Isolation of useful scented rice mutants and comparative assessment of genetic diversity.

A set of 36 scented rice mutants were developed through recurrent mutagenesis Pusa basmati-1, Pusa Sugandha-2 and Ketakijoha local with ethyl methane sulphonate (EMS), N-methyl N-nitro N-nitrosoguanidine (NG) and a combination of 0.4% EMS and 0.015% NG over two successive generations. ORM 256-8-10 and ORM 256-8-6 (mutants of PB-1) and ORM 228-1 (mutant of Pusa Sugandha 2) had shown significantly higher grain yield than Geetanjali (standard check), as well as, their respective parent varieties. The above test genotypes were analysed by 12 RAPD and 11 ISSR primers. RAPD and ISSR primers amplified 92 and 77 bands ranging from 4-15 and 4-12 bands per respective primer exhibiting higher level of polymorphism (86.95% and 94.80%). RAPD primer OU 1 and ISSR primer OUAT 7 produced maximum number of 15 (280-1830bp) and 12 polymorphic bands (420-1260bp), respectively. ISSR revealed higher polymorphic information content (PIC) values than RAPD primers indicating better allelic diversity. Resolving power revealed higher efficiency of RAPD primers. OU-1 with high GC content (80%) and two ISSR primers OUAT-7 (GC = 66.7%) and OUAT-15 (GC = 88.2%) produced higher number of polymorphic amplicons. ORM 228-1, Pusa Sugandha-2, ORM 256-8-10 and Ketakijoha were identified to be highly divergent genotypes based on RAPD and ISSR analyses. RAPD analysis revealed divergence of ORM 256-2 and ORM 256-8-12 while ORM 256-8-6 isolated from rest of the genotypes in case of ISSR. This could be attributed to genotype-specific RAPD and ISSR alleles. The above diverse genotypes with high yield identified in the present pursuit would enrich the basmati gene pool for further genetic improvement for grain quality and yield per se.