Genetics of Plant Resistance to Bacterial Wilt: Round Table Report

Abstract

Although an increasing body of knowledge exists concerning the molecular mechanisms of pathogenicity in Ralstonia solanacearum, as witnessed in various presentations at this meeting, very little is known about the nature of host plant resistance at the molecular level. Since host resistance is agronomically very important, much work has already been done by several groups over the course of many years to identify of sources of resistance in different crop plants, and to breed resistant varieties in different geographic locations. However, resistance loci have been mapped in only in a few cases to date under very limited environmental conditions, in two varieties of tomato and one ecotype of the model plant Arabidopsis. Several people communicated their experiences concerning the influence of environmental factors, on the expression of resistance of different lines to attack by R. solanacearum. These include bacterial strains present, daylength, plant physiology and temperature. The use of molecular markers for genetic analyses of appropriate populations can be of fundamental and practical value, for example for (1) identification and mapping of resistance loci, (2) estimating the size and genetic nature of the resistance effect, (3) estimating the effects of the environment on the individual loci (e.g. bacterial strain, cultural conditions), (4) introgression of useful resistance traits into new varieties in breeding programmes, and (5) providing a future basis for map-based cloning of resistance genes.