|Hoy, Jeff - Louisiana State University|
|Veremis, John - Animal And Plant Health Inspection Service (APHIS)|
Submitted to: International Society of Sugar Cane Technologists Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/16/2009
Publication Date: 3/7/2010
Citation: Hale, A.L., Hoy, J., Veremis, J.C. 2010. Identification of sources of resistance to sugarcane red rot. In: Proceedings of International Society of Sugar Cane Technologists, ISSCT XXVII Congress, March 7-11, 2010, Veracruz, Mexico, 27:1-8.
Interpretive Summary: Red rot is a fungal disease that rots planted stalks of sugarcane. The fungus primarily enters stalks through cut surfaces, and then proceeds to damage the buds along the stalk from which the new crop develops. Red rot can cause yield reductions and even complete stand failures. The most effective way to control the disease is through the development of resistant varieties. Unfortunately, genes for resistance are not plentiful in the current sugarcane genepool. However, there are other potential sources of resistance. In this study, several species of Erianthus, a group of grasses related to sugarcane, were screened in multiple years for their ability to resist infection by sugarcane red rot in comparison to a susceptible sugarcane variety. Stalks of these species were inoculated with the red rot causal fungus and subsequently evaluated for their disease response. Varieties within the Erianthus genus showed near complete resistance to the disease. In addition, some varieties from within the more closely related species, Saccharum spontaneum and S. barberi, were identified as possessing resistance. Varieties which showed stable resistance over multiple years should be considered as potential sources of genes for resistance to the disease. The Erianthus genus possesses high resistance and should be used as parental material in breeding programs where enhanced red rot resistance is needed. Other more easily utilized sources of resistance to red rot within the Saccharum germplasm are selected S. spontaneum and S. barberi accessions.
Technical Abstract: Red rot, caused by Colletotrichum falcatum, adversely affects sugarcane stand establishment in Louisiana by rotting planted stalks. Since cultivar resistance is the most effective control method, a study was conducted to identify sources of resistance to red rot and evaluate variability within Saccharum species and Erianthus. Saccharum spontaneum, S. robostum, S. sinense, S. officinarum, S. barberi, and Erianthus clonal accessions were evaluated for resistance alongside susceptible commercial cultivars in three experiments. Harvested stalks were inoculated with C. falcatum. Following a 6-week incubation, each stalk was split and rated for red rot symptoms including number of nodes passed (NP), number of nodes rotted (NR), internode rot severity (IRS), and a rot index (RI). Significant differences were detected among species and accessions within species for all traits. Among the Saccharum species, S. barberi, S. robustum and S. spontaneum exhibited the lowest red rot symptom severity means, while S. officinarum and S. sinense had the highest severity means. A high level of variation was observed within S. spontaneum with RI means ranging from two to 29. Three of 31 accessions (10%) had an NR mean less than 5, and 26% had a mean less than 10. S. barberi exhibited a high level of resistance, with RI means ranging from one to 20. Four of 14 accessions (29%) had an RI mean of less than 5, and six (43%) had a mean of 10 or less. The least amount of variation was seen among the Erianthus accessions, with all showing little, if any, red rot symptoms. The Erianthus genus possesses high resistance and should be used as parental material in breeding programs where enhanced red rot resistance is needed. Other more easily utilized sources of resistance to red rot within the Saccharum germplasm are selected S. spontaneum and S. barberi accessions.