Source: Max Planck Institute for Chemical Ecology, newsletter July 06

Volatiles modulate the development of plant pathogenic rust fungi.
Kurt Mendgen, Stefan G. R. Wirsel, Andreas Jux, Jochen Hoffmann, Wilhelm Boland (2006).
Planta, DOI 10.1007/s00425-006-0320-2.

ABSTRACT

Rust fungi are obligate biotrophic pathogens that differentiate a series of specialized cells to establish infection. One of these cell types, the haustorium, which serves to absorb nutrients from living host cells, normally develops only in planta. Scientists from the university of Konstanz as well as from the Max Planck Institute for Chemical Ecolgy now showed that the rust fungus Uromyces fabae (Pers.) Schroet. stimulates volatile emission of its host, broad bean (Vicia faba L.). Volatiles were identified and shown to be perceived by the fungus in in vitro assays that excluded the host. Three of them, nonanal, decanal, and hexenyl acetate promoted the development of haustoria on artificial membranes. In contrast, the terpenoid farnesyl acetate suppressed this differentiation. In assays using whole plants, farnesyl acetate reduced rust disease not only on broad bean but also on several cereals and legumes including soybean. This natural substance was effective against all rusts tested when directly applied to the host. This demonstrated that farnesyl acetate may serve as a powerful novel agent to combat rust fungi including Phakopsora pachyrhizi that currently threatens the production of soybeans worldwide.