Metabolic Acclimation in Winter Cereals by Interacting Low Temperature Stresses

Abstract

Overwintering crop plants are subject to an array of stresses before and during winter. This chapter is concerned with the effects of these stresses and their interactions on the survival of winter cereal plants and the ability of the crop to provide an adequate economic yield. Interactions influencing survival at low temperature have been studied in controlled environment simulations. Low temperature flooding (2°C) markedly reduces the cold hardiness of winter cereal seedlings, but simultaneously increases their tolerance to ice encasement at 1 °C. This constitutes a metabolic acclimation to severe hypoxia, and provides a valuable means to search for increased tolerance of ice encasement. Pre-ice flooding induces higher levels of ethanol and CO₂ production in plant crowns during subsequent ice encasement, together with higher activity of alcohol dehydrogenase and higher total adenylates and adenylate energy charge. We have been unable to demonstrate increased activity of the glycolytic kinases (PFK, PK), but the accumulated evidence indicates an increased flux through glycolysis during ice encasement as a result of pre-ice flooding. Several polypeptides unique to the flood-ice treatments of winter wheat have been revealed by ³⁵S-methionine labelling and image-analysis of 2-D electrophoretograms. Current work is examining the nature of the unique polypeptides to determine if they may be exploited as markers for ice tolerance.