QTL and candidate gene mapping for polyphenolic composition in apple fruit

Abstract

BackgroundThe polyphenolic products of the phenylpropanoid pathway, including proanthocyanidins, anthocyanins and flavonols, possess antioxidant properties that may provide health benefits. To investigate the genetic architecture of control of their biosynthesis in apple fruit, various polyphenolic compounds were quantified in progeny from a 'Royal Gala' × 'Braeburn' apple population segregating for antioxidant content, using ultra high performance liquid chromatography of extracts derived from fruit cortex and skin.ResultsConstruction of genetic maps for 'Royal Gala' and 'Braeburn' enabled detection of 79 quantitative trait loci (QTL) for content of 17 fruit polyphenolic compounds. Seven QTL clusters were stable across two years of harvest and included QTLs for content of flavanols, flavonols, anthocyanins and hydroxycinnamic acids. Alignment of the parental genetic maps with the apple whole genome sequence in silico enabled screening for co-segregation with the QTLs of a range of candidate genes coding for enzymes in the polyphenolic biosynthetic pathway. This co-location was confirmed by genetic mapping of markers derived from the gene sequences. Leucoanthocyanidin reductase (LAR1) co-located with a QTL cluster for the fruit flavanols catechin, epicatechin, procyanidin dimer and five unknown procyanidin oligomers identified near the top of linkage group (LG) 16, while hydroxy cinnamate/quinate transferase (HCT/HQT) co-located with a QTL for chlorogenic acid concentration mapping near the bottom of LG 17.ConclusionWe conclude that LAR1 and HCT/HQT are likely to influence the concentration of these compounds in apple fruit and provide useful allele-specific markers for marker assisted selection of trees bearing fruit with healthy attributes.

Allelic Variation in Paralogs of GDP-l-Galactose Phosphorylase Is a Major Determinant of Vitamin C Concentrations in Apple Fruit

“…Only the QTL cluster on LG 9 (both parents) and on the cv Telamon LG 16 were specific for skin AsA concentrations. These regions on LG 9 and LG 16 have both been shown to contain major QTL for apple fruit polyphenolic contents (Chagné et al, 2007(Chagné et al, , 2012Khan et al, 2012). We have previously reported that the sunexposed (red) side of apples has higher anthocyanin and AsA concentrations and is more resistant to both biotic and abiotic stress than the shaded (green/ yellow) side (Davey et al, , 2007, and recently, Bulley et al (2012) demonstrated that transgenic fruits from tomato and strawberry with elevated AsA contents also had an approximately 50% larger polyphenolic pool.…”

In silico integration of quantitative trait loci for seed yield and yield-related traits in Brassica napus

“…Chagné et al (2012) found seven stable QTL clusters for the content of flavanols, anthocyanins, and hydroxycinnamic acids across two years (Chagné et al 2012). The most persuasive explanation for the phenomenon may be pleiotropism, or a closely-linked relationship between genes controlling the different traits.…”

QTL Analysis of Fruit Quality Traits in Peach [Prunus Persica (L.) Batsch] Using Dense SNP Maps

“…Biochemical and genetic studies on the mechanisms of action of phytochemicals provide a functional explanation of how and why a diet rich in fruits and vegetables is considered healthy (Russo et al, 2012). It is now believed that polyphenols may exert their beneficial action through the modulation of gene expression and the activity of a wide range of enzymes and cell receptors (Chagné et al, 2012, and references therein). However, the health effects of dietary antioxidant compounds depend on the total amount consumed and on their bioavailability.…”

“…However, the health effects of dietary antioxidant compounds depend on the total amount consumed and on their bioavailability. In addition, the content in antioxidant compounds can vary according to the location within the fruit (skin vs flesh), the stage of fruit maturity and even the location of the fruit within the tree (Chagné et al, 2012).…”