Increased Regeneration Efficiency in Seed Derived Callus of Rice (Oryza sativa L.)

In five cultivated rice varieties e.g., Nonabokra, PNR 381, Taipei 309, Koshika and TKM 11 the response in the initiation of callus and its size varied greatly among varieties, salt concentrations (NaCl and Na2SO4) and their interaction. Better regeneration ability of Nonabokra, Koshika and TKM 11 was found to be correlated to small size callus with a high concentration of Na2SO4. The regeneration ability found here was dependent on variety/genotype, callus type and size, source of salt and their concentration. Regeneration ability enhanced three tenfolds from Na2SO4 stressed callus compared to the control i.e. without Na2SO4. Vigorous rooting was also observed in the regenerated plants obtained from the calli induced in the medium containing Na2SO4. In NaCl supplemented medium, on the other hand, regeneration and rooting ability were poor. Introduction Rice (Oryza sativa L.) is the most important and staple food crop of Bangladesh as well as 60% of the global population (Uchimiya et al. 2002). As the population in the world is increasing continued increase of rice production poses a major issue for world food security. Global rice production has increased, almost threefold over the past three decades (Christopher 2002), but further increase in yield and nutrition may only be possible using the biotechnological tools to meet the rising demand of the population. Recent advances in in vitro plant cell, tissue and organ culture as an additional method for crop improvement has been well augmented. Successful application of in vitro techniques of somatic tissue offers a wide scope of achieving somaclonal variants in regenerated plants from the rice calli. Seed derived calli of rice have been shown to be superior in efficient regeneration (Hiei et al. 1994). The regenerants could be obtained from calli under initial salt stress as a supplement to the callus induction medium (Kishor et al. 1999). *Author for correspondence. Email: [email protected] 1Present address: Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Santosh, Tangail 1902, Bangladesh.