Genes in the defence against fungi

Fungal diseases have been one of the main causes of crop losses for years. Control of fungal diseases has traditionally involved three strategies: husbandry techniques, such as crop rotation and confinement of contaminated soil and plant material, breeding of resistant crop cultivars and application of fungicides. Although conventional plant breeding has made a significant impact by improving crop resistance to many important diseases, it still requires extended periods of time to develop a new variety and there may not be any natural sources of resistance to major diseases available to the breeder (Oerke 1994). In modern agriculture farmers employ a variety of fungicides, but their use is being restricted because of their high costs and growing concerns about the degradation of the environment. Furthermore, the excessive use of fungicides frequently results in the development of resistant fungal strains.

The advent of advanced molecular techniques for plant breeding has allowed the development of crops resistant to a number of fungal pathogens. There have been mainly two approaches to generate broad-spectrum, fungal-resistant crops: one relies on the overexpression of genes encoding antifungal proteins (AFP) and the other aims to enhance pathogen perception, by manipulation of certain pathogen and plant R genes.