Preservation, Utilization and Exchange of Germplasm
Introduction
Germplasm refers to the total genetic resources of plants, animals, or microorganisms that are of actual or potential value for breeding, conservation, and research.
In plant breeding, germplasm includes landraces, wild relatives, obsolete cultivars, advanced breeding lines, and modern varieties. Effective preservation, utilization, and exchange of germplasm are essential for food security, crop improvement, and sustainable agriculture.
I. Preservation (Conservation) of Germplasm
Preservation of germplasm ensures the long-term availability of genetic diversity and prevents genetic erosion.
1. Need for Germplasm Preservation
Loss of traditional varieties due to modernization
Climate change and environmental stress
Replacement of landraces by high-yielding varieties
Natural disasters, pests, and diseases
Future breeding and research requirements
2. Methods of Germplasm Preservation
A. In situ Conservation
Conservation of germplasm in its natural habitat.
Examples:
Wild relatives conserved in forests
Landraces grown by farmers in traditional farming systems.
Advantages:
Continuous evolution and adaptation
Low maintenance cost
Preserves ecosystem interactions
Disadvantages:
Risk from human activities and climate change
Difficult to manage and monitor
B. Ex situ Conservation
Conservation of germplasm outside its natural habitat.
(a) Seed Gene Banks
Seeds stored under low temperature and low humidity
Orthodox seeds stored at –18°C
Examples:
National Bureau of Plant Genetic Resources (NBPGR), India
Svalbard Global Seed Vault, Norway
Advantages:
Long-term storage
Easy handling and distribution
(b) Field Gene Banks
Living plants maintained in fields
Used for vegetatively propagated crops
Examples:
Banana, sugarcane, potato, mango
Limitations:
High maintenance cost
Risk of pests, diseases, and natural calamities
(c) In vitro Conservation
Storage of tissues or plantlets under controlled laboratory conditions
Advantages:
Suitable for clonal crops
Requires less space
(d) Cryopreservation
Storage at –196°C in liquid nitrogen
Materials Stored:
Meristems
Embryos
Pollen
Advantages:
Very long-term storage
No genetic changes
II. Utilization of Germplasm
Utilization involves using conserved germplasm for crop improvement, research, and development.
1. Direct Utilization
Cultivation of landraces or wild species
Use as rootstocks or parents
2. Utilization in Plant Breeding
Germplasm serves as a source of valuable genes, such as:
Trait
Source
Disease resistance
Wild relatives
Drought tolerance
Landraces
High yield
Improved varieties
Quality traits
Exotic germplasm
Methods of Utilization:
Hybridization
Backcross breeding
Mutation breeding
Marker-assisted selection
Genetic engineering
3. Pre-breeding
Transfer of useful genes from unadapted germplasm into usable breeding material
Bridges gap between conservation and breeding
4. Research and Education
Genetic diversity studies
Evolutionary studies
Teaching and training
III. Exchange of Germplasm
1. Importance of Germplasm Exchange
Broadens genetic base
Introduces new traits
Avoids inbreeding depression
Supports global crop improvement
2. Types of Germplasm Exchange
National exchange: Between institutions within a country
International exchange: Between countries and international centers
3. Agencies Involved in Germplasm Exchange
FAO (Food and Agriculture Organization)
CGIAR centers (IRRI, CIMMYT, ICRISAT)
NBPGR (India)
National gene banks
4. Procedures for Germplasm Exchange
Request and approval
Phytosanitary certification
Quarantine checks
Material Transfer Agreement (MTA)
5. Legal and Ethical Aspects
Convention on Biological Diversity (CBD)
International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA)
Protection of farmers’ and breeders’ rights
Prevention of biopiracy
Conclusion
Preservation, utilization, and exchange of germplasm form the foundation of plant breeding and biodiversity conservation. Effective conservation safeguards genetic diversity, utilization enhances crop productivity and resilience, and exchange promotes global agricultural development. Integrated efforts at national and international levels are essential for sustainable food security.
Germplasm refers to the living genetic resources—such as seeds, tissues, or DNA—that contain the hereditary information of a species. In agriculture, germplasm is the "raw material" used by breeders to develop new, improved varieties.
1. Preservation of Germplasm (Conservation)
Preservation ensures that genetic diversity is not lost due to "genetic erosion" (extinction of wild species or replacement of local landraces by hybrids). There are two primary strategies:
A. Ex Situ Conservation (Outside Natural Habitat)
This is the most common method for agricultural crops.
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Seed Gene Banks: Seeds are dried to low moisture (5–7%) and stored at low temperatures.
- Short-term: 10 to 15°C (working collections).
- Medium-term: 0 to 5°C.
- Long-term: -18 to -20°C (base collections).
.
- Field Gene Banks: For plants that do not produce seeds or have "recalcitrant" seeds (e.g., Mango, Rubber, Cocoa), germplasm is maintained as live plants in orchards.
- Cryopreservation: Storage of tissues or embryos in liquid nitrogen at -196°C. This stops all metabolic activity, allowing for "indefinite" storage.
- In Vitro Banks: Using tissue culture to maintain plants in a slow-growth state on artificial media.
B. In Situ Conservation (In Natural Habitat)
- Biosphere Reserves: Protecting the entire ecosystem where wild relatives of crops grow.
- On-Farm Conservation: Encouraging farmers to continue growing traditional landraces in their fields.
2. Utilization of Germplasm
Conservation is useless if the material is not utilized to improve food security. The process follows these steps:
A. Characterization and Evaluation
Before use, the germplasm must be screened.
- Morphological: Plant height, leaf shape, flowering time.
- Biochemical/Molecular: DNA profiling to identify unique genes.
- Stress Resistance: Screening for resistance to pests, diseases, drought, and salinity.
B. Pre-Breeding (Genetic Enhancement)
Often, wild germplasm has "bad" traits mixed with "good" ones (e.g., a wild tomato might be disease-resistant but tiny and sour). Pre-breeding transfers the specific "good" gene into a usable breeding line.
C. Development of New Varieties
Breeders use the evaluated germplasm in:
- Hybridization: Crossing two different germplasms to combine traits.
- Selection: Choosing the best offspring over multiple generations.
- Genetic Engineering: Directly inserting a gene from the germplasm into a high-yielding variety.
3. Exchange of Germplasm
Since no country is self-sufficient in genetic resources, international exchange is vital. However, it is strictly regulated to prevent Bio-piracy and the spread of pests.
A. International Frameworks
- **ITPGRFA (The "Plant Treaty"): An agreement that ensures "facilitated access" to the world's most important food crops (Annex I crops).
- CBD (Convention on Biological Diversity): Establishes that countries have sovereign rights over their genetic resources.
- Nagoya Protocol: Focuses on "Access and Benefit Sharing" (ABS). If a company uses a local plant to make a profit, they must share those benefits with the source country.
B. Tools for Exchange
- MTA (Material Transfer Agreement): A legal contract that defines how the recipient can use the germplasm.
- Phytosanitary Certificate: A mandatory document ensuring the germplasm is free from quarantine pests and diseases.
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