9629728 White A novel set of ecological interactions between grasses and the fungi that live inside them (endophytic fungi or endophytes) has been revealed over the last few years. In many cases the fungi appear to confer enhanced drought tolerance on their grass hosts. But the fungi also produce metabolites that may be toxic to grazing animals like cattle and others, which may lead to commercial losses. While ecological research continues on this interaction, taxonomic studies are also needed to improve understanding of the range and diversity of fungal species involved. Dr. James White at Rutgers University with local and foreign colleagues is studying the systematics and phylogeny of a major group of these fungal endophytes, placed in the tribe Balansieae of the ascomycete family Clavicipitaceae (the ergot group of fungi). Building on his previous work, he employs a broad array of methods to gather data on morphology, life history, mating compatibility, chromosome number, and gene-sequence diversity for samples of fungi collected in North and South America and Europe. One major complication, and challenge, in devising a reliable classification of these fungi is the widespread occurrence of asexual forms that persist for many generations, forms that have been given their own species and genus names. In a growing number of cases, because of research by Dr. White and others, these forms can now be linked with the sexually reproducing species from which they have been derived phylogenetically. Although traditional morphological and life-history studies have facilitated these kinds of linkages, new molecular data from mitochondrial and nuclear gene sequences are providing some of the strongest evidence on which robust classifications can be based. New data from morphological studies, tests of mating compatibility under laboratory growth conditions, and DNA sequences of nuclear ribosomal genes will be integrated in analyses of biological diversity of the fungi that inhabit grass plants and oth er taxa, as "endophytes." Improved taxonomic understanding of these fungi will advance knowledge about their evolution and ecology.
