A comparative screening of abiotic stress tolerance in early flowering rice mutants.

Oryza sativa L. (Rice) a grain crop grown considerably in areas frequented with abiotic stresses has a higher heat and drought tolerance and is deemed a model crop for tolerance studies. Manifold environment testing facilitates recognition of constant genotypes of rice mutants for adverse abiotic stress conditions. Mutants are an imperative genetic reserve which can help as an informative basis of natural disparity. We assessed EMS induced early flowering rice mutants (Control, BM6, BM6´ and BM9) for potential study of stress tolerance under limited water, salinity and high zinc conditions by testing for plant growth (biophysical and biochemical) traits, as well ascytotoxicity and genotoxicity determination assay via MTT and epifluoresence microscopy methods in root tissues of the mutants. Environmental effect was more significant than genotypic contribution on biophysical and biochemical parameters. BM9 mutant was found to be the most stable genotype in tolerance studies among other mutants in artificially created stress environments viz. mannitol (moderated drought), sodium chloride (salinity stress), zinc sulfate (heavy metal stress) and zinc oxide nanoparticles for a time duration. These mutants are a valuable resource for varietal advancements and to determine genes for tolerance to multiple abiotic stresses. To our knowledge this is the first account on validation of manifold abiotic stresses in early flowering rice mutants. This study can additionally assist fastidious detection of stress-tolerance genes in this vital crop.