Showing papers on "Epichloë published in 1990"

Fungal endophytes of grasses.

Abstract: Mutualistic interactions between species are receiving increased attention from ecologists, although research lags far behind analogous work on competition or predator-prey interactions. Most research has focused on rather showy mutualisms such as pollination or fruit dispersal and has suggested that mutualisms are more important in tropical communities than in temperate communities (67). Plant-microbial mutualisms, in contrast, have prompted little ecological research. Plant-microbial associations are more difficult to observe and manipulate than plant-animal associations. Many plants are always infected (e.g. legumes by rhizobia, forest trees by mycorrhizal fungi), so it is easy to consider the microorganisms merely as a special type of plant organ. Further, plant-microbial mutualisms historically have been outside the realm of ecology, in other areas of biology like microbiology and mycology. Recent research has revealed a widespread mutualistic association between grasses, our most familiar and important plant family, and endophytic fungi. Asymptomatic, systemic fungi that occur intercellularly within the leaves, stems, and reproductive organs of grasses have dramatic effects on the physiology, ecology, and reproductive biology of host plants. Through the production of toxic alkaloids, endophytic fungi defend their host plants against a wide range of insect and mammalian herbivores. Poisoning of domestic livestock has spurred a great deal of research on endophytic fungi in pasture grasses. This research has shown clearly that plants benefit from

Fungal endophyte-infected grasses: Alkaloid accumulation and aphid response.

Abstract: The occurrence of the alkaloidsN-formyl andN-acetyl loline, peramine, lolitrem B, and ergovaline and the response of aphids to plants containing these compounds were determined in species and cultivars ofFestuca,Lolium, and other grass genera infected with fungal endophytes (Acremonium spp., andEpichloe typhina). Twenty-nine of 34 host-fungus associations produced one or more of the alkaloids, most frequently peramine or ergovaline. Three alkaloids (lolines, peramine, and ergovaline) were found in tall fescue and in perennial ryegrass infected withA. coenophialum, while peramine, lolitrem B, and ergovaline were present in perennial ryegrass and in tall fescue infected withA. lolii and inF. longifolia infected withE. typhina. WhileA. coenophialum andA. lolii produced similar patterns of alkaloids regardless of the species or cultivar of grass they infected, isolates ofE. typhina produced either no alkaloids or only one or two different alkaloids in the grasses tested. Aphid bioassays indicated thatRhopalosiphum padi andSchizaphis graminum did not survive on grasses containing loline alkaloids and thatS. graminum did not survive on peramine-containing grasses. Ergovaline-containing grasses did not affect either aphid.

The β-tubulin gene of Epichloë typhina from perennial ryegrass (Lolium perenne).

Abstract: Epichloe typhina is a biotrophic fungal pathogen which causes choke disease of pooid grasses. The anamorphic state, Acremonium typhinum, is placed in the section Albo-lanosa along with related, mutualistic, seed-disseminated endophytes. As an initial study of gene structure and evolution in Epichloe and related endophytes, the beta-tubulin gene, tub2, of the perennial ryegrass choke pathogen (EtPRG) was cloned and sequenced. The coding sequence and the predicted beta-tubulin amino acid sequence were highly homologous to the Neurospora crassa homologs, and to one of the two beta-tubulin genes of Emericella nidulans. However, two introns characteristic of the N. crassa and Em. nidulans genes were absent in the E. typhina gene. Furthermore, one of the remaining introns possessed the uncommon 5' splice junction, GC. In contrast to published observations concerning other Ascomycetes, a mutant of EtPRG, selected for resistance to methyl-2-benzimidazole carbamate (benomyl), possessed no alteration of its beta-tubulin coding sequence.