Alleles
Context: In 2025, scientists finally identified the genetic basis of all seven traits studied by Mendel in peas, solving a 160-year-old mystery using next-generation sequencing and revealing new alleles and complex genome interactions.
Important Pointers:
Mendel’s Experiment (1856–1865): Gregor Mendel conducted experiments on over 10,000 pea plants to understand trait inheritance.
Rediscovery in 1900: His work was rediscovered 16 years after his death by Hugo de Vries, Carl Correns, and Erich von Tschermak.
Seven Traits Studied: Mendel observed inheritance in traits like seed shape, seed colour, pod shape, pod colour, flower colour, flower position, and plant height.
Dominant vs Recessive: Traits like round seeds and yellow pods showed dominance over wrinkled seeds and green pods in the first generation.
Alleles: Alleles are alternate forms of a gene; one inherited from each parent, they determine the trait expression.
3:1 Ratio: Mendel observed a consistent 3:1 phenotypic ratio in second-generation hybrids (F2).
Basis of Genetics: His findings became the foundation of modern genetics and inheritance.
Alleles and Gene Theory: One allele can mask another; this dominance explains first-generation uniformity.
Chromosome Theory: Mendel’s work laid the groundwork for the chromosome theory of inheritance.
Unresolved Traits Solved (2025): Scientists finally identified the genes responsible for all seven of Mendel’s traits in a 2025 Nature study.
Next-Generation Sequencing: Researchers sequenced DNA from 697 pea variants, generating 60 terabases of genetic data.
Additional Allelic Variants: New alleles were discovered even for well-known traits like flower colour.
Pod Colour Gene Identified: A deletion near the ChlG gene causes yellow pod colour by affecting chlorophyll synthesis.
Pod Shape Genetics: Variants near MYB and CLE-peptide genes were linked to the constricted pod trait.
Flower Position Gene: A deletion near the CIK-like-coreceptor-kinase gene determines the flower position on the stem.
Pisum Genus Complexity: Genetic analysis revealed 8 groups within 4 known species due to admixture and hybridization.
Beyond Mendel’s Traits: The study revealed 72 agriculturally important traits including seed and root architecture.
Future Applications: Findings can boost crop yield, disease resistance, and environmental adaptation strategies.
Legacy of Mendel: Mendel's simple curiosity has led to breakthroughs in plant genetics and biotechnology today.