Canopy attachment position influences metabolism and peel constituency of European pear fruit

Authors: SERRA, SARA - Washington State University; SULLIVAN, NATHANAEL - Former ARS Employee; Mattheis, James; MUSACCHI, STEFANO - Washington State University; Rudell, David

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2018
Publication Date: 12/18/2018
Citation: Serra, S., Sullivan, N., Mattheis, J.P., Musacchi, S., Rudell Jr, D.R. 2018. Canopy attachment position influences metabolism and peel constituency of European pear fruit. Biomed Central (BMC) Plant Biology. 18:364. https://doi.org/10.1186/s12870-018-1544-6.
DOI: https://doi.org/10.1186/s12870-018-1544-6

Interpretive Summary: Proper postharvest handling is critical for provision of consistently ripened, high quality pears to consumers. Different positioning of pears within a tree canopy can lead to inconsistent ripening and quality throughout the cold chain. We determined how extensive these differences are using comprehensive evaluation of chemical changes in pear peel during long term storage. Chemistries impacted included those expected to be associated with quality such as color, aroma, and sweetness but also included those linked with protection of the peel surface and risk of postharvest browning disorders. Results demonstrate how tree position could influence how individual fruit react to almost every management and distribution decision in the entire cold chain. Most revealing is the influence of tree position on the final quality of the ripe product where inconsistency can mean reduced consumer preference and loss of overall shelf space. Results point to chemicals associated with tree position that could be potential targets for non-destructive fruit sorting to reduce inconsistency of batches before entering the cold chain.

Technical Abstract: Background: Inconsistent pear fruit ripening resulting from variable harvest maturity within tree canopies can contribute to postharvest losses through senescence and spoilage that would otherwise be effectively managed using crop protectant and storage regimes. Because those inconsistencies are likely based on metabolic differences, non-targeted metabolic profiling peel of ‘d’Anjou’ pears harvested from the external or internal canopy was used to determine the breadth of difference and link metabolites with canopy position during long-term controlled atmosphere storage. Results: Differences were widespread, encompassing everything from expected distinctions in flavonol glycoside levels between peel of fruit from external and internal canopy positions to increased aroma volatile production and sucrose hydrolysis with ripening. Some of the most substantial differences were in levels of triterpene and phenolic peel cuticle components among which acyl esters of ursolic acid and fatty acyl esters of p-coumaryl alcohol were higher in the cuticle of fruit from external tree positions, and acyl esters of a-amyrin were elevated in peel of fruit from internal positions. Possibly the most substantial dissimilarities were those that were directly related to fruit quality. Phytosterol conjugates and sesquiterpenes related to elevated superficial scald risk were higher in pears from external positions which were to be potentially rendered unmarketable by superficial scald. Other metabolites associated with fruit aroma and flavor became more prevalent in external fruit peel as ripening progressed and, likewise, with differential soluble solids and ethylene levels, suggesting the final product not only ripens differentially but the final fruit quality following ripening is actually different based on the tree position. Conclusions: Given the impact tree position appears to have on the most intrinsic aspects of ripening and quality, every supply chain management strategy would likely lead to diverse storage outcomes among fruit from most orchards, especially those with large canopies. Metabolites consistently associated with peel of fruit from a particular canopy position may provide targets for non-destructive pre-storage sorting used to reduce losses contributed by this inconsistency.