Rare amber reveals Sal tree hasn’t changed much in 17 million years

Researchers said the biomolecules called terpenoids that were preserved in amber are produced and used by plants to interact with its immediate biotic environment

In a first, Indian scientists discovered unaltered biomolecules from a 17-million-year-old amber from a sedimentary rock in Mizoram. The amber, a fossilised resin, was produced by a sal tree which is found in India and Southeast Asia.

The study led by IIT-B along with the Birbal Sahni Institute of Palaeosciences, Lucknow and Mizoram University, was published in Scientific Reports on Friday.

“In geological samples, biomolecules in old amber become impermeable with time. But this is an exceptional preservation because all biomolecules were intact, as they were protected against oxidation and decomposition,” said lead investigator Suryendu Dutta, associate professor, department of earth sciences, Indian Institute of Technology – Bombay (IITB). “Amber with biomolecules that have stayed intact for 17 million years has never been reported.”

Researchers said the biomolecules called terpenoids that were preserved in amber are produced and used by plants to interact with its immediate biotic environment. These molecules, through their aroma, protect plants when attacked by herbivores, insects or pathogens by repelling them. The aromas of some molecules also attract pollinators.

“We found that the biomolecules, used by the modern species of this tree family, are the same as the 17-million-year-old amber. It is evident from this study that the tree family had evolved the biosynthetic mechanisms to produce these volatile molecules in geological deep-time. The significance of this study is that biomolecules can be preserved for a very long time in geological samples in rocks,” said Dutta.

The study led by IIT-B along with the Birbal Sahni Institute of Palaeosciences, Lucknow and Mizoram University, was published in Scientific Reports on Friday.

Studies have shown that plants can talk to each other. “Some of the compounds present in this amber sample signifies or suggests that this plant family also communicated with each other,” said researchers.

The team said the research work offers a new approach to unravel the geological evolution of chemically-mediated interactions between plants and their immediate biotic environment.