| The alien chromosome substitution line of durum
wheat I. Substitution of the chromosome e1 of Agropyron elongatum
for the chromosome 1B of Triticum durum cv. Stewart Hajime ONO Laboratory of Genetics, Faculty of Agriculture, Kobe University, Kobe Out of eighteen F1 plants obtained from the cross between monosomic 1B of Triticum durum cv. Stewart and disomic addition of the chromosome e1 of Agropyron elongatum (2n=14) to the durum wheat, 10 monosomic substitution e1(1B) having 13"+2' at meiotic metaphase were selected. The alien monosomic substitution was indistinguishable from durum wheat in morphology, except for fertility. Seed-set in the monosomic substitution was approximately 0.57 per spilelet, whereas 1.1 in monosomic 1B and 2.4 in euploid durum. Mochizuki (1962) reported that e1 chromosome which was added to the chromosomes of durum wheat paired with wheat chromosomes in 2.62% of PMCs. In the present experiment, however, no pairing of the alien chromosome with any wheat chromosomes was found. Since it was ascertained that the substitution gametes, [ (AB)-1B+e1], more or less involved in fertilization for the production of F1s from durum x monosomic substitution e1(1B) and its reciprocal crosses, the plants having 28 chromosomes from self-pollinated monosomic substitution will be expected to include the disomic substitution el(1B), [(AABB)-1B1B+e1e1]. The number of root tip chromosomes and chromosome configurations at meiotic metaphase in 114 plants from self-pollinated monosomic substitution e1(1B) were given in Table 1. In Table 1, 38 plants having 14" at meiosis were similar in morphology, however, 8 of those expressed the different rate of fertility from the remaining 30 plants. Average seed-set in the formers was 0.47 per spikelet and 2.1 in the latters. This greater reduction of fertility suggest that alien chromosome substitution occurred in the former 8 plants. To verify the substitution occurred actually, each plant with 14" and low fertility was crossed with durum wheat. 58 F1 plants from this cross had 13"+2' at meiosis without exception. This provided a evidence that a pair of Agropyron chromosomes indeed had replaced a pair of wheat chromosomes. |