Moss Polytrichum Commune Research Articles

Studies on Moss Spores. VI. Production of Carotenoids in Germinating Polytrichum commune Spores

Carotenoids begin to form during the first six hours of spore germination in Polytrichum commune Hedw., when spore swelling and germ tube protrusion are taking place. Thus, carotenoid synthesis commences before the first chloroplast replication. The 72-hour-old sporelings contained carotenes (292%), violaxanthin (789%), lutein + antheraxanthin (379%), neoxanthin (334%) and zeaxanthin (689%), compared with the contents of ungerminated spores. The ratio of carotenes to xanthophylls changes during germination: the ungerminated spores contain 32% carotenes and 68% xanthophylls; 72-hour-old sporelings, 23% carotenes and 77% xanthophylls. During germination the amount of carotenoids per chloroplast decreases. Polytrichum commune spores contain chloroplasts with a well-developed grana system (Paolillo, 1969; Karunen, 1972) rich in chlorophylls and carotenoids (Karunen, 1971). The main carotenoids of the spores, carotenes, violaxanthin, lutein, antheraxanthin, neoxanthin and zeaxanthin, are the same as those found in photosynthetic tissues of higher plants (Karunen & Ihantola, 1977). Germination of angiosperm seeds always involves a greening process characterized by differentiation of chloroplast lamellae and biosynthesis of chlorophylls and carotenoids. Germination of Polytrichum commune spores apparently does not involve further differentiation of chloroplast lamellae (Reighard, 1967; Karunen, 1972). The chlorophyll content of the original chloroplasts of the spores does not increase during the first hours of germination; rather, chlorophyll synthesis starts in conjunction with chloroplast replication (Karunen, 1973). The purpose of this investigation was to study the formation of various carotenoids of germinating Polytrichum commune spores in relation to the germination phases. MATERIAL AND METHODS The spore material of the moss Polytrichum commune was collected in the area of Erikvalla Bog, Turku, southwest Finland. The germination capacity of this material was nearly 100% during the experimental work. Spores were stored, cultivated and microscopically examined as described by Karunen (1972, 1973). Carotenoids were extracted as described by Karunen & Ihantola (1977), separated by TLC and determined according to the method of Hager & Meyer-Bertenrath (1966). SInstitute of Biology, Department of Botany, University of Turku, SF-20500 Turku 50, Finland. This content downloaded from 157.55.39.72 on Thu, 15 Sep 2016 05:54:36 UTC All use subject to http://about.jstor.org/terms 314 THE BRYOLOGIST [Volume 80 2 5 0 0 lutein + antheraxanthin

The conservation of poly-A-containing RNA during the dormant state of the moss Polytrichum commune.

The moss Polytrichum commune can be dried to less than 2% of free water and kept for some weeks without losing its viability. Upon rehydration of the moss, protein synthesis starts about 60 minutes before incorporation of radioactive precursors into RNA can be observed. Pulse labeled total RNA and poly-A-containing RNA do not show quantitative or qualitative alterations during desiccation up to 20 days.

Notes on water relations ofPolytrichum communeHedw.

Abstract Water loss in the endohydric moss Polytrichum commune was found to be controlled by a complex series of leaf arrangement changes, and by changes in water potential deficit of the shoots. This contrasted with the water relations of the ectohydric moss Rhacomitrium lanuginosum in which there was apparently little control over loss. Water conduction in Polytrichum was predominantly internal under high evaporative flux, and external under moderate flux, but under many stress conditions both pathways would probably be necessary to maintain an optimum water balance.