Development of disease-resistant CP sugarcane cultivars in Florida

Authors: Sood, Sushma; DAVIDSON, WAYNE - Florida Sugarcane League; COMSTOCK, JACK - Retired ARS Employee; Gordon, Vanessa; Islam, Md; BALTAZAR, MIGUEL - Florida Sugarcane League; SANDHU, HARDEV - University Of Florida; Zhao, Duli

Submitted to: International Society of Sugar Cane Technologists Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2019
Publication Date: 8/30/2019
Citation: Sood, S.G., Davidson, W.R., Comstock, J.C., Gordon, V.S., Islam, M.S., Baltazar, M., Sandhu, H., Zhao, D. 2019. Development of disease-resistant CP sugarcane cultivars in Florida. International Society of Sugar Cane Technologists Proceedings. 30, 1882-1887, 2019.

Interpretive Summary: Ratoon stunt (RSD), leaf scald, mosaic, smut, brown rust and orange rust are economically important diseases in Florida. Screening varieties for appropriate resistance/tolerance to these diseases is an important selection criterion in the Canal Point Sugarcane Cultivar Development Program (CP program). The objective of this study is to evaluate the criteria and procedures for the selection of the disease resistant cultivars in the CP program. Selection of clones for disease resistance in different stages of the CP program rely on both natural infections and artificial inoculations. Selections of disease resistant clones in seedlings, first (Stage 1) and second (Stage 2) clonal stages are completely based on natural infection. Moreover, Stage 2 has disease spreader plots and rows for the above-mentioned diseases. Clones in Stage 2 are also evaluated for the presence of Bru1 gene. Artificial inoculations begin in the third clonal stage (Stage 3 consists 135 clones each for muck and sand soils) for RSD, brown and orange rust. Screenings for eye spot, leaf scald, mosaic, and smut begin in the final year of Stage 3 (40 clones for each soil) and continued on all clones in Stage 4 (13 clones for each soil). Selections of resistant clones in Primary and Secondary increases are based on three to five years of artificial inoculation and natural infection data; clones in these stages are also evaluated for natural infection of RSD and yellow leaf. Although results reveal that there is continuous increase of disease resistant clones in different stages of the CP program but to enhance it further, populations were characterized for diseases and identified markers associated with disease resistance, these markers will be incorporated in the future selection process. The CP program continuously monitor disease status of its new cultivars and breed for improved disease resistance and tolerance while maintaining high yields.

Technical Abstract: The Canal Point Sugarcane Cultivar Development Program (CP program) continuously monitors the disease status of its new cultivars and strives to breed for improved disease resistance and tolerance while maintaining high yields. Ratoon stunting disease (RSD), leaf scald, mosaic, smut, brown rust, and orange rust are economically important sugarcane diseases in Florida. Screening clones for appropriate resistance/tolerance to these diseases is a decisive selection criterion in the CP program. We evaluate the criteria and procedures for the selection of the disease-resistant cultivars in the CP program. In 2011, the CP program integrated two independent selection programs, which are managed in similar fashions: one on muck soil and one on sand soil. Selections of clones for disease resistance rely on both natural infection and artificial inoculation throughout the progressive CP program stages. Natural infection is used to screen and select for disease resistance in the seedling, first (Stage 1), and second (Stage 2) clonal stages. Stage 2 clones are also evaluated for the presence of the Bru1 gene. Artificial disease inoculations for RSD, brown rust, and orange rust begin in the third clonal stage (Stage 3 – consisting of 135 clones each for muck and sand soils). Screenings for leaf scald, mosaic, and smut begin in the Stage 3 increase (40 clones for each soil type) and continue across all clones in Stage 4 (13 clones for each soil type). Selections of resistant clones in primary and secondary seed-increases are based upon 3-5 years of artificial inoculation and natural infection data, as well as evaluation for natural infection of RSD and yellow leaf virus. Although results reveal a continuous increase of disease-resistant clones in the different CP program stages, populations were characterized for diseases to identify markers associated with disease resistance. These markers will be incorporated to augment future selection processes.