PB Ch 3, Centre of Origin and Plant Genetic Resources

The geographical regions where crop species first evolved are known as the centres of origin. These specific geographic pockets hold an incredibly rich array of genetic diversity, which is absolutely essential for the continuous improvement and breeding of crop varieties. As one of the recognized global centres of origin, India bears a unique and critical responsibility to conserve, meticulously document, and sustainably utilize its vast plant genetic resources (PGR).

3.1. Vavilov's Concept of Centres of Origin

Scientific Definition: A centre of origin is defined as a geographical region where a group of organisms, either domesticated or wild, first developed its distinctive properties, typically characterized by the maximum genetic diversity of that crop and its wild relatives.

In Simple Terms: Think of the centre of origin as the evolutionary "birthplace" or "cradle" of a plant. Because the plant has lived and evolved there the longest, that specific area is packed with the highest number of different varieties, shapes, sizes, and natural defenses for that specific crop.

• Historical Context: Nikolai Ivanovich Vavilov (1887–1943) was a prominent Russian botanist, geneticist, and the founding father of the N.I. Vavilov Institute of Plant Industry in St. Petersburg.
• Expeditions and Collections: Driven by a mission to end famine, Vavilov conducted over 180 exhaustive botanical collection expeditions across 64 different countries between the years 1916 and 1940. Through these efforts, he successfully built the world's largest seed bank of that era.
• Key Publication: In 1926, Vavilov published his seminal work, "Studies on the Origin of Cultivated Plants," in which he initially proposed 8 primary centres of origin worldwide.
• A Tragic End: Tragically, despite his lifelong dedication to fighting global hunger, Vavilov was persecuted under Stalin's regime and died of starvation in a Soviet gulag in 1943—a profound irony for a scientist who dedicated his life to food security.

Vavilov's 8 Centres of Origin

⚑ Previous Year Question: IFoS 2025 (Q3a, 15M) Explain gene pool concept along with different groups of gene pools. Name the scientist who proposed centres of origin along with the total number of centres of origin of plants in the world.

3.2. Vavilov's Law of Homologous Series in Variation

Scientific Definition: Formulated in 1922, this biological law states that closely related species and genera exhibit parallel series of heritable morphological and physiological variations.

In Simple Terms: If you observe a specific genetic trait (like drought resistance or a specific grain color) in one type of plant, there is a very high probability that you will find a similar, parallel trait in its evolutionary "cousins" or closely related species.

• Biological Examples:

  • Awned, awnless, and hooded morphological forms exist simultaneously in wheat, barley, and rye.

  • Glabrous (smooth), hairy, and glaucous (waxy) leaf forms can be found across all species within the Triticum (wheat) genus.
  • Variations like red, yellow, and white grain colors are consistently found across various cereal crops, including wheat, rice, barley, and maize.
• Significance in Agriculture:

  • It allows breeders to mathematically and biologically predict the presence of useful variations in currently unexplored wild plant species.

  • It systematically guides plant exploration and germplasm collection expeditions.
  • It acts as a reliable roadmap for researchers searching for specific traits, such as disease resistance, pest resistance, or drought tolerance.
  • It laid the foundational principles for wide hybridization techniques involving wild crop relatives.

3.3. Harlan & de Wet's Gene Pool Concept (1971)

In 1971, renowned scientists Jack R. Harlan and J.M.J. de Wet devised a highly practical classification system for crop genetic resources. They categorized related plant species into three distinct "gene pools" based strictly on the biological ease of crossing them with cultivated species to produce fertile offspring.

Primary Gene Pool (GP-1)

• Scientific Definition: This pool encompasses the cultivated species alongside its wild progenitor species that can cross-pollinate easily and yield fully fertile F1 hybrids.
• Human Terms: These are the immediate botanical family members. You can breed them together naturally without any scientific struggle, and the resulting "baby" plants will be perfectly healthy and able to reproduce.
• Characteristics: Gene transfer within this pool is completely straightforward, making conventional hybridization highly effective without any reproductive barriers.
• Examples:

  • Wheat: Triticum aestivum (cultivated wheat) paired with T. spelta, T. macha, or T. compactum.

  • Rice: Oryza sativa paired with its direct wild progenitor, O. rufipogon.
  • Maize: Zea mays crossed with Z. mexicana (commonly known as teosinte).

