Genes involved in plant defence mechanisms


Historically, pathogen infection and insect infestation of staple crops have led to food shortages and considerable economic losses. Resistant varieties have, therefore, been developed by plant breeders for a number of years to reduce such losses, but pathogens are eventually able to overcome this resistance. Many pesticides have been developed to combat crop losses, with the consequence that plant disease control has become heavily dependent on these compounds. Yet the use of pesticides has also resulted in significant costs to public health and the environment. Plant biotechnology (gene isolation and plant transformation techniques), together with conventional breeding programmes, could make significant contributions to sustainable agriculture. In this regard, there has been intensive research in agricultural biotechnology aimed at plant protection. This section will describe the main defence-related mechanisms that plants display to cope with pathogen infection. Subsequently, the current status of the genes identified for resistance against virus, fungi, insects and nematodes, with an emphasis on their role in resistance to pathogens in transgenic plants, will be discussed. Reference will be made to the use of species of Trichoderma as a biological control agent.