Clonal micropropagation is an alternative way to preserve plant biodiversity

Author: E.N. Kutas (Central Botanical Garden of the National Academy of Sciences of Belarus, Minsk, Belarus).

Recently, the need has arisen for setting on a fundamentally new level the tasks of studying, preserving and using biological diversity as the basis for the sustainability and stability of the biosphere. The reduction of biological diversity is considered as one of the main global environmental problems facing humanity at the present stage.

As is well known, the concept of biological diversity unites all species of plants, animals and microorganisms, as well as ecosystems that include them. It is divided into three independent, but interrelated levels:

  1. genetic diversity - intraspecific and intrapopulation heterogeneity;
  2. species diversity in general or individual large taxa;
  3. diversity of ecosystems, including previous levels and representing habitats for species.

Biological diversity is given the status of a common type of natural resources, like the atmosphere, oceans, etc., which are vital for the global community.

Sharing the concerns of many countries of the world about the global threat to biological diversity and realizing the special responsibility for its preservation within the national territory, representatives of the Government of the Republic of Belarus together with the leaders of more than 100 countries signed the Convention on Biological Diversity in 1992 in Rio de Janeiro. In 1993, the Convention was ratified by Parliament. In accordance with Article 6 of the Convention in the Republic of Belarus, a National Strategy and Action Plan for the Conservation and Sustainable Use of Biological Diversity of the Republic of Belarus was developed, which in 1997 were officially approved by the government ). These documents were developed and adopted with the aim of identifying and scientifically justifying priority activities and measures for the conservation and sustainable use of biological diversity for the near and more distant future.

The flora of Belarus includes 11.5 thousand plant species (2100 species of higher and 9400 species of lower plants), of which 96 species are listed in the Red Book of Belarus [2].

In recent years, the problem of biodiversity and its conservation has been given great importance. Plant introduction is considered as one of the possible effective methods of plant biodiversity conservation.

It is well known that one of the ways to preserve and restore rare plant species is to introduce them into botanical gardens. The Botanical Garden of the National Academy of Sciences of Belarus is practically the only organization conducting a serious bioecological study in the culture of rare and protected plant species in Belarus. About 100 rare species of local flora have been introduced here. More than 9 thousand species, forms, varieties of trees and shrubs, ornamental, technical, forage, aromatic and medicinal plants have been collected. In the dendrological collections more than 1500 taxa are represented. An arboretum was created, containing about 500 species and forms of East Asian and over 400 species of North American flora [2].

One of the alternative ways of preserving and restoring rare plant species, from our point of view, is clonal micropropagation. This is one of the priority areas of biotechnology, which was created and successfully developed in the Central Botanical Garden of the National Academy of Sciences of Belarus.

The plant can be regenerated by several methods:

  1. through activation of axillary meristem;
  2. induction of somatic embryogenesis in callus culture;
  3. kidney differentiation in callus culture;
  4. somatic embryogenesis in explant tissue;
  5. differentiation of the kidney in the explant tissue [1].

Regenerants obtained through callus culture (from somatic embryos or kidneys) tend to cast doubt on their genetic stability. Unfortunately, in the literature there is still no clear separation of views on the issue with which method of regeneration genetically stable material can be obtained, and with which it can be variable. However, despite the complexity of the problem regarding the quality of regenerants obtained in cell and tissue culture, analysis of the literature material leads to the conclusion that genetically stable material can be obtained with almost any method of regeneration, observing strict control over morphogenesis occurring in cell culture and tissue, using histological, karyological and cytogenetic analyzes of the regenerated material. The highest percentage of the release of genetically stable regenerants can be achieved by using the methods of activation of the axillary meristem, direct somatic embryogenesis and the formation of shoots directly from the explant tissue, bypassing the stage of callus formation on the nutrient medium.

At present, the advantage of clonal micropropagation over traditional methods of vegetative and generative reproduction of plants is indisputable. The areas of its application are diverse: agriculture and forestry, floriculture, medical and food industries. Recently, there has been a tendency to their expansion: the preservation of rare and endangered plant species, the protection of the environment. Thanks to clonal micropropagation, it became possible to create a bank of plant genotypes in the form of a collection of sterile cultures. So, the Central Library of the National Academy of Sciences of Belarus has created a collection of sterile crops, including the introduced varieties of high blueberry, lingonberry, rhododendron species, breeding hybrids, representatives of this. Vacciniaceae S.F.Gray.

Clonal micropropagation is not accidental; it is economically profitable. Using it, you can increase the multiplication factor to 106 copies per year from one mother plant, which is hundreds of thousands of times more compared to conventional breeding methods. To obtain improved material, to achieve an accelerated transition from the juvenile phase of plant development to reproductive, to propagate plants that do not vegetatively reproduce or reproduce with difficulty, and also have low viability or seed productivity, which is especially characteristic of rare and endangered plant and introduced species.

