Twenty five strains of marine cyanobacteria were screened for their ability to promote carrot somatic embryogenesis. Hot water extracts prepared from 21 of these strains promoted plantlet formation. Extracts from four strains increased plantlet numbers to an average of over 3.7-fold. Dialysates and nondialysates of each of these extracts also increased plantlet formation. For extracts from filamentous cyanobacteria, Nostoc sp. and Anabaena sp., dialysate was more effective (4.2-fold increase) than nondialysate (3.0-fold increase), whereas for unicellular strains Synechococcus sp. and Xenococcus sp., nondialysate was more effective (5.2-fold increase) than the dialysate (3.2-fold increase). These cyanobacterial extracts also promoted embryolike structure formation from two-year old carrot cell cultures which were unable to produce plantlets using the usual methods. Here, we demonstrate the existence in marine cyanobacterial extracts of low and high molecular weight factors which strongly promote somatic embryogenesis in carrot cell cultures.
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