Survey of ‘d’Anjou’ Pear Metabolic Profile Following Harvest from Different Canopy Positions and Fruit Tissues

Abstract

<jats:p>Physiological variability within a large canopy ‘d’Anjou’ tree results from agronomic and environmental factors. Fruit diversity within the canopy was surveyed using metabolic profiling to identify metabolism associated variability within the canopy. Different portions of the same fruit were evaluated to determine future precise sampling protocols for metabolic profiling of pear. We expected that the metabolic profile of the peel and cortex would be diverse and these differences would highlight specific metabolic pathways as influenced by these conditions. Another focus of this work was developing an untargeted metabolic profiling protocol tailored for pear using a combination of extractions coupled with GC-MS and LC-MS analysis. ‘d’Anjou’ pear fruit harvested from two different zones of trees trained to an open vase canopy were maintained at room temperature for 24 days to observe any changes in external phenotype and metabolic profile. Fruit harvested from the internal canopy were greener as also indicated by high Index of Absorbance Difference (I<jats:sub>AD</jats:sub>) and hue angle values. Metabolic profile differences between tree positions were widespread and included metabolites from many pathways beyond those associated with peel color. In addition, peel metabolic profile was different depending upon the tissue position (top vs. bottom) sampled from the pears. Specific pathways altered by tree position included those potentially linked to fruit quality and ripeness, including malic acid and aroma volatile (V) levels, as well as light environment, such as flavonol glycoside levels. Present results warrant further future work targeting these changes over time during storage and alongside fruit quality analyses to validate the impacts on ripening and tree factors. In addition, outcomes indicate tissue sampling strategies require consistency with respect to the region of the pear fruit sampled for metabolomics.</jats:p>

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

“…An earlier report [11] presents the scope of our profiling strategy which employs zwitterionic hydrophilic interaction chromatography to estimate not only sugars, organic acid, and amino acids but, also, relatively polar, non-volatile metabolites, including providing a more thorough assessment of phenylpropanoid pathway products particularly more prominent in peel than cortex [32]. Our analysis detects and has been used to identify, with varying degrees of confidence, an array of compounds included in earlier reports including quercetin and isorhamnetin glycosides, hydroxy and methoxy cinnamic acid esters, arbutin, and flavan-3-ols (Additional files 1 and 2: Tables S1 and S2; [28, 33, 34]).…”

“…Orchard temperature, which may be expected to be different between external and more shaded portions of the tree as well as different sides of the fruit, can also substantially influence postharvest behavior [10]. Our preliminary survey of ‘d’Anjou’ metabolites without cold storage indicated that multiple pathways may be influenced by tree position including those likely related to light exposure such as flavonol glycosides, chlorophyll levels, and potentially quality-related metabolites including sugars [11]. This study was limited yet warranted more comprehensive long-term storage comparisons using non-targeted metabolic profiling to determine the scope of processes altered by tree position.…”

Postharvest Dry Matter and Soluble Solids Content Prediction in d’Anjou and Bartlett Pear Using Near-infrared Spectroscopy

“…Trees from Orchard 2 were planted in the 1970s at a spacing of 6 • 6 m (278 trees/ha). In this block, fruit were harvested from extreme internal and the external position of the canopy based on light interception to capture a broad range of fruit materials that characterize those large canopies (Rudell et al, 2017). Fruit intercepting more than 70% light were considered external, less than 30% were considered internal.…”

Targeted Metabolic Profiling Indicates Apple Rootstock Genotype-Specific Differences in Primary and Secondary Metabolite Production and Validate Quantitative Contribution From Vegetative Growth

“…Additionally, samples in the fourth experiment ( Contribution of live plant metabolic activity to rhizodeposits , detailed below) were also analyzed with an LC-MS method using a zicpHILIC column for quantifying organic acids, amino acids, sugars, and other polar compounds as described in Rudell et al ( 2017 ).…”

“…Trees were placed whole in a drying oven for subsequent dry weight correction for rhizodeposit metabolites. Rhizodeposits were analyzed for both untargeted phenolic compounds per the LC-MS phenolic method as described above and other untargeted polar compounds using the zicpHILIC method detailed in Rudell et al ( 2017 ).…”