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sea buckthorn genes both in homozygous and heterozygous states. O f particular interest are

marker traits such as fruit colouring and mass, absence of thorns on seedlings, dwarfism

and semi-dwarfism and some others. The fruit colouring is one of the most clearest genetic

markers in sea buckthorn. By analysing the rate of propagation of plants with differently

coloured fruits there may be estimated the intensity of natural selection in population with

different habitat factors and there may be performed the genetic control of traits splitting

throughout hybridisation of different forms. The key factor influencing the amount of

carotenoids in fruits and being the most important property for pharmacological activity of

sea buckthorn oil is the fruit genetically conditioned colouring. According to results of

several authors and to our data the greater amount of carotenoids is reported in red-coloured

fruits, much less in yellow-coloured and much more in milky-white fruits in the Caucasian

population. Data published and results of our investigations allow to conclude that fruit-

colouring in Siberian sea buckthorn populations is being controlled by two allelic genes

responsible for yellow and red colouring. In Caucasian populations there is reported another

gene completely or partly blocking the synthesis of colouring markers in fruits. Plants with

orange fruits are heterozygotes with intermediate expression of the trait: between yellow

and red for Siberia and between yellow (or red) and colourless for the Caucasus.

Comparing to yellow and red-fruited forms, the intermediate content of carotenoids in

orange forms confirms this assumption.

In the mutational plant breeding the following is to be taken into account::

1. Plants display new traits only as a result of gene mutability. Hybridisation chiefly

drives to recombination of genes or to the transfer of recessive mutations from

heterozygous into homozygous state as a result of random combination of mutant gametes;

2. Gene phenotypic manifestation to a considerable extent depends on its genotypical

environment. Optimal phenotypical environment may be created not only throughout

hybridisation but also by gradual mutagenesis with the treatment of seeds with a mutagene

in Mi, М

and so on. The possibility to develop varieties with new traits by using

experimental mutagenesis is proved by our new sea buckthorn cultivar Zyrianka (authors -

G.F. Pryvalov, N.S. ,Shchyapov, L.P. Solonenko) Thdt has ibeen widely spread in many

regions of thjs country.

One of the promising trends in this field is application of the method of reverse

mutations (reversions) that allow new types of mutations being recessive or dominant by

their nature. By data accumulated the rate of appearance of induced dominant mutations is

higher if mutant with recessive and not dominant traits are used as initial material. It seems

more expedient to use mutant forms defective for certain traits (weak in growth, with

chlorophyll deficiency etc.) and not the varietal material.

The next stage in the mutational plant breeding is creation of such mutant forms that

provide optimal genotypical environment for the work of recessive and dominant genes, the

latter being the goal of plant breeding.

That may be achieved by two ways:

1. Experimental creation of reverse mutation (reverse breeding);

2. crossing of mutants with varieties or cultivars from other ecological zones

(combinative selection).

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