Allotetraploid segregation for single-gene morphological characters in quinoa (Chenopodium quinoa} Willd.)

Cytological evidence suggests the Andean grain crop quinoa is an allotetraploid, but in the few genetic studies which have been published a functionally diploid (disomic-monogenic) model has been assumed for segregation at individual loci in this species. In this study, controlled crosses using male sterile plants as female parents produced F1 and F2 generations segregating for three different single-gene morphological traits. Allelic segregation analysis revealed a range of F1 and F2 ratios indicative of both disomic-digenic and tetrasomic inheritance in two of these traits, as well as distorted F2 ratios suggesting erratic multivalent formation at meiosis. These results are consistent with allotetraploidy in quinoa, with functional alleles having been retained at some duplicate loci and at least some association occurring between homoeologous chromosomes. Tetrasomic segregation ratios observed in a minority of families may be due to reciprocal fragment exchange between homoeologues. The occurrence of tetraploid segregations at some loci in quinoa complicates breeding and genetic studies in the crop.