Roth during micropropagation in some genotypes the cases of change of the development program were pointed out – reversion to the common leaf plate (wild type). Possible reasons of such variability are discussed.