Location: Sugarcane Field Station
2023 Annual Report
Objectives
1. Identify pathogenic variation in sugarcane pathogens that are endemic and emerging within the United States. 1. A: Identify variation in sugarcane pathogens that are endemic and detect emerging pathogens in Florida. 1. B: Characterization of endophytes of sugarcane during disease development. 2. Screen germplasms of sugarcane and related grasses for resistance to major diseases such as brown rust, orange rust, leaf scald, sugarcane mosaic, smut, and ratoon stunting diseases. 2. A: Screen sugarcane clones for brown rust, orange rust, leaf scald, sugarcane mosaic, smut, and ratoon stunting diseases. 2. B: Molecular approach to develop disease-resistant cultivars
Approach
Natural infections of sugarcane clones in Stage IV, small and large seed increases at ten commercial production locations across the sugarcane production region in FL will be surveyed in the spring and fall for all the economically important diseases. Unusual disease symptoms or disease outbreaks on previously disease-resistant cultivars will be investigated as possible emerging pathogens or new pathogenic races\strains of an endemic pathogen. Studies by light, confocal laser scanning microscope, or/and electron microscopy will be conducted to determine if there is any cytological structural difference in the interaction between orange rust race and host. Microbial diversity of a sugarcane variety susceptible to leaf scald and mosaic caused by Xanthomonas albilineans and Sugarcane mosaic virus, respectively. Sugarcane clones in the Stage 3 increase and Stage 4 of the Canal Point Sugarcane Cultivar Development Program will be screened for their reactions to leaf scald, mosaic, ratoon stunt, and smut diseases in artificial inoculation tests. Incidence of Sugarcane yellow leaf virus and ratoon stunt will be determined in the sugarcane clones of small and large seed increases to provide stakeholder status of these diseases in seed canes. Genome-wide markers for mapping genes controlling particular disease resistance in sugarcane will allow finding candidate resistance genes and gene variations. A database to select the reliable and low dosage SNPs for R-gene; SNP array development to realize high throughput genotyping of mapping populations for rapid identification of markers linked to disease resistance in sugarcane; identify haplotype variation associated with diseases (Brown and orange rust, Leaf scald, Smut, and Ratoon Stunting Disease) resistance.
Progress Report
Sugarcane is an economically important crop in Florida, generating 12,500 jobs with a positive impact of $3.3 billion in Florida’s economy. Florida produces more than 50% of the total sugar produced in the USA from sugarcane and about 20% of the total sugar produced in the USA from sugarcane and sugar beets. The USA produces only 2/3rd of the sugar that is consumed. Disease resistance plays an essential role in the success of the cultivars. A major disease can cause 10 to 60% yield losses in the susceptible cultivars under environmental stress on the host or favorable conditions for the pathogen and both. Emerging pathogens and pathogenic variability in endemic pathogens are threats to commercial cultivars.
Under Objective 1A, ARS researchers at Canal Point, Florida, evaluated the variation in leaf scald pathogen isolates by inoculation tests on three replications of a set of the cultivars CP 16-1488 (Highly Susceptible), CPCL 13-4079 (Susceptible), CP 80-1743 (moderately susceptible), CP13-1223 (moderately resistant) and CP 72-2086 (Resistant) by the decapitation method. We inoculated four-month-old plants with a bacterial suspension or water (for a negative control). Rated the disease after four weeks and continue until 12 weeks after inoculations. We surveyed for the new diseases in several fields throughout the sugarcane growing area.
Under Objective 1B cooperative plant–microbe interactions can promote the recruitment of beneficial microorganisms and limit the development of pathogens. Plant microbiota may thus constitute a key factor in addressing plant health challenges by predicting future plant defense and crop resistance. We planted a trial to test how the microbiota plays a role in leaf scald and mosaic disease development. We have inoculated the clones with sugarcane mosaic virus (strain E) and Xanthomonas albilineans. We will collect samples from leaves, stalks, and roots to evaluate difference in microbiome (fungal and bacterial) between control and inoculated plants.
In regard to Objective 2A, economic losses caused by brown and orange rusts, leaf scald, sugarcane mosaic virus, ratoon stunt disease (RSD), and smut are significant. Thus, the Canal Point Sugarcane Breeding and Cultivar Development Programs (CP programs) screen its germplasm for resistance to these diseases. ARS researchers obtained disease reaction data by natural infection and inoculated trials, ensuring that resistant or tolerant clones are advanced and released. Because pathogenic changes occur over time, selecting disease-resistant cultivars is an ongoing process in the CP programs. We obtained disease reaction data for clones in the Sucrose Cultivar Development Program for approximately 10,000 in Stage I, 1,500 in Stage II, 80 in Stage III increase (CP 19 Series), and 26 in Stage IV (CP 18 Series). Collected natural infection and inoculated trial data yearly to advance and release disease-resistant or tolerant clones from the program. We advanced and released high-yielding and disease-resistant or tolerant clones.
