Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 12, 2008
Publication Date: January 16, 2008
Citation: Chen, J., Xu, W., Burke, J.J. 2008. Characterization of high temperature tolerance mechanisms in Maize[abstract]. Plant and Animal Genome Conference. San Diego, California. January 12-16, 2008. Technical Abstract: High temperature, combined with drought, is a major environmental stress that greatly depresses yield and reduces the quality of maize plants in the Southern Plains area. Maize inbred lines vary greatly in thermotolerance based on field observations. Two contrasting maize inbred lines, B76, heat-tolerant and B106 heat-sensitive, were chosen to conduct detailed physiological, biochemical, and gene expression profiling analyses to identify mechanisms accounting for the thermotolerance between the two lines. Photosynthetic capability measured by chlorophyll fluorescent yield started to decrease in B106 at 33-34'C, whereas no significant reduction in fluorescence yield was observed in B76 until temperature was increased to 37 to 38ºC. Phenotype and electrolyte leakage results revealed that high temperatures caused cell injury and eventually cell death in young leaf tissue of B106, indicating that the cell membranes of B106 are more sensitive to high temperature stress than those of B76. Lipid profiles revealed that B106 contained an extremely low amount of phosphatidic acid (PA). In addition, among all lipids analyzed, PA was the only lipid that was induced significantly by heat stress. Recent studies indicate that PA acts as a lipid mediator and is involved in multiple signal transduction pathways and membrane trafficking. It also plays regulatory roles in plant response to ABA, biotic and abiotic stresses. The close correlation between thermosensitivity and level of PA in the two inbred lines and the increase in PA levels in response to high temperatures suggest that PA plays a critical role in thermotolerance in maize.