2.2.130
VEGETATIVE COMPATIBILITY IN SCLEROTINIA MINOR
VEGETATIVE COMPATIBILITY IN SCLEROTINIA MINOR
HA MELOUK 1and SS ABOSHOSHA2
1 USDA-ARS, and Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Ok, USA; 2 Department of Plant Pathology, Faculty of Agriculture, Alexandria University, Alexandria, Egypt
Background and objectives
Sclerotinia blight, caused by Sclerotinia minor, is a devastating disease of peanut in Oklahoma and Texas, United States of America. The pathogen produces numerous sclerotia on culture media, and on infected plant tissues as a mechanism of survival. Reaction of peanut germplasm and breeding lines to S. minor is performed under greenhouse conditions [ 1 ] as well as in small field plots. A non-sclerotia-forming (NSF) isolate of S. minor was recovered from the field, and was found to be non-pathogenic to peanut under greenhouse conditions. The objective of this research was to examine the degree of compatibility among sclerotia-forming (SF) and NSF isolates of S. minor.
Materials and methods
Thirteen isolates were initially paired, in a Latin Square design, in 9-cm-dia Petri plates filled with 15 ml potato-dextrose-agar medium containing 100 mg streptomycin sulfate/L, to determine the macroscopic characteristics of reaction between the isolates. The microscopic examination of mycelial fusion among isolates was performed using the cellophane technique [2].
Results and conclusions
The NSF isolate macroscopically exhibited incompatibility with all the SF isolates, where a distinct no-growth area separated the paired cultures on the petri plates. Also, two SF isolates were incompatible with the rest of the SF isolates in paired cultures. Mycelial fusion among compatible isolates ranged from 47 to 69%. Although macroscopically incompatible a low degree of mycelial fusion (<20%) occurred between the two SF isolates and some of the SF isolates. No mycelial fusion occurred between the NSF isolate and any of the SF isolates. The pathological significance of these findings are being investigated.
References
1. Melouk HA, Akem CN, Bowen C, 1992. Peanut Science 19, 58-62.
2. Carling DE, Leiner RH, Kebler KM, 1987. Phytopathology 77, 1609-1612.