Phenolic and anthocyanin content characterization related to genetic diversity analysis of Solanum tuberosum subsp. tuberosum Chilotanum Group in southern Chile

Abstract

The potato (Solanum tuberosum L) is one of the four most important crops worldwide in production and consumption. It originated from South America along the Andes, where six hotspots of diversity known as subcenters of origin are described from Venezuela to Chiloe Island in Chile, and where the greatest diversity of potatoes in the world is found. Today, the use of ancestral genetic resources has gained significant relevance, recovering and producing foods with a greater nutrient content and beneficial to human health. Therefore, native potatoes possess a set of characteristics with great potential for use in potato breeding guided primarily to produce better feed, especially potatoes of the Chilotanum Group that are easily crossed with conventional varieties. The primary objective of this study was to evaluate 290 accessions of S. tuberosum subsp tuberosum belonging to the Chilotanum Group using a set of molecular markers and correlate them to its phenotypic traits for future use in breeding programs. For this purpose, 290 accessions were analysed through 22 specific microsatellites described previously, correlating them with flesh and skin colour, total phenolic content, and anthocyanin content. A division into groups considering all the 290 accessions resulted in two clusters using STRUCTURE analysis and seven different genetic clusters using UPGMA. The latter exhibited common phenotypic characteristics as well as anthocyanin content, strongly supporting a correlation between phenotypic traits and the genetic fingerprint. These results will enable breeders to focus on the development of potatoes with high polyphenol and anthocyanin content.

Keywords: Chilotanum Group; SSR; Solanum tuberosum; anthocyanin; diversity analysis; native potatoes; total phenolic content.

Figure 1

Characterization and distribution of accessions in terms of primary (main) or secondary color of the tuber skin (upper panel) and according to primary or secondary flesh color (lower panel).

Figure 2

Concentration of total phenolic compounds (µg Gallic acid/g DW) determined by Folin–Ciocalteu method (upper panel) and total anthocyanin content (µg/g of cyanidin 3-glucoside) were extracted in ethanol acidified using Abdel-Aal and Hucl (1999) method (lower panel) in the 290 accessions of the Potato GenBank at the UACh.

Figure 3

Correlation between (A) the total phenolic content (TPC) and (B) anthocyanin content, related to tuber flesh colors with the CIP score.

Figure 4

Anthocyanin profile in tubers for accession groups with different flesh color. The number of accessions for each group represented in the figure is cream-yellow = 2; cream/red = 1; white-yellow/pink = 6; cream-light yellow/purple = 4; pink/cream = 7; and purple/cream = 5. The X axis shows the combinations of primary and secondary colors in the flesh according to how accessions were grouped. Images show one accession representative of each group.

Figure 5

(A) Plot for Delta K at different K values. Higher value at K = 4 with Delta K = 14. (B) Bar plot of STRUCTURE assuming K = 4 subpopulations showing 2 clusters of genotypes.

Figure 6

Hierarchical clustering of varieties. (A) The DendroUPGMA server was used to calculate the Dice similarity matrix coefficients between accessions using the UPGMA method to calculate an agglomerative hierarchical clustering representation of mean genetic relatedness within each species represented in a dendrogram with regard to allelic profiles contained within the 22 SSRs. (B) Cophenetic correlation coefficients of UPGMA clusters, values close to 1 represent the usefulness of the clustering method, and values between 0.6 and 1 are those with the highest correlation. (C) Total number of accessions distributed in the different genetic subgroups determined in this study.

Figure 7

Relationship between genotype and phenotype within the accessions considering the genotypes above the respective mean values in (A) TPC, (B) anthocyanin content and the 290 accessions assigned to clusters A–G.