Haplotype diversity and population structure in cultivated and wild barley evaluated for Fusarium head blight responses

Fusarium head blight (FHB) is a threat to barley (Hordeum vulgare L.) production in many parts of the world. A number of barley accessions with partial resistance have been reported and used in mapping experiments to identify quantitative trait loci (QTL) associated with FHB resistance. Here, we present a set of barley germplasm that exhibits FHB resistance identified through screening a global collection of 23,255 wild (Hordeum vulgare ssp. spontaneum) and cultivated (Hordeum vulgare ssp. vulgare) accessions. Seventy-eight accessions were classified as resistant or moderately resistant. The collection of FHB resistant accessions consists of 5, 27, 46 of winter, wild and spring barley, respectively. The population structure and genetic relationships of the germplasm were investigated with 1,727 Diversity Array Technology (DArT) markers. Multiple clustering analyses suggest the presence of four subpopulations. Within cultivated barley, substructure is largely centered on spike morphology and growth habit. Analysis of molecular variance indicated highly significant genetic variance among clusters and within clusters, suggesting that the FHB resistant sources have broad genetic diversity. The haplotype diversity was characterized with DArT markers associated with the four FHB QTLs on chromosome 2H bin8, 10 and 13 and 6H bin7. In general, the wild barley accessions had distinct haplotypes from those of cultivated barley. The haplotype of the resistant source Chevron was the most prevalent in all four QTL regions, followed by those of the resistant sources Fredrickson and CIho4196. These resistant QTL haplotypes were rare in the susceptible cultivars and accessions grown in the upper Midwest USA. Some two- and six-rowed accessions were identified with high FHB resistance, but contained distinct haplotypes at FHB QTLs from known resistance sources. These germplasm warrant further genetic studies and possible incorporation into barley breeding programs.     

QTL identification for early blight resistance (Alternaria solani) in a Solanum lycopersicum × S. arcanum cross

Alternaria solani (Ellis and Martin) Sorauer, the causal agent of early blight (EB) disease, infects aerial parts of tomato at both seedling and adult plant stages. Resistant cultivars would facilitate a sustainable EB management. EB resistance is a quantitatively expressed character, a fact that has hampered effective breeding. In order to identify and estimate the effect of genes conditioning resistance to EB, a quantitative trait loci (QTL) mapping study was performed in F2 and F3 populations derived from the cross between the susceptible Solanum lycopersicum (syn. Lycopersicon esculentum) cv. ‘Solentos’ and the resistant Solanum arcanum (syn. Lycopersicon peruvianum) LA2157 and genotyped with AFLP, microsatellite and SNP markers. Two evaluation criteria of resistance were used: measurements of EB lesion growth on the F2 plants in glasshouse tests and visual ratings of EB severity on foliage of the F3 lines in a field test. A total of six QTL regions were mapped on chromosomes 1, 2, 5–7, and 9 with LOD scores ranging from 3.4 to 17.5. Three EB QTL also confer resistance to stem lesions in the field, which has not been reported before. All QTL displayed significant additive gene action; in some cases a dominance effect was found. Additive × additive epistatic interactions were detected between one pair of QTL. For two QTL, the susceptible parent contributed resistance alleles to both EB and stem lesion resistance. Three of the QTL showed an effect in all tests despite methodological and environmental differences.     

Three QTLs for <Emphasis Type="Italic">Botrytis cinerea</Emphasis> resistance in tomato

Tomato (Solanum lycopersicum) is susceptible to grey mold (Botrytis cinerea). Partial resistance to this fungus was identified in accessions of wild relatives of tomato such as S. habrochaites LYC4. In order to identify loci involved in quantitative resistance (QTLs) to B. cinerea, a population of 174 F₂ plants was made originating from a cross between S. lycopersicum cv. Moneymaker and S. habrochaites LYC4. The population was genotyped and tested for susceptibility to grey mold using a stem bioassay. Rbcq1, a QTL reducing lesion growth (LG) and Rbcq2, a QTL reducing disease incidence (DI) were identified. Rbcq1 is located on Chromosome 1 and explained 12% of the total phenotypic variation while Rbcq2 is located on Chromosome 2 and explained 15% of the total phenotypic variation. Both QTL effects were confirmed by assessing disease resistance in two BC₂S₁ progenies segregating for either of the two QTLs. One additional QTL, Rbcq4 on Chromosome 4 reducing DI, was identified in one of the BC₂S₁ progenies. F₂ individuals, homozygous for the Rbcq2 and Rbcq4 alleles of S. habrochaites showed a reduction of DI by 48%. QTLs from S. habrochaites LYC4 offer good perspectives for breeding B. cinerea resistant tomato cultivars. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Molecular dissection of Tomato leaf curl virus resistance in tomato line TY172 derived from Solanum peruvianum

Tomato yellow leaf curl virus (TYLCV) is devastating to tomato (Solanum lycopersicum) crops and resistant cultivars are highly effective in controlling the disease. The breeding line TY172, originating from Solanum peruvianum, is highly resistant to TYLCV. To map quantitative trait loci (QTLs) controlling TYLCV resistance in TY172, appropriate segregating populations were analyzed using 69 polymorphic DNA markers spanning the entire tomato genome. Results show that TYLCV resistance in TY172 is controlled by a previously unknown major QTL, originating from the resistant line, and four additional minor QTLs. The major QTL, we term Ty-5, maps to chromosome 4 and accounts for 39.7–46.6% of the variation in symptom severity among segregating plants (LOD score 33–35). The minor QTLs, originated either from the resistant or susceptible parents, were mapped to chromosomes 1, 7, 9 and 11, and contributed 12% to the variation in symptom severity in addition to Ty-5.     

