Location: Sugarcane Research
2019 Annual Report
Objectives
Objective 1: Identify germplasm of hybrid sugarcane and wild relatives of sugarcane for resistance to economically limiting diseases that breeders can use for parental clones.
Sub-objective 1.A. Classify available clones from different taxa for disease resistance.
Sub-objective 1.B. Identify DNA markers that are closely linked to genes for disease resistance.
Objective 2: Determine molecular and biological characteristics of economically important sugarcane pathogens that can be applied to effective diagnostic protocols.
Objective 3: Develop useful methods to monitor potential emergence of exotic pathogens and identify genetic diversity among pathogen populations that affect sugarcane.
Sub-objective 3.A. Characterize races, strains, or other biotypes of endemic pathogens and determine their distribution.
Sub-objective 3.B. Monitor the Louisiana sugarcane industry for the emergence of new pathogens.
Approach
To identify and develop parental germplasm with resistance to the economically limiting diseases affecting sugarcane in the United States, highly domesticated and wild clones of sugarcane and near relatives will be evaluated for disease resistance following either natural infections or artificial inoculation. To identify molecular markers that are linked to genes for disease resistance, Random Amplification of Polymorphic DNA (RAPD), Amplified fragment length polymorphism (AFLP), and Simple Sequence Repeats (SSR) markers in combination with the bulk segregant analysis (BSA) will be used to screen potential DNA markers for resistance to smut and other important diseases. Variations among the DNA sequences of polymorphic DNA fragments will be analyzed and used to design new pairs of specific primers to develop SCAR (Sequenced Characterized Amplified Region) and or single-nucleotide polymorphism (SNP) markers. Genotypic and phenotypic expressions of variability within populations of pathogens will be used to identify the genetic variability among pathogen populations and determine the distribution of races, strains, or biotypes. The domestic sugarcane industry will be monitored for the introduction of exotic pathogens.
Progress Report
In fiscal year (FY) 2019, progress was made in identifying sugarcane germplasm resistant to economically important diseases. Varieties (43) for possible release into commercial production within the next five years were screened through artificial inoculation in the field for susceptibility to smut and leaf scald. In other Agricultural Research Service breeding trials and nurseries, candidate varieties were observed for natural infection by pathogens that cause mosaic, brown and orange rust, sugarcane yellow leaf, smut and leaf scald diseases. Pathology recommendations were made at variety advancement and variety release meetings. Disease rating were used as criteria to release a new sugarcane variety (Ho 12-615) in 2019.
Analysis of total deoxyribonucleic acid (DNA) extractions from a population of 96 sugarcane clones has been completed. The population is made up of clones that are either susceptible or resistant to sugarcane smut. From the analysis of the DNA from this population, SCAR (sequence characterized amplified region) markers are being developed to identify clones resistant to smut.
In FY 2019, populations of the viruses that cause mosaic in sugarcane were monitored for genetic diversity. Sorghum mosaic virus (SrMV) remains the predominant virus causing mosaic. No isolates were identified as Sugarcane mosaic virus (SCMV), another virus that causes mosaic symptoms in sugarcane, from samples collected among commercially released and experimental varieties. The nucleic acid sequences of an increasing number of isolates of SrMV do not match those of pathogenic strains of SrMV characterized by the symptoms they cause on different susceptible host plants. Sequence data suggest the SrMV population contains multiple genotypes. Current studies are being conducted to further characterize these isolates and their relationship to earlier characterized strains.
Climatic conditions were favorable for orange rust among variety trials at the USDA-ARS research farm in Houma, Louisiana; however, no epidemics have been observed in commercial fields. Highly susceptible clones were not advanced to the next stage of the variety development program.
In collabative studies with the researchers in the Rio Grande Valley sugarcane production area of Texas, orange rust was observed for the first time in 2017. Orange rust was observed in variety trials in 2019, but was not observed in commercial plantings, although the most widely grown variety, CP 89-2143 is known to be susceptible.
Accomplishments
Review Publications
Todd, J.R., White, W.H., Dufrene Jr, E.O., Tew, T.L., Pan, Y.-B., Duet Jr, M.J., Verdun, D.L., Hale, A.L., Dalley, C.D., Grisham, M.P., Gravois, K.A., Jackson, W.R., Miller, J.D. 2018. Registration of ‘HoCP 04-838’ sugarcane. Journal of Plant Registrations. 12:324–332. https://doi.org/10.3198/jpr2017.10.0069crc.
Wu, Q., Gao, S., Pan, Y.-B.., Su, Y., Grisham, M.P., Guo, J., Xi, L., Que, Y. 2018. Heterologous expression of a Glyoxalase I gene from sugarcane confers tolerance to several environmental stresses in bacteria. PeerJ. 6:e5873. https://doi.org/10.7717/peerj.5873.
Todd, J.R., Dufrene Jr, E.O., Pan, Y.-B., Tew, T.L., White, W.H., Hale, A.L., Duet Jr, M.J., Verdun, D.L., Grisham, M.P., Petrie, E.C., Gravois, K., Waguespack, H., Abbott, T.E. 2019. Registration of ‘HoCP 09-804’ sugarcane. Journal of Plant Registrations. 13:161–169. https://doi.org/10.3198/jpr2017.08.0052crc.
Todd, J.R., Hale, A.L., Pan, Y.-B., Milligan, S.B., Dufrene Jr, E.O., Duet Jr, M.J., Verdun, D.L., Landry, C.J., Grisham, M.P., Comstock, J.C., Collins, K., Gravois, K., Bischoff, K.P., Pontif, M.J., Jackson, W.R., Waguespack, H.L., Scott, A.W., Hernandez, E., Klostermann, M., Nuessly, G., White, W.H., Richard, R.T. 2019. Registration of ‘HoCP 11-537’ sugarcane. Journal of Plant Registrations. 13:187-192. https://doi.org/10.3198/jpr2018.10.0066crc.
Rice, J.L., Hoy, J.W., Grisham, M.P. 2019. Sugarcane mosaic distribution, incidence, increase, and spatial pattern in Louisiana. Plant Disease. 103:2051-2056. https://doi.org/10.1094/PDIS-01-0099-RE.
