ABSTRACT
Introduction .................................................................................................................................... 238 Genetic Approaches ....................................................................................................................... 239
Major Components (Traits) Controlling Resistance to Freezing Stress: Tolerance, Avoidance, and Acclimation Ability ......................................................................................... 239 Independent Genetic Control for Nonacclimated Freezing Tolerance and Capacity to Cold Acclimate ..................................................................................................................................240 Only a Limited Number of Genes Confer Cold Acclimation Ability in Potato .......................242 Mode of Inheritance of Frost Hardiness ...................................................................................242 Implications in Breeding for Frost Tolerance in Potatoes: Evidence That It Is Possible to Improve Both NAFT and CAC of Cultivated Potatoes ............................................................. 243 Independent Selection for Freezing Tolerance and Freezing Avoidance and Combining These Traits to Alleviate Frost Problems in Carrots ................................................................245 Evidence for Variability in Speeds of Cold Acclimation and Deacclimation among Related Genotypes .................................................................................................................... 247 Quantitative Trait Loci for NAFT and CAC .............................................................................248
Physiological Mechanisms/Approaches .........................................................................................248 Freeze-Thaw Stress in Nature ..................................................................................................248 Membrane Transport Alteration: Early Site of Injury ..............................................................249 Recovery of Injury .................................................................................................................... 251 Membrane ATPase Hypothesis ................................................................................................. 252 Mechanisms of Alteration in Functions of Plasma Membrane ATPase ................................... 253 Role of Calcium in Plant Responses to Abiotic Stresses .......................................................... 253 Mitigation of Enhanced Ion Efux Following Freeze-Thaw Stress by Extracellular Ca2+ .....254 Loss of Membrane-Associated Ca2+: A Key Process in Initiation and Progression of Freezing Injury ..........................................................................................................................254 Membrane Lipids as a Site of Perturbation during Freeze-Thaw Stress ..................................254 Specic Membrane Lipid Compositional Changes That Accompany Cold Acclimation and Increase in Freezing Tolerance ..........................................................................................256
