A MAP OF RYE CHROMOSOME 4R WITH CYTOLOGICAL AND ISOZYME MARKERS

The progeny of two crosses between a structural heterozygote for a rec iprocal translocation (4RL/5RL) and a homozygote for the standard chro mosome arrangement and of four crosses between standard chromosome hom ozygotes were analysed in rye (Secale cereale L. cv 'Ailes') for the e lectrophoretic patterns of five different leaf and endosperm isozymes (LAP, PGM, NDH, ADH and EPER). The presence or absence of the quadriva lents at metaphase I (MI) was also tested. Loci Adh-1, Pgm-1 and Ndh-1 were located on chromosome arm 4RS, and locus Eper-1 on chromosome ar m 4RL. Locus Lap-2 was located on the 4RS chromosome arm. The estimate d distances among the different linked loci support the following gene order: Eper1..(breakpoint-centromere)..Lap-2....Adh-1 ....Pgm-1....Nd h-1. These results provide evidence for the chromosomal location of La p-2 locus on chromosome arm 4RS in cv 'Ailes'. A high negative interfe rence was detected between the zones delimited by centromere and Lap-2 , and Lap-2 and Pgm-1 in plants with the 4RL/5RL translocation.