Secondary Gene Pool (GP-2)

• Scientific Definition: This includes species that can cross with the cultivated species, but the resulting F1 generation is typically partially sterile or hindered by distinct biological crossing barriers.
• Human Terms: These are the distant botanical cousins. You can force them to cross, but it is difficult, and the offspring might be weak or infertile without a little help from scientists in a lab.
• Characteristics: Successful gene transfer usually mandates advanced tissue culture techniques such as embryo rescue, or the artificial doubling of chromosomes to restore fertility.
• Examples:

  • Wheat: Crosses involving Triticum monococcum, T. timopheevii, and various Aegilops species.

  • Rice: Incorporating traits from O. glaberrima (African rice) or O. nivara.
  • Maize: Crosses with more distant species within the Zea genus.

Tertiary Gene Pool (GP-3)

• Scientific Definition: The extreme outer limit of potential genetic resources, comprising species that cannot naturally or easily cross with the cultivated species due to severe lethality or complete sterility.
• Human Terms: These plants are complete strangers to the crop. Trying to breed them naturally will fail entirely. Moving genes from these plants requires high-tech genetic engineering or complex laboratory procedures.
• Characteristics: Successful gene transfer from GP-3 demands highly specialized biotechnology, including extensive embryo rescue, somatic cell hybridization, or direct transgenic (GMO) methodologies.
• Examples:

  • Wheat: Attempting to cross wheat with distant grasses like Agropyron (wheatgrass), Hordeum (barley), or rye (Secale).

  • Rice: Utilizing Porteresia coarctata (a mangrove grass) to introduce extreme salt tolerance into cultivated rice.
  • Cotton: Crosses involving highly distant Gossypium species, which typically result in lethal F1 hybrids.

▶ PRACTICAL APPLICATION FOR BREEDERS:

— GP-1 serves as the immediate first choice for breeding programs due to the absence of genetic barriers.

— GP-2 acts as a valuable backup reservoir for highly specific or special traits, though it requires laboratory intervention like embryo rescue.

— GP-3 is considered the absolute last resort, heavily reliant on transgenic techniques or complex bridge crosses. Ultimately, this tiered concept expertly guides breeders on where and how to source novel genetic material, especially for critical traits like disease resistance and environmental stress tolerance.

3.4. Plant Genetic Resources (PGR) — Definition & Significance

Scientific Definition: According to the Food and Agriculture Organization (FAO), Plant Genetic Resources (PGR) refers to any genetic material of plant origin that possesses actual or potential value for food and agriculture.

In Simple Terms: PGR is the entire global "library" of plant DNA. It includes every single seed, leaf, root, or wild weed that carries genetic codes that could one day help us grow better, stronger, or more nutritious food.

• Comprehensive Scope of PGR: The term encompasses a wide variety of plant forms, including:

  • Cultivated varieties, which include both modern High-Yielding Varieties (HYVs) and older, previously released commercial varieties.

  • Landraces and farmers' varieties, which have been historically developed and preserved by traditional farming communities over generations.
  • Obsolete varieties that are no longer actively cultivated but still hold valuable genetic code.
  • Wild relatives of cultivated crops that survive in natural ecosystems.
  • Advanced breeding lines and specific genetic stocks, including artificially created mutants and aneuploids.
  • Tribal or folk varieties and primitive cultivars found in isolated communities.
• Why is PGR Critically Important?

  • It serves as the ultimate source of novel genes required to breed plants with improved disease resistance, pest resistance, environmental stress tolerance, and enhanced nutritional quality.

  • It acts as an irreplaceable biological insurance policy against unforeseeable threats such as rapid climate change, the emergence of novel plant pathogens, or the accidental loss of current elite cultivars.
  • It represents deeply rooted cultural and historical agricultural heritage.
  • It forms the absolute biological foundation upon which all future crop improvement and global food security depend.

⚑ Previous Year Questions IFoS 2025 (Q2b, 15M): What do you understand by plant genetic resources? Explain the methods of conservation and utilization of plant genetic resources. IFoS 2020 (Q2c, 10M): What do you mean by conservation of plant genetic resources? Explain their contribution in crop improvement in India.

3.5. Conservation of Plant Genetic Resources

The systematic preservation of PGR is achieved through two primary strategic approaches: In-Situ (on-site) and Ex-Situ (off-site) conservation.

A. In-Situ Conservation

• Scientific Concept: The conservation of plant species within their natural, original ecosystems and natural habitats where their distinctive properties originally evolved.
• Human Terms: Protecting the plants by protecting the forests or wild areas where they naturally live, allowing nature to take its course without pulling the plants out of their home environment.
• Ideal Candidates: This method is highly suitable for the wild relatives of crops, forest tree species, valuable medicinal plants, and various threatened species.
• Conservation Methods:

  • Protected Areas: National Parks (such as Kaziranga, Jim Corbett, and Bandipur) and specialized Wildlife Sanctuaries.

