Pak. J. Bot., 40(6): 2541-2552, 2008. | Back to Contents | ||||
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Updated: 09-07-09 | ||||
EFFECT OF OSMOTIC STRESS ON PROLINE ACCUMULATION, PHOTOSYNTHETIC ABILITIES AND GROWTH OF SUGARCANE PLANTLETS (SACCHARUM OFFICINARUM L.)
Suriyan Cha-um* and Chalermpol Kirdmanee
Abstract: Disease-free sugarcane plantlets derived from meristem cutting were photoautotrophically grown on the MS medium and subsequently exposed to 0, 100, 200, 300 or 400 mM mannitol for 7 days. Osmotic pressure in the culture medium was increased with increase in mannitol concentration, causing low water use efficiency (WUE) (r2 = 0.88) and chlorophyll degradation (r2 = 0.92). Chlorophyll a (Chla), chlorophyll b (Chlb) and total carotenoids (Cx+c), concentrations in the osmotic stressed leaves decreased, especially in 400 mM mannitol treatment, degrading 44, 81 and 72%, respectively when compared to control. In contrast, proline content in osmotic stressed plantlets was accumulated and peaked at 2,236.75 mmol g-1 FW in 300 mM mannitol treatment. The WUE and chlorophyll degradation were correlated with maximum quantum yield of PSII (Fv/Fm) (r2 = 0.75) and photon yield of PSII (FPSII) (r2 = 0.83), respectively. The Fv/Fm and FPSII in drought acclimatized plantlets decreased, when non-photochemical quenching (NPQ) reached. The reduction of FPSII was positively related to net-photosynthetic rate (NPR) (r2 = 0.85) as well as the proline content and NPQ (r2 = 0.81). The NPR, stomatal conductance (Gs) and transpiration rate (E) in osmotic stressed plantlets were significantly dropped, leading to growth reduction (r2 = 0.95). The basic knowledge of osmotic stressed responses may further be applied as effective indices for drought tolerance in sugarcane breeding program.
National Center for Genetic Engineering and Biotechnology (BIOTEC) National Science and Technology Development Agency (NSTDA) 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand |
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