Advancements in the physiological and biochemical characterization of the cyanobionts from the aquatic pteridophyte azolla

Abstract

The Azolla- Anabaena system is important agronomically due to its capacity to fix atmospheric nitrogen. In addition to the use as biofertilizer the system has multifaceted uses as green manure, bioremediator, cattle and poultry feed etc. The nitrogen fixing capacity of the system is due to the presence of a symbiotic cyanobacterium Anabaena azollae which occurs in the dorsal leaf cavities of the host Azolla plant. This symbiosis is referred to as perpetual symbiosis due to the tight coupling between the cyanobiont and host which is different from other cyanobionts reported so far. There are many similarities as well as dissimilarities between the cyanobiont and free living cyanobacteria. Despite advancements in Azolla biology, the interaction between the host and its cyanobiont has not been elucidated in considerable detail. This has been attributed to the difficulties encountered in the isolation as well as culturing of the cyanobionts. In spite of these constraints we still have some leads on its physiological and biochemical aspects of the cyanobionts. Characterization of the cyanobiont is therefore important to further understand its interaction with the host and advancement in molecular biology tools and protocols may help to better understand the intricacies of the complex system. This may pave ways for the manipulation of the symbiosis to enhance the agricultural utility of the system. Therefore the present article highlights some of the important developments in the characterization of the cyanobiont associated with Azolla. © 2017 by Nova Science Publishers, Inc. All rights reserved.