Molecular Approaches to Low-Temperature-Stress Tolerance In Maize”.

Cold temperatures limit the geographical areas of maize cultivation and restrict the duration of its growth.  Chilling temperatures reduce photosynthetic efficiency of the plant, and when combined with high light, this can lead to photo-oxidative damage.  Freezing temperatures lead to severe yield reduction and can even cause complete crop failure.  In attempting to understand the physiological and molecular basis for tolerance to low-temperature stress in maize, we conducted comparative evaluation of maize germplasm with tolerance or susceptibility to low-temperature stress.  Differential changes in gene- and protein-expression profiles were identified during exposure to chilling and freezing temperatures.  Shared pathways for cold, drought and salt tolerance were also recognized.  The resulting information was used to generate transgenic plants for potential tolerance to low-temperature stress.  Select transgenes have been evaluated in Arabidopsis, maize, wheat or barley for tolerance to either chilling or freezing temperatures, and the results of this evaluation will be discussed. 

Acknowledgement:  We wish to acknowledge The International Maize and Wheat Improvement Center (CIMMYT) for seeds of the tropical highland line, CML349.