| Crosses between a TAF1 substitution line and the complete Chinese
Spring monosomic, monotelosomic or monoisosomic stocks used as female parents
indicated that the Ag. intermedium chromosome in this case replaced
wheat chromosome pair 3A and that chromosomes 5B and 7B were involved in
the translocation difference between Vilmorin and Chinese Spring. Hybrids
with 41 chromosomes in all crosses excepting those involving monotelo-3A,
monoiso-5B or monoiso-7B showed 1IV+17II+3I
at meiotic metaphase I, whilst the corresponding 42-chromosome plants exhibited
1IV+17II+t1II (or i1II)+2I.
Two hybrids with 41 chromosomes from the cross with monotelo-3A exhibited
1IV+18II +1I whilst the meiotic configuration
in three 42-chromosome plants was 1IV+18II+1I+tI.
Forty-one chromosome hybrids in crosses involving monoiso-5B or -7B showed
1III+18II+2I. Certain exceptional F1
plants were observed in this series of crosses. One plant from the monotelo-2D
cross possessed 40 chromosomes without a moniososome, with a 1IV+16II+4I
meiotic configuration, indicating probably spontaneous loss of a wheat chromosome
other than 3A, 5B, 7B or 2D. A forty chromosome plant in the cross involving
monoiso-5B exhibiting 1III+17II+3I can
be explained in like manner. Two exceptional plants occurred in the cross
involving monotelo-3A. The first showed 1IV+ 17II+2I+tI,
presumably due to loss of a wheat chromosome other than 5B or 7B, the unpaired
telocentric being 3A from Chinese Spring. The second plant possessed 63
chromosomes including a telocentric. This triploid plant apparently arose
from the fertilization of a 20+tI egg by an unreduced male gamete
with 42 chromosomes lacking the 3A wheat pair (40 wheat and two Ag. intermedium
chromosomes). The modal meiotic pairing in this plant was 1IV+14III+6II+4I+tI.
The translocation in Vilmorin 27 involves the same two chromosomes as in Poso (SEARS 1953). DRISCOLL and QUlNN (1968) have suggested the possibility of producing from such material a translocation aneuploid stock deficient for the long arm of 5B which might be expected to encourage wheat-alien homoeologous pairing. Hybrids involving TAF1 and TAF2 substitution lines may have direct application in this proposal. Literature Cited ANDERSON, L. M. and C. J. DRISCOLL 1967. The production and breeding behaviour of a monosomic alien substitution line. Can. J. Genet. Cytol. 9: 399-403. BAKSHI, J. S. and A. M. SCHLEHUBBR 1958. Identification of a substituted chromosome parr in a Triticum Agropyron line. Proc. Ok1. Acad. Sci. 39: 16-21. DRISCOLL, C. J. and C. J. QUINN 1968. Wheat alien hybrids involving a chromosome 5B translocation. Can. J. Genet. Cytol. 10: 217-220. JOHNSON, R. 1966. The substitution of a chromosome from Agropyron elongatum for chromosomes of hexaploid wheat. Can. J. Genet. Cytol. 8: 279-292. KIMBER, G. and E. R. SEARS 1968. Nomenclature for the description of aneuploids in the Triticinae. Proc. 3rd. Intern. Wheat Genet. Symp. Pp. 468-473. KNOTT, D. R. 1958. The inheritance in wheat of a blue endosperm colour derived from Agropyron elongatum. Can. J. Botany 36: 371-4. KNOTT, D. R. 1964. The effect on wheat of an Agropyron chromosome carrying rust resistance. Can. J. Genet. Cytol. 6: 500-507. NANDA, J. S. 1968. Cytogenetic studies on a number of Triticum Agropyron derivatives. Ph.D. Thesis, Univ. Saskatchewan, Canada. SEARS, E. R. 1953. Nullisomic analysis in common wheat. Amer. Nat. 87: 245-52. SHARMA, D. and D. R. KNOTT 1966 The transfer of leaf rust resistance from Agropyron to Triticum by irradiation. Can. J. Genet. Cytol. 8: 137-143. WIENHUES, A. 1965. Cytogenetische Untersuchungen uber die chromosomale Grundlage der Rostresistenz der Weique Zucher 35: 352-354. WIENHUES, A. 1966. Transfer of rust resistance of Agropyron to wheat by addition substitution and translocation. Proc. 2nd Intern. Wheat. Symp. Hereditas, Suppl. 2: 328-341. (Received March 19, 1970) |
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