Characterization of the expression of an oxygenase involved in chilling-induced damage in citrus fruit
María J. Gosalbes, Lorenzo Zacarías and María T. Lafuente ,
Postharvest Biology and Technology Volume 33, Issue 3 , September 2004, Pages 219-228
2004
บทคัดย่อ
Exposure of chilling-sensitive citrusfruitto low, non-freezing, temperatures may end up withchilling injury(CI), manifested as necrotic areas in the peel. In this study, we have examined changes in the expression of a gene isolated from the flavedo of ‘Fortune’ mandarin, showing sequence homology with oxygenase genes in other plants, in the response of citrusfruitto chilling. Low temperature storage (1.5 °C) caused a transient increase in CIOX (for chilling-induced oxygenase) mRNA accumulation in the flavedo offruitof the chilling-susceptible ‘Fortune’ mandarin but this gene was not activated in ‘Hernandina’fruit,which belongs to the class of chilling-tolerant mandarins. CIOX transcript accumulated in ‘Fortune’ mandarins when CI symptoms were initiated, to sharply decrease thereafter although chilling symptoms continuously increased duringfruitstorage at 1.5 °C. Moreover, it has been shown that applying a high concentration (1 mM) of abscisic acid (ABA) and conditioning thefruitfor 2 days with 10L L-1 ethylene, which sharply increases ABA levels in the flavedo, increased chilling-induced damage in ‘Fortune’ mandarins and accelerated the transient increase in CIOX mRNA accumulation. By contrast, increasing ABA levels did not cause peel damage in ‘Hernandina’ mandarins kept at 1.5 °C or in ‘Fortune’ mandarins stored at a non-chilling temperature (12 °C) and failed to induce CIOX mRNA accumulation. Thus, this gene appears not to be regulated by ABA but its expression was favored by the combination of low temperature and ABA, conditions that enhanced chilling damage in chilling-susceptible citrusfruit.These results indicate that CIOX expression may serve as a molecular marker for chilling susceptibility and/or damage in citrusfruit.