Genetic length and interference in telo-substituted interchange heterozygotes of rye

Substituting one of the (sub)metacentric chromosomes of a simple interchange complex by the two corresponding telocentrics marks one of the unchanged arms, one of the interchange segments and one of the interstitial segments. When the two telocentrics can be distinguished and when only infrequently MI configurations are formed for which more than a single origin is possible, rather exact estimates of the frequency of occurrence of chiasmata in the six segments can be obtained. When the two telocentrics can not be distinguished and in addition the frequency of MI configurations with more than one possible origin is not negligible, the analysis is more complex. With some previous knowledge of the interchange and some simplification an acceptable simple solution remains possible. — Of both cases an example for rye, Secale cereale, is given, together with an analysis of interference between these segments, and a conversion of probabilities of being bound at MI to genetic length.