Pooid Grasses Research Articles

The ?-tubulin gene of Epichlo� typhina from perennial ryegrass (Lolium perenne)

Epichloë 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 Epichloë 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.

Skin test evaluation of tropical and temperate grass pollen in hay fever subjects in London

Abstract Patients from the West Indies with a history of hay fever in that region were free from symptoms during their first two or three seasons in London. Europeans with allergic sensitivity to pooid grasses are free from symptoms when first exposed to tropical grass pollen. We therefore investigated the possible antigenic relationships between species representative of pooid and tropical grasses by the skin-prick test. It is shown by multivariate analyses (Reciprocal Averaging and Principal Components Analysis) that a reaction to one species has a limited predictive value for reactivity to others. Use of aqueous extracts shows a common antigenicity throughout the grasses, and studies on the antigenicity of grass pollen by both in vivo and in vitro methods are briefly reviewed. It is concluded that aqueous extracts lack species specificity and attention is drawn to the report of Stanford (1983) that the purified proteins of Mycobacterium tuberculosis when used as skin test reagents, cross-react with other species of Mycobacteria, contain little species specific antigen and that molecules of mixed specificity play the largest part in skin test reactions. It is suggested that species specific antigens in grass pollen may be lipid or lipid associated and this appears worthy of investigation both in relation to pollinosis and incompatibility reactions in grasses.

Miscellaneous Notes on Pooid Grasses

Summary. The genus Neuropoa is described, and Danthorhiza discussed. Pseudobromus, Danthoniastrum and Sinochasea are reduced to synonymy. The combinations Deschampsia minor, Festuca africana, Helictotrichon canescens, Metcalfia compacta, Neuropoa fax, Ortachne erectifolia and Pseudodanthonia trigyna are made. Danthorhiza Tenore, Fl. Nap. 1: x (1810) nom. inval. based on D. versicolor (Vill.) Tenore (= Helictotrichon versicolor (Vill.) Pilger). The name Danthorhiza was published in a Prodromus at the beginning of Fl. Nap., accompanied by a description of the single species D. versicolor. The generic name does not reappear later in the main body of the text, but Avena has been expanded there to include A. versicolor Vill. (Fl. Nap. 3: 96, 1824-29), and it is reasonable to conclude that D. versicolor was indirectly based upon that species. Since it is not a new species the genus cannot be validated by a combined generico-specific description, and cannot therefore claim priority over Helictotrichon Schultes (1827).