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A wheat line 14-569 developed from a hybrid of common wheat cv. Chuannong 10 with the wheat–Thinopyrum intermedium partial amphiploid TAI7045 exhibits stable double spikelets per node character in the lower middle portion of a spike, is highly resistant to stripe rust, and produces kernels with a higher 1000-kernel weight than those of its wheat parent. Chromosome counting and an analysis of meiosis demonstrated that line 14-569 is a disomic addition line with 2n = 44, 22II. Sequential genomic in situ hybridization and non-denaturing fluorescence in situ hybridization analyses indicated that one pair of St-genomic chromosomes from Th. intermedium was added to the wheat complement and that the wheat complement included one pair of 1RS/1BL wheat–rye translocation chromosomes. PCR-based landmark unique gene molecular marker analysis revealed that the added pair of chromosomes comprised 3St chromosomes, which suggested that the added 3St chromosomes from Th. intermedium might carry the genes to control the high yield-related characters and stripe rust resistance. This addition line will potentially be useful resource for improvements in wheat yields and stripe rust resistance.

Wheatgrass Thinopyrum intermedium (Host), or Agropyron intermedium (Host) (2n = 42; genome formula, EEEstEstStSt) is one of the most valuable sources of highly effective resistance genes in wheat breeding. Bread wheat cultivars Tulaikovskaya 5, Tulaikovskaya 10, and Tulaikovskaya 100 derived from wheat—Thinopyrum crosses are highly resistant to leaf rust and powdery mildew, and moderately resistant to stem and yellow rust. C-banding, in situ hybridization, and assays with PLUG and SSR markers have demonstrated that wheat chromosome 6D in all three cultivars is substituted by the Th. intermedium homoeologous chromosome, 6Ai. This chromosome was designated 6Ai#2, because it differs from the earlier described homoeologous chromosome 6Ai#1. In situ hybridization with Pseudoroegneria spicata and Dasypyrum villosum genomic DNAs has allowed chromosome 6Ai#2 to be assigned to the E (=J) subgenome. Chromosome 6Ai#2 remained intact over long-term breeding efforts. Tests of leaf rust resistance of in F2 and F3 populations from a cross of a leaf rust–susceptible cultivar with Tulaikovskaya 10 has demonstrated that chromosome 6Ai#2 carries at least one gene locus for leaf rust resistance. This locus was designated Lr6Ai#2. It must be different from the known gene locus Lr38, located on the long arm of chromosome 7Ai#2 and now present in many translocation variants in bread wheat. The effect of a chromosome from the Th. intermedium subgenome E on resistance to powdery mildew, stem and yellow rust in Tulaikovskaya 5, Tulaikovskaya 10, and Tulaikovskaya 100 is discussed.

Wheat streak mosaic virus (WSMV) is one of the most important diseases limiting winter wheat (Triticum aestivum L.) production in the western Great Plains of North America. There is no known effective WSMV resistance within the primary gene pool of wheat. However, a resistance gene (Wsm1) has been transferred to wheat from a perennial relative, intermediate wheat-grass [Thinopyrum intermedium (Host) Barkworth & DR Dewey]. Nebraska-adapted winter wheat lines carrying Wsm1 were used to characterize the effects of this alien introgression on agronomic and quality traits. Sister-lines from six breeding populations were evaluated under virus-free conditions, and under a naturally occurring viral infection. In uninfected locations, no significant difference for grain yield was detected between resistant (R) and susceptible (S) lines, when averaged over populations, but resistant lines had significantly higher test weights. Within populations, significantly higher grain yield was observed only in population 1, while significantly higher test weights occurred in populations 1, 2, 5 and 6. At the infected location, resistant lines were significantly higher in yield in five of six populations. In two of six populations, susceptible lines were significantly higher in bread loaf volume and bake mix time, while in the remaining populations, no significant quality differences were observed. As the Wsm1 gene provided yield advantages under viral infection, and there was no yield detriment in the absence of the virus, its deployment in hard winter wheat cultivars merits consideration.

A partial amphiploid, TE-3, between Triticum aestivum cv. Chinese Spring (CS) and Thinopyrum intermedium ssp. trichophorum was characterized by cytological observation, genomic in situ hybridization (GISH), seed storage protein electrophoresis and disease resistance screening. The TE-3 plants were deeply covered with pubescence, which is characteristic of the Th. intermedium ssp.trichophorum parent. Feulgen staining of the somatic metaphases revealed that the chromosome number varied from 52 to 56. TE-3 pollen mother cells (PMCs) regularly showed two to four univalents and 25 to 27 bivalents, indicating a degree of cytological instability. Giemsa-C banding showed that the Thinopyrum chromosomes in TE-3 produced strong heterochromatin bands. GISH analysis suggested that the alien chromosomes in TE-3 consisted of eight St chromosomes, four Js chromosomes, and two J genome chromosomes, as well as two St-J translocation chromosomes. Seeds storage proteins separated by acid polyacrylamide gel electrophoresis (APAGE) and sodium dodecyl sulphate – polyacrylamide gel electrophoresis (SDS-PAGE) showed that TE-3 expressed some of Th. intermedium ssp. trichophorum specific gliadin and glutenin bands. When inoculated with stripe rust and powdery mildew isolates, TE-3 expressed resistance derived from its Thinopyrum parent. It appears that TE-3 can be used as a donor source in wheat breeding programs to introduce novel variation for quality and disease resistance.

We developed some wheat-Th. intermedium translocation lines,Yw642, Yw443 and Yw243, etc., showing good BYDV resistance from L1by induced homoeologous pairing using CS ph mutant. Characterization ofthese wheat lines was carried out by GISH and RFLP analysis. The resultsof GISH showed that the lines, YWw42, Yw443 and Yw243, etc., arehomozygous wheat-Th. intermedium translocation lines, in which thechromosome segments of Th. intermedium were transferred to thedistal end of a pair of wheat chromosomes. RFLP analysis indicated that thetranslocation chromosome of the wheat lines is T7DS · 7DL-7XL. Thebreakpoint of the translocation is located on the distal end of 7DL, betweenXpsr965 and Xpsr680 about 90–99 cm from the centromere. The BYDVgene is located on the distal end of 7XL around Xpsr680, Xpsr687 andXwg380. The RFLP markers of psr680, psr687 and wg380 werecosegregated with the BYDV resistance respectively and could be used formolecular assisted selection (MAS) in wheat breeding program for BYDVresistance.