Transmission of a wheat alien chromosome translocation with resistance to the wheat curl mite in common wheat, Triticum aestivum L.

1986 ◽  
Vol 28 (2) ◽  
pp. 294-297 ◽  
Author(s):  
E. D. P. Whelan ◽  
R. L. Conner ◽  
J. B. Thomas ◽  
A. D. Kuzyk

A translocation between a common wheat (Triticum aestivum L.) chromosome and chromosome 6 of Elytrigia pontica (Podp.) Holub conferred resistance to feeding by Eriophyes (= Aceria) tulipae Keifer, the mite vector of wheat streak mosaic virus and the wheat spot mosaic agent. Resistance was dominant, but differential transmission occurred between the pollen and the egg. Transmission of resistance through the pollen was low, about 3% in 'Cadet', 'Rescue', and 'Winalta', but significantly higher in 'Norstar' (9.1%). Significant differences also were detected in transmission through the egg. 'Cadet' had the highest transmission (50.9%) and 'Rescue' the lowest (40.5%). However, there were no significant differences among varieties in the frequencies of resistance (50.3–54.5%) in the F2. Less than 10% of the F2 plants were homozygous resistant. Selfed progeny from monosomic or disomic F1 plants from crosses between the homozygous translocation and group-6 monosomics all segregated for susceptibility. Meiotic studies of 25 susceptible F2 plants from these F1 monosomics showed that 21 were either monosomic or disomic and only 4 were nullisomic, indicating that the translocation did not involve any of the group-6 homoeologues. The translocation is considered to be a noncompensating translocation involving a whole arm of chromosome 6 of E. pontica.Key words: wheat, mite (wheat curl), translocation, Triticum.

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 293-298 ◽  
Author(s):  
Ernest D. P. Whelan

One of the group 6 chromosomes from Agropyron elongatum (Host) Beauv. confers resistance to colonization by the wheat curl mite (Aceria tulipae Keifer). The transmission of this chromosome was evaluated when added to or substituted for the group 6 homoeologues in two cultivars of common wheat (Triticum aestivum L.). Female transmission of the alien chromosome was similar for all substitutions (8.9%) but significantly less than expected. Male transmission (39.7%) differed among the substituted chromosomes and also was lower than expected except for the substitution involving chromosome 6A. These reduced transmission frequencies were reflected in lower than expected resistance in the F2 progeny. Both male (14.5%) and female (5.2%) transmission of the alien chromosome were reduced in monosomic additions. Meiotic analyses detected all expected F2 cytotypes but some of their frequencies differed among the substituted chromosomes. A possible wheat –alien translocation was detected in BC1F1 progeny.Key words: Agropyron elongatum, Thinopyrum, Elytrigia, Lyphopyrum, wheat curl mite, chromosome substitution.


Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 289-292 ◽  
Author(s):  
E. D. P. Whelan ◽  
G. E. Hart

The wheat curl mite (Eriophyes tulipae Keifer) is the vector of wheat streak mosaic virus, a damaging disease of winter wheat. A translocation between a common wheat (Triticum aestivum L.) chromosome and a group 6 chromosome (6Ag) from decaploid Agropyron elongatum (Host) Beauv. resulted in transfer of resistance to colonization by the wheat curl mite. Transmission of resistance through the pollen and the egg were similar and not significantly different from 50%. The frequency of resistance in the F2 generation (65.6%) was lower than expected for a single, dominant gene. In the F2, 26.7% of the resistant plants were homozygous for resistance. Selfed progeny from monosomic and disomic F1 plants from crosses between the translocation line and monosomics for 6A and 6B segregated with frequencies similar to normal F2 progeny but the progeny of monosomics for 6D were primarily resistant (93.2%). Crosses between the translocation line and chromosome 6D telocentrics and studies of four enzymes that are encoded by genes on the group 6 homoeologous chromosomes showed that the translocated chromosome consists of the q arm of chromosome 6D of 'Rescue' and the p arm of chromosome 6 of A. elongatum. Because the new stock was derived from a double monosomic, the translocation was probably a Robertsonian fusion of misdivided centromeres. The resistance is being backcrossed into winter wheat.Key words: Agropyron elongatum, Thinopyron, Elytrigia, Lophopyrum, Robertsonian translocation, isozyme structural genes, wheat curl mite.


