A University of Kentucky research team led by Dr. George Wagner, department of agronomy - UK College of Agriculture, has demonstrated the feasibility of specifically modifying the natural chemicals which are secreted on the leaf surface of plants. This exciting development, a first in the field of plant biotechnology, has potential applications in the development of crop plants with improved insect and disease resistance, and in the production of new materials via "molecular farming."

Glandular hairs on the surface of the leaves of many plants, called trichomes, produce exudated substances that are thought to provide a defense against microbes, insects, and herbivores. In a research article published in the April issue of Nature Biotechnology, Dr. George Wagner, Dr. Susheng Gan, Dr. Erming Wang and colleagues describe the development of novel tobacco plants with a specific alteration in a key step in the formation of this leaf "exudate."

By altering the expression of a gene encoding one of the enzymes responsible for the biosynthesis of surface diterpenes, the researchers produced plants with changed exudate composition. These plants exhibited reduced attack by aphids, confirming that constituents of the exudate play an important role in protecting the plant against insect damage.

"We have shown that modifying the chemistry of massive trichome exudate accumulation in a plant can significantly enhance natural- product-based, aphid-exudate interactions," said Wagner. "Our results suggest that metabolic engineering of trichome glands, together with the massive accumulation potential of this specialized tissue, may be exploited to develop a new production route for useful natural products. Through collaborations with Dr. Gan's laboratory and other research groups at UK and elsewhere, we are further exploring the potential of this remarkable leaf-surface system."

This research was funded in part by the tobacco biotechnology program of the UK Tobacco and Health Research Institute (THRI).

"THRI is privileged to contribute funding to Drs. Wagner and Gan in support of this entirely novel application of biotechnology to the leaf surface." said Dr. Maelor Davies, Director of THRI. "We are excited at the potential of the technology to add value to molecular farming strategies, thereby increasing the economic appeal of plants as large-scale production systems for useful natural products. We hope that this will facilitate the commercialization of novel tobacco and other plants producing new materials, thereby helping to create new markets for growers."