and estimation of the copy number of P1 genes in the different high altitude landraces. Individual kernel images from the different high altitude landraces analyzed, B73 and P1-rr; A: Arrocillo Amarillo; B: Cacahuacintle; C: Confite Puneño; D: Conico Norteño; E: Mishca (white pericarp); F: P1-rr and G: B73. The determination of the P1 copy number was performed by quantitative PCR analysis. The P-rr allele was used as a reference, and the ACT-1 gene was used as control of DNA template. Genomic DNA was quantified and each reaction was normalized using the Ct values corresponding to the Act-1 transcript. Location of primers used in shown in Additional file 1: Figure S1B. All measurements were done in triplicate using biological replicates.