Several new loci have been recently placed on chromosome six based on linkage using multiple marker stocks and pseudolinkage. Franckowiak (BGN 20: 31 - 36) has obtained close linkage between the orange lemma (o) and msg 28as, msg 34av and reasonable linkage between o and msg 39dm, msg 39ff and msg 40ac. This would place two new msg loci near the orange lemma locus and two more loci at some distance from the orange lemma locus but on chromosome 6. Additional linkage studies will be undertaken with these male sterile sources and other chromosome 6 markers. Boyd (P.W. Boyd, MSc Thesis, University of Guelph) has found tight pseudolinkage between.the ant2l locus and a series of 12 translocations all involving chromosome 6. His data indicate that the ant2l locus is quite close to the centromere. Further studies with this stock and other chromosome 6 markers are currently underway.

Falk (BGN 22: ) has clarified the location of the centromere of chromosome 6 between the o and sex1 loci. This study also confirms the location of msg 6cf on the short arm and places ant13 locus on the long arm. A previous report on the location of the o locus with respect to the short arm fragment of an acrocentric chromosome Falk BGN 20: 25) suggests that the o locus is somewhat distal to the centromere cytologically; while it shows very close genetic association with loci on the opposite side of the centromere (eg. sexl, ant13 and uc). This is evidence for considerable crossover interference in the centromere region of chromosome 6.