Expression profile of EXP, Succ-CoA and ALDH genes in soursop (Annona muricata L.) fruits during ripening in response to refrigeration conditions

Soursop (Annona muricata L.) is a climacteric fruit characterized by its rapid softening. Although many studies have improved the understanding of postharvest shelf life in soursop, the expression of genes involved in the loss of flesh firmness, organic acids and acetaldehyde metabolism are less well understood. We evaluated the expression profile of genes related to fruit softening, tricarboxylic acid cycle and acetaldehyde metabolism during ripening of soursop fruit stored at 28 +/- 2 degrees C and 15 +/- 2 degrees C. The fruit stored at 15 +/- 2 degrees C prolonged the postharvest shelf life up to 9 days and showed higher firmness at 3 days compared to those stored at 28 +/- 2 degrees C. Moreover, the postharvest storage at 15 +/- 2 degrees C induced the expression of expansin (EXP), succinyl CoA ligase (Succ-CoA) and aldehyde dehydrogenases (ALDH) genes at 3 days. On the other hand, we recorded an increase in the gene expression of EXP and Succ-CoA at 6 days in fruit stored at 28 +/- 2 degrees C. Based on the different gene expression patterns, we concluded that the postharvest storage at 15 +/- 2 degrees C triggers the expression of EXP, Succ-CoA and ALDH genes at the early stages of soursop ripening. This suggests their role in cell disorganization, organic acids, acetaldehyde metabolism as well as in response to refrigeration during ripening.