Scientists finally solve the 160-year-old problem of Mendel’s peas

Historical Context

• In 1856, Gregor Mendel began experiments on pea plants to study inheritance.
• He identified 7 discrete traits, noticing dominant and recessive patterns.
• His findings (1866) were largely ignored during his lifetime.
• In 1900, three scientists — Hugo de Vries, Carl Correns, Erich von Tschermak — independently rediscovered Mendel’s work.

Relevance : GS 3(Science)

Mendel’s Key Discoveries

• Traits followed predictable 3:1 ratios in second-generation crosses.
• Introduced the concepts of dominant/recessive traits and discrete units of heredity (now called genes).
• Formed the foundation for modern genetics, later leading to the chromosome theory of inheritance.

The Unresolved Mystery

• Despite scientific advancements, genetic basis for all 7 traits Mendel studied was not fully explained.
• Only 4 traits were genetically characterised until recently:
  • Seed shape
  • Seed colour
  • Plant height
  • Flower colour

Breakthrough Study in Nature (2025)

• Paper: ‘Genomic and genetic insights into Mendel’s pea genes’ (Feng et al.).
• Used next-generation sequencing on 697 pea variants.
• Generated a 60 terabase DNA dataset (≈14 billion pages worth of genetic data).

Major Scientific Breakthroughs

1. Genetic Basis for Remaining 3 Traits Identified:
   1. Pod Colour: Deletion near ChlG gene disrupts chlorophyll, causing yellow pods.
   2. Pod Shape: Changes in MYB and CLE-peptide genes cause constricted pods.
   3. Flower Position: Deletion in CIK-like-coreceptor-kinase gene and a modifier locus leads to terminal flower positioning.

• Complexity of Pea Plant Genetics Revealed:
  • Though peas belong to 4 species, genetically cluster into 8 groups due to admixture.
  • Discovered additional alleles for traits previously thought to be simple — e.g., a variant that turns white flowers purple.
• Expanded Trait Mapping:
  • Identified 72 agriculturally important traits (e.g., architecture of seed, pod, root).
  • Created a genomic map for deep trait-tracking and breeding research.

Scientific and Agricultural Implications

• Resolves a 160-year-old puzzle in genetics.
• Provides a blueprint for plant breeding — improved crop yield, disease resistance, stress adaptation.
• Demonstrates the power of combining classical genetics with modern genomics.

Reflection

• Mendel’s curiosity in a monastery garden laid the groundwork for centuries of biological advancement.
• The study underscores how fundamental research can yield profound future applications.