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ARS Home » Southeast Area » Canal Point, Florida » Sugarcane Field Station » Research » Research Project #432517

Research Project: Identification of Resistant Germplasm and Markers Associated with Resistance to Major Diseases of Sugarcane

Location: Sugarcane Field Station

Project Number: 6030-22000-011-00-D
Project Type: In-House Appropriated

Start Date: Mar 20, 2017
End Date: Mar 19, 2022

Objective:
1. Identify disease resistant sugarcane and energy cane clones for high yielding commercial production. 2. Develop methodologies to efficiently screen germplasm for resistance and to identify new molecular markers associated with resistance. 3. Identify pathogenic variation in sugarcane pathogens that are endemic and emerging within the United States.

Approach:
Objective 1: Sugarcane clones in the cultivar development program for both sucrose and bio-energy will be screened for their disease reaction in artificial inoculation tests separate from the cultivar development plots with the major pathogens and ratings will be determined based on incidence and severity of disease. Objective 2: For Sugarcane Yellowleaf Virus (SCYLV) existing markers will be tested against our known historical clones having both resistance and susceptible reaction. Two new populations will be screened for SCYLV resistance and genotyping by sequencing (GBS) to identify new markers. For ratoon stunt disease and smut two populations will be screened for disease reaction and GBS to identify markers. For orange rust we will test published markers and perform fine mapping using a larger population and whole genome sequencing of the parents and bulked progeny to identify markers for screening the whole population. Objective 3: Orange rust spores have been collected over the last two years from different cultivars and locations in Florida and stored for determining possible pathogenic variation. Specifically, cultivars CP 80-1743 (the susceptible cultivar first observed with orange rust in Florida), CL 85-1040 (susceptible) and two cultivars CP 88-1762 and CP 89-2143 that were originally resistant but became susceptible will be used to evaluate pathogenic variation. The whorl inoculation technique (Sood et al. 2009) that is routinely used to evaluate brown and orange rust reactions will be used to evaluate variation between the isolates. The whorl technique has been shown to give consistent results, as seen by the sample data in Table 2 of the Appendix. These will be used along with the new collections described. Sentinel plots of orange rust susceptible and resistant sugarcane cultivars will be planted at 5 different locations and from grower’s fields where the “breaking down” of resistance is reported. Fields will be observed monthly from March to July when orange rust is most prevalent. Orange rust pustules that develop on previously resistant cultivars will be collected and compared using the whorl inoculation techniques to isolate the collected spores from different cultivars differing in susceptibility over several years. Mass rust spore collections from the field will be inoculated on plants of the same cultivar twice as a means to help purify the isolate. Variation in symptom development of isolates on specific cultivars will be used to identify pathogenic differences. Unfortunately, pathogen variation will be limited to isolates from Florida because isolates from outside the state are prohibited from introduction.