Azolla-Anabaena Relationship

Publisher Website
Google Scholar
Abstract
Photosynthesis in the Azolla caroliniana-Anabaena azollae association was characterized with respect to photorespiration, early products of photosynthesis and action spectra. Photorespiration as evidenced by an O2 inhibition of photosynthesis and an O2-dependent CO2 compensation concentration occurred in the association, and endophyte-free fronds, but not in the endophytic Anabaena. Analysis of the early products of photosynthesis indicated that both the fern and cyanobacterium fix CO2 via the Calvin cycle. The isolated endophytic Anabaena did not release significant amounts of amino acids synthesized from recently fixed C. The action spectra for photosynthesis in the Azolla-Anabaena association indicated that the maximum quantum yield is 650-670 nm, while in the endophyte the maximum is 580-640 nm. Although the endophytic cyanobacterium is photosynthetically competent, any contribution it makes to photosynthesis in the intact association was not apparent in the action spectrum.