Mechanisms of plant acquisition of cold tolerance

Abstract

Low temperature is a major factor that limits plant growth and productivity.　I have identified the OsMKK6-OsMPK3 chilling stress sig­naling pathway in rice.　The OsMKK6-OsMPK3 pathway is regulated by redox and activated by Reactive Oxygen Species （ROS） generated by mild chilling stress.　Constitutive activation of the OsMKK6-OsMPK3 pathway resulted in tolerance against sever chilling stress.　I also identified that trehalose biosynthesis is activated in response to mild chilling stress.　Decreasing trehalose 6-phosphate level by OsTPP1 may contribute to chilling tolerance through regulating photosynthesis under chilling.　In contrast, winter crops such as wheat are chilling tolerant and develop freezing tolerance through cold acclimation （CA）.　Among many genes induced through CA, I focused our research on the cold shock domain proteins （CSPs）.　Arabidopsis AtCSP3 functions as an RNA chaperone and positively regulates freezing tolerance independent of the CBF regulatory pathway.　CA also induces a set of pathogenesis related proteins which may contribute to the defense against snow mold fungus during overwintering.