Abstract
ABSTRACT Heterosporous ferns of the genus Azolla contain an N2-fixing cyanobacterium, designated Anabaena azollae, in specialized leaf chambers. Our studies of the symbiosis per se have been primarily restricted to A. caroliniana. However, comparative studies have encompassed four of the six known Azolla species: A flliculoides, A. mexicana and A. pinnata, in addition to A. caroliniana. The physiological, biochemical, morphological and ultrastructural studies which support a current hypothesis of host-symbiont interactions and structure-function relationships are described. The latter is largely based on recent studies of the ontogenetic sequence of leaf development and associated events in the symbiotic cyanobacterium. Under optimal growth conditions the four Azolla species double their biomass within two days and maintain an N content of 5–6% of the dry weight with N2 as the only N source. Results of subsequent comparative studies of photosynthesis, respiration, nitrogen fixation and associated processe...
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
