Hypoxic acclimation prevents avocado mesocarp injury caused by subsequent exposure to extreme low oxygen atmospheres

Avocado fruit (Persea americana Mill., cv. Hass), preclimacteric and ripening-initiated, were either hypoxically pretreated (HPT, 3% O(2) for 24 h) or exposed directly to I and 0.25% O(2) for 1-3 days (NHPT) at 20 degreesC. Low O(2) treatments resulted in fruit maintaining higher flesh firmness. Hypoxic acclimation of preclimacteric and ripening-initiated avocado fruit increased their tolerance to subsequent 0.25 and 1% O(2) levels, as assessed by visual quality attributes when the fruit returned to air. Hypoxic pre-treatment also produced a stronger expression of the anaerobically induced ADH isoenzymes than in NHPT avocado fruit that were subjected directly to I and 0.25% O(2) for 1-3 days at 20 degreesC. Thus, acclimation of avocado fruit to hypoxia resulted in a beneficial increase in tolerance to subsequent ultra-low O(2) treatments. (C) 2001 Elsevier Science B.V. All rights reserved.