Characterization of Protein Changes Associated with Sugar Beet (Beta vulgaris) Resistance and Susceptibility to Fusarium oxysporum.

Authors: Larson, Rebecca; Hill, Amy; Nunez, Alberto

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2007
Publication Date: 8/23/2007
Citation: Larson, R.L., Hill, A.L., Nunez, A. 2007. Characterization of Protein Changes Associated with Sugar Beet (Beta vulgaris) Resistance and Susceptibility to Fusarium oxysporum.. Journal of Agricultural and Food Chemistry. 55:7905-7915.

Interpretive Summary: Fusarium oxysporum, the causal agent of Fusarium Yellows in sugar beet, is a major threat to sugar beet production worldwide. There are resistant sugar beet lines available to growers, but it has been observed that the resistance varies depending on the location in which the beets are grown. In an effort to help elucidate the reason for this variability, analysis of the protein changes associated with resistance was completed. A better understanding of the basis for resistance will provide clues about the types of and diversity of resistance sources within sugar beet. Using multidimensional liquid chromatography, 950 total proteins were detected in sugar beet leaf and root tissue. Only twelve percent exhibited differences in expression in the presence of F. oxysporum. The resistance-related proteins were differentially regulated over time, suggesting some are important for early defense activation, while others may be needed for long term pathogen control. Of the 70 total proteins analyzed by mass spectrometry, 33 were positively identified and were associated with gene expression and protein turnover, classical defense response pathways and the oxidative burst, an early response in plant resistance activation.

Technical Abstract: Fusarium oxysporum is serious threat to sugar beet production worldwide. Although certain sugar beet lines appear to have resistance against F. oxysporum, little is understood about the basis for that resistance. Examination of F. oxysporum-induced changes in the sugar beet proteome has the potential to serve two purposes: to identify candidate genes for use in marker-assisted selection and to elucidate mechanisms responsible for resistance. Sugar beet genotype C1200.XH024, with resistance to F. oxysporum isolate F-19, analyzed at 2- and 5-days post inoculation and compared to mock-inoculated beets. These times correlate with initial infection and vascular tissue penetration, respectively. A total of approximately 950 proteins were reproducibly detected in the sugar beet leaf and root protein extracts using multidimensional liquid chromatography. One hundred twenty-one proteins were differentially expressed during resistance to F-19. Fourteen were only expressed during initial infection, forty-three once the vascular system was penetrated and forty-nine were expressed at both points. Fifteen proteins were repressed in F-19 challenged tissue in comparison to the mock inoculated control. Seventy protein peaks were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, the remaining protein peaks were below the level of detection. Thirty-three proteins were positively identified and were found to be associated with gene expression and protein turnover, salicylic acid-dependent resistance, and the oxidative burst