Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 19, 2007
Publication Date: January 1, 2008
Citation: Obenland, D.M., Vensel, W.H., Hurkman, W.J. 2008. Alterations in protein expression associated with the development of mealiness in peaches. Journal of Horticultural Science and Biotechnology. 83(1):85-93. Interpretive Summary: Peaches become dry and mealy in texture as a result of cold storage, but the cause of this important storage disorder is poorly understood. Five proteins were identified that significantly differed in amount between peaches that had mealy flesh and those that remained juicy following 3 weeks of cold storage, and included proteins involved in basic metabolism and stress response. One of the proteins was found to be a key component in the ripening process and may be important in controlling the occurrence of mealiness in peaches. This finding will assist researchers in the eventual development of varieties of peaches that will remain juicy following long periods of cold storage.
Technical Abstract: Two-dimensional electrophoresis (2-DE) combined with mass spectrometry was utilized to identify proteins related to the development of mealiness in peaches. Five proteins were identified that significantly differed in amount between peaches that had mealy flesh and those that remained juicy following 3 weeks of storage at 5°C and subsequent ripening for 3 to 4 d at 23°C. Accumulation of ACC oxidase (ACO), a key enzyme of ethylene biosynthesis, decreased in amount in mealy peaches. Immunoblots reacted with ACO antibodies confirmed the 2-DE results and further showed that the relationship of ACO and mealiness also exists within individual fruit. Phosphoglycerate kinase, an enzyme in the glycolytic pathway, was reduced in amount in mealy fruit. In contrast, two heat shock proteins and hydroxymethylbutenyl-4-diphosphate synthase (also known as GCPE) increased in amount in mealy peaches. The results regarding ACO are of interest due to the known association of mealiness and ethylene and, given the regulatory effect of ethylene on cell wall degrading enzymes, suggest that loss of ACO expression during cold storage and subsequent ripening may be pivotal in the development of the disorder.