Comparison of the expression of chlorophyll-degradation-related genes during ripening between stay-green and yellow-pear cultivars

- We examine the molecular mechanism of chlorophyll degradation of pear fruit.
- 'Le Lectier' pears turned yellow with concomitant loss of chlorophylls.
- Chlorophyll content in 'La France' pears did not change significantly.
- Several genes might be related to the stay-green characteristics.

Chlorophyll degradation is a key component of the changes in pigment composition that typically occur in fruit peel at the onset of ripening. In this study, two pear cultivars, which are different in color development patterns, were used to clarify the molecular mechanism of chlorophyll degradation during ripening. Fruit was harvested and stored at 1 °C for cold treatment and then transferred to 20 °C for ripening. 'Le Lectier' pears turned yellow during ripening with concomitant loss of chlorophylls a and b, and carotenoids. In contrast, 'La France' pears stayed green even when fully ripe. In this cultivar, chlorophyll and carotenoid contents did not change significantly. Ethylene was normally produced in 'La France' pears, indicating that the stay-green characteristics do not result from an inability of the fruit to produce ethylene. The expression levels of the chlorophyll degradation related genes, including chlorophyllase 1, pheophorbide a oxygenase, non-yellow coloring 1, and NYC1-like were lower in 'La France' than those in 'Le Lectier' pears. Suppression of these genes in 'La France' pears might be related to the stay-green characteristics when fully ripened.