Currently the numerous chromosome 6-marker stocks collected by K. J. Kasha are being characterized, purified, increased and catalogued. Most of the multiple marker stocks include the orange lemma (o) gene near the centromere of chromosome 6.

A trisomic stock has been developed where the extra chromosome is a fragment of chromosome 6 containing the long arm and a small piece of the short arm. The line developed is homozygous for the orange lemma (o) and uniculm (uc2) on the pair of normal chromosomes. The fragment balances the uc2 locus but not the o locus, therefore the trisomic progeny of this line are orange lemma (oo) and multiculm (Uc2 uc2 uc2) while the diploid progeny are orange lemma (oo) and uniculm (uc2 uc2) and easily distinguished. This stock confirms that the orange lemma locus is on the short arm while the uniculm locus is probably on the long arm or close to the centromere. This line is being used to assign genes to the long vs short arms of chromosome 6.

The ant13 locus was assigned to chromosome 6 earlier (Falk, 1985) and has been found to be closely linked to the sex1, o, and msg6 genes in crosses but is outside the chromosome segment containing these genes, based on a few rare crossover plants which occurred in later generation materials. As there have been no crossovers within the sex1-o-msg6 segment, it is not. possible to determine which side of this gene cluster the ant13 locus is located.

Reference

Falk, D. E. Genetic studies with proantocyanidin-free barley. 1985. BGN 15:27-30.