The first seedling or all-stage resistance (R) R gene against stripe rust isolated from Moro wheat (Triticum aestivum L.) using a map-based cloning approach was identified as Yr10. Clone 4B of this gene encodes a highly evolutionary-conserved and unique CC-NBS-LRR sequence. Clone 4E, a homolog of Yr10, but lacking transcription start site (TSS) and putative TATA-box and CAAT-box, is likely a non-expressed pseudogene. Clones 4B and 4E are 84% identical and divergent in the intron and the LRR domain. Gene silencing and transgenesis were used in conjunction with inoculation with differentially avirulent and virulent stripe rust strains to demonstrate Yr10 functionality. The Yr10 CC-NBS-LRR sequence is unique among known CC-NBS-LRR R genes in wheat but highly conserved homologs (E = 0.0) were identified in Aegilops tauschii and other monocots including Hordeum vulgare and Brachypodium distachyon. Related sequences were also identified in genomic databases of maize, rice, and in sorghum. This is the first report of a CC-NBS-LRR resistance gene in plants with limited homologies in its native host, but with numerous homologous R genes in related monocots that are either host or non-hosts for stripe rust. These results represent a unique example of gene evolution and dispersion across species.

, H. 2003. Impact of powdery mildew on the yield of soft white spring wheat cultivars. Can. J. Plant Sci. 83: 725-728. The effect of powdery mildew (Blumeria graminis f. sp. tritici) on the grain yield and protein content of one susceptible, Springfield, and three moderately resistant cultivars, Fielder, AC Reed and AC Nanda, of soft white spring wheat (Triticum aestivum) was examined at two field locations near Lethbridge and Vauxhall, Alberta, in 1999 and 2000. At the start of heading, powdery mildew development was suppressed in half of the plots of each cultivar by a single spray application of the fungicide Tilt (propiconazole). Severe powdery mildew infection of the susceptible cultivar Springfield resulted in yield reductions ranging from 11.4 to 19.9%. The grain yield of the moderately resistant cultivar Fielder was significantly reduced at both sites in 1999 by 7.6-10.5% while AC Reed suffered a significant yield loss (7.6-9.1%) at Lethbridge in both years. The moderately resistant cultivar AC Nanda consistently had the lowest powdery mildew ratings and its yield was unaffected by the disease. A single fungicide application prevented disease buildup on the moderately resistant cultivars, but not on Springfield. The grain protein content of the moderately resistant cultivars was unaffected by powdery mildew, but it decreased in Springfield by 0.6-0.7%. , on a pulvérisé le fongicide Tilt (propiconazole) sur la moitié des parcelles pour lutter contre la maladie. Une grave infection du cultivar sensible Springfield par le blanc a entraîné une baisse de 11,4 à 19,9 % du rendement. Le rendement grainier du cultivar moyennement résistant Fielder a sensiblement diminué (de 7,6 à 10,5 %) aux deux endroits, en 1999, alors que celui de AC Reed en a fait autant (baisse de 7,6 à 9,1 %) à Lethbridge, les deux années. AC Nanda présentait toujours la plus faible cote pour le blanc et la maladie n'a pas affecté son rendement. Une seule application de fongicide suffit à prévenir l'aggravation de la maladie pour les cultivars modérément résistants, mais pas pour Springfield. Le teneur en protéines du grain n'est pas touchée par le blanc chez les cultivars moyennement résistants, mais elle diminue de 0,6 à 0,7 % chez Springfield.

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Common root rot, caused by Cochliobolus sativus (Ito and Kurib) Drechs. ex Dastur, is a major soil-borne disease of spring and winter wheat (Triticum aestivum L. em Thell.) on the Canadian prairies. Resistance to common root rot from Thinopyrum ponticum (Podp.) Liu and Wang was transferred into wheat via crossing with Agrotana, a resistant wheat - Th. ponticum partial amphiploid line. Evaluation of common root rot reactions showed that selected advanced lines with blue kernel color derived from a wheat x Agrotana cross expressed more resistance than the susceptible T. aestivum 'Chinese Spring' parent and other susceptible wheat check cultivars. Cytological examination revealed 41 to 44 chromosomes in the advanced lines. Genomic in situ hybridization, using total genomic DNA from Pseudoroegneria strigosa (M. Bieb) A. Löve (St genome) as a probe, demonstrated that the blue kernel plants had two pairs of spontaneously translocated J-Js and Js-J chromosomes derived from the J and Js genome of Th. ponticum. The presence of these translocated chromosomes was associated with increased resistance of wheat to common root rot. The lines with blue aleurone color always had a subcentromeric Js-J translocated chromosome. The subtelocentric J-Js translocated chromosome was not responsible for the blue kernel color. The genomic in situ hybridization analysis on meiosis revealed that the two spontaneous translocations were not reciprocal translocations.

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