| Scope and method of study. There are several goals of this study. First was to document and putatively identify the culturable bacterial endophytes isolated from surface sterilized crown tissue of Midlawn and Tifgreen cultivars of bermudagrass, secondly, to test these endophytes for antagonistic properties against the Spring Dead Spot (SDS) soilborne fungal pathogen, Ophiosphaerella herpotricha, and thirdly, to identify promising candidates for a biological control agent against SDS. Another major goal was to develop a real-time quantitative PCR assay for O. herpotricha using TaqManRTM chemistry and use this assay to document the spatial distribution of O. herpotricha infection in plant and soil samples and document the relationship between resistant and susceptible cultivars of bermudagrass and SDS.; Findings and conclusions. Seventy-seven Gram-negative and 51 Gram-positive culturable bacterial endophytes, including 31 with in vitro antifungal attributes, were readily isolated from the crown tissue of Midlawn and Tifgreen cultivars of bermudagrass, infected with O. herpotricha and non-infected. This study is the first, to my knowledge, to document a Geodermatophilus sp. and a Amycolatopsis sp. as plant endophytes, and of in vitro antifungal attributes of a Chryseobacterium sp. The abundance and diversity of culturable bacterial endophytes in bermudagrass demonstrate that turfgrasses are good hosts and valuable resources for endophytes with antifungal properties. The cohort of in vitro antifungal bacterial endophytes has potential as biological control agents for SDS. A standard-curve real-time quantitative PCR assay with TaqManRTM chemistry was developed to identify and quantify the DNA levels of O. herpotricha in plant and soil samples. This assay has proven to be quantitative, sensitive, selective, rapid, and easy to perform and may lead to its application to the study of other plant diseases. |
