EFFECT OF LOW O2 ON THE INDUCTION OF THE ALTERNATIVE OXIDASE, AND CHANGES IN INVERTASE IN POTATOES AT CHILLING TEMPERATURES

in HortScience

It has been demonstrated previously that 1.5% 02 suppresses the rise in respiration and appreciably diminishes the accumulation of sugars associated with the transfer of potatoes to chilling temperatures. The temporal relationships between respiration and the capacities of the terminal mitochondrial oxidases, and between sucrose metabolism and invertase activity were studied in tubers kept in air and under 1.5% at 1° C. Chilling temperatures induced de novo synthesis of the alternative oxidase. Initially there was a close temporal relationship between rise in respiration and capacity of the alternative oxidase. With time the rate of respiration declined while the capacity of the AO continued to increase. Low oxygen inhibited by 94-97% the rise in the AO. Paralled with the rise in glucose and fructose there was an increase in invertase activity which increased by twofold after 20 days at 1°. Four isoforms of invertase were identified with PI values of 5.8, 5.6, 5.4 and 5.17 from chilled tubers. Low O2 suppressed the rise in invertase.

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