Metabolic profiling variations within D’Anjou pear fruit from different canopy positions

Authors: Rudell, David; Sullivan, Nathanael; Mattheis, James; MUSACCHI, STEFANO - Washington State University

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2017
Publication Date: 12/18/2017
Citation: Rudell Jr, D.R., Sullivan, N.L., Mattheis, J.P., Musacchi, S. 2017. Metabolic profiling variations within D’Anjou pear fruit from different canopy positions. HortScience. 52(11):1501–1510. https://doi.org/10.21273/HORTSCI12375-17.
DOI: https://doi.org/10.21273/HORTSCI12375-17

Interpretive Summary: European pear quality can be inconsistent within a single orchard, especially when trees are very large. Fruit inconsistency can result in a range of costs incurred by the producer including loss due to spoilage or postharvest disorders, less effective postharvest crop protectant application, and inconsistent ripening leading to consumer dissatisfaction. In this study, we account for some of these differences based on the differences in chemistry that can be attributed to various aspects impacting ripening rate, the eating quality and, potentially, storability of the fruit. There were large overall differences in peel chemistry based on the position on the tree where fruit grew on. Fruit grown on the outside of the tree were more yellow in appearance than those from the inside of the tree. As expected, differences of appearance were reflected by differences of overall peel chemistry. However, the differences were attributable to differences in not only ripening, but also exposure to light during growing. Our work here warrants more exhaustive studies of metabolism during the pear supply chain to identify why ripening is actually different so that better orchard systems and postharvest sorting strategies can be developed.

Technical Abstract: The characteristics of fruit ripening can contribute to the overall quality of the final product. European pear (Pyrus communis L.) ripening is impacted by a combination of cultural practices and storage conditions. One of the main pre-harvest factors affecting fruit maturity and ripening is fruit position within a tree canopy. Tree position can impact the overall metabolism associated with ripening and fruit flavor and quality. We expected that the metabolic profile would be different and these differences would highlight metabolism influenced by tree position. ‘d’Anjou’ pear fruit harvested from two different zones (internal and external) of trees trained to an open vase canopy were maintained at room temperature for more than 3 weeks to ripen. Both peel and cortex were also sampled from both the stem and calyx end of the fruit to account for any differences attributed to this factor. We evaluated fruit quality and employed multiple GC and LC-MS approaches accounting for metabolites of a wide range of polarity and volatility to track metabolic differences in external and internal fruit occurring alongside ripening. The peel of fruit harvested from the internal canopy was greener than the external fruit. Overall metabolism was different depending upon the fruit position. Overall metabolism was only different between stem and calyx in for peel emphasizing the importance of precise sampling to limit or account for this factor. Some differences in the metabolic profile from different canopy tissue are potentially linked fruit quality and ripeness including malic acid and aroma volatile levels, as well as light environment, such as flavonol glycoside levels. These metabolic profiles coincide with observed differences in peel color and fruit maturity as assessed by differential absorbance. Results indicate metabolism related to fruit quality is altered by tree position and warrant further work targeting these changes over time during storage to validate the impacts on ripening and tree factors that may result in these differences.