Rajesh Kumar Kachouli, Rakesh Maithil, Sachin Dubey, Vipin Kaithwas, Vinod Krishna Sethi and Santosh Bhargava
Keywords: Cyanobacterium, intracellular proline, Nostoc muscorum, osmotic stress, salinity stress.
Abstract: Growth and percent survival in the cyanobacterium Nostoc muscorum severely inhibited, when challenged with salinity (NaCl) and osmotic (sucrose) stresses. The spontaneously occurring NaCl-R and sucrose-R (Su-R) mutant clones were examined with regards to their cross-resistant relationships. The NaCl-R mutant when challenged with salinity and osmotic stresses simultaneously showing cross-resistance with the sucrose stress. In contrast, the Su-R mutant showing resistant only to osmotic stress and was salinity sensitive. The physiological response towards osmotic stress in both the mutant clones was the over-production of proline. The ionic component of the salinity stress in the NaCl-R mutant was overcome by the Na+-efflux. The Su-R mutant clones missing Na+ efflux mechanism, consequently, they became salt sensitive. These findings highlight that the organic osmolyte strategy in N. muscorum assured osmotic resistance.
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