OSCILLATIONS OF RESPIRATION-RELATING GENE EXPRESSION IN POSTHARVEST CABBAGE HEAD UNDER DIFFERENT CONTROLLED ATMOSPHERE (CA) STORAGE REGIMES

Exposure of fresh horticultural crops to modified/controlled atmospheres (low O₂ and/or increased CO₂) within the range tolerated by each commodity reduces their respiration rate and cellular metabolisms. However, outside this range respiration and metabolism of fresh produce can be altered indicating a stress response. This stress can contribute to incidence of physiological disorders and increased susceptibility to decay. In order to understand the response behavior of cabbage under stress such as controlled atmosphere (CA) treatment, gene expression patterns in cabbage tissues which were held in nine regimes with different CO₂ and O₂ concentrations were examined at 24 or 48 h after the treatment. The differential increases in gene expression level of cabbage under CA treatment were clearly observed. Changing pattern of each gene also appeared to depend on different percentages of CO₂ and O₂. Obvious elevated gene expression were detected in the BoGAPDH (glyceraldehyde 3-phosphate dehydrogenase (GAPDH)-encoding gene), BoADH (alcohol dehydrogenase (ADH)-encoding gene), and BoCTS (citrate synthase (CTS)-encoding gene) at 24 h after the treatment. These genes reveal the close relationship to the CA practice. However, the expression of BoHXK1 and BoHXK2 (hexokinase (HXK)-encoding gene), and BoGDH (glutamate dehydrogenase (GDH)-encoding gene) was observed at low level during investigation period. Additionally, changes in sugar concentration during 2 days of this investigation seemed not to be influenced by CA treatment and gene expression.