II. 27. A pericentric inversion in chromosome 3 of a translocation line of barley.
Ib Linde-Laursen, Agricultural Research Department, Risø National Laboratory, DK-4000 Roskilde, Denmark. "R"
In barley only paracentric inversions have so far been reported in mutagen-treated material (Ekberg 1974). However, during a study aimed at localizing translocation breakpoints to chromosome arms a pericentric inversion was observed in chromosome 3 of the translocation line 'Tl-6i'. As previously reported (BGN 1, 1971), 'Tl-6i' also carried a reciprocal translocation involving the chromosome 1 arm designated 1S and the long arm of barley chromosome 6 (Fig. 1). The chromosomes were identified by their Giemsa C-banding patterns (Linde-Laursen 1975).
The lengths of the arms of chromosome 3 were similar, or nearly so, in 'Tl-6i' and in the variety 'Bonus', in which the mother line 'ert-a23' of 'Tl-6i' was selected (BGN 1, 1971). Also the C-banding patterns constituted by C-bands at centromeric and intercalary positions were the same in the two lines (variant 3A; cf. Linde-Laursen et al. 1982). However, the C-bands situated in the short arm of chromosome 3 of 'Bonus' were found in the long arm of chromosome 3 of 'Tl-6i' and vice versa (Fig. 1). In contrast to this, the larger telomeric C-bands were situated at the ends of the short arms in both lines. These observations suggest that chromosome 3 of 'Tl-6i'has been produced through breaks in the middle segment of the long arm distally to C-band position 312 (cf. Linde-Laursen 1982) and distally in the short arm of a standard chromosome 3 as present in 'Bonus' with ensuing interchange of end segments. Forty cells of the hybrid 'Tl-6i' x 'Bomi' at metaphase I all had one quadrivalent and five bivalents. In six of the cells one rod bivalent was observed; the remainder of the bivalents were closed. No bridges and fragments were observed in cells at anaphase I. Thus, excepting those meiotic disturbances attributable to the presence of the interchanged chromosome 1 and 6, both end segments of the inverted chromosome 3 were apparently large enough to allow a normal progress of meiosis in chromosome pair 3 in the hybrid.
The inverted chromosome 3 and the chromosomes carrying the reciprocally translocated segments, respectively, are being transferred separately into a 'Bonus' background.
Ekberg, I. 1974. Cytogenetic studies of three paracentric inversions in barley. Hereditas 76:1-30.
Linde-Laursen, I. 1975. Giemsa C-banding of the chromosomes of 'Emir' barley. Hereditas 81:285-289.
Linde-Laursen, I. 1982. Linkage map of the long arm of barley chromosome 3 using C-bands and marker genes. Heredity 49:27-35.
Linde-Laursen, I., H. Doll, and G. Nielsen. 1982. Giemsa C-banding patterns and some biochemical markers in a pedigree of European barley. Z. Pflanzenzuchtg. 88:191-219.
