Submitted to: Journal of Sugarbeet Research
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2003
Publication Date: 7/1/2003
Citation: Hanson, L.E., Hill, A.L., Panella, L.W. 2003. Variable virulence and genetic diversity in fusarium oxysporum from sugar beet. Journal of Sugarbeet Research. Interpretive Summary:
Technical Abstract: Variable virulence and genetic diversity in Fusarium oxysporum from sugar beet. Fusarium yellows of sugar beet can cause reductions in root yield in addition to reducing sucrose percentage and purity in the root. The primary causal agent is Fusarium oxysporum f. sp. betae (FOB). Some strains of FOB also infect spinach and some weed species, so FOB may have a less restricted host range than is usually reported for forma specialis. We investigated the variability in strains of F. oxysporum isolated from sugar beets from seven states in terms of their pathogenicity and virulence on sugar beet in greenhouse tests and their variability in RAPD banding patterns. Four-week-old beet plants (Fusarium-susceptible line FC716) were inoculated by dipping clipped roots in spore suspensions of the different isolates. From a total of 98 isolates, 26 were pathogenic on sugar beets and 24 were identified as FOB. These pathogenic isolates were from three states, CO, MT and OR. One isolate each of F. solani and F. accuminatum also were pathogenic in our greenhouse assay. Twelve isolates of FOB were analyzed by RAPD analysis using nine primers. Based on RAPD patterns, the eight isolates of FOB from Colorado clustered together, but some non-pathogenic isolates clustered with the FOB strains. FOB strains from Montana and Oregon showed divergent patterns and also clustered with non-pathogenic isolates. Thus FOB appears to be a diverse group within F. oxysporum. When a subset of isolates were tested on a set of sugar beet varieties with reported resistance to Fusarium yellows, some isolates gave different reactions with the varieties. This may indicate the existence of races within FOB.