• Azolla;
  • Anabaena;
  • antigenic analysis;
  • lectin;
  • symbiosis


Antigenic cross-reactivity between symbiotic Anabaena azollae and its Azolla host was detected by an indirect immunofluorescence technique. Antiserum against Anabaena-free Azolla cell extract cross-reacted with A. azollae freshly separated from different species of Azolla, but did not cross-react with any of the free-living Anabaena species tested, including A. azollae (Newton), which was claimed to be isolated from Azolla.

Cell extracts of the whole Azolla-Anabaena symbiosis and of Anabaena-free Azolla plants both caused agglutination of human and rabbit erythrocytes whereas extracts of symbiotic A. azollae freshly separated from Azolla plants or free-living A. azollae (Newton) did not cause haemag-glutination. Of the several sugars tested α-D-galactose inhibited the haemagglutination. Free-living A. azollae (Newton) showed no cross-reaction at any growth phase of its life cycle with antiserum against Anabaena-iree Azolla nor could it bind the haemagglutinating factor from the Azolla-Anabaena symbiosis.

The possible significance of common antigens and lectin in the Azolla-Anabaena symbiosis is discussed.