Fruit Characteristics and Quantitative Trait Loci (QTLs) Associated with Quality Traits in Blueberry (Vaccinium spp.)

Heeduk Oh, PhD Defense Seminar
October 4th, 2024, 1:00 pm
Under the direction of Dr. Massimo Iorizzo and Dr. Penelope Perkins-Veazie (Co-Chairs)
Department of Horticultural Science, NCSU

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 Oh.Abstr.pdf

In blueberry (Vaccinium spp.), improving fruit quality aspects of texture, taste/flavor, and shelf-life have become important breeding priorities for the industry. However, the lack of empirical data and DNA tools limits the selection for better fruit quality in breeding programs. To address this gap, four studies were conducted to associate fruit characteristics (sugars, organic acids, size, texture) with quality in terms of shelf-life (texture change, water loss, wrinkle) and sensorial texture and to dissect the genetic mechanisms controlling these fruit characteristics.

In the first two studies, fruit characteristics such as size, texture, and non-volatile chemical composition were used to predict shelf-life indicators and sensorial texture. Shelf-life indicators such as texture change, weight loss, and fruit wrinkling could be predicted using fruit characteristics measured at harvest (T₀) or two weeks (T₂) post-storage. The sensorial texture attributes, springiness, hardness, snap/crisp, force to grind, juiciness, and dissolvability, could be predicted with medium to high accuracy using texture parameters measured at the harvest.

As the physiochemical properties of total soluble solids (TSS) and titratable acidity (TA) play a critical role in consumer acceptance, TSS, TA, pH, sugars, and organic acids variation among 61 cultivars were followed over 0 to 6 weeks of storage. Larger variability was observed for parameters related to acidity, such as pH, TA, and total organic acid content. Changes over storage were minimal and cultivar-specific.

Elucidating the genetic basis underlying fruit quality traits could enable marker- or genomic-assisted selection strategies in breeding programs. Major-effect QTLs associated with pH, TA, citric acid, quinic acid, and shikimic acid were consistently detected across two years. Candidate genes for these QTLs were identified using comparative transcriptomic analysis. No QTL was detected for malic acid content, TSS, and sugar content, while a number of minor-effect QTLs were identified for texture- and size-related parameters.

These studies provide insights into the associations between fruit characteristics and quality traits in blueberry. Additionally, a framework is offered for breeding programs to utilize predictive models to enhance selection for improved shelf-life and desired sensory texture attributes. Moreover, our findings provide valuable information on the genetic basis that underlies fruit quality traits in blueberry, facilitating DNA-informed selection strategies in breeding programs.