Genome ◽  
1992 ◽  
Vol 35 (3) ◽  
pp. 468-473 ◽  
Author(s):  
Ernest D. P. Whelan ◽  
G. B. Schaalje

Aneuploid seedlings of the common wheat (Triticum aestivum L.) cv. Chinese Spring (CS) that are nullisomic or telosomic for the long arm of chromosome 6D are susceptible to chilling injury under prolonged exposure to 6 °C; normal euploids or telosomics for the short arm are not. Studies of seedling grown for various durations at 20 °C prior to growth at 6 °C showed that chilling injury was a juvenile phenomenon and that the extent of injury was inversely proportional to the duration of growth at 20 °C to a maximum of about 14 days. When reciprocal crosses were made between susceptible 6D nullisomics or long-arm ditelocentrics of CS and resistant 6D nullisomics of three spring and one winter wheat cultivars, progenies from aneuploid F1 hybrids all segregated for susceptibility as a recessive trait and at a frequency approximating a dihybrid ratio; no cytoplasmic effects were detected. Aneuploids of the group 6 homoeologues of the spring wheat cvs. Cadet and Rescue were resistant, as were group 6 whole-chromosome substitutions of eight different donor wheats in the recipient parent CS and 56 other euploids tested. Genes for resistance to chilling injury appear to involve the group 6 chromosomes and the short arm of 6D in Chinese Spring. In contrast with chilling injury, all aneuploid lines with only four doses of the "corroded" loci on group 6 chromosomes exhibited chlorotic symptoms.Key words: Triticum aestivum, chilling injury.


Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 1033-1036 ◽  
Author(s):  
E. D. P. Whelan ◽  
J. B. Thomas

Wheat streak mosaic is a destructive disease of wheat caused by wheat streak mosaic virus. Wheat streak mosaic virus is vectored by the wheat curl mite (Eriophyes tulipae Keifer). A single dominant gene conditioning resistance to colonization by the mite vector was transferred from Aegilops squarrosa L. to a synthetic amphiploid (AC PGR 16635) and then to common wheat (Triticum aestivum L. em. Thell.) through backcrossing. Because of its origin, the transferred gene was probably located in the D genome. Monosomics 1D through 7D were crossed with a homozygous resistant line with the pedigree Norstar*4/AC PGR 16635. Both 41- and 42-chromosome F1 plants were identified and selfed to obtain F2 seed. The observed proportion of resistant and susceptible plants in 6 of the 7 F2 families from monosomics, and in all 7 of the F2s from disomics, did not deviate significantly from a 3:1 ratio. However, the proportion of resistant plants from the F2 of monosomic 6D was significantly (p < 0.01) in excess of this ratio and susceptible plants from this family were nullisomic for all or part of 6D. In crosses with standard ditelosomic stocks, telocentrics from a ditelosomic derivative of susceptible individual of this F2 paired with 6D(L) but failed to pair with 6D(S). The F2 of heterozygous resistant plants that were monotelodisomic for the long arm of 6D(L) segregated approximately 19 resistant to 1 susceptible, while those from monotelodisomics for the short arm segregated normally (3 resistant to 1 susceptible, p = 0.27). These data show that the gene Cmcl for mite resistance is located on the short arm of chromosome 6D. Key words: Aegilops squarrosa, wheat streak mosaic virus.


1980 ◽  
Vol 18 (5-6) ◽  
pp. 465-482 ◽  
Author(s):  
K. M. Soliman ◽  
J. E. Bernardin ◽  
C. O. Qualset

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