Abstract
Cyanobacteria form a morphologically diversified group. Particularly in filamentous taxa, vegetative cells can mature in four developmental directions in response to environmental conditions. Hormogonia are transiently differentiated small-celled filaments and are often capable of gliding and/or buoyant motility. Their function is to provide immotile strains with a means of dispersal. They also play an important role as infective units in the establishment of symbiotic association with plant hosts.
To identify genes involved in hormogonia differentiation, transposon mutants of Nostoc punctiforme ATCC29133 were screened. Three clones neither or seldom produce hormogonia nor infect the host plant Blasia pusilla. The transposon and flanking DNAs were recovered and sequenced from the isolated mutants. Predicted proteins encoded by the identified genes include membrane protein, sugar transport and signaling pathways.
Continued study of hormogonia formation will provide a clue to understand molecular mechanisms that control cyanobacterial cell differentiation as well as cyanobacteria-plant symbiosis.
