Abstract
At the present time the taxonomic position of the cyanobacterium
symbiont of the aquatic fern Azolla is still controversial. Usually it
is reported as Anabaena azollae Strasb, but recently Komareck and Anagnostidis have assigned it to Trichormus azollae (Strasb.) Kom. and Anagn. Various attempts to clarify the identity of this microorganism is difficult due to the lack of information regarding the akinetes, whose developmental pattern represents a diacritic character for the
Nostocacean taxonomy. The object of this study was to examine the
akinetes in the sporocarps of two strains of Azolla filiculoides.
Akinetes were examined using a light and a fluorescent microscope
equipped with different filters and their ultrastructure was determined
by TEM and SEM. Akinetes and mainly rod shaped bacteria were found under
the indusium of the sporocarps. The akinetes appeared in chains without
interspersed vegetative cells and they were embedded in a film of
mucilagenous material. A multilayer envelope was evident and the cells
contained cyanophycin, glycogen, chlorophyll and phycobiliproteins.
Differences in pigment content and ultrastructure have been detected
between the akinetes present in the megasporocarps and microsporocarps.
In the latter the Anabaena cells had lower contents of chlorophyll.
Based on the developmental patterns and morphological characteristics
the assignment of the Azolla endophyte to Trichormus azollae Kom. and Anagn. appears to be acceptable.
Lingua originale | Inglese |
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pagine (da-a) | 247-264 |
Numero di pagine | 18 |
Rivista | Symbiosis |
Volume | 14 |
Stato di pubblicazione | Pubblicato - 1993 |
Keywords
- SPOROCARPS