Transmission of a chromosome from decaploid Agropyron elongatum that confers resistance to the wheat curl mite in common wheat

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.

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. 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.


1970 ◽  
Vol 12 (1) ◽  
pp. 145-150 ◽  
Author(s):  
Ruby I. Larson ◽  
T. G. Atkinson

A derivative of Triticum aestivum L. emend Thell. cultivar Rescue3 (2n = 42) × Agropyron elongatum (Host.) Beauv. (2n = 70) is immune to wheat streak mosaic virus Marmor virgatum McK., has 21 pairs of chromosomes, and hybridizes readily with wheat. By crossing with lines ditelosomic for known chromosomes it was determined that Agropyron chromosomes have replaced wheat chromosomes 4D, 5D, and 6D. In growth habit the immune line is like Rescue, but its long slender spikes, absence of awns, and small, slender, blue seeds resemble Agropyron.


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 (1) ◽  
pp. 30-34 ◽  
Author(s):  
E. D. P. Whelan

Phenotypic markers of chromosomes are useful for determining chromosome behavior in cytogenetic studies. Transmission of an alien, telocentric addition from Agropyron tricophorum (Link) Richt. that confers purple aleurone pigment and blue seed color was evaluated in common wheat (Triticum aestivum L.). Twenty-five of 2570 seeds from bagged heads of eight ditelocentric-addition sister plants were almost white rather than blue. Seven of these 25 seeds and 4 of 336 blue seeds segregated 41.4%:58.6% blue:white. Meiotic analyses showed that all plants grown from these 11 seeds were spontaneously produced monotelocentric additions. Transmission of the alien telocentric chromosome through the egg and the pollen was estimated to be 19.5 and 14.3%, respectively, based on BC1F1 seed color. About 28% of F2 and F3 seeds were blue; of these 7.4% were ditelocentric additions. The frequency of blue seed in F2 progeny from spontaneous monotelocentric additions (41.4%) was significantly greater than that of monotelocentric additions from controlled crosses (28%). Penetrance of the blue seed color gene(s) associated with the alien telocentric chromosome was good. Misclassification of seed color for 1595 BC1F1 seeds was less than 3% based on BC1F2 progeny.Key words: Agropyron tricophorum.


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