Natural variation of sucrose, glucose and fructose contents in Colombian genotypes of Solanum tuberosum Group Phureja at harvest

BACKGROUND Potato frying quality is a complex trait influenced by sugar content in tubers. Good frying quality requires low content of reducing sugars to avoid the formation of dark pigments. Solanum tuberosum Group Phureja is a valuable genetic resource for breeding and for genetic studies. The sugar content after harvest was analyzed in a germplasm collection of Group Phureja to contribute to the understanding of the natural variation of this trait. RESULTS Sucrose, glucose and fructose genotypic mean values ranged from 6.39 to 29.48 g kg(-1) tuber dry weight (DW), from 0.46 to 28.04 g kg(-1) tuber DW and from 0.29 to 27.23 g kg(-1) tuber DW, respectively. Glucose/fructose and sucrose/reducing sugars ratios ranged from 1.01 to 6.67 mol mol(-1) and from 0.15 to 7.78 mol mol(-1) , respectively. Five clusters of genotypes were recognized, three of them with few genotypes and extreme phenotypic values. CONCLUSION Sugar content showed a wide variation, representing the available variability useful for potato breeding. The results provide a quantitative approach to analyze the frying quality trait and are consistent with frying color. The analyzed germplasm presents extreme phenotypes, which will contribute to the understanding of the genetic basis of this trait. © 2016 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.