Cytogenetic studies on a heterozygous reciprocal translocation in the wheat (Triticum aestivum) cultivar Atlas 66

Abstract

PRIMARD, S. J., MORRIS, R., and PAPA, C. M. 1991. Cytogenetic studies on a heterozygous reciprocal translocation in the wheat (Triticum aestivum) cultivar Atlas 66. Genome, 34: 313-316. The wheat ( Triticum aestivum L.) cultivar Atlas 66 possesses a heterozygous reciprocal translocation that has persisted through seven generations of self-pollination and also has appeared in progeny of crosses between cv. Atlas 66 and other wheat cultivars or lines. Crosses were made between cv. Atlas 66 and the 21 cv. Chinese Spring double ditelosomics to identify the chromosomes involved in the translocation. F, plants testing chromosomes 2A and 2D had a chain with one telosome attached and the other unpaired in some metaphase I cells, indicating that 2A and 2D were involved in the translocation. The F,s testing the other 19 chromosomes had a chain of four and a trivalent that included the two telosomes. F, meiotic configurations from crosses between cv. Altas 66 and cv. Chinese Spring ditelosomics 2AS, 2AL, 2DS, and 2DL indicated that the breakpoints were in 2AL and 2DL and that the breakpoint in 2DL was closer to the end of the arm than the breakpoint in 2AL. The short translocated 2DL segment could explain the occurrence of chains as well as rings when cv. Atlas 66 was self-pollinated, and a predominance of chains in crosses with other cultivars or lines. There was evidence for the transmission of duplicate-deficient gametes from the translocation. Key words: heterozygous reciprocal translocation, Triticum aestivum, wheat, cv. Atlas 66. PRIMARD, S. J., MORRIS, R., et PAPA, C. M. 1991. Cytogenetic studies on a heterozygous reciprocal translocation in the wheat (Triticum aestivum) cultivar Atlas 66. Genome, 34 : 3 13-3 16. Le cultivar de ble Atlas 66 (Triticum aestivum L.) possede une translocation heterozygote reciproque qui a persiste a travers sept generations d'autopollinisation et qui s'est maintenue chez les descendants de croisements entre le cv. Altas 66 et 21 des doubles ditelosomiques du cv. Chinese Spring, pour identifier les chromosomes impliques dans la translocation. Les plantes F, testees pour les chromosomes 2A et 2D a la metaphase I possedaient des cellules ayant un chaine de chromosomes avec un telosome attache et une autre chaine non appariee, ce qui indique que les chromosomes 2A et 2D etaient impliques dans la translocation. Les F, ont d'autre part ete testees pour les 19 autres chromosomes; elles avaient des cellules possedant une chaine de quatre chromosomes et un trivalent comportant les deux telosomes. Les configurations meiotiques des F, issues de croisements entre le cv. Atlas 66 et les ditelosomiques de cv. Chinese Spring 2AS, 2AL, 2DS et 2DL ont indique que les fractures etaient localisees dans le 2AL et le 2DL et que, chez les 2DL, la fracture etait situee plus pres de l'extremite du bras que celle du 2AL. Le court segment du 2DL transfere pourrait expliquer l'occurrence de chaines ainsi que d'anneaux lorsque le cv. Atlas 66 est autopollinise et une predominance de chaines dans les croisements ave...

Brazilian Origin and Inheritance of a Heterozygous Reciprocal Chromosome Translocation in Wheat (Triticum aestivum L.)

“…Varieties more closely related to 'Frondoso' did not necessarily form more quadrivalents . Although the 'Atlas 66' translocation is readily transmitted in crosses (Primard et al 1991), the frequency of a heterozygous translocation can change because of selection (Bailey et al 1978). Therefore, in the present study, quadrivalent frequency may not only reflect the pedigree of a variety, but also the selection pressures it was subjected to.…”

“…The exchange in `Frondoso' involves the same chromosomes forming a reciprocal translocation in 'Atlas 66' (Primard et al 1991). Since Prondoso' is the Brazilian parent of 'Atlas 66' (Heyne 1958), `Frondoso' is quite probably the source of the 'Atlas 66' translocation.…”