Researchers from Michigan State University (MSU) have discovered that a wild tomato variety, the Solanum pennellii, native to the Atacama desert in Peru, produces a sticky compound on the tips of its trichomes (hairs) that gives them protection against pests.
The sticky substance on the hairs of the plant repels insects, and probably evolved as a defense mechanism to ensure reproduction and future survival. For the study, the researchers analyzed this enzyme compound and the genes responsible for its production.
The finding could allow breeders to reintroduce the enzyme into garden tomatoes and create natural plants resistant to insects.
To analyze the specific genes and signaling pathways responsible for the compound, the research team used cutting-edge genetic technology, including the CRISPR gene editing tool.
The analysis led to the discovery of the functions of the genes, metabolites and signaling pathways responsible for the production of the compound. With this information, the researchers identified an enzyme located specifically at the tips of the hairs, which allows the plant to create the sticky insect repellent.
The type of enzyme identified is known to regulate many aspects of the plants' growth and development, but in the specific case of this wild tomato variety, the enzyme evolved to facilitate the production of new insecticidal compounds.
The reason why garden tomatoes lack this natural insecticide is because it was eliminated by breeders who, in order to improve tomatoes for consumers, eliminated undesirable traits, such as stickiness.
This discovery represents a step towards understanding the natural resistance to insects of Solanum pennellii plants.