MicroRNAs (miRNAs) are very small RNA molecules found in plants (and animals) that do not code for proteins, but instead help control gene expression.
They are usually about 21–24 nucleotides long and act as regulators that decide how much of a certain protein should be made in a cell.
Here’s how they work in plants:
- Formation of microRNAs
miRNAs are produced from special genes called miRNA genes. These genes are copied into longer RNA molecules that fold into a hairpin shape. Enzymes then cut them into short miRNA pieces. - Binding to messenger RNA (mRNA)
The mature miRNA attaches to specific messenger RNAs that carry genetic instructions for making proteins. - Blocking protein production
When the miRNA binds to its target mRNA, it can either:- Break down the mRNA so it cannot be used, or
- Block translation, preventing the ribosome from making the protein.
- Role in plant functions
In plants, microRNAs help regulate many important processes such as:- Growth and development (leaf shape, root formation, flower timing)
- Hormone signaling (auxins, gibberellins)
- Stress responses (drought, salinity, and pathogens)
- Nutrient balance (like nitrogen and phosphate levels)
In short, microRNAs act as gene silencers that fine-tune how much protein is made from specific genes. This helps plants grow properly and respond quickly to changes in their environment.