Abstract
Generation, screening and isolating mutants for any developmental and adaptive traits plays a major role in plant functional genomics research. Identification and exploitation of mutants possessing contrasting root growth behavior and salinity tolerance in rice will help us to identify key genes controlling these traits and in turn will be useful for manipulating abiotic stress tolerance through tilling and genetic engineering in rice. In this study, we have screened about 1500 mutants (M 2 generation) generated by treating an upland drought tolerant genotype Nagina 22 with Ethyl Methane Sulfonate (EMS), for their root growth behavior and salinity tolerance under hydroponic conditions. Six independent mutant lines possessing significantly shorter roots and three mutant lines exhibiting greater degree of salinity tolerance than the wild type plants were identified. The identified mutant lines were advanced to M 5 generation to allow the mutants to reach homozygosity, and the fixed mutants were confirmed for their phenotype. One mutant namely N22-C-241-5-6 was found to possess significantly shorter roots than wild type N22, and it was also noticed that the mutant was devoid of root cap. Among the three salinity tolerant mutant lines identified, N22-C-334-3 was found to possess a greater degree of tolerance upto 250 mM Nacl stress at germination stage. These identified mutant lines can be used for further physiological, biochemical and molecular biology experiments to identify candidate gene(s) controlling root growth behavior and salinity tolerance in rice. Keywords : Rice, mutation, EMS, altered rood growth and salinity tolerant mutant African Journal of Biotechnology Vol. 12(40), pp. 5852-5859
Highlights
Abiotic stresses such as drought and salinity are major yield limiting factors for upland and rainfed lowland rice ecosystems
In all the six mutant lines, root length was more than 50% less than the wild type (Table 1 and Figure 1B)
Reduction in root length was found to be associated with reduction in plant height as in the case of semi-dwarfing genes
Summary
Abiotic stresses such as drought and salinity are major yield limiting factors for upland and rainfed lowland rice ecosystems. Improving rice yield with no additional lands available for cultivation depends mainly on the development of drought and salinity resistant rice genotypes suitable for these marginal environments. Developing rice genotypes with the right combination of characters for specific drought and salinity prone environments require an understanding of the physiological processes of the plant, environment and interaction between them (O'Toole and Chang, 1979). In this context, biotechnology offers us a powerful means of manipulating drought and salinity tolerance in rice through various approaches. Functional genomics helps us to generate knowledge on networks of stress perception, signal transduction and defensive responses
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