| A fertile amphiploid from the cross Triticum aestivum
L. em Thell. x Agropyron distichum (Thunb.) Beauv. R. DE V. PIENAAR Department of Genetics, University of Stellenbosch. South Africa By using the embyro culture technique, F1 hybrids were obtained from the crosses of the two hexaploid bread wheat (Triticum aestivum var. aestivum) cultivars, Chinese Spring and Inia 66, with the single indigenous tetraploid and perennial Agropyron species, A. distichum (PIENAAR et al. 1977; PIENAAR,1979). The self-sterile F1 hybrids on open-pollination with bread wheat set a few kernels which produced plants with chromosome numbers ranging from 43 to 68 (Table 1). Colchicine treatment of the Chinese Spring x A. distichum F1 hybrids yielded no fertile amphiploid spikes. The single Inia 66 x A . distichum F1 hybrid plant was cloned to produce 13 plants, 10 of which were treated with 0.1% colchicine in 2% DMSO for 24 hours. Nine of the 10 plants had no fertile sectors, but one plant produced a spike with a few dehiscent anthers. It was decided to back cross the spike to Inia 66, and 40 kernels were obtained which produced plants with chromosome numbers ranging from 52 to 69 (Table 2). Only 6 of the 38 backcross progeny had the expected chromosome number of 2n=56; one plant resulted from selfpollination and was a monosomic decaploid with 2n=69, the others had chromosome numbers ranging from 52 to 55. It was evident from these results that the meiosis in the fertile sector of the C1 plant must be slightly irregular. This was borne out by a meiotic study of a few PMC's - see below. |
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