Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 1999
Publication Date: N/A
Technical Abstract: The impact of water stress on the high temperature protection systems of cotton seedlings was evaluated. Polyethylene glycol (PEG) or partially- moistened vermiculite was used to establish a water stress of -0.4 MPa. Seeds were germinated in water-moistened paper towels and transferred to the water-stress condition 30 hours after imbibition. PEG-treated seedlings showed reduced hypocotyl elongation and root growth compared wit well-watered controls. Protein analysis with antibodies to two heat shock proteins showed that water-stressed seedlings maintained elevated HSP101 and HSP17.6 protein levels in the cotyledons long after their disappearance from well-watered seedlings. Characterization of the inherent and acquired thermotolerance levels determined by the Chl accumulation bioassay revealed no enhancement in seedling protection in the water-stressed seedlings despite the presence of HSP101 and HSP17.6 proteins. The delay in the loss of the seeds' HSPs in the water-stressed seedlings appears to track the loss of stored reserves. The findings of this study show that the presence of HSP101 and HSP17.6 proteins in cotton seedlings do not enhance acquired thermotolerance. Further research is needed to elucidate the evolutionary significance of HSPs found in seeds.