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  • 1
    ISSN: 1432-2242
    Keywords: Key words Erysiphe graminis ; Powdery mildew resistance ; QTL ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Powdery mildew is one of the major diseases of wheat in regions with a maritime or semi-continental climate and can strongly affect grain yield. The attempt to control powdery mildew with major resistance genes (Pm genes) has not provided a durable resistance. Breeding for quantitative resistance to powdery mildew is more promising, but is difficult to select on a phenotypic basis. In this study, we mapped and characterised quantitative trait loci (QTLs) for adult-plant powdery mildew resistance in a segregating population of 226 recombinant inbred lines derived from the cross of the Swiss wheat variety Forno with the Swiss spelt variety Oberkulmer. Forno possibly contains the Pm5 gene and showed good adult-plant resistance in the field. Oberkulmer does not have any known Pm gene and showed a moderate susceptible reaction. Powdery mildew resistance was assessed in field trials at two locations in 1995 and at three locations in 1996. The high heritability (h2=0.97) for powdery mildew resistance suggests that the environmental influence did not affect the resistance phenotype to a great extent. QTL analysis was based on a genetic map containing 182 loci with 23 linkage groups (2469 cM). With the method of composite interval mapping 18 QTLs for powdery mildew resistance were detected, explaining 77% of the phenotypic variance in a simultaneous fit. Two QTLs with major effects were consistent over all five environments. One of them corresponds to the Pm5 locus derived from Forno on chromosome 7B. The other QTL on 5A, was derived from the spelt variety Oberkulmer and did not correspond to any known Pm gene. In addition, five QTLs were consistent over three environments, and six QTLs over two environments. The QTL at the Pm5 locus showed a large effect, although virulent races for Pm5 were present in the mixture of isolates. Molecular markers linked with QTLs for adult-plant resistance offer the possibility of simultaneous marker-assisted selection for major and minor genes.
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  • 2
    ISSN: 1432-2242
    Keywords: Key words Lodging ; Morphological traits ; QTL ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Lodging can strongly affect both the grain yield and the quality of wheat. Lodging represents a quantitative trait and is difficult to assess on a phenotypic basis. Marker-assisted selection (MAS) could therefore become an important tool in breeding for lodging resistance. In this study, we mapped and characterised quantitative trait loci (QTLs) for lodging resistance, as well as morphological traits correlated with lodging, in a segregating population of 226 recombinant inbred lines derived from the cross of the lodging-resistant wheat variety Forno with the susceptible spelt variety Oberkulmer. Lodging, plant height, leaf width, leaf-growth habit, culm stiffness, culm swinging, culm thickness, days to ear emergence and days to flowering were assessed in field trials at two locations in 1996 and at one location in 1997. Additionally, at one location weight and length parameters were also assessed. Plant height and culm stiffness explained 77% of the phenotypic variance of lodging in a multiple regression model over all three environments. QTL analysis of lodging and morphological parameters was based on a genetic map containing 230 loci with 23 linkage groups (2469 cM). With the method of composite interval mapping nine QTLs for lodging resistance were detected, explaining 63% of the phenotypic variance in a simultaneous fit. Seven of these QTLs coincided with QTLs for morphological traits, reflecting the correlations between these traits and lodging. In our population the most efficient way to improve lodging resistance would be by a combination of indirect selection on plant height and culm stiffness together with MAS on the two QTLs for lodging resistance which did not coincide with QTLs for morphological traits.
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  • 3
    ISSN: 1573-5060
    Keywords: hybrids ; crosses ; spelt ; Triticum spelta ; wheat ; Triticum aestivum ; yield components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary F1 and F2 hybrids were produced using three winter wheat varieties (Bernina = biscuit wheat, Arina and Forno = bread wheat) and two spelt cultivars (Oberkulmer and Rouquin). Data are based on field trials in 1989 and 1990. All the combinations tested gave a very high relative heterosis on grain yield per ear, varying between 29.9% and 47.6% with an average of 42.1%. Even the higher parent was outyielded by 24.1% to 45.7%. This was the result of a heterosis effect on the two yield parameters grain number per ear and single grain weight. In the F2, heterosis for grain yield per ear was not significant with a range between 3.9% and 12.0%. F1 hybrids showed a heterosis effect on plant height but no hybrid was taller than the spelt parents. These data show that the gene pool of spelt could be potentially usefull for the selection of parents for hybrid production. For practical applications there remain several problems to be solved. Despite the very high heterosis effect the yield potential of spelt needs to be improved. No short spelt varieties exist at present to produce hybrids short enough for commercial application. Technical problems in the seed production arise because of the close tightness of the spelt glumes hampering either the pollination by the wheat parent or the pollen dispersal if used as a pollinator. However, a breeding effort to select for improved parents within the gene pool of spelt appears useful for future F1 hybrids between spelt and wheat.
    Type of Medium: Electronic Resource
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