Characterizing the Profiles and Relationships of Sugars and Anthocyanins in Strawberry Cultivars and Selections from the North Carolina Breeding Program

In North Carolina, strawberry breeding objectives are to develop cultivars suitable for the climatic conditions encountered in the USDA hardiness zones 5 to  8 (western mountains to eastern shoreline) for use with the annual plasticulture production system.  The California varieties ‘Chandler’ and ‘Camarosa’ are still used for much of the short day acreage in the mid-South and genetic improvements in agronomic performance and fruit quality are industry requirements.  Fruit from the most promising North Carolina selections, and of ‘Chandler’, ‘Camarosa’, and ‘Benicia’ were harvested weekly from trials at the Piedmont Research Station in Salisbury, NC for three weeks during the spring of 2013.  At each harvest date, 10 marketable fruit per genotype (free from rot and malformations, over 15 g fruit weight and uniform ripeness determined by full color development) were combined for each weekly sample.  Fruit were freeze dried and fruit powder (excluding achenes) was used to determine sugar and flavonoid composition using HPLC equipped with diode array.  Of the 61 NC selections, 14 had 20% or more sucrose, as did ‘Chandler’ and ‘Camarosa’, and 17 selections had less than 10% sucrose.  The remaining 30 selections and ‘Benicia’ were intermediate in sucrose (10-20% of total sugars).   When expressed as a percentage of total sugars, percent sucrose was positively and linearly related to the total amount of sucrose.  However, the percent soluble solids content could not be used to predict percent sucrose in strawberry germplasm, or total sugar content.   Five selections per low, medium, and high sucrose category and of the three commercial cultivars were then used to determine anthocyanin content.  The anthocyanin pelargonidin-3-glucoside made up 88.7% of total anthocyanin when averaged across all selections, followed by 7.6% pelargonidin-3-rutionside, 0.7% pelargonidin-3-malonylglucoside and 3% cyanidin-3-glucoside.  Percent sucrose in strawberry was negatively correlated with pelargonidin-3-glucoside and pelargonidin-3-malonyl-glucoside. Strawberries low in sucrose were highest in pelargonidin-3-malonyl glucoside, pelargonidin-3-glucoside, and total anthocyanin. Our results indicate that North Carolina strawberry selections show a range of sucrose accumulation, which may be helpful in selection of flavor, and that sucrose content may play a role in strawberry anthocyanin profile.