  • Biosphere Reserves: Large protected ecosystems (e.g., Nilgiri, Nanda Devi, Sundarbans, Manas, Gulf of Mannar) — India currently maintains 18 such reserves.
  • Sacred Groves: Traditional community-protected forest patches, predominantly found and respected in states like Maharashtra, Kerala, and Meghalaya.
  • On-Farm Conservation: An active approach where traditional farmers purposefully continue to cultivate heritage or traditional varieties as their primary crops (e.g., cultivating Navara rice in Kerala or Chinnor rice in Madhya Pradesh).
• Key Advantage: It permits the continuous, dynamic evolutionary process of the plant, ensuring its ongoing biological adaptation to naturally changing environmental conditions and emerging pests.
• Major Disadvantage: The populations remain highly vulnerable to unpredictable natural disasters, human encroachment, industrialization, and subsequent habitat destruction.

B. Ex-Situ Conservation

• Scientific Concept: The deliberate conservation of biological diversity components completely outside their natural habitats, typically within highly controlled scientific facilities.
• Human Terms: Taking seeds, tissues, or whole plants out of the wild and keeping them safe in high-tech refrigerators, botanical gardens, or laboratories.
• Primary Focus: This is the absolute most critical method for safeguarding cultivated agricultural crops and extremely threatened wild species.

Primary Methods of Ex-Situ Conservation:

• 1. Seed Storage (Gene Banks):

  • Recognized as the most efficient and economical method for storing "orthodox seeds" (seeds that can safely survive severe desiccation and sub-zero temperatures).

  • FAO Storage Classifications:

    • Short-term (Working Collection): Kept at 5°C with 60% relative humidity; remains viable for 1–5 years.

    • Medium-term (Active Collection): Stored between 0 to 5°C with 30–40% relative humidity; remains viable for 10–25 years.
    • Long-term (Base Collection): Frozen at −18 to −20°C with extremely low seed moisture (3–7%); guarantees viability for 50–100 years.
  • The ICAR-NBPGR (National Bureau of Plant Genetic Resources) acts as the apex institute in India, maintaining a massive National Gene Bank in New Delhi that houses over 440,000 unique accessions, making it one of the largest globally.
  • 2. Field Gene Banks:

    • Required specifically for "recalcitrant seeds" (seeds that die if dried, such as mango, jackfruit, coconut, cocoa, and rubber) and vegetatively propagated species (like sugarcane, banana, potato, cassava, and sweet potato).

    • These resources are physically planted and meticulously maintained as living plants in massive agricultural repositories. Examples include ICAR-IIHR in Bangalore for horticultural crops and ICAR-CISH in Lucknow for mangoes and guavas.
  • 3. In Vitro Conservation:

    • A highly controlled tissue culture-based method involving meristem culture, callus culture, or organ culture.

    • It is exceedingly useful for safely storing vegetatively propagated and recalcitrant species in glass tubes on slow-growth chemical mediums.
  • 4. Cryopreservation:

    • The ultimate biological suspension, involving conservation at ultra-low, cryogenic temperatures (–196°C) using liquid nitrogen.

    • At this temperature, all cellular metabolic activity instantly halts, theoretically allowing for indefinite biological storage. It is used extensively for seeds, pollen, meristems, embryos, and cell suspensions.
    • ICAR-NBPGR operates a state-of-art Cryogenebank holding over 12,000 accessions—the largest facility of its kind in Asia.
  • 5. DNA and Pollen Banks:

    • DNA banks permanently store extracted genomic DNA, which is vital for complex molecular studies and future gene discovery.

    • Pollen banks safely store viable pollen specifically for use in delayed distant crosses and sophisticated hybrid seed production.

  3.6. Passport Data & Germplasm Documentation

  Scientific Definition: Passport data comprises the fundamental, standardized descriptive information comprehensively recorded at the exact time and location of a germplasm's field collection.

  In Simple Terms: It is literally a "birth certificate" and a "passport" combined for a collected seed. It tells scientists exactly who found it, precisely where on Earth it came from, and what the local farmers called it, ensuring the plant's identity is never lost.

  • Purpose: It definitively identifies the specific accession and allows researchers to accurately trace its entire historical and geographical origins.
  • Required Information (Based on FAO MCPD Descriptors):

    • Accession number: A strict, unique alphanumeric identifier assigned by the gene bank.

