Scientists finally solve the 160-year-old problem of Mendel’s peas, Pg9

Scientists have finally resolved the mystery behind four of the seven pea plant traits that Gregor Mendel studied in the 1800s but did not fully explain at the genetic level.

• Mendel’s experiments showed dominant vs recessive inheritance patterns, but four traits remained genetically uncharacterised.

• A 2025 study (Nature, April) identified the genes responsible for pod colour, pod shape, flower position, and flower colour, completing the genetic explanation behind all seven classic Mendelian traits.

Detailed Insights:

• Mendel’s Unexplained Traits:

  • Mendel observed clear dominance (e.g., round vs wrinkled seeds) but could not explain the molecular basis.

    • The recent study decoded the DNA of 687 pea plant variants, sequencing their full genomes using next-generation techniques, analysing nearly 11 billion base pairs.

  • Major Discoveries:

    1. Yellow vs green pod colour: Identified a gene called CHLP responsible for chlorophyll production. Its deletion causes yellow pods.

    2. Flower position: Traced to a mutation in CLE-like-coreceptor-kinase gene, controlling inflorescence structure.

    3. Pod shape and flower colour: Explained through complex gene clusters and promoter–enhancer interactions.

  • Implication of Gene Clusters:

    • Many of the traits Mendel treated as single-gene based actually involve multiple gene interactions.

    • Suggests Mendel’s traits were simplified expressions of a more complex genetic architecture.

  • Genomic Tools and Impact:

    • This breakthrough was enabled by whole genome sequencing, high-throughput allele analysis, and AI-based mapping tools.

    • Paves the way for better plant breeding, especially in legumes, and informs yield prediction, resistance traits, and flowering control.

Mains Mock Question:

Mendel’s experiments laid the foundation of modern genetics. Discuss how recent advancements in genomics have enhanced our understanding of classical Mendelian traits and their implications for agricultural biotechnology.