|Hoy, Jeffrey - LSU Agcenter|
Submitted to: American Phytopathological Society Press
Publication Type: Book / Chapter
Publication Acceptance Date: 10/12/2016
Publication Date: 1/1/2017
Citation: Grisham, M.P., Hoy, J.W. 2017. Detection of Leifsonia xyli subsp. xyli in sugarcane. In: Fatmi, M’Barek, Walcott, Ron R., Shaad, Norman W. editors. Detection of Plant-Pathogenic Bacteria in Seed and Other Planting Material, Second Edition. St. Paul, MN:American Phytopathological Society Press. p. 331-336.
Technical Abstract: Ratoon stunt, caused by the xylem-limited bacterium Leifsonia xyli subsp. xyli (Lxx), is arguably the most important disease of sugarcane worldwide. The primary effect of ratoon stunt is a mild to severe reduction in growth that typically becomes more severe in ratoon crops. Because infection of a plant with Lxx does not produce a characteristic external symptom, visual inspection of a sugarcane field is not sufficient to recognize the presence of the disease. The disease is managed primarily through programs to provide pathogen-free vegetative planting material which depends on laboratory-based protocols for pathogen diagnosis in seed-cane. Diagnostic protocols vary in the ease-of-use, cost, required technical expertise, equipment and expendable supplies, and sensitivity. The choice of the most effective or efficient protocol will differ depending on factors including plant growth stage, the stage of seed-cane production, sensitivity required, and number of samples to be tested. Two detection protocols, tissue-blot enzyme-immunoassay (TB-EIA) and quantitative, real-time polymerase chain reaction (PCR), are presented this chapter. Among immunoassay techniques, TB-EIA provides an accurate protocol for detecting Lxx in maturing stalks where titer of the bacterium is high. An added benefit of TB-IEA is that it also provides a quantitative comparison of infection level in stalks based on the number of vascular bundles colonized by the bacterium. Real-time PCR provides a detection technique for situations when greater sensitivity is needed, for example, when young plants in which the bacterial titer is low must be tested or when a high level of assurance is needed that the test plants are pathogen free as in quarantine situations.