Changes in Respiratory Metabolism during Aging in Seeds and Isolated Axes of Soybean

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Cyanide-sensitive O_2 uptake was observed in the isolated embryonic axis of soybean [Glycine max L. merr. cv. 'Essex'] within 5 min after wetting and the O_2 uptake rate during the first h of imbibition was directly proportional to axis moisture content. Within 10 min after wetting, O_2 uptake was lower in aged low vigor (LV) axes than in high vigor (HV) axes imbibed either in water (LV axes sustain imbibition injury) or in 30% w/v polyethylene glycol (LV axes do not sustain imbibition injury). Mitochondria isolated from LV axes after 4- and 24-h imbibition were characterized by lower O_2 uptake, ADP:O, and respiratory control ratios relative to HV mitochondria. A plot of O_2 uptake vs temperature between 10 and 25℃ revealed a break in the slope between 13 and 16℃ for HV, but not LV, axes. Since LV axes sustained water uptake injury at all temperatures tested, whereas HV axes sustained chilling injury only below 16℃, the data indicate two temperature-O_2 uptake relationships: one for injured tissues and one for non-injured tissues. We conclude that deterioration per. se involves impairment of respiratory metabolism in the soybean embryonic axis. Chilling (10℃; HV and LV axes) and imbibitional (25℃; LV axes) injuries during the initial min of imbibition further disrupt respiratory metabolism and interfere with subsequent mitochondrial development and axis growth.
日本植物生理学会の論文