R Genes - The Natural Arsenal of Plants and their Role in Plant-Pathogen Interactions

Efforts have been on for several years now in introgressing disease-resistant genes into elite cultivars through conventional breeding. With the rapid strides made in the development of transgenic plants as well as in the understanding of disease resistance at the molecular level, it is now possible to devise more efficient strategies for the development of disease-resistant varieties. An attempt has been made in this article to describe the advances made in the basic understanding of plant disease resistance genes (R genes) – the plant's natural arsenal against pathogens – and discuss the application of this knowledge towards enhancing disease resistance in crops. A number of R genes have been cloned and characterized in terms of their structure and function. The models proposed for interactions of R proteins and Avr proteins have now been supported by adequate molecular evidence. Both host and non-host resistance R genes have been used to engineer disease resistance in crop plants. Although our current knowledge on molecular basis of plant-pathogen interactions is only fragmentary, given the advances being made, it is reasonable to expect that in the years to come, we would be able to devise suitable strategies that will provide effective and eco-friendly protection against plant diseases.