    • Taxonomic identity: Both the local vernacular name and the exact scientific botanical name.
    • Geographic origin /strong> Country, state, exact latitude, longitude, and precise elevation/altitude.
    • Collection logistics: The specific date and the exact scientific method utilized for collection.
    • Source identification: Whether it was found in a farmer's field, bought in a local market, transferred from another gene bank, or provided by a breeder.
    • Collector details: The full name and organizational affiliation of the scientist or explorer.
    • Ethnobotanical /strong> Detailed notes on local cultivation practices, unique tribal uses, or verbally reported special agricultural traits.
    • Archival history: Detailed logs of subsequent seed multiplication and rejuvenation cycles during storage.
  • Strategic Importance: Proper passport data rigorously ensures traceability across the globe, prevents expensive duplicate entries in gene banks, and provides the foundational legal evidence required to support Intellectual Property Rights (IPR) claims.
  • Data Evolution: Following the passport phase, researchers later append Characterization Data (recording morphological and agronomic traits) and Evaluation Data (testing for yield, quality, and stress responses).
  • Global Documentation: All this data is systematically digitally archived in massive global databases such as GENESYS, the PGR Portal (operated by NBPGR in India), and GRIN (operated by the USDA).

  ⚑ Previous Year Question: IFoS 2023 (Q1b, 8M) What do you understand by passport data of genetic resources? Write its importance in germplasm collection and conservation.

  3.7. ICAR-NBPGR — National Bureau of Plant Genetic Resources

  • Foundation & Network: Established dynamically in 1976 with its national headquarters stationed at Pusa, New Delhi. It operates a vast geographic network through strategic regional stations located in Akola, Bhowali, Hyderabad, Jodhpur, Ranchi, Shillong, Shimla, Srinagar, and Thrissur.
  • Core Scientific Mandate: To execute total, comprehensive Plant Genetic Resources management. This includes rigorous exploration, collection, controlled introduction, international exchange, detailed characterization, absolute conservation, and digital documentation of plant genetic materials.
  • Premier Facilities:

    • National Gene Bank (NGB): Dedicated to the long-term, sub-zero storage of orthodox seeds, possessing an astonishing holding capacity of one million individual accessions.

    • Cryogenebank: A futuristic facility utilizing liquid nitrogen to safely harbor over 12,000 delicate accessions.
    • In Vitro Gene Bank: Specifically engineered for the delicate laboratory conservation of recalcitrant plant species.
    • Field Gene Banks: Expansive living botanical repositories maintained at regional stations explicitly for perennial trees and vegetatively propagated agricultural crops.
    • National Herbarium of Cultivated Plants (NHCP): Serves as the ultimate dried botanical taxonomy reference center.
    • Plant Quarantine Division: Acts as the strict biological gateway, providing mandatory phytosanitary clearance and intensive screening for all plant imports and exports to prevent the entry of exotic pests.
  • International Role: The NBPGR serves as India's official National Designated Authority operating under international mandates such as the ITPGRFA and the CBD.

  3.8. PPV&FR Act 2001 — Protection of Plant Varieties & Farmers' Rights

  India developed a unique sui generis (of its own kind) legal system specifically designed for plant variety protection. This sophisticated legislation perfectly meets the strict intellectual property obligations of the WTO's TRIPS Article 27.3(b), while concurrently and aggressively protecting the historical rights of traditional farmers. Enacted in 2001, it led to the establishment of the Protection of Plant Varieties & Farmers' Rights Authority (PPV&FRA) in 2005, headquartered in New Delhi.

  Categories of Varieties Registrable Under the Act

  • New Variety: A novel creation that strictly fulfills the scientific criteria of DUS (Distinctness, Uniformity, and Stability) in addition to absolute novelty. It receives robust legal protection for 15 years (extended to 18 years for trees and vines).
  • Extant Variety: An established variety that is already known and currently in cultivation; it also receives 15 years of legal protection.
  • Farmers' Variety: A historical, traditional variety that has been actively cultivated, evolved, and conserved by farming communities. It is officially protected as an invaluable piece of agricultural heritage.
  • Essentially Derived Variety (EDV): A new variety that is predominantly derived from a pre-existing protected variety, featuring only minor, albeit distinct, genetic changes. Commercializing an EDV mandates the explicit legal consent of the original breeder.

  Comprehensive Rights Granted

  • Breeder's Rights: Confers upon the creator the absolute, exclusive commercial right to produce, sell, market, distribute, import, or export the registered variety for the duration of the 15-year term.
  • Farmers' Rights (A Globally Unique Indian Feature):

    • The fundamental right to freely save, use, sow, re-sow, exchange, share, or sell the raw farm produce harvested from a legally protected variety, exactly as they did before the Act existed (with the sole exception that they cannot legally package and sell it under the breeder's branded name).

