Location: Sugarbeet and Bean Research
2018 Annual Report
Accomplishments
1. Reclassification of Rhizoctonia with molecular insights. Root rots have been a major constraint on beet yield for many years and have been identified as the most important yield-limiting diseases affecting beets. Root rot pathogens affecting beet show high genetic variability that does not relate to current methods of classification. Molecular testing of Rhizoctonia solani, done in collaborative work by ARS scientists in East Lansing and Salinas, California has identified three genetically distinct groups that affect beet rather than the two groups used in previous classification and has shown the prior groups are not relevant based on genetic relatedness. New classification methods allow for improved tracking of the pathogens as well as for investigation of the interaction with beet and rotation crops which may help to explain some of the variability in strains found in different growing regions. Research in East Lansing has shown a correlation between these genetic groups and variable responses with crop growth stage for at least one rotation crop, dry bean. Varied responses will allow for targeted assessment of differences in the crop at these growth stages that could aid in resistance breeding in the future. It also allows for assessment of alternative disease management strategies, such as impact of crop rotation on the pathogen population. The research is causing interest in other locations, with ARS scientists, university researchers, and company breeders submitting isolates for characterization within the new phylogenetic schema and asking for assistance in identifying the types of R. solani in their growing regions or being used in breeding programs.
Review Publications
Pethybridge, S.J., Kikkert, J.R., Hanson, L.E., Nelson, S.C. 2018. Challenges and prospects for building resilient disease management strategies and tactics for the New York table beet industry. Agronomy. 8:112. https://doi.org/10.3390/agronomy8070112.
Funk, A., Galewski, P., McGrath, J.M. 2018. Nucleotide-binding resistance gene signatures in sugar beet, insights from a new reference genome. Plant Journal. 95(4):659-671.