Prospects for a genetic solution to the management of ratoon stunting disease

Ratoon stunting disease (RSD,) caused by a bacterium (Leifsonia xyli subsp. xyli), is one of the most important diseases of sugarcane in Australia. RSD is an inconspicuous and highly infectious disease and can spread unnoticed causing significant yield loss across entire regions and industries. Developing varieties with resistance to RSD has been proposed at different times as a possible solution. This paper provides a review of the resistance status of the sugarcane germplasm, the effective range in reactions to the disease, and the efficacy of current practices used for RSD management. Examination of the Australian germplasm and historical resistance records show that material with effective RSD resistance has never been identified. Published literature has occasionally suggested that there are resistant varieties/clones, but these putative sources of resistance have failed to demonstrate commercially-effective disease control. Currently, there are no validated sources of resistance available to be used as parents in the breeding program. Evidence from overseas and Australia demonstrates that RSD can be successfully managed through disease-free planting material and farm hygiene. A genetic solution for RSD may only be considered if an effective source of resistance can be identified and validated. Key words Ratoon stunting disease, RSD, Leifsonia xyli subsp. xyli, resistance screening , sugarcane