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Research Projects
Fungal Endophytes and Turfgrass Improvement
An aspect of turfgrass improvement that we are pursuing is the relationship of the Neotyphodium fungal endophytes to their grass hosts. The long- range goal is to help develop the use of endophytic fungi to improve the performance of turfgrasses. Many cultivated and wild grass species are hosts to fungal endophytes. These associations are ecologically and agronomically significant, yet little is known regarding the physiological aspects of the interaction. In many instances the endophyte-grass association is strictly mutualistic, with the plant supplying nutrients to the fungus, and the fungus conferring benefits to the plant. One of these benefits is reduced herbivory by insects and animals due to the production of toxic alkaloids. Several grass species used for turf are naturally infected with endophytes, which is desirable due to the insect resistance they confer. Despite the commercial importance of the fungal endophytes, very little is known about how they interact with their grass hosts.
We have focused on fungal secreted proteins since they are likely to be important components of the mutualistic interaction as they are located at the interface of the two species. We have cloned and characterized several fungal enzymes present in the apoplast of the host grass, a subtilisin-like proteinase, a b-1,6-glucanase, a chitinase, and an N-acetylglucoseaminidase. Investigations such as these will add to our understanding of this agriculturally important but not well-characterized symbiotic interaction
Dollar Spot Resistance in Creeping Bentgrass
We are investigating the potential of interspecific hybridization in improvement of dollar spot resistance in creeping bentgrass. Interspecific hybridization is, of course, a classic breeding strategy but has not previously been used with creeping bentgrass. Although interspecific hybridization between creeping bentgrass and other Agrostis spp. occurs at low frequencies, it may be a useful new method that could be implemented in bentgrass breeding programs.
One of the related species that can hybridize with creeping bentgrass is colonial bentgrass which has good resistance to dollar spot. Colonial bentgrass also has the same chromosome number, 28, as creeping bentgrass which may make introgression of dollar spot resistance through backcrossing possible. In 2001 and 2002 colonial bentgrass x creeping bentgrass hybrids were field tested for dollar spot resistance. Some of the plants had excellent resistance, exhibiting almost no disease symptoms. These results are very exciting regarding the possibility of improving dollar spot resistance in creeping bentgrass. The first backcross progeny are currently being field-tested.
We are also investigating the molecular basis of dollar spot resistance. Using suppression subtractive hybridization we have identified genes over-expressed or unique to the resistant hybrid, relative to the susceptible creeping bentgrass parent. Further characterization of these genes is one of the main areas of research in my lab currently.
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We are also interested in improvement of
disease resistance in creeping bentgrass, the primary turfgrass species
used on golf course greens and fairways in temperate climates of North
America. Dollar spot disease, caused by the fungal pathogen
Sclerotinia homoeocarpa, is one of the biggest management problems
on golf courses. Development of improved cultivars with better natural
dollar spot resistance would be of great benefit to the golf course
industry and the communities they serve.