ARS | Publication request: Seedling Resistance to Rhizoctonia Solani in Sugar Beet

Submitted to: American Phytopathological Society Annual Meeting
Publication Acceptance Date: March 31, 2004
Publication Date: July 31, 2004
Publisher's URL: http://www.apsnet.org/meetings/2004/abstracts/a04ma0499.htm http://www.apsnet.org/meetings/2004/abst
Citation: Nagendran, S., Mcgrath, J.M. 2004. Seedling Resistance To Rhizoctonia Solani In Sugar Beet [abstract]. Phytopathology. 94:s74. Paper No. P-2004-0499-Ama.

Technical Abstract: Rhizoctonia solani in sugar beet (Beta vulgaris L.) causes damping'off at the seedling stage and crown and root rot in the adult plant. Managing damping-off by azoxystrobin fungicides is promising but genetic resistance is being sought. Phenotypic and microscopic analysis of disease progress patterns in compatible and incompatible interactions showed that virulent (AG2-2 R1) and hypo-virulent (AG2-2 W2) strains of R. solani produced infection structures that penetrated hypocotyls of growth-chamber, soil-grown, 2-week-old seedlings. Seedlings infected with AG2-2 W2 initially showed symptoms but most survived, unlike those infected with AG2-2 R1 which uniformly died. Pre-inoculation with AG2-2 W2 did not protect seedlings from subsequent infection by AG2-2 R1. Similar results were obtained in the greenhouse and field disease nursery settings. In the field, a recent USDA-ARS germplasm release, EL51 bred for resistance to crown and root rot, showed putative resistance to Rhizoctonia seedling damping-off. cDNA AFLP analyses of compatible and incompatible interactions are being used to further define disease progress towards understanding molecular events associated with their interaction becoming compatible or incompatible.