Germplasm Conservation:
The sum total of all the genes present in a crop and its related species constitutes its germplasm; it is ordinarily represented by a collection of various strains and species. Germplasm provides the raw materials (= genes), which the breeder uses to develop commercial crop varieties. Therefore, germplasm is the basic indispensable ingredient of all breeding programmes, and a great emphasis is placed on collection, evaluation and conservation of germplasm.
Limitations of conventional methods:
• Conventionally, germplasm is conserved as seeds stored at ambient temperature, low temperature or ultralow temperature. But many crops produce recalcitrant or short-lived seeds, and in case of clonal crops seeds are not the best material to conserve in view of their genetic heterogeneity and unknown worth.
• Roots and tubers lose viability rapidly and their storage requires large space, low temperature and is expensive.
• In addition, materials modified by genetic engineering may sometimes be unstable, and hence may need to be conserved intact for future use.
In such cases, the following approaches of germplasm conservation may be applied:
• freeze preservation,
• slow-growth cultures.
• DNA-clones and
• desiccated somatic embryos/artificial seeds.