The TrichOME is part of an integrated NSF funded project, entitled: "Comparative genomics of secretory trichomes – biofactories for production of plant secondary metabolites" (#0605033).
Collectively, plants are a rich source of natural products, chemicals that often function to protect the plant from infection or insect pests. Natural products also form the basis of many currently used drugs, such as aspirin, morphine, taxol or the antimalarial compound artemesinin. Plant natural products are often synthesized and accumulated in secretory trichomes, which are epidermal appendages found on the aerial organs of many plants. Trichomes have a unique capacity for chemical synthesis and secretion, and have been described as biofactories for the production of natural products. However, with few exceptions, little is known about the molecular aspects of trichome metabolism and secretion. Many trichome-specifically expressed genes are probably poorly represented in the whole organ cDNA libraries which constitute the basis of most existing plant EST databases. Therefore, TrichOME will be an important addition to plant genome sequence information, as genes only expressed in trichomes may be under-represented in non-tissue-targeted EST sequencing projects.
The production of many natural products in specialized trichome cells facilitates genomics-based approaches to characterize biosynthetic and secretory processes. In this project, a large number of expressed sequence tags (ESTs) will be generated corresponding to genes expressed in trichomes of five species representing different plant families and both model and crop plants; Medicago truncatula and M. sativa (alfalfa), Leguminosae; Nicotiana benthamiana and Lycopersicum esculentum (cultivated tomato), Solanaceae; and hops (Humulus lupulus), Cannabaceae. Potato leafhopper resistant and susceptible alfalfa lines will also be compared. The study will allow comparisons between paired species from the same plant family but with very different trichome chemistries.
The project is multidisciplinary, combining genomics, informatics and molecular biology with analytical biochemistry, enzymology, and metabolic engineering. The EST and "omics" data generated from the project will be mined for genes involved in the regulation, biosynthesis and transport of natural products, and the functions of a selection of those genes that are common to multiple species will be determined by over- or under-expressing them in Arabidopsis thaliana. At the same time, the full spectrum of natural products produced in the trichomes of studied species will be determined.