As seen in Table l, in the 1995-1996 growing season, crossability percentages of D-genome substitutions of Langdon with rye varied from 1.25 to 54.6. When the crossability percentages were compared, it was shown that the substitution lines 4D(4B), 5D(5A), 6D(6A) and 7D(7A) were significantly higher than the control, while 2D(2A), 2D(2B), 3D(3B) and 5D(5B) were significantly lower than the control. Furthermore, 4D(4B) and 7D(7A) had a higher crossability than 5D(5A), while 2D(2B) and 3D(3B) had a lower crossability than 5D(5B), which was supported by the further studies in the following growing season, as seen in Table 2 .

In fact, using an open pollinate rye as male tester, Genc et al. (1996) have found that most of the 14 substitutions of Langdon showed differences according to Langon, of which 7D(7A) had the highest crossability with rye and 2D(2B) had the lowest crossability. They suggested that the variation in crossability involved in the relnainder chromosomes, except IA, 8B, 5A and 5B, was probably caused by the heterozygosity present in the open pollinate rye parent, a Turkish landrace. However, in this paper, because of using an inbred rye as male parent, the variation can not be attributed to the heterozygosity of rye. The previous works have shown that except the weak kr3 on chromosome 5D, no other crossability genes have been located on D-genome chromosome of cv. Chinese Spririg, which provided the substituted D-genome chromosomes for the disomic substitution lines in durum wheat Langdon. Krolow (1970) Iocated kr3 on chromosome 5D, but other authors, such as Riley and Chapman (1967), reported that kr3 has no significant effects on crossability with rey. We think that the higher crossability than control in lines 4D(4B), 5D(5A), 6D(6A) and 7D(7A) indicates that chromosomes 4B, 5A, 6A and 7A of Langdon suppress crossability with rye. The lower crossability in lines 2D(2A), 2D(2B), 3D(3B) and 5D(5B) indicates that chromosomes 2A, 2B, 3B and 5B of Langdon carry crossability genes. Of which, chromosomes 2B and 3B showed a stronger effect on crossability than chromosome 5B, and chromosomes 4B and 7A showed a stronger effect than chromosome 5A.

On the other hand, the crossability genes in hexaploid wheat, kr1, kr2, kr3 and kr4 were respectively located on chromosome 5B, 5A, 5D and IA (Riley and Chapman 1967, Krolow 1970, Zheng et al. 1992), and among them, the effect of kr1 on chromosome 5B is the greatest. Thus, it is more logical to suggest that tetraploid wheat cv. Langdon has a different kr system regulating crossability with rye in comparison with that of hexaploid wheat.

Meanwhile , the results of present study with regard to specific substitution line show some differences in comparison with those reported by Gene et al. (1996), such as the lines 4D(4B), 5D(5A) were reported to have low crossabiltiy with rye whereas we obtained high crossability. The differences may be caused by the different cultivars of rye in the crosses.


Acknowledgments

The authors are highly thankful to Science and Technology Committee of Sichuan Province for their financial support. We particularly thank L.R. Joppa for providing the D-genome substitutions of Langdon, and Mr. Y. Liu and Ms. Y. Zhou for emasculation work.


References

Gen9 I, Ozkan H and Yagbasanlar T ( 1996) Crossability of D-genome chromosomes substitution lines of durum wheat (Triticum turgidum ssp. turgidum conv. durum) with Secale cereale and Aegilops squarrosa . Wheat Inf Serv 83: 1-6.

Krowlow KD (1970) Untersuchungen uber die Kreuabarkeit zwischen Weizen und Roggen. Z Pflanzenzucht 64: 44.72.

Lein A (1943) Die genetische Grundlage der Kreuzbarkeit zwischen Weizen und Roggen. Z Ind Abst Vererb Lehre 81: 28-61.

Liu DC, Yen C, Yang JL and Zheng YL Chromosomal distribution of genes in diploid Lophopyrum elongatum (Host) A Love that influences crossability of wheat with rye. Wheat Inf Serv 86 : 13-18.

Luo MC, Yen C and Yang JL ( 1989) The crossability of landraces of common wheat in Sichuan with Aegilops tauschii and rye. J Sichuan Agric Univ 7: 77-81.

Miner TE, Reader SM and Gale MD (1983) The effect of homoeologous 3 chromosomes on chromosome paring and crossability in Triticum aestivum. Can J Genet Cytol : 634-644.

Riley R and Chapman V (1967) The inheritance in wheat of crossability with rye. Genet Res, Cambridge 9: 259.267.

Zheng YL, Luo MC Yen C and Yang JL (1992) Chromosome location of a new crossability gene in common wheat. Wheat Inf Serv 75: 36-40.

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