Transposable elements (TEs), also known as jumping genes, are DNA sequences that can move from one position to another within the genome. Their movement can cause changes in the DNA sequence, leading to genetic variation in plants.
How transposable elements work
Transposable elements move around the genome using enzymes they produce themselves.
There are two main types:
- Retrotransposons – move by copying themselves through an RNA intermediate (copy and paste).
- DNA transposons – move directly from one place to another (cut and paste).
How they affect genetic variation
- Gene disruption – When a TE inserts into a gene, it can change or stop the gene’s normal function, creating new traits.
- Altered gene expression – If a TE inserts near a gene, it can affect how strongly that gene is expressed, either increasing or reducing its activity.
- Chromosomal rearrangements – Movement of TEs can cause deletions, duplications, or inversions in chromosomes, changing the plant’s genetic makeup.
- Creation of new genes – Sometimes, pieces of TEs combine with normal genes, forming new genes with new functions.
- Increased genome size – Repeated copying of TEs adds more DNA to the genome, which can affect genome evolution.
Examples in plants
- In maize (corn), Barbara McClintock discovered transposable elements that change kernel color by disrupting pigment genes.
- In rice and wheat, TEs contribute to genetic diversity and adaptation to different environments.
Importance
- Transposable elements are a major source of natural genetic variation.
- They help plants adapt to stress and evolve new traits.
- In plant breeding, they can be useful tools for gene tagging and genome studies.
Summary
Transposable elements create genetic variation in plants by moving within the genome, altering genes, and changing gene expression. Their activity contributes to plant evolution, diversity, and adaptation.