The karyotype of tuleen 346 barley.

Tuleen 346 barley is a triple homozygote for 3 unequal interchanges, T1-5v, T2-6y and T3-7d, which were induced independently in the variety, 'Bonus'. It has great potential value in studying differences in behaviour and position among chromosomes within the same cell in barley and its hybrids since at least 5 and usually all 7 chromosome types can be identified in Feulgen preparations, compared with only 3 types in normal barley. Measurement of chromosome arm and satellite lengths in 10 haploid root-tip metaphases showed that in all comparisons except of the longest with the next longest, the 7 chromosome types were distinct in total length (P<0.001-0.05) and in 8 of the 10 cells, the longest chromosome had a smaller arm ratio than the next longest. In these preparations, each of the 5 shortest chromosomes was easily identifiable by size and morphology. The longest chromosome was about 2.2 times as long as the shortest. C-banding showed that each of the 7 chromosome types had a clearly unique band pattern. The C-band patterns of interchange chromosomes confirmed and increased the precision of previously published breakpoint locations, viz. the short arms of chromosomes 1, 2, 3 and 7 and the long arms of chromosomes 5 and 6.