Correcting for Classification Errors when Estimating the Number of Genes Using Recombinant Inbred Chromosome Lines

Abstract

Techniques based on intercultivar chromosome substitution lines in wheat (Triticum aestivum L.) have been used to identify and locate the genes controlling quantitative traits on a specific chromosome. For a particular trait, the number of segregating loci affecting differences between two parental lines are generally determined by the frequency distribution of recombinant inbred chromosome lines (RICLs). Recombinant inbred chromosome lines are the inbred progeny of crosses between a chromosome substitution line and its parent cultivar. The determination of the presence and the number of segregating loci becomes difficult (i) when the distribution exhibits no clear discrete classes, (ii) when there is a considerable chance of misclassifying lines into parental and recombinant types, and (iii) when loci are linked. We describe an approach to estimate the number of segregating loci responsible for the difference between a chromosome substitution line and parental cultivar using the derived RICLs when classification errors are likely. We also discuss the effects of linked loci on the estimates. The method was used to estimate the number of genes on chromosome 3A controlling grain yield, kernels spike−1, kernel weight, spikes m−2, grain volume weight, plant height and anthesis date in wheat.