In regard to Objective 2B, sugarcane germplasm collections have great diversity and probably many valuable alleles for disease resistance. For breeders to use these germplasm accessions, it will be very informative to determine all the resistance gene and allele versions within the accessions of the sugarcane germplasm collections.
ARS researchers selected 150 CP breeding parental lines frequently used in the last ten years and 40 wild accessions and collected their DNA for further studies.
Accomplishments
1. Identify variations in sugarcane pathogens that are endemic and detect emerging pathogens in Florida. ARS researchers in Canal Point, Florida, found four morphologically distinct isolates of leaf scald pathogen Xanthomonas albilineans. We also found sugarcane mild mosaic virus (SCMMV) in the Canal Point parental lines. We surveyed SCMMV in sugarcane germplasms at Canal Point and the world collection of sugarcane at Miami. We found that this virus is more prevalent than reported previously.
2. Characterization of endophytes from sugarcane plants with different disease reactions. ARS researchers in Canal Point, Florida, found that inoculation of Xanthomonas albilineans (pathogen of leaf scald disease) affected the bacterial and fungal microbiome in a pre-trial. We planted another trial in November 2023 to reproduce the results of our pre-trial. A February freeze event killed above ground canopy of sugarcane at Canal Point. It took a couple of months for plants to recover from freeze damage. After recovery, we inoculated the clones with sugarcane mosaic virus (strain E; cause mosaic) and Xanthomonas albilineans.
3. Screen sugarcane clones for brown rust, orange rust, leaf scald, sugarcane mosaic, smut, and ratoon stunting diseases. Sugarcane is a genetically complex polyploid clonally propagated and has multi-year crop cycles. The major diseases in Florida are brown and orange rusts, leaf scald, sugarcane mosaic virus, ratoon stunt disease (RSD), and smut. These diseases could cause 10 to 60% yield losses in the susceptible cultivars under stressed conditions. Therefore, the local sugarcane industry must cultivate high-yielding disease-resistant cultivars for sustainable and profitable sugar production. Sugarcane growers in Florida rely entirely on the improved Canal Point (CP) sugarcane cultivars. The development of the disease resistant cultivars starts with the crossing and later selection of resistant clones at every stage of the program and takes more than ten years. In June 2023, Florida Sugarcane Variety Committee released five new cultivars for organic soil CP 12-2479, CP 14-1933, CP 16-1825, CP 16-1883, CP 16- 2283, and three for mineral soil CP 12-2035, CP 15-4302, and CP 13-4165 that are resistant and tolerant to the diseases mentioned earlier, developed by the ARS scientists at Canal Point, in collaboration with the University of Florida and the Florida Sugar Cane League. The CP cultivars have significantly contributed to sustainable sugarcane production in Florida.
Review Publications
Sood, S.G., Momotaz, A., Baltazar, M., Coto Arbelo, O., Davidson, W.R., Islam, M.S., Sandhu, H., Zhao, D., Gordon, V.S. 2023. Registration of ‘CP 14-1377’ sugarcane for organic soils in Florida. Journal of Plant Registrations. 17:114-124. https://doi.org/10.1002/plr2.20275.
Sood, S.G., Gordon, V.S., Coto, O. 2023. Effect of sugarcane yellow leaf virus in the second clonal stage of the Canal Point cultivar development program. International Sugar Journal. 148:408-411. https://doi.org/10.36961/si29966.
Coto Arbelo, O., Momotaz, A., Sandhu, H.S., Sood, S.G., Davidson, W.R., Baltazar, M., Zhao, D. 2023. Selection of new sugarcane genotypes for sandy soils in Florida with enhanced sucrose yield. Agriculture. 13:1079. https://doi.org/10.3390/agriculture13051079.
Coto Arbelo, O., Davidson, W.R., Islam, M.S., Sandhu, H.S., Zhao, D., Sood, S.G., Momotaz, A., Baltazar, M., Gordon, V.S. 2022. Registration of ‘CP 14-1934’ sugarcane for Florida organic soils. Journal of Plant Registrations. 17:91-101. https://doi.org/10.1002/plr2.20260.
Islam, M.S., Qin, L., Mccord, P.H., Sood, S.G. 2023. Enhancing prediction accuracy by incorporating known locus (Bru1) as fixed effect for brown rust resistance in sugarcane. International Society of Sugar Cane Technologists Proceedings. 31:443-446.
Momotaz, A., Baltazar, M., Coto Arbelo, O., Davidson, W., Islam, M.S., Sandhu, H., Zhao, D., Sood, S.G., Gordon, V.S. 2022. Registration of ‘CP 14-1490’ sugarcane. Journal of Plant Registrations. 17:102-113. https://doi.org/10.1002/plr2.20264.
Islam, M.S., Sandhu, H.S., Zhao, D., Sood, S.G., Momotaz, A., Baltazar, M., Coto Arbelo, O., Davidson, W.R., Gordon, V.S. 2022. Registration of ‘CP 13-4474’ sugarcane for sand soils. Journal of Plant Registrations. 1-11. https://doi.org/10.1002/plr2.20259.
