Population biology ofAmmophila breviligulataandCalamovilfa longifoliaon Lake Huron sand dunes. II. Ultrastructure of organelles and photosynthetic properties

摘要

Organellar ultrastructure and photosynthetic properties of two grasses,Calamovilfa longifolia(Hook) Scribn. andAmmophila breviligulataFern., growing on Lake Huron sand dunes were compared. Thylakoids ofC.longifoliacontained a relatively greater complement of the photosystem I (PSI) ndash; chlorophyllandash; protein complex, whereas thylakoids fromA.breviligulatahad a relatively greater complement of light-harvesting chlorophyllaensp;+ensp;bcomplex. The chlorophylla/bratios of the mesophyll chloroplast thykaloids reflected the content of chlorophyllndash;protein complexes present in the membranes. Digitonin fractionation of mesophyll thylakoids fromC.longifoliarevealed that the PSI-enriched fraction contained more chlorophyll than the photosystem II (PSII) enriched fraction. Conversely, the PSII-enriched fraction accounted for the larger proportion of total chlorophyll in thylakoids fromA.breviligulata. Whole chain electron transport (PSIIensp;+ensp;PSI) activity was greater inC.longifoliamesophyll thylakoids, at all light intensities. Chloroplast and mitochondrial ultrastructure were compared. The bundle sheath chloroplasts ofC.longifoliacontain extensive grana stacking and are distributed throughout the cell. The mitochondria of the bundle sheath and mesophyll cells are strikingly dimorphic. A suberin lamella is apparently absent from the bundle sheath cell walls. These results support the designation ofC.longifoliaas a C4species of the nicotinamide adenine dinucleotide ndash; malic enzyme type.