Freezing Tolerance Mechanisms of Suspension Cells Derived from Alfalfa Cultivars Differing in Fall Dormancy. N.E. Kalengamaliro, J.A. Gana, S.M. Cunningham, and J.J. Volenec Department of Agronomy, Purdue University, West Lafayette, IN 47907-1150 A major factor limiting persistence of alfalfa in the Northern US is poor winter hardiness.
Cold acclimation increases tolerance of fall dormant alfalfa to subsequent freezing temperatures.
Our objective was to determine if suspension cells derived from cultivars exhibiting contrasting fall dormancy reaction also differed in freezing tolerance. 5262 is a fall dormant, winter hardy cultivar, whereas 5929 is a nondormant, nonhardy cultivar. Sugar concentrations increased 31-fold during cold acclimation of 5262 when compared to cold acclimated 5929 cells. Starch concentrations of acclimated 5262 cells also were greater than those of acclimated 5929 cells. High levels of a -amylase activity occurred in cells derived from 5929 irrespective of temperature.