    • The right to officially register and protect their traditional heritage varieties under the distinct "Farmer's Variety" category.
    • The legal right to demand financial compensation if a breeder's promised traits (like promised high yields) dramatically fail in the field.
    • Absolute legal protection against harsh accusations of innocent, unintentional intellectual property infringement.
    • Formal recognition and monetary rewards for exceptional community conservation efforts, awarded through the prestigious Plant Genome Saviour Awards.
  • Researcher's Rights: Ensures scientists retain the free, unhindered right to use any protected variety strictly for the purposes of scientific research and as a foundational parent line for breeding totally new varieties.

  The National Gene Fund

  A specialized financial repository administered directly by the PPV&FR Authority. It actively collects mandatory benefit-sharing royalties from commercial breeders. These funds are then systematically disbursed to the specific indigenous farmers or rural communities who originally contributed the raw germplasm utilized to develop those highly profitable registered varieties, providing tangible economic recognition to indigenous knowledge holders.

  3.9. International Treaties & Agreements

  1. International Treaty on Plant Genetic Resources for Food & Agriculture (ITPGRFA)

  • Adopted globally by the FAO in 2001 and officially entering into force in 2004, with India ratifying it early in 2002. It is widely known in agricultural circles as the "Plant Treaty" or the "Seed Treaty".
  • It established a revolutionary Multilateral System (MLS) designed to guarantee facilitated, uninterrupted access to the genetic materials of 64 critically important food and fodder crops (listed formally in Annex I).
  • Crops covered under the MLS: Include vital staples like wheat, rice, maize, sorghum, pearl millet, finger millet, potato, sweet potato, cassava, banana, pigeonpea, chickpea, cowpea, lentil, and pea. Together, these specific crops account for approximately 80% of all human food calories consumed globally.
  • Access to these resources and the subsequent sharing of any derived commercial benefits are strictly governed by a legal framework known as the Standard Material Transfer Agreement (SMTA).

  2. Convention on Biological Diversity (CBD), 1992

  • A landmark global treaty signed dynamically at the historic Rio Earth Summit, entering into international legal force in 1993.
  • It is built upon three non-negotiable objectives:

    1. The total conservation of global biological diversity.

    2. The sustainable, ecologically sound use of all biodiversity components.
    3. The fair and absolutely equitable sharing of any commercial benefits arising from the utilization of global genetic resources.
  • It fundamentally abolished the older view that genetic resources were the "common heritage of mankind," legally replacing it with the principle that individual nations possess absolute sovereign rights over the biological resources found within their geographical borders.

  3. Nagoya Protocol (2010)

  • A critical supplementary agreement to the CBD that legally entered into force in 2014.
  • It provides intense, detailed legal specifications for Access and Benefit-Sharing (ABS) rules worldwide.
  • It mandates that researchers or corporations must obtain official Prior Informed Consent (PIC) and establish Mutually Agreed Terms (MAT) before they are legally allowed to access another nation's genetic resources.
  • India successfully executes these international mandates domestically through the robust Biological Diversity Act of 2002 and the highly specific Nagoya Protocol Implementation Rules of 2014.

  4. TRIPS Article 27.3(b)

  • A crucial component of the WTO's overarching TRIPS Agreement (1994). Article 27.3(b) explicitly allows sovereign nations to legally exclude complex lifeforms like plants and animals from standard patentability.
  • However, it concurrently mandates that countries must provide an effective sui generis (unique, customized) legal system for the robust protection of plant varieties.
  • India boldly chose to forge its own sui generis path, resulting in the PPV&FR Act of 2001, deliberately rejecting the stricter, breeder-heavy UPOV-compliant systems favored by Western nations.

  ★ UPSC KEY TAKEAWAYS

  • Centres of origin: Proposed by N.I. Vavilov; 8 primary global centres (India falls under the Hindustan Centre II).
  • Gene pools: A concept introduced by Harlan & de Wet in 1971, categorizing species into Primary, Secondary, and Tertiary pools based on their crossability.
  • India's PGR custodian: The ICAR-NBPGR, located in New Delhi, safeguarding over 4.4 lakh plant accessions.
  • Farmers' rights: The defining, globally unique feature of the Indian PPV&FR Act of 2001, balancing corporate breeding with indigenous heritage.
  • Global Stance: India is a committed party to major treaties like the ITPGRFA, CBD, and the Nagoya Protocol, but crucially, it is NOT a party to UPOV, having successfully chosen its own unique legal path to protect its farmers.