Fusarium head blight (FHB) caused by Fusarium culmorum is an economically important disease of wheat that may cause serious yield and quality losses under favorable climate conditions. The development of disease-resistant cultivars is the most effective control strategy. Worldwide, there is heavy reliance on the resistance pool originating from Asian wheats, but excellent field resistance has also been observed among European winter wheats. The objective of this study was to map and characterize quantitative traits loci (QTL) of resistance to FHB among European winter wheats. A population of 194 recombinant inbred lines (RILs) was genotyped from a cross between two winter wheats Renan (resistant)/Récital (susceptible) with microsatellites, AFLP and RFLP markers. RILs were assessed under field conditions For 3 years in one location. Nine QTLs were detected, and together they explained 30-45% of the variance, depending on the year. Three of the QTLs were stable over the 3 years. One stable QTL, QFhs.inra.2b, was mapped to chromosome 2B and two QTLs QFhs.inra.5a2 and QFhs.inra5a3, to chromosome 5A; each of these QTLs explained 6.9-18.6% of the variance. Other QTLs were identified on chromosome 2A, 3A, 3B, 5D, and 6D, but these had a smaller effect on FHB resistance. One of the two QTLs on chromosome 5A was linked to gene B1 controlling the presence of awns. Overlapping QTLs for FHB resistance were those for plant height or/and flowering time. Our results confirm that wheat chromosomes 2A, 3A, 3B, and 5A carry FHB resistance genes, and new resistance factors were identified on chromosome arms 2BS and 5AL. Markers flanking these QTLs should be useful tools for combining the resistance to FHB of Asian and European wheats to increase the resistance level of cultivars.

In a context where agricultural practices in Europe are likely to go toward extensive systems with lower inputs, it is important to determine the genetic improvement of winter wheat (Triticum aestivum L.) not only in high‐input agricultural systems but also in low‐input systems. This study assesses the improvement in agronomic traits of winter wheat cultivars cultivated in France during the second half of the 20th century at four agronomic treatments: two levels of fungicide were combined with two levels of nitrogen fertilizer. Fourteen cultivars introduced between 1946 and 1992 were grown for two years (1994 and 1995) at five locations. Selection played a major role in the increase in winter wheat yield after 1946. The contribution of selection to this increase depended on the agronomic treatment and varied from one third to one half. Reduction of height was the most important factor. New cultivars with shorter straw expressed higher harvest index values and more consistent higher yields since they were less susceptible to lodging. The ability to produce more kernels from a given total above‐ground biomass was the second factor. The number of kernels per unit area had increased over time without alteration of the weight of the kernels. The negative relationship between 1000‐kernel weight and kernel number/m2 was therefore shifted and new cultivars were thus able to fill more kernels than older entries. Modern cultivars used N more efficiently than their predecessors. The future challenge will be to obtain, in low‐input systems, the same genetic gains as in high‐input systems.

usually provides more directly comparable information, particularly about yield components. The main results In a context where agricultural practices in Europe are likely to of such studies are given in Table 1. Genetic gains for go toward extensive systems with lower inputs, it is important to determine the genetic improvement of winter wheat (Triticum aesti-grain yield varied from 5.8 kg ha Ϫ1 yr Ϫ1 to 59 kg ha Ϫ1 vum L.) not only in high-input agricultural systems but also in low-yr Ϫ1 . Theses gains represent 33 to 63% of the national input systems. This study assesses the improvement in agronomic M. Brancourt-Hulmel, INRA, Unité de Gé né tique et d'Amé lioration des Plantes, 80200 Estré es-Mons, France; G. Doussinault and M. Trotimproved NUE resulted from either an improved uptet, INRA, Unité de Gé né tique et d'Amé lioration des Plantes, 35650 take efficiency (plant N per unit of N taken up from Le Rheu, France; C. Lecomte, INRA, Station de Gé né tique et d'Amé lthe soil) or a greater N utilization efficiency (grain yield ioration des Plantes,

Stripe rust, caused by Puccinia striiformis f. tritici, is one of the most widespread and destructive wheat diseases in areas where cool temperatures prevail. The wheat cv. Renan, carrying the specific gene Yr17, has shown effective resistance for a long time, even though some pathotypes overcame the Yr17 gene. The objectives of this study were to locate and map genetic loci associated with adult-plant resistance (APR) to stripe rust in a recombinant inbred line population derived from a cross between Renan (resistant) and Récital (susceptible). Field assays were performed for 4 years (1995, 1996, 2005, and 2006) to score disease-progress data and identify APR quantitative trait loci (QTLs). Three QTLs, QYr.inra-2BS, QYr.inra-3BS, and QYr.inra-6B, with resistance alleles derived from Renan were detected in 1995 to 1996 with the 237E141 pathotype, which is avirulent against genotypes carrying Yr17. These QTLs were stable and explained a major part of the phenotypic variation seen in 2005 to 2006, when the 237E141 V17 pathotype was used. Each of these QTLs contributed approximately 4 to 15% of the phenotypic variance and was effective at different adult plant stages. Interactions were observed between some markers of the Yr17 gene and three Renan QTLs: QYr.inra-2BS, QYr.inra-3BS, and QYr.inra-6B. Resistance based on the combination of different APR types should provide durable resistance to P. striiformis.

