Relationship between alcohol dehydrogenase activity and low-temperature in two maize genotypes, Silverado F1 and Adh1-Adh2- doubly null

We have examined the role of alcohol dehydrogenase (AD H, E.C.1.1.1.1) in chilling tolerance using maize (Zea mays L.) Adh1(-)Adh2(-) doubly null mutant. Adh1(-)Adh2(-) doubly null seedlings were found to have lowered survival rates compared to non-doubly null maize seedlings (Silverado F-1) when held at 2 degreesC for varying periods. Exposure to ethanol did not increase the chilling tolerance in either Silverado F-1 or Adh1(-)Adh2(-) doubly null. ADH activity in Silverado F-1 remained steady when held at 2 degreesC for up to 3 d. ADH 1 protein accumulation in chilled Silverado F, seedlings remained unchanged throughout the period of cold exposure. Chilling led to a significant inhibition of the P-H+-ATPase (E.C. 3.6.3.6) activity in Adh1(-)Adh2(-) doubly null, but minimal inhibition was seen in Silverado F-1. Though P-H+-ATPase activity in Adh1(-)Adh2(-) decreased, P-H+-ATPase protein levels remained constant during the chilling period. Levels of ATP slightly fluctuated in both types of seedlings during the duration of chilling. Lipid peroxidation levels in Adh1(-)Adh2(-) doubly null increased with chilling exposure, but not in the Silverado F-1. We suggest that ADH activity may play a role in chilling tolerance that is not related to maintenance of glycolysis and ATP production as has been observed during oxygen depravation. (C) 2004 Elsevier SAS. All rights reserved.