MECHANISM OF COLD INJURY IN SWEET POTATOES II. BIOCHEMICAL MECHANISM OF COLD INJURY WITH SPECIAL REFERENCE TO MITOCHONDRIAL ACTIVITIES

摘要

Respiratory activity of sweet potato root tissues, stored at 0°(chilled) and 20°(control), was measured. The activity of the control sample remained approximately constant, while that of the chilled one declined sharply after about ten days of the treatment. Just before this time, DNP-stimulated respiratory activity began to drop in the chilled sample, but remained constant in the control.Oxidative and phosphorylative activities of mitochondria from the chilled tissues were compared with those from the control. Exactly as in respiration of the intact root tissues, a sharp decline in mitochondrial oxidative activity was found in the chilled tissue after about ten days of the treatment, but not in the control. In spite of the decrease in oxidative activity of mitochondria, the P/O ratio remained fairly constant throughout the storage. Protein nitrogen of mitochondria in root tissues also remained constant.Content of polyphenolic substances did not show any significant difference between the chilled and control tissue