Abstract
BackgroundPotato frying color is an agronomic trait influenced by the sugar content of tubers. The candidate gene approach was employed to elucidate the molecular basis of this trait in Solanum tuberosum Group Phureja, which is mainly diploid and represents an important genetic resource for potato breeding. The objective of this research was to identify novel genetic variants related with frying quality in loci with key functions in carbohydrate metabolism, with the purpose of discovering genetic variability useful in breeding programs. Therefore, an association analysis was implemented with 109 SNP markers identified in ten candidate genes.ResultsThe analyses revealed four associations in the locus InvGE coding for an apoplastic invertase and one association in the locus SssI coding for a soluble starch synthase. The SNPs SssI-C45711901T and InvGE-C2475454T were associated with sucrose content and frying color, respectively, and were not found previously in tetraploid genotypes. The rare haplotype InvGE-A2475187C2475295A2475344 was associated with higher fructose contents. Our study allowed a more detailed analysis of the sequence variation of exon 3 from InvGE, which was not possible in previous studies because of the high frequency of insertion-deletion polymorphisms in tetraploid potatoes.ConclusionThe association mapping strategy using a candidate gene approach in Group Phureja allowed the identification of novel SNP markers in InvGE and SssI associated with frying color and the tuber sugar content measured by High Performance Liquid Chromatography (HPLC). These novel associations might be useful in potato breeding programs for improving quality traits and to increase crop genetic variability. The results suggest that some genes involved in the natural variation of tuber sugar content and frying color are conserved in both Phureja and tetraploid germplasm. Nevertheless, the associated variants in both types of germplasm were present in different regions of these genes. This study contributes to the understanding of the genetic architecture of tuber sugar contents and frying color at harvest in Group Phureja.
Highlights
Potato frying color is an agronomic trait influenced by the sugar content of tubers
Potato frying color is influenced by the sugar content of the tubers, because the hydrolysis of sucrose by invertase is the main source of the reducing sugars glucose and fructose, which are precursors of the Maillard reaction
The test of primers in 16 candidate genes allowed the sequence analysis of 12 amplicon sequences from ten genes in 108 Group Phureja accessions. This analysis led to the identification of 109 SNP markers, 44 of which were previously reported for tetraploid genotypes (Table 1)
Summary
Potato frying color is an agronomic trait influenced by the sugar content of tubers. The candidate gene approach was employed to elucidate the molecular basis of this trait in Solanum tuberosum Group Phureja, which is mainly diploid and represents an important genetic resource for potato breeding. It is of particular interest to identify variants of genes related to low tuber sugar content at harvest Such variants might be useful diagnostic markers in breeding programs aimed at improving frying quality. Association mapping is a strategy to study the genetic basis of complex traits that has advantages compared to linkage mapping for the discovery of diagnostic molecular markers [9]. Association mapping is advantageous because it analyses the effects of multiple alleles in a single experiment This is important for the efficient development of diagnostic molecular markers for traits of interest in breeding populations, with the purpose of contributing to the selection of genotypes with the desired qualities [12]
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