Callus growth and proline accumulation in response to polyethylene glycol- induced osmotic stress in rice, Oryza sativa L.
2002
Al-Bahrany, A.M. (King Faisal Univ., Hassa (Saudi Arabia). Dept. of Horticulture)
The 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 l-1. 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 l-1 PEG, but the inhibitory concentration was identified to be 200 g l-1. 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 1-1 PEG. This study serves as a precursor for genetic improvement efforts to enhance the tolerance of Hassawi rice to water stress.
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