Author
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Kuykendall, Larry |
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Submitted to: Annual Beet Sugar Development Foundation Research Report
Publication Type: Other Publication Acceptance Date: 5/1/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Cercospora beticola causes leafspot disease in sugar beets and reduces sucrose yields by as much as a third. A pathogen derived gene cfp has been modified in vitro and confers resistance, a new method of directly selecting cercosporin resistant cell lines was devised, and a new Pseudomonas species exhibiting antagonistic behavior toward virulent pathogenic Cercospora beticola was discovered. This will prove beneficial to plant breeders, agronomists, and tissue culture experts working with sugar beets they will can utilize these results and work toward controlling Cercospora leafspot. Technical Abstract: Theoretically disease resistance in sugar beet can be improved by using DNA transformation and regeneration for biotechnological improvement of this important crop. Transgenic sugar beet clones were identified and have been vegetatively propagated with the plan of examining a number of healthy greenhouse-grown plants for their ability to resist infection by Cercospora. Transfer into sugar beet is being performed on a modified cfp gene from Cercospora under the control of a stress-inducible promoter from potato. A whole series of in vitro DNA manipulations have been performed, and now, finally, our constructs can be used to transform. Since cercosporin toxin is thought to be a virulence factor, transgenics expressing the toxin pump protein encoded by cfp may possess immunity from Cercospora infection. Beneficial fluorescent Pseudomonas bacteria from the rhizosphere of healthy plants were bacteriologically cloned and found to produce antibiotics against Cercospora. We have Pseudomonas syringae, P. corrugata and an unclassified Pseudomonas similar to five well-characterized species. Two species carry genes encoding antibiotics potent against Cercospora. Pseudomonas strain ND9L is being extensively characterized in particular as a potential gene-source for Cercospora-killing antibiotics. Lastly, a new means of directly selecting cercosporin-resistant clones was devised. Embryogenic callus of sugar beet is incubated under light on a rotary shaker in medium containing the appropriate growth regulator and uM quantities of cercosporin toxin. |
