| Forth interspecific hybrids, between Ae. columnaris and Ae.
biuncialis (CuMb) were backcrossed twice by Ae.
columnaris, because B1 plants backcrossed by Ae. columnaris
were sterile owing to low chromosome pairing at meiosis. Of course, these
B2 populations were similar to the recurrent parent or Ae.
columnaris in chromosome constitution and morphology. This points out
that this combination which is sterile in B1 generation, produces
less modification in cytological and morphological traits. Since the substitution-type backcross pollinated by pollen parent needs about three more backcrosses for recovering of fertility, it is suggested that the restitution-type backcross produces more number of introgressed plants for morphology as well as chromosome constitution than the substitution-type backcross. Hybrids between the synthesized tetraploids carrying one genome in common (SbA and MuA) released larger chromosome variation in their F4 plants (Furuta and Tanaka unpublished). This is maybe due to the unestablished cytological stability in synthesized strains. References FURUTA, Y. 1981. Intraspecific variation in Aegilops variabilis and Ae. kotschyi revealed by chromosome pairing in F1 hybrids. Jpn. J. Genet. 56: 495-504. FURUTA, Y. 1982. Study on the chromosomal and morphological differentiation by interspecific hybridization in tetraploid species of section Polyeides in genus Aegilops (in Japanese with English summary). Res. Bull. Fac. Agr. Gifu Univ. 47: 1-92. FURUTA, Y. 1983. Experimental chromosome introgression in tetraploid species of section Polyeides in genus Aegilops. Proc. 6th Int. Wheat Gene. Symp., Kyoto, Japan, 1983: 49-53. FURUTA, Y., KOSHIKAWA, K., TANAKA, S. & NISHIKAWA, K., 1984. Chromosome structural variation in 83 strains of Aegilops triuncialis. Seiken Ziho 32: 9-19. FURUTA, Y. & TANAKA, M., 1970. Experimental introgression in natural tetraploid Aegilops species. Jpn. Genet. 45: 129-145. ZOHARY, D. & FELDMAN, M., 1962. Hybridization between amphidiploids and the evolution of polyploids in the wheat (Aegilops-Triticum) group. Evolution 16: 44-61. |
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