ANEUPLOID AND OTHER CYTOLOGICAL TESTER SETS IN RYE

Cytological tester sets include series of aneuploids (nullisomics, mon osomics, trisomics of different types, tetrasomics), series of rearran ged chromosomes (translocations, inversions, duplications, deficiencie s) and series of chromosomes recognizable by specific microscopically visible markers (C- or other banding, molecular markers). In rye, only a few (mainly tertiary and telocentric) monosomics and no viable null isomics have been found. Several sets of primary trisomics and some te locentric sets, usually not fully complete, have been developed, but f ew are still available for gene localization. A few tertiary trisomics have been derived from translocation heterozygotes. Extensively used are different sets of additions of rye chromosomes to wheat. A relativ ely widely distributed set of marked chromosomes is the Wageningen tra nslocation tester set, complemented with translocations from different other institutions. A disadvantage of rye translocations is insuffici ent heterozygote semisterility. Series of otherwise rearranged chromos omes have not been reported. Sets of lines with chromosomes conspicuou sly differing from the standard C-banding pattern have been obtained. Molecular markers are available for most rye chromosome, but lack of h eterozygosity, necessary for classification after in situ hybridizatio n is a restriction for use as cytological testers. In the cases of mos t translocations, C-banding and in situ molecular markers, each separa te plant in a segregating population must be screened cytologically, w hereas with aneuploid markers or with translocations having sufficient heterozygote semisterility, analyzing segregations is sufficient.