Summary
The theoretical consequences of using inbred testers for an F2 and F∞ triple test cross in which the allelic differences are associated as opposed to dispersed are described for four situations of increasing complexity that arise from the presence of non-allelic interaction and a linkage disequilibrium either singly or jointly. The theoretical expectations are confirmed by analyses of two F∞ triple test crosses on a random sample of 60 inbred families from the cross of varieties 2 and 12 of Nicotiana rustica for which the inbred testers are the two varieties and the two extremes of the 60 inbred families in respect of final height and flowering time.
In the presence of non-allelic interaction and a linkage disequilibrium between interacting or non-interacting genes, the expectations of the mean squares in the analysis of variance of a triple test cross and of the estimates of the additive genetic, dominance and epistatic components obtained from them, differ characteristically according to whether a dispersed or an associated pair of inbred testers have been used. The pattern of the differences can, therefore, be used to detect these complex effects.
Comparison of the corresponding mean squares and estimates from the two F∞ triple test crosses shows that non-allelic interactions and a linkage disequilibrium are present but there is no significant evidence that the disequilibrium involves interacting genes.
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Pooni, H., Jinks, J. Comparison of associated and dispersed testers in the triple test cross. Heredity 50, 73–83 (1983). https://doi.org/10.1038/hdy.1983.8
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DOI: https://doi.org/10.1038/hdy.1983.8
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