Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → États-Unis → 1971 → THE TAXONOMY AND MORPHOLOGY OF THE LICHEN GENUS ACAROSPORA AND ITS PHYCOSYMBIONT TREBOUXIA

University of Arizona (1971)

THE TAXONOMY AND MORPHOLOGY OF THE LICHEN GENUS ACAROSPORA AND ITS PHYCOSYMBIONT TREBOUXIA

Duewer, Elizabeth Ann Hubbard

Titre : THE TAXONOMY AND MORPHOLOGY OF THE LICHEN GENUS ACAROSPORA AND ITS PHYCOSYMBIONT TREBOUXIA

Auteur : Duewer, Elizabeth Ann Hubbard,

Université de soutenance : University of Arizona

Grade : Doctor of Philosophy (PhD) 1971

Résumé partiel
Lichens are unique organisms composed of an alga (phycosymbiont) and a fungus (mycosyni’biont) which live together in a mutually beneficial association, a symbiosis. Thus, any given lichen presents a taxonoinic problem since each of the symbionts belongs to a different group. There are four major types of growth forms in lichen thalli : fruticose, squamulose, foliose, and crustose. The crustose lichen genus Acarospora, in the family Acarosporaceae, is divided into two easily distinguished subgenera, Xanthothal11a, those with a yellow thallus, and Phaeothallia, those with a brown thallus. Within each of the subgenera, however, species of Acarospora eire not always distinguishable morphologically. In such instances, color reaction tests, crystal tests, or a combination of the two tests may be used to aid in detection of lichen acids and identification of the lichen species, since a given lichen generally produces certain lichen acids. Research indicates that phy cosynibionts could possibly be used to aid in identification of the lichen species. The phycosymbionts of Acarospora schleicherl (Ach.) Mass., A^. badiof us ca (Nyl.) Th. Fr. , A_. f uscata (Schrad.) Arn., A. smaragdula (Wahlemb. ex Ach.) Mass., and A_. veronensis Magn. were successfully isolated and cultured in liquid and on agar using Trebouxia organic nutrient medium. These isolates ivere used for stock cultures and morphological studies for descriptive taxonomy. Acarospora novomexicana Magn. and A_. oxytona (Ach.) Mass. were also studied, but no successful isolations were made from these species. The phycosymbionts were also cultured (l) in Trebouxia organic liquid medium in shaker and stationary culture ; (2) in Bold’s mineral medium with biotin added at the rates of 0.05, 0.1, 0.2, and 0.4 [i.g/ml ; (3) in Trebouxia organic liquid medium at 500, 1,500, 2,500, 3,500, and 4,500 lux ; and (4) on Trebouxia organic agar plates with antibiotic discs added to study the effects of growth, the effects of varying light intensities on growth, and sensitivity to antibiotics. The phycosymbionts grew best : in shaker cultures ; at 0.05 and 0.1 (j,g biotin/ml ; at 500 and 4,500 lux, and were sensiti

Présentation

Version intégrale (5,75 Mb)

Page publiée le 23 février 2018