MODIFICATION OF SPECIFIC RIPENING PROTEINS BY LOW TEMPERATURE STORAGE OF CHERIMOYA (ANNONA CHERIMOLA, MILL.) FRUITS

The short ripening period of harvested cherimoya fruit (5-6 days) is the major factor limiting its production and marketing (Brown et al., 1988). Low temperature storage has been applied to extend the ripening process, but symptoms of chilling injury (Wang, 1990) which usually develop below 8C impair fruit quality.
Control of this deleterious effect might ensure normal fruit ripening following storage.

Studies on different fruits have shown that certain physiological and biochemical changes are induced by exposure to low temperatures (Wang, 1990). These changes may be related to either an accumulation or a decrease in specific mRNAs and proteins in response to cold (Watkins et al., 1990). Although much physiological work has been performed on postharvest Annona fruit (Wills et al., 1984; Brown et al., 1988), there have been no reports of protein modifications associated with low temperature storage.
We have studied the relationship between two physiological parameters (respiration rate and ethylene production) and the changes in protein pattern of cherimoya fruit caused by low temperature storage.

Gas chromatography determinations have shown that CO₂ and C₂H₄ production patterns of cherimoya fruit (Annona cherimola, Mill. cv.
Fino de Jete) are temperature dependent.
The production of CO₂, reached two peaks around the 1st and 5th day of storage at 20C. By contrast, storage at 10, 8, and 6C showed reduced CO₂ levels.
The single peak in C₂H₄ production, in turn, occurred around the 3rd day of storage, was retarded and modified under storage at 10C. Ethylene levels decreased significantly at 8C and were nearly undetectable at 6C. These results are consistent with physiological data obtained in this and other Annonaceous fruits (Kosiyachinda and Young, 1975; Bruinsma and Paull, 1984; Wills et al., 1984; Brown et al., 1988; Batten, 1990), suggesting a general decrease in metabolic activity of this fruit during low temperature storage.

In order to determine changes in protein pattern, we have carried out electrophoretic analyses of proteins from fruits at three relevant ripening stages: a) first respiration peak, b) maximum ethylene production, and c) second respiration peak.
These protein patterns were compared to those obtained from fruits stored at 6, 8 and 10C. A highly efficient extraction procedure was developed to obtain total proteins from pulp tissues (Montero et al., unpublished results).

SDS-PAGE analysis showed a preferential accumulation of some specific polypeptides at the maximum ethylene production ripening stage.
Major differences were observed in polypeptides of 21, 23, and 31 kDa.
While absent during storage at 6 and 8C, these polypeptides appeared at 10C also concomitant with the corresponding ethylene production peak, although they reached lower concentrations than at 20C. A more sensitive double Coomassie blue-silver stain showed relevant accumulation of polypeptides in unripe fruit (24 and 33 kDa, as well as in fruit at the first (26 and 27 kDa) and second (34 kDa) respiration

Physiological Basis of Postharvest Technologies

L.M. Montero, J.P. Zamorano, J.L. de la Plaza, C. Merodio

https://doi.org/10.17660/ActaHortic.1993.343.62