Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 1999
Publication Date: March 1, 2000
Citation: Chenault, K.D., Melouk, H.A. 2000. Detection of genetic variation among Sclerotinia minor isolates using RAPD-PCR and DNA-DNA reassociation analyses [abstract]. Phytopathology. 90:S14. Interpretive Summary: Sclerotinia blight, caused by the fungus Sclerotinia minor Jagger, has become a major factor limiting peanut production in many U.S. regions. Yield losses from this disease may range from 10 to 50% depending on the severity of infection. Very few peanut cultivars have been developed that contain any resistance to S. minor infection. Over the past several years we have obtained isolates of S. minor from infected peanut fields. These isolates vary in their basis biology and pathogenicity. A better understanding of the differences between these and other S. minor isolates will enable us to identify them in the field and possibly predict severity of infection. In this study we define the molecular relationships that exist between the S. minor isolates that we have collected. We found that the S. minor isolates could be placed into three groups according to how closely they were related genetically. These results suggest that much genetic variation can exist among S. minor isolates, even when they are collected from a small geographic region. This information will help in the identification of S. minor field isolates and possibly aid in the prediction of both the severity of a field infection and the yield loss.
Technical Abstract: Sclerotinia minor Jagger is a severe fungal pathogen responsible for Sclerotinia blight, a disease that can result in significant yield loss in peanut. Two techniques, RAPD-PCR and DNA-DNA reassociation analysis, were used to identify genetic variation among 13 Oklahoma isolates of S. minor. DNA polymorphisms were detected among different isolates using 14 oligonucleotide primers, and three overlapping groups of isolates were identified. The DNA-DNA reassociation values further determined the levels of relatedness among the S. minor isolates and supported the existence of the three groups identified by RAPD-PCR profiles. These results are indicative of the genetic variation that can exist among S. minor isolates in a small geographic region.