Location: Sugarcane Field Station2016 Annual Report
1a. Objectives (from AD-416):
1. Optimize assessment technologies for evaluating sugarcane disease resistance. 2. Characterize biological and molecular variation of endemic and emerging sugarcane pathogens. 3. Evaluate sugarcane and energy cane clones to identify resistant germplasm to diseases that are economically important and threatening in the varietal development programs. 4. Identify parental clones and characterize populations that will enhance the development of resistant cultivars for commercial release.
1b. Approach (from AD-416):
1. For brown rust, seedlings of three crosses that vary in the proportion of brown rust susceptible progeny will be in inoculation experiments to evaluate conditions that have promoted infection using older plants. 2. Sentinel plots of susceptible cultivars that were previously rated resistant and resistant commercial cultivars will be planted with two replications in each of the ten Stage IV locations annually (the test has a three crop cycle). Spores will be collected separately from each variety of this test and inoculated to a duplicate set of standard cultivars (of all cultivars that spores were collected from plus B4362). Differences in rust reaction based on sporulation between the isolates on each cultivar will be recorded and verified by repeating the inoculation test. For orange rust, similar experiments as described above will be conducted once handling procedures are developed that eliminate problems with spore viability. For other diseases/pathogens, clones will be surveyed at two month intervals on the Sugarcane Field Station and in 6 growers’ fields for outbreaks of both exotic and endemic diseases. Once something new is suspected the pathogen (pathogenic race) will be identified and similar experiments as that described for brown rust above will be conducted. 3. Sugarcane clones in the cultivar development programs for sucrose and bio-energy will be screened for their disease reactions to the major pathogens in artificial inoculation tests and ratings will be determined based on incidence and severity of disease. 4. Sugarcane progeny of selected families, parental clones in the Canal Point (CP) Cultivar Development Program and clones in other populations will be inoculated using standard procedures and disease resistant individuals will be identified.
3. Progress Report:
Economic losses are caused by sugarcane diseases; thus, the CP Cultivar Development Program screens its germplasm for resistance. Data are obtained in natural infection and inoculated trials ensuring only resistant clones are advanced and released from the program. Because pathogenic changes occur over time, developing resistance is continuous in the program. Resistant cultivars were released last year.
1. The Cultivar Development Program requires the elimination of susceptible clones. Thus, all susceptible clones in the seedling, Stage I and Stage II are eliminated if exhibiting disease symptoms based on natural infection. In the Cultivar Development Program clones in both the muck and sand programs were screened in inoculation tests at Stage III (135), Stage III increase (40) and Stage IV (13) for their disease reactions to ratoon stunt, smut, brown rust, orange rust, leaf scald and mosaic. All clones with unacceptable susceptibility levels were discarded. A total of eight clones were released (1 for both muck and sand soils, 2 for muck only and 5 for sand only). These resistant cultivars will allow Florida sugarcane growers to continue to economically grow sugarcane and produce approximately 20% of the sugar consumed in the United States and provide growers an effective means of controlling diseases.
2. Sugarcane yellow leaf disease is caused by Sugar Cane Yellow Leaf Virus and aphids transmit the virus. Unfortunately, there is not an efficient screening method to determine resistance consequently a molecular marker for resistance will be most beneficial. A typical population (X02-724) has been evaluated for its yellow leaf reaction for 4 years based on natural field exposure to infection. The phenotypic disease data obtained from this segregating population are important for future marker development.
5. Significant Activities that Support Special Target Populations:
Comstock, J.C., Ovalle, W., Chavarria, E., Glynn, N.C., Castlebury, L.A., Raid, R.N., Orozco, H. 2015. La Roya naranja de la caña de azúcar, una enfermedad emergente: su impacto y comparación con la roya marrón English Translation: Orange rust of sugarcane, an emerging disease: its impact and comparison to brown rust. Ciencia y Tecnologia de los Cultivos Industriales INTA. pp. 12-21.
Sandhu, H.S., Gilbert, R.A., Comstock, J.C., Gordon, V.S., Korndorfer, P., El-Hout, N., Arundale, R. 2016. Registration of ‘UFCP 82-1655’ Sugarcane. Journal of Plant Registrations. 10(1):22-27. doi: 10.3198/jpr2014.10.0074crc
Song, J., Yang, X., Resende, M., Neves, L.G., Todd, J.R., Zhang, J., Comstock, J.C., Wang, J. 2016. Natural allelic variations in highly polyploidy Saccharum complex. Frontiers in Plant Science. 7:804. DOI: 10.3389/fpls.2016.00804.
Gordon, V.S., Comstock, J.C., Sandhu, H.H., Gilbert, R.A., Korndorfer, P., El-Hout, N., Arundale, R., Sood, S.G. 2016. Registration of 'UFCP 87-0053' sugarcane for use as a biofuel feedstock. Journal of Plant Registrations. 10:258-264.
Espinoza Delgado, H., Kaye, C., Hincapie, M., Boukari, W., Wei, C., Fernandez, J., Mollov, D.S., Comstock, J., Rott, P. 2015. First report of Sugarcane yellow leaf virus infecting Columbus Grass (Sorghum almum) in Florida. Plant Disease. 100:1027.
Mollov, D.S., Tahir, M., Wei, C., Kaye, C., Lockhart, B., Comstock, J., Rott, P. 2016. First report of Sugarcane mosaic virus infecting Columbus Grass (Sorghum almum) in the United States. Plant Disease. 100:1510.