Possible origin of ratoon stunting disease following interspecific hybridization of Saccharum species

Abstract

Ratoon stunting disease (RSD) is the most economically significant disease of sugarcane, and, although it was first discovered in 1945, surprisingly little is understood of the nature of the relationship between the host and the pathogen, Leifsonia xyli subsp. xyli. This review traces RSD to the release of modern commercial hybrids, and provides evidence that Saccharum officinarum, the major progenitor of modern sugarcane cultivars, is not the natural host for L. xyli subsp. xyli. Rather, it is proposed that the wild relative, S. spontaneum, is more likely to be the original host, and that L. xyli subsp. xyli was acquired during interspecific hybridization work undertaken in Java during the 1920s. The release of the universally adopted variety POJ2878 then facilitated the dissemination of a single, worldwide clone of L. xyli subsp. xyli. The implications of the hypothesis are discussed in relation to plant improvement and the potential for new diseases to emerge through further attempts at broadening the genetic base of commercial sugarcane.