In a breakthrough study, researchers at the Indian Institute of Science (IISc) have uncovered the mystery behind how lac insects create a vibrant pigment known as laccaic acid, commonly used in food coloring, textiles, and art.
For many years, scientists were puzzled about how these insects, which feed on the sap of specific trees, produced this bright red compound without any clear genetic evidence in their DNA. The lac insect, which is known for secreting a sticky resin called shellac, has been an important source of the lac pigment in India for thousands of years.
The research team made a surprising discovery: the pigment is actually produced by a yeast-like organism that lives within the lac insect. This organism carries the genes necessary for synthesizing laccaic acid, which the insect itself cannot produce.
Dr. Shantanu Shukla, an assistant professor in the Department of Developmental Biology and Genetics at IISc, explained, “Laccaic acid production was a significant puzzle. Our findings show that the insect relies on this symbiotic organism to acquire crucial components needed for the pigment’s synthesis.”
One essential ingredient for making laccaic acid is an amino acid called tyrosine, which the lac insect cannot obtain from its diet of tree sap. Typically, insects depend on symbiotic bacteria or fungi for such missing nutrients. The research team sequenced the entire microbiome of the lac insect and identified two key candidates: a type of bacterium from the Wolbachia genus and the yeast-like fungus.
While previous studies hinted at the existence of the fungus, this research is groundbreaking because it has successfully identified and sequenced its genome. The team found that only the yeast-like organism carried the entire set of genes required for the production of laccaic acid. This includes genes that code for specific enzymes needed to create aromatic compounds, which are the building blocks of the pigment.
Interestingly, this yeast-like fungus resides inside the insect’s egg cells. It circulates in the insect’s blood-like fluid and attaches itself to the egg cells as they mature, ensuring its survival through generations.
This discovery not only clarifies the process behind the production of a significant natural pigment but also highlights the sophisticated relationships between insects and their symbiotic partners. As India continues to be a leading producer of lac pigment, this research could have important implications for future production and the understanding of ecological relationships.
-Rashmi kumari
