Evidence for Spontaneous Inversions in Cultivated Barley1

Anaphase I microsporocytes of fifteen barley varieties and their hybrids have been examined cytologically. Approximately 2% of the microsporocytes of hybrids involving OAC 21 had bridges, fragments, or both, as well as other aberrations. The usual occurrence of very small fragments of uniform size accompanied by a bridge suggested the presence of one or possibly two small paracentric inversions in OAC 21. Analyses of other hybrids indicated that at least two other varieties also possessed inversions. These findings tend to support the very limited genetic evidence for inversions in cultivated barley. The difficulty in detecting inversions in barley having localized chiasmata as well as the possible influence of such inversions on recombination are discussed.