TISSUE CULTURE STORAGE OF BRAZILIAN MEDICINAL PLANTS GERMPLASM

Abstract

Modern agriculture depends on a coordinated system to evaluate, introduce, distribute and maintain germplasm, since plant germplasm is the base for a productive agriculture. It is estimated that 90% of the germplasm collections are stored as seeds, of which 40% are cereals. Medicinal plants are particularly difficult to store as seeds, due to the lack of knowledge of their reproduction biology and seed behavior. Besides, there are a large number of important tropical and subtropical medicinal plants species which produce recalcitrant seeds that quickly lose viability and do not survive desiccation, hence conventional seed storage strategies are not possible. There is also a number of other import species that are sterile or do not easily produce seeds, or seeds are highly heterozygous and clonal propagation is preferred to conserve elite genotypes. Although field genebanks provide easy access to conserved material for use, they have a risk of destruction by natural calamities, pest and diseases. For this reason, safety duplicates of the living collections are established using alternate strategies of conservation and it is in this area that biotechnology contributed significantly by providing complementary in vitro conservation options through tissue culture techniques. In vitro conservation also offers other distinct advantages. For example, the material can be maintained in a pathogen-tested state, thereby facilitating safer distribution and germplasm exchange. Further, the cultures are not subject to environmental disturbance. The National Genetic Resources and Biotechnology Research Center (CENARGEN), was created by the Brazilian Organization for Agricultural Research (EMBRAPA), an institution linked to the Ministry of Agriculture, in order to coordinate and organize all activities related to genetic resources in Brazil, including genetic resources of medicinal plants. The in vitro collection of medicinal plants of CENARGEN is constituted by at least 395 accessions of five genus: Mentha (74), Lippia (47), Pfaffia (15), Stevia (16) and Cochlospermum (10). Experiments have shown that in vitro shoot cultures stored at temperature in the range of 18-20°C on half strength Murashige and Skoog medium nutrient with 2% sucrose reduce the plant growth and significantly extend the subculture intervals of accessions to fresh medium. We conclude that this in vitro conservation system can be greatly useful for conservation and exchange of genetic resources of these medicinal plants.