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 (ADH, 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 F₁) when held at 2°C 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 F₁ remained steady when held at 2°C for up to 3 d. ADH1 protein accumulation in chilled Silverado F₁ 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 F₁. 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 F₁. 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.