[CYTOGENETIC RESPONSE OF SCOTS PINE (PINUS SYLVESTRIS L.) TO CADMIUM AND NICKEL].

We studied cytogenetic polymorphism of the seeds of Pinus sylvestris L. in response to heavy metals exposure in laboratory settings over 2 years' time. We compared results obtained from the seedlings of different years: 2012 and 2013. With an increase in Ni2+ and Cd2+ concentration we observed a decrease in mitotic activity with concurrent rise in the percentage of cells in the prophase. This fact demonstrates the heavy metals act similar to both fixatives and substances that block cleavage spindle formation. In terms of pathological mitosis and the frequency of micronuclei cells, Cd2+ shows higher mutagenity compared to Ni2+. In addition, in the experimental samples, we have distinguished abnormalities such as fragmentations and agglutinations of chromosomes and especially C mitosis occurrence, which are not observed in the control.

[Karelian birch (Betula pendula Roth. var. carelica Merkl.) as a model for studying genetic and epigenetic variation related to the formation of patterned wood].

The results of long-term pioneering studies on in vitro micropropagation of Karelian birch patterned forms and simultaneous cytological analysis of plants multiplied using different periods of in vitro culturing are published for the first time. The patterned wood character has been shown to be correlated with the degree of mixoploidy of its somatic tissue, which is higher in the plants obtained from callus cultures during the first years of culturing. Subsequent intracellular selection leads to a decrease in mixoploidy and, hence, in a later expression and lower expressivity of the patterned wood character in regenerant plants. It is also known that extreme growth conditions stimulate the formation of patterned wood. Thus, Karelian birch may serve as a model object for studying the forms of variability (both genetic and epigenetic) that result in patterned wood. The genetic variability is expressed in the variation of the degree of mixoploidy of somatic tissue as a result of various mitotic aberrations. The epigenetic variability is not related to changes in the DNA structure; it is caused by different phenotypic effects of genes located in cells with different ploidy/aneuploidy levels, the ratio between which varies depending on the environmental conditions. The expression of genes, in particular, rRNA genes, is affected by extreme conditions. The appearance of a residual nucleolus at the mitotic metaphase-telophase stages is a cytological expression of this phenomenon.

[Genetic engineering of forest woody plants]. / Geneticheskaia inzheneriia lesnykh drevesnykh rastenii.

The present state of genetic engineering (GE) of forest woody plants is considered with special reference to the materials of the International Conference "Wood, Breeding, Biotechnology and Industrial Expectations" held in France in June, 2001. Main tree species subjected to GE are listed, aims of constructing transgenic plants discussed, and methods described. Major achievements in the field are considered along with the problems associated with the employment of GE in the breeding of forest woody plants.