BIOLOGICAL EFFECTS OF A HERBICIDE ON A NITROGEN-FIXING CYANOBACTERIUM (BLUE-GREEN ALGA): AN ATTEMPT FOR INTRODUCING HERBICIDE-RESISTANCE

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Summary

The herbicide monuron [3-(4-chlorophenyl)-1, 1-dimethylurea] inhibits growth and heterocyst formation in the nitrogen-fixing cynobacterium Nostoc muscorum. These inhibitory effects are glucose-reversible in both N2 (nitrogen-free) and NO3 media. A spontaneous mutant of this cyanobacterium, resistant to a dose of monuron normally applied to the rice-fields of North India, has been isolated and preliminarily characterized as having no requirement for an organic carbon source for its normal physiology under monuron-treated conditions. The behaviour of the mutant has been tentatively explained as resulting from a permeation mutation preventing monuron entry into N. muscorum.

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