Sorting Genes Controlling Freezing Stress Resistance

Abstract

Factors that contribute to a plant’s ability to survive winter or a frost episode include: a) freezing tolerance, i.e. tolerance of stresses associated with extracellular ice; b) freezing avoidance, i.e. ability to prevent ice formation; c) capacity to cold acclimate, i.e. ability to increase freezing tolerance and/or avoidance upon exposure to low (usually non-freezing) temperatures; and d) speeds of acclimation and deacclimation. We have demonstrated that freezing tolerance in the nonacclimated state and capacity to cold acclimate are under independent genetic control. In support of these genetic studies we have found that distinct plasma membrane lipids are associated with freezing tolerance in the nonacclimated state, and these lipids are different than those that are associated with increase in freezing tolerance during cold acclimation. We have also found evidence for genetic variations for the speeds of cold acclimation and deacclimation. In addition we have found that it is possible to independently select for freezing tolerance and freezing avoidance and then recombine them to get desired plants. Our results not only provide insight into molecular mechanisms of freezing stress resistance, but also provide avenues for improving frost/winter survival of crop plants.