Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2002.1294.1296Oryza sativa L.]]>M. Al-BahranyAbdulaziz 122002512The responses of Hassawi rice (Oryza sativa L.) callus was studied to varying degrees of polyethylene glycol (PEG)-induced water stress including callus growth, water content and proline accumulation. To characterize callus growth in response to PEG, 2.5 g embryogenic callus was grown in 125 ml flasks containing 50 ml each of liquid MS medium supplemented with PEG (MW 8000) at 0, 50, 100, 150, 200, 250 and 300 g l1. Results revealed that increasing water stress induced by increasing concentration of PEG caused a progressive reduction in callus fresh weight. Significant reduction in callus weight was observed in response to 50 g l1 PEG, but the inhibitory concentration was identified to be 200 g l1. Increasing PEG concentration was also associated with a progressive reduction in callus water content, which caused increase in proline accumulation reaching significant increase over the control at 100 g l1 PEG. This study serves as a precursor for genetic improvement efforts to enhance the tolerance of Hassawi rice to water stress.]]>Al-Khayri, J.M. and A.M. Al-Bahrany,2002Oryza sativa L.).]]>45609611Al-Khayri, J.M. and A.M. Al-Bahrany,2000In vitro plant regeneration of Hassawi rice (Oryza sativa L.) from mature embryo-derived callus.]]>3602605Al-Khayri, J.M., C.M. Shamblin, R.W. McNew and E.J. Andreson,199632227232Attree S.M., D. Moore, V.K. Sawhney and L.C. Fowke,1991Picea glauca (Moench) Voss] somatic embryos: Effects of a non-plasmolysing water stress and abscisic acid.]]>68519525Bates, L.S., R.P. Waldren and I.D. Teare,197339205207Bhaskaran, S., R.H. Smith and R.J. Newton,198579266269Bornman, C.H. and W.Huber,1979Nicotiana tabacum callus studies. IX. Development in stressed explants.]]>174345356Chauhan, V.A. and G. Prathapasenan,199820197200Cress, W.A. and G.V. Johnson,1987Atriplex canescens and Hilaria jamesii.]]>65799801Handa, A.K., R.A. Bressan, S. Handa and P.M. Hasegawa, 198269514521Hare, P.D., W.A. Cress and J. van Staden,199950413434Hasegawa, P.M., R.A. Bressan, S. Handa and A.K. Handa,198419371377Heyser, J.W. and M.W. Nabors,1981Nicotiana tabacum var. Samsum) grown on sodium chloride.]]>67720727Heyser, J.W., T.A. Dykes, K.J. DeMott and M.W. Nabors,198329175182Hohl, M. and P. Schopfer,199195716722Lutts, S., J.M. Kinet and J. Bouharmont,1996Oryza sativa L.) callus cultures.]]>149186195Murashige, T. and F. Skoog,196215473497Newton, R.J., S. Sen and J.D. Puryear,1989Pinus taeda L.) callus.]]>134746750Oard, J.H. and J.N. Rutger,198828565567Reddy, P.C. and S.N. Vajranabhaiah,1996Oryza sativa L.) calli.]]>9143147Reddy, P.C., S.N. Vajranabhaiah and A.H. Prakash,199471217Rueb, S., M. Leneman, R.A. Schilperoort and L.A.M. Hensgens,1994Oryza sativa L.).]]>36259264Santos-Diaz, M.S. and N. Ochoa-Alejo,1994962129Tschaplinski, T.G., G.M. Gebre, J.E. Dahl, G.T. Roberts and G.A. Tuskan,1995Populus clones cultured on nutrient medium containing polyethylene glycol.]]>2514251433Aspinall, D. and L.G. Paleg,19811981pp: 206-240pp: 206-240Newton, R.J., S. Bhaskaran, J.D. Puryear and R.H. Smith,198681626629Handa, A.K., R.A. Bressan, S. Handa and P.M. Hasegawa,198680938945Santos-Diaz, M.S. and N. Alejo-Ochoa,199437118