The bacterial pathogen Xanthomonas oryzae pathovar oryzae causes a ser
ious disease of rice. Over the last decade, considerable progress has
been made in the application of the techniques of genetics and molecul
ar biology towards understanding the rice-Xanthomonas interaction. Sev
eral interesting pathogen genes for virulence and avirulence have been
cloned. DNA fingerprinting studies have provided information about th
e genetic diversity within populations of this pathogen. A number of r
ice genes that confer resistance against X. oryzae pv. oryzae have bee
n tagged with closely linked molecular markers. Rice breeding lines wi
th multiple resistance genes have been obtained by using these markers
. The sequence of one of these genes suggests that it encodes a putati
ve receptor kinase which recognizes an elicitor produced by the pathog
en and initiates a signal transduction cascade. that ultimately result
s in resistance.