Model Answer
0 min readIntroduction
The escalating global food security concerns and the impacts of climate change highlight the critical need for resilient and diverse crop varieties. At the heart of this lies the concept of genetic resources, which are intrinsically linked to the 'gene pool' and susceptible to 'genetic erosion'. The FAO estimates that 75% of the world’s food is derived from just 12 plants and 5 animal species, emphasizing the reliance on a limited genetic base. Understanding these concepts and the potential losses is crucial for sustainable agriculture and food security. This answer will define these terms and classify the gene pool of a crop.
What is a Gene Pool?
A gene pool refers to the total collection of genes within a species or population. It represents the genetic variation available for natural selection and adaptation. Essentially, it's the sum of all alleles (different versions of a gene) for all genes in a population. A larger gene pool indicates greater genetic diversity, which is vital for a species' ability to withstand environmental changes, diseases, and pests. The health of a crop’s gene pool directly impacts its resilience and productivity.
What is Genetic Erosion?
Genetic erosion is the loss of genetic diversity within a species or population. This occurs when a particular gene or allele becomes less common or disappears entirely due to various factors like intensive agriculture, selective breeding, habitat destruction, and climate change. It reduces the ability of a species to adapt to changing environments, making it more vulnerable to diseases and pests. The Convention on Biological Diversity (CBD) recognizes the urgent need to conserve genetic diversity to mitigate this loss.
Classification of a Crop's Gene Pool
The gene pool of a crop can be classified into three main categories based on its relationship to the cultivated species:
1. Primary Gene Pool (Closely Related Landraces)
- Contains genes that can be crossed with the cultivated variety through conventional breeding methods.
- These are typically wild relatives or landraces (locally adapted varieties) that have close genetic affinity to the crop.
- Example: Wild rice (Oryza rufipogon) is part of the primary gene pool of cultivated rice (Oryza sativa).
2. Secondary Gene Pool (Distant Wild Relatives)
- Contains genes that can be introduced into the primary gene pool through advanced breeding techniques like chromosome doubling or protoplast fusion.
- These are wild relatives that are more distantly related to the cultivated crop.
- Example: Several wild barley species are considered part of the secondary gene pool for cultivated barley (Hordeum vulgare).
3. Tertiary Gene Pool (Unrelated Species)
- Contains genes from unrelated plant species that can be transferred to the cultivated crop through complex genetic engineering techniques.
- This is the least likely to contribute directly to crop improvement through conventional breeding.
- Example: Genes for disease resistance from a completely different plant species might be introduced into a crop using genetic modification.
| Gene Pool | Genetic Relationship | Breeding Techniques | Example |
|---|---|---|---|
| Primary | Closely related | Conventional breeding | Wild rice (Oryza rufipogon) for rice |
| Secondary | Distant relatives | Chromosome doubling, protoplast fusion | Wild barley species for barley |
| Tertiary | Unrelated species | Genetic engineering | Disease resistance genes from a different plant into a crop |
Importance of Conserving Gene Pools
Conserving crop gene pools is vital for several reasons:
- Adaptation to Climate Change: Diverse gene pools provide the raw material for breeding crops that can tolerate drought, heat, or flooding.
- Disease Resistance: New genes from wild relatives can be used to develop varieties resistant to emerging diseases.
- Nutritional Enhancement: Wild relatives often possess genes for enhanced nutritional content (e.g., higher iron or vitamin A).
India's National Bureau of Plant Genetic Resources (NBPGR) maintains a vast collection of germplasm (seeds and other plant genetic resources) from across the world. This serves as a critical resource for crop improvement and conservation.
Conclusion
In conclusion, understanding the concept of gene pools and the threat of genetic erosion is paramount for ensuring future food security. Classifying gene pools into primary, secondary, and tertiary categories helps prioritize conservation efforts and guide breeding strategies. The continued loss of genetic diversity weakens the resilience of our crops and necessitates proactive measures to conserve and utilize these valuable resources through both conventional breeding and advanced biotechnological approaches. A concerted global effort is needed to safeguard these genetic treasures for generations to come.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.