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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Genetic Improvement for Fruits & Vegetables Laboratory » Research » Publications at this Location » Publication #370275
Title: A low citric acid trait in cranberry: genetics and molecular mapping of a locus impacting fruit acidity

Author
item FONG, STEPHANIE - Rutgers University
item KAWASH, JOSEPH - Orise Fellow
item WANG, YIFEI - Ohio University
item JOHNSON-CIRCALESE, JENNIFER - Rutgers University
item Polashock, James
item VORSA, NICHOLI - Rutgers University

Submitted to: Tree Genetics and Genomes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2020
Publication Date: 5/4/2020
Publication URL: https://handle.nal.usda.gov/10113/6931907
Citation: Fong, S.K., Kawash, J., Wang, Y., Johnson-Circalese, J., Polashock, J.J., Vorsa, N. 2020. A low citric acid trait in cranberry fruit: genetics, molecular mapping and relationship to titratable acidity. Tree Genetics and Genomes. https://doi.org/10.1007/s11295-020-01432-4.
DOI: https://doi.org/10.1007/s11295-020-01432-4

Interpretive Summary: American cranberry fruit has a tart, acidic taste. The fruit acidity of cranberry is significantly higher than other freshly consumed fruits, e.g., tangerines and apples. This requires the addition of sugar to cranberry products to make them more palatable. The primary contributors to acidity in cranberry are citric (CA) and malic (MA) acids. The present study characterizes a cranberry with naturally low citric acid to reduce the amount of added sugar needed for palatability. Our results show that the low citric acid trait is controlled by a single recessive gene. We localized the causal gene to chromosome 1. Markers for the gene will be used to speed breeding for low citric acid in commercial cranberry varieties. Breeders will benefit form the markers. The food industry will be able to manufacture more healthful (reduced added sugar) products and consumers will ultimately benefit.

Technical Abstract: The fruit of American cranberry (Vaccinium macrocarpon Ait.) has a tart, acidic taste. Fruit acidity of cranberry is quantified as titratable acidity (TA) in citric acid equivalents and typically ranges from 2.3-2.5%. Commercially grown cranberries have significantly higher TA than other freshly consumed fruits, e.g, tangerines and apples, where TA is < 1.0%. The primary contributors to TA in cranberry are citric (CA) and malic (MA) acids. Levels of both CA and MA each reach approximately 8 mg/g fresh weight. The present study characterizes an undomesticated cranberry germplasm accession with significantly reduced TA (˜1.5%), resulting from low citric acid concentration of about (˜ 1 mg/g). When this accession was used in crosses, the observed phenotypic segregation indicated that the low citric acid trait is largely recessive and is consistent with single-locus Mendelian inheritance. Bulk segregant analysis, using simple sequence repeat (SSR) markers, identified an SSR marker within 1 cM of the low citric acid locus (cita). Homozygosity for the low acid SSR marker allele resulted in plants with the lowest citric acid levels. Biparental crosses, segregating for citric acid levels and using the linked SSR marker, indicated that the cita locus is multiallelic with a series of alleles having relative levels of partial dominance. Genotyping-by-sequencing identified additional single nucleotide polymorphisms (SNP) marker haplotypes which placed the cita locus on a distal end of chromosome 1. These markers will facilitate marker assisted selection for low citric acid phenotypes and the development of reduced-acidity cranberry cultivars.