Clonal micropropagation in the countries of Western Europe (Czech Republic, Poland, France, Italy) of North and South America (Canada, USA, Brazil), Japan, Southeast Asia (India, Indonesia) is of particular importance. Indonesia's forest vegetation is represented by tropical rain forests. The largest forest area (1 220 000 km2) Indonesia ranks second in the world (among the countries of the tropical belt) after Brazil. Intensive logging in recent years has led to a significant reduction in forest area. To compensate for forest losses, the Indonesian government has adopted a wide reforestation program. The need for planting material is 780 million copies per year, while the real possibility does not exceed 4 million copies per year. In the coming years, a lot of objective factors did not allow to significantly increase the yield of seedlings: irregular flowering of rocks, poor seed quality, etc. In order to carry out the government program in the laboratory of forest crops, experiments on in vitro clonal micropropagation of the material were started. Trees such as Tectona grandis L. f., Dalbergia latifolia Roxb., Acacia magnum Wild., Eucalyptus urophylla S. T. Blake. et al. [5].

There are publications in the literature indicating the successful use of clonal micropropagation for the preservation of rare and endangered plant species. So cacti euphorbia Euphorbia handiensis Burchd - a narrow, endangered Canarian endemic, was propagated in vitro in culture. Similarly, the Canarian endangered species of Senecio hermosae Pitard was preserved. As explants, shoot apexes isolated from plants growing in natural habitat were used. The regenerated plants obtained in this way subsequently constituted a stable population in the botanical garden [3-4].

Rare species of deer deer (Drosera rotundifolia L., D. Capillaris Poir., D. Burkeana Planch., D. Hilaris Cham. Et Chlecht.), Canarian endemics, some species of onions (Pskemsky, Altai, blue -blue), rare orchid species of the temperate zone and many others.

As a result of a comprehensive study conducted on induced morphogenesis and regeneration, as well as structural and functional adaptation of regenerants when transferring them from the culture vessels to the conditions of the greenhouse and open ground. We have developed technologies of clonal micropropagation for fruit and berry plants (14 introduced varieties of high blueberry and 5 varieties of lingonberry) and ornamental plants (13 species of rhododendrons and 5 varieties of common lilac) [1].

The developed technologies make it possible to put on an industrial basis the production of a healthy, environmentally friendly planting material of such valuable plants as introduced high-quality blueberry, lingonberry, lilac varieties, introduced rhododendron species with nutritional and medicinal value, as well as radioprotective effects (lingonberry, blueberry) and meet the needs of the national economy of Belarus and other regions of the CIS affected by the Chernobyl accident in this product.

Three methods of regeneration of introduced varieties of blueberry high, lingonberry, lilac, introduced species of rhododendrons were developed: 1) through activation of axillary meristem, 2) proliferation of callus and further regeneration of plants from it, 3) directly from leaf tissue, bypassing the callus formation stage. Regeneration of introduced high-quality blueberry varieties, lilacs, lingonberries, introduced rhododendron species directly from leaf tissue can be used in the genetic transformation system in order to produce transgenic plants with new properties; regeneration through the proliferation of callus - in breeding work; regeneration through activation of axillary meristem - for clonal micropropagation of plants, preservation of rare and endangered species, maintenance of plant biodiversity, its gene pool.

The results of experimental studies obtained on induced morphogenesis and plant regeneration, allowed to create a genotype bank, represented by a collection of sterile cultures, including more than 30 species and varieties of representatives of this. Vacciniaceae S. F. Gray and Ericaceae Juss., Serving as one of the ways to preserve plant biodiversity.
Therefore, clonal micropropagation can be used as a tool to help maintain, preserve and enhance plant biodiversity.

Bibliography

  1. Kutas E.N., Sidorovich E.A., Reshetnikov V.N. Clonal micropropagation of introduced plants // Biological diversity of plants. His research, preservation and use in the Republic of Belarus. Minsk: UE “Technoprint,” 2003. p. 243-270
  2. The first national report on the implementation of the Convention on Biological Diversity in Belarus. Mn .: BelEKS, 1998. - 125 p.
  3. Ortega G., Gonzales A. Contribution to the "ex situ" conservation of canary species in danger: "in vitro" propagation of Senecio hermosae Pitard // Bot. Macaronesian 1985. № 14. P. 59-72.
  4. Gonzales A., Gonzales O., Rubio H. Propagation "in vitro" of endangered Canarian endemisms: Euphorbia handiensis Burchd // Bot. Macaronesian 1988. № 16. P. 25-28.
  5. Umboh I., Setiawan I. et al. L'application of techniques of culture in vitro to the multiplication d'espeses tropical forestieres in Indonesie // Bull. Soc. Bot. Actual Fr. Bot. 1989. Vol. 136, № 3-4. P. 179-184.