Specificity and Diversity of the Symbiotic Cyanobacteria

Until recently very little was known about the biodiversity and specificity of symbiotic cyanobacteria in cycads. Heterologous Southern hybridisations using cloned genes from the free-living cyanobacterium Anabaena sp. strain PCC 7120 demonstrated a diversity when analysing cyanobacterial DNA prepared from a large number of pooled coralloid roots collected from cycads in their natural habitat in Mexico (Lindblad et al. 1989). In a more detailed study the diversity and host specificity of the...

Vertical Transfer of the Cyanobiont during Sexual Reproduction

Azolla Indusium

The development of the megasporocarp of AzoZZa and the cyanobacterial infection process has previously been examined using light and electron microscopy (Calvert et al. 1985 Zheng et al. 1988 Perkins and Peters 1983). These works showed that the partitioning of the cyanobionts into developing sporocarps was facilitated by sporangial trichomes (ST) (Fig. 13b). A schematic drawing based on these observations is presented in Fig. 14. The colonization of the AzoZZa sporocarps by cyanobacteria start...