The fruit of American cranberry (Vaccinium macrocarpon Ait.) is known for its tart, acidic taste. Although some acidity is required for expressing fruit flavor, the high acidity of cranberry requires considerable amounts of “added-sugars” to make cranberry products palatable. Reducing acidity of cranberry would allow for less sugar to be added to cranberry products. In fruit, total acidity is quantified as titratable acidity (TA) in citric acid equivalents and typically ranges from 2.3 to 2.5% in cranberry. This study characterized the genetics of a low acid trait (TA≈1.5%), due to lower citric acid (~ 2 mg/g fresh weight), identified in an undomesticated cranberry germplasm accession. To determine the inheritance of this trait, this accession was used in a series of crosses. The progeny of these crosses exhibited phenotypic segregation consistent with single-gene Mendelian inheritance, with the low citric acid trait being largely recessive. Bulk segregant analysis using simple sequence repeat (SSR) markers identified two SSR markers within < 1 cM that co-segregated with the low citric acid trait. Genotypic variation indicated that the locus, referred to as CITA, was multi-allelic with a semidominant hierarchy of alleles. Further fine mapping, through genotyping-by-sequencing, identified single nucleotide polymorphisms (SNPs) that placed the CITA locus on a distal end of chromosome 1. Competitive allele-specific PCR (KASP) assays generated based on selected SNPs, in combination with the SSR markers identified, will facilitate marker-assisted selection (MAS) for low citric acid phenotypes in cranberry. Utilization of MAS will accelerate the development of reduced acidity cranberry cultivars.

美国蔓越莓（越桔宏果）的果实Ait。）以其酸的酸味而闻名。尽管表达水果风味需要一定的酸度，但酸果蔓的高酸度需要大量的“加糖”才能使酸果蔓产品变得可口。降低酸果蔓的酸度可以减少向酸果蔓产品中添加的糖量。在水果中，总酸度以柠檬酸当量来量化为可滴定酸度（TA），在蔓越莓中通常为2.3％至2.5％。这项研究的特点是低酸性状（TA≈1.5％）的遗传学特征，这归因于未驯化的蔓越莓种质中的柠檬酸含量较低（〜2 mg / g鲜重）。为了确定该性状的遗传，在一系列杂交中使用了该种质。这些杂交的后代表现出与单基因孟德尔遗传一致的表型分离，低柠檬酸性状在很大程度上是隐性的。使用简单序列重复（SSR）标记的大量分离物分析确定了在<1 cM内与低柠檬酸性状共分离的两个SSR标记。基因型变异表明该基因座，称为CITA是具有等位基因等位基因的多等位基因。通过测序进行进一步的精细定位，确定了单核苷酸多态性（SNP），该位点将CITA基因座置于染色体1的远端。基于所选SNP的竞争性等位基因特异性PCR（KASP）分析方法与确定的SSR标记将有助于蔓越莓中低柠檬酸表型的标记辅助选择（MAS）。MAS的利用将加速酸度降低的蔓越莓品种的发展。