Journal of Applied Sciences Research, 4(4): 451-458, 2008 © 2008, INSInet Publication Corresponding Author: A.H. Kabir, c/o Dr. Md. Alfaz Uddin, W-75/D, Rajshahi University Campus, Rajshahi 6205, Bangladesh. Email: ahkabir777@yahoo.com 451 Indirect Organogenesis and Somaclonal Variation in Four Rice Cultivars of Bangladesh A.H. Kabir, Istiak Mahfuz, M.A. Razvy, M. Bulbul Ahmed and M.F. Alam 1 2 1 1 1 Department of Botany, Rajshahi University, Bangladesh. 1 Department of Zoology, Rajshahi University, Bangladesh. 2 Abstract: An investigation was made on the initiation and maintenance of callus from explants (mature seeds) of four rice cultivars, viz., BRRI-28, BRRI-29, BRRI-30 and BRRI-32. Mature seeds were used as explants. MS medium supplemented with 2 mgL of 2, 4-D was found suitable for inducing high -1 amount of embryogenic calli in the studied genotypes. In this hormonal concentration, maximum 86.11% callus was induced in BRRI-28, followed by 80.55% in BRRI-30. The range of shoot was 1-8 and the highest mean number of shoot were (5.8±0.67) obtained from calli by using MS medium containing 0.5 mgL BAP and 0.1 mgL IBA in BRRI-28. Maximum shoot induction (85.33%) was also observed -1 -1 in the same media component in BRRI-28. BRRI-28 has been found most suitable for in vitro culture among the four genotypes used. Plants regenerated in vitro were successfully established in soil and produced fertile seeds. The regenerated plants showed wider range of variability in comparing with different agronomic traits. The wider variability among the regenerated plants shows the use of in vitro culture technique for creating genotypic variability and subsequent selection for desirable variants. Key words: Callus induction, panicle, variation, transplantation INTRODUCTION Rice is a monocotyledonous cereal crop plant produces an edible grain. The cultivated species of rice ( Oryza sativa ) is originated in south and southeast tropical Asia and there is a great diversity in the cultivated rice forms here. Rice is the primary food for half the people in the world. In many regions it is eaten with every meal and provides more calories than any single food. Due to increasing world population, rate of rice eaters is increasing day by day and the number of rice consumers will probably twofold by the year 2020 . Therefore, varietal improvements of rice [20] for resistance against insects, pathogens and other stresses including nutritional quality are necessary. The study of in vitro tissue culture of rice was intended to screen different rice varieties for their ability to produce embryogenic calli and regenerate into whole plant . Genotype differences in both callus [2,16,12,11] induction and organ differentiation and subsequent callus growth and plant regeneration potential have not been fully understood. Induction of callus is one of the major step for genetic transformation and somaclonal variation. Successful callus culture of rice was first achieved by Fujiwara and Yatazama who cultured [13] the nodes of young seedlings on Hellers medium with vitamins and 2, 4-D (2ppm). Nishi et al. [28] successfully re-differentiated rice callus tissue from seeds into intact plantlet. Several laboratories have also described regeneration of plants from various rice explants . Although immature embryos and [17,21,23,10,1,5] mature seeds are commonly used for callus induction, the use of mature seeds has the advantage. Because they can be obtained at anytime throughout the year regardless of growing season . The aim of this [4] research was to characterize somaclonal variation in populations derived from callus, as well as to select and characterize somaclonal lines in four rice cultivars in Bangladesh. MATERIAL AND METHODS Plant Materials: The experimental materials (BRRI-28, BRRI-29, BRRI-30, BRRI-32) were collected from the Regional Research Station of Bangladesh Rice Research Institute (BRRI), Rajshahi, Bangladesh. Mature rice grain embryos were used as the sources of primary explant. Mature seeds were used as explant. Mature seeds of the studied cultivars were dahusked carefully so that the embryo remains intact. In explant selection diseases and unhealthy seeds were avoided.