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

Abstract

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. F1 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 F1s testing the other 19 chromosomes had a chain of four and a trivalent that included the two telosomes. F1 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.