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-Seventy two wheat cultivars and breeding lines were tested for at least two years in up to ten European countries for resistance against leaf rust under field conditions. In addition, seedling resistance was determined with local races and with defined isolates to postulate resistance genes. Nine entries (Batis, Capo, RE9001, RE9801, Terza, Toronit, Titlis, Barra, Beaufort) were highly resistant at all locations, and were regarded as excellent sources of resistance for breeding programs. Two thirds of the 72 entries possess adult plant and/or partial resistance. Cultivars with the gene Lr13 differed greatly in disease response showing that Lr13 alone does not provide adequate resistance in Europe. Gene Lr37 provided generally good adult plant resistance but seedlings with this gene were moderately susceptible. Many of the wheat cultivars/lines investigated possess unidentified adult plant resistance gene(s). Seedling resistance was attributable mostly to the genes Lr1, Lr3a, Lr3ka, Lr10, Lr14a, Lr17b, Lr20 or Lr26. Triticum aestivum / Puccinia recondita / wheat / leaf rust / resistance Résumé -Résistance du germplasme de blé d'hiver européen à la rouille des feuilles. Pendant au moins deux ans, 72 cultivars et lignées de sélection avancées de blé ont été testées aux champs dans dix pays européens pour évaluer la résistance à la rouille des feuilles. De plus, la résistance a été évaluée lors d'essais en laboratoire sur des plantules infec-

During 2 years and at five locations in Europe, 56 winter wheat genotypes were evaluated for resistance to Fusarium head blight (FHB). The genotypes were both parents and selected recombinants taken from the following populations previously tested for FHB resistance: ÔArinaÕ/ÔFornoÕ, ÔArinaÕ/ÔRibandÕ, ÔDreamÕ/ÔLynxÕ, G16-92/ ÔHussarÕ, ÔRenanÕ/ÔRe´citalÕ, SVP-72017 · ÔCapoÕ and ÔCapoÕ/ÔSumai-3Õ. In addition, a few control lines were included. FHB resistance was evaluated in replicated experiments under artificial inoculation, disease severity was assessed by repeated visual scorings. The highest level of FHB resistance was found in lines selected from crosses of FHBresistant winter wheat · ÔSumai-3Õ. The best lines selected from crosses of moderately resistant winter wheat with susceptible winter wheat were similar in their resistance response to the resistant parent. The level of FHB resistance was correlated with stability of resistance. Susceptible wheat lines tended to exhibit severe symptoms under high disease pressure. The symptoms on resistant lines remained comparatively low even under high disease pressure.

Barley yellow dwarf (BYD) is one of the main viral diseases of small-grain cereals. This disease, reported on numerous plant species of the Poaceae family, is caused by a complex of eight viral species including the species Barley Yellow Dwarf Virus-PAV (BYDV-PAV), frequently found in western Europe. Resistance sources against BYDV-PAV are scarce and only identified in perennial Triticineae. Some BYDV-resistant wheat lines have been obtained by introgressing these resistances into bread wheat germplasms. Genetic and biological characterization of the resulting lines has been undertaken. However, little information on the resistant behaviour of these lines during the early stages of the infection process is available. To evaluate the resistance of two genetically distinct resistant lines (Zhong ZH and TC14), 1740 young plantlets, belonging to susceptible reference hosts (barley cv. Express and wheat cv. Sunstar), Zhong ZH or TC14 wheat lines, were inoculated in controlled conditions with French BYDV-PAV isolates. The infection process was monitored during the first 21 days after inoculation (DAI) using a semi-quantitative ELISA. A standardized protocol including five successive samplings of leaves from all inoculated plants and the collection of plant roots at the end of the monitored period was carried out. This protocol enabled an assessment of the infection percentage and the evolution of the viral load in plants from the 7th DAI to the 21st DAI. Statistical analyses of the BYDV infection kinetics using raw ELISA data, a model of the timedependent variation of the percentage of infected plants and the area under concentration progress curves (AUCPC) demonstrated that Zhong ZH and TC14 lines (1) reduce the development rate of the BYD disease during the first days of infection, (2) decrease the infection efficiency of BYDV-PAV isolates, in the leaves, from 98.7% for susceptible plant genotypes to 81.9% and 71.7% for Zhong ZH and TC14, respectively, (3) reduce the virus load in the leaves of infected plants and (4) are not spared from BYDV infection, as 95.1% of Zhong ZH and 90.2% of TC14 inoculated plants accumulated viral particles in roots and/or in leaves at 21 DAI. These results confirm the BYDV-partial resistant behaviour of both Zhong ZH and TC14 lines. The development rate of the disease was the single parameter that allowed the distinction between the two resistant sources present in the tested lines.