Location: Sugarbeet and Bean ResearchTitle: Root rot symptoms in sugar beet lines caused by Fusarium oxysporum f. sp. betae
|DELUCCHI, CHIARA - University Of Padua|
|STEVANATO, PIERGIORGIO - University Of Padua|
|SELLA, LUCA - University Of Padua|
|DE BIAGGI, MARCO - Retired Non ARS Employee|
|CONCHERI, GUISEPPE - University Of Padua|
Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2017
Publication Date: 7/24/2017
Citation: Hanson, L.E., De Lucchi, C., Stevanato, P., McGrath, J.M., Panella, L.W., Sella, L., De Biaggi, M., Concheri, G. 2017. Root rot symptoms in sugar beet lines caused by Fusarium oxysporum f. sp. betae. European Journal of Plant Pathology. doi: 10.1007/s10658-017-1302-x.
Interpretive Summary: Fusarium oxysporum is an important pathogen of sugar beet throughout the world. It causes yellowing and loss of leaves, wilting, and in some cases death of plants. The pathogen can cause either a wilt disease, known as Fusarium yellows, or a root rot, known as Fusarium root rot. Both have similar foliar symptoms but differ in whether there is an external rot of the root tissue. Previously different forms of Fusarium oxysporum were found to cause either the yellows or root rot. In the current study a root rot associated with Fusarium oxysporum had been observed on some European germplasm. When these were inoculated with isolates previously known to cause Fusarium yellows, a root rot resulted. Four sugar beet germplasm from Italy and four from the United States were compared for their response to three strains of Fusarium oxysporum. The germplasm were all reported to be susceptible to Fusarium oxysporum, but two of the Italian germplasm had significantly more disease than the other six. The three F. oxysporum isolates varied in the disease severity caused on the germplasm. All showed foliar symptoms and vascular damage, but the germplasm from Italy also had root rot for all three strains of Fusarium oxysporum while two of the strains caused similar foliar symptoms but no root rot on any of the US germplasm tested. These results show that Fusarium root rot can be induced not only with different strains of the pathogen but also due to factors in the host.
Technical Abstract: The soil-borne fungus Fusarium oxysporum may cause both Fusarium yellows and Fusarium root rot diseases with severe yield losses in cultivated sugar beet worldwide. These two diseases cause similar foliar symptoms but different root response and have been proposed to be due to two distinct F. oxysporum formae speciales. Fusarium yellows, induced by F. oxysporum f.sp. betae, presents vascular discoloration, whereas Fusarium root rot, due to F. oxysporum f.sp. radicis-betae, is characterized by black rot visible on the root surface. The aim of this work was to study the host-pathogen interaction of sugar beet lines from two different sugar beet breeding programs with isolates originally characterized as Fusarium oxysporum f. sp. betae. Eight susceptible sugar beet lines, selected by the USDA-ARS (US) and UNIPD (University of Padova, Italy) breeding programs, were inoculated with three different isolates of F. oxysporum f. sp. betae, the causal agent of Fusarium yellowing representing varied genetic groups. All inoculated lines developed disease symptoms, but disease severity as area under the disease progress curve (AUDPC) differed significantly (P<0.05) among lines. Two lines from UNIPD, 6 and 9, were the most susceptible to the disease, whereas the other lines showed similar levels of disease. The three isolates of F. oxysporum f. sp. betae, differed significantly (P<0.05) in disease severity. Five weeks after inoculation the plants were harvested and the roots examined. Severe root rot was observed in the susceptible UNIPD lines inoculated with isolates that had never shown root rot in the USDA germplasm. Our results show that Fusarium root rot is induced not only from different Fusarium oxysporum isolates that infect plants, but also due to variable host factors.