Characterization of mutants of the red microalga Porphyridium aerugineum (Rhodophyceae) resistant to DCMU and atrazine

In an attempt to obtain genetic markers in the red rnicroalga Porphyridium aerugineum Geitler, two stable spontaneous mutants were isolated that were resistant to the herbicides diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (designated D9)] and atrazine [2-chloro-4-ethylamino-(isopropylamino)-1,3,5-triazine (designated A10)]. The mutant resistant to DCMU was also found to be resistant to atrazine, whereas the atrazine-resistant mutant proved sensitive to DCMU. When the wild-type P. aerugineum was grown in the presence of the herbicides, the cellular contents of chlorophyll a, phycocyanin, zeaxanthin, and protein were higher, but the amounts of P-carotene and of cell wall polysaccharide were lower as compared to cells grown in herbicide-free medium. In the mutants, the herbicides did not have a significant effect on these cellular features.