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: 7/5/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Sugar beet is an important crop with a persistent disease problem, leafspot. Cercospora are the fungi that cause leafspot. The USDA is using plant molecular biology and molecular microbiology approaches to improve Cercospora resistance in sugar beet. Preliminary results indicate that a particular transgenic plant called 'OOT' can produce some in vitro inhibition of growth of Cercospora. This report also discusses other biotechnological approaches being initiated to address the leafspot disease problem. Plant breeders will find this new information interesting and helpful because it clearly demonstrates exciting new potential means for constructing germplasm useful for enhancing resistance to Cercospora. Technical Abstract: The strategy of using a fungal gene for cercosporin transport (cfp) for enhancing sugar beet resistance to Cercospora leaf spot disease was proposed. The cfp gene was obtained from R. G. Upchurch at N.C. State University in Raleigh, NC. The plasmid carrying cfp was transformed into E. coli in order to increase the quantity of DNA available for in vitro manipulation. Currently a suitable promoter is being used to construct a chimeric gene that should be adequately expressed in sugar beet. Transgenic sugar beet plants carrying introduced genes specifying antimicrobial peptides were examined under axenic conditions, free of complications due to the absence of other microbes, for their ability to inhibit the growth of Cercospora beticola, the microorganism responsible for leafspot disease in sugar beet. Transgenic clone OOT has recently been identified as a potential candidate that may adequately express the production of a potent antimicrobial peptide. This genotype has a barley thionin gene and the potato osmotin gene both under the wound-inducible control of the osmotin promoter. Plants are currently being grown for greenhouse evaluation. In vitro analyses had evidently been complicated by the fact that most of the new sugar beet genotypes as well as the parental germplasm of REL-I evidently stimulated the growth of C. beticola on chemically defined medium and under other artificial conditions. Perhaps it is not surprising that axenic sugar beet shoot segments supply phytopathogenic fungi with growth factors. Rhizosphere bacteria isolated at the North Dakota lab, supplied by Garry Smith, are being examined for biocontrol potential and are being microbiologically characterized. |
