FRONT COVER DIAGRAM
Telotrisomics have been useful in locating the centromere position
in the linkage maps and associating genes with chromosome arms in barley.
Triplo 5L, the telotrisomic for the long arm of chromosome 5 (5L) was the
first telotrisomic cytologically established by karyotype analysis (Tsuchiya,
1972a, BGN 2:90-92; Tsuchiya, 1972b, J. Hered. 63:373-375). The genetic
data from telotrisomic analysis (Fedak, 1969, Ph.D. Thesis; Fedak et al,
1972, Can. J. Genet. Cytol. 14:949-957; Tsuchiya, 1972, BGN 2:93-98; Tsuchiya
and Singh, 1973, BGN 3:75-78) in combination with the cytological data
resulted in a reversal of the linkage map of chromosome 5; the previous
long and short arm became the short and long arm, respectively (Tsuchiya,
1972a,b). As a result of this revision, it was also found that almost all
of the resistant genes for powdery mildew are located in the short arm
of chromosome 5 (Jensen, 1980, BGN 10:88-100).
Figure 1 shows karyotype of two complete cells at somatic metaphase.
Figure 2 shows the previous (a) and the revised map (b) of chromosome
5 in barley.