The genetic and functional analysis of flavor in commercial tomato: the FLORAL4 gene underlies a QTL for floral aroma volatiles in tomato fruit

Tomato (Solanum lycopersicum L.) has become a popular model for genetic studies of fruit flavor in the last two decades. In this article we present a study of tomato fruit flavor, including an analysis of the genetic, metabolic and sensorial variation of a collection of contemporary commercial glasshouse tomato cultivars, followed by a validation of the associations found by quantitative trait locus (QTL) analysis of representative biparental segregating populations. This led to the identification of the major sensorial and chemical components determining fruit flavor variation and detection of the underlying QTLs. The high representation of QTL haplotypes in the breeders’ germplasm suggests that there is great potential for applying these QTLs in current breeding programs aimed at improving tomato flavor. A QTL on chromosome 4 was found to affect the levels of the phenylalanine‐derived volatiles (PHEVs) 2‐phenylethanol, phenylacetaldehyde and 1‐nitro‐2‐phenylethane. Fruits of near‐isogenic lines contrasting for this locus and in the composition of PHEVs significantly differed in the perception of fruity and rose‐hip‐like aroma. The PHEV locus was fine mapped, which allowed for the identification of FLORAL4 as a candidate gene for PHEV regulation. Using a gene‐editing‐based (CRISPR‐CAS9) reverse‐genetics approach, FLORAL4 was demonstrated to be the key factor in this QTL affecting PHEV accumulation in tomato fruit.     

Interval mapping of genes for quantitative resistance of maize to Setosphaeria turcica,cause of northern leaf blight,in a tropical environment

Quantitative trait loci (QTL) involved in the resistance of maize to Setosphaeria turcica, the causal agent of northern leaf blight, were located by interval mapping analysis of 121 F_2:3 lines derived from a cross between Mo17 (moderately resistant) and B52 (susceptible). A linkage map spanning 112 RFLP loci with 15 cM mean interval length was constructed, based on marker data recorded in a previous study. Field tests with artificial inoculation were conducted at three sites in tropical mid- to high-altitude regions of Kenya, East Africa. Host-plant response was measured in terms of incubation period, disease severity (five scoring dates), and the area under the disease progress curve (AUDPC). Heritability of all traits was high (around 0.75). QTL associated with the incubation period were located on chromosomes 2S and 8L. For disease severity and AUDPC, significant QTL were detected in the putative centromeric region of chromosome 1 and on 2S, 3L, 5S, 6L, 7L, 8L and 9S. On 2S the same marker interval which carried a gene enhancing latent period was also associated with reduced disease severity of juvenile plants. QTL on chromosomes 3L, 5S, 7L and 8L were significant across environments but all other QTL were affected by a large genotype x environment interaction. Partially dominant gene action for resistance as well as for susceptibility was prevailing. Single QTL explained 10 to 38% of the phenotypic variation of the traits. All but the QTL on chromosomes 1, 6 and 9 were contributed by the resistant parent Mo17. On chromosome 8L a QTL mapped to the same region as the major race-specific gene Ht2, supporting the hypothesis that some qualitative and quantitative resistance genes may be allelic.Abbreviations AUDPC area under the disease progress curve - CIMMYT International Maize and Wheat Improvement Center - KARI Kenya Agricultural Research Institute - NCLB northern corn leaf blight - QTL quantitative trait locus/loci     

QTL analysis of Fusarium head blight resistance using a high-density linkage map in barley

Fusarium head blight (FHB) resistance was evaluated in a set of recombinant inbred (RI) lines from a cross between Russia 6 (resistant) and H.E.S. 4 (susceptible), which had one of the widest differences of FHB resistance reactions among ca. 5,000 barley germplasm accessions in Okayama University. Field-grown spikes were sampled and inoculated by the ‘cut-spike test’. Resistance reactions on the parents and RI lines were scored by eleven grades, from resistant (0) to susceptible (10). Quantitative trait loci (QTL) analysis detected three QTL: two located on the long arm of chromosome 2H, and another on the short arm of chromosome 5H. A QTL located on chromosome 2H was coincident with the vrs1 locus, which governs inflorescence row type. The other QTL on chromosome 2H was positioned in the vicinity of cleistogamy locus (cly1 or Cly2) that determines inflorescence opening/closing. Resistant gene analog (RGA) and expressed sequence tag (EST) markers with homology for disease resistance genes were integrated into the high-density linkage map. Most of these markers were not localized near the identified resistance QTL, except for one RGA marker (FXLRRfor_XLRRrev170) localized in the vicinity of the cly1/Cly2 locus. Five AFLP markers localized in the vicinity of the identified QTL were sequenced to convert them into sequence tagged site (STS) markers. Genotyping of each RI line using two AFLP–STS markers and the vrs1 locus indicated that the RI lines with three Russia 6 QTL alleles exhibited the same level of high FHB resistance reactions as Russia 6. In contrast, RI lines with three susceptible alleles showed reactions close to H.E.S. 4. Therefore, the markers closely linked to the QTL can be efficiently used for the selection of resistance.     

Correlative evidence for peroxidase involvement in disease resistance against <Emphasis Type="Italic">Alternaria</Emphasis> leaf blight of tomato

Eighteen tomato genotypes, with varying degree of response to Alternaria leaf blight disease (ALBD) were used to assess the possible involvement of protease and peroxidase activities in disease response. Pre-infectional protease activity varied noticeably in tested genotypes. Highest pre-infectional protease activity was observed in susceptible genotype CLN-2123. Post-infectional protease activity level was generally lower when compared with pre-infectional level in all genotypes with exception of unchanged level in Tibrido. There was no correlation between post-infectional protease activity and percent disease index (%DI). In contrast, pre- and post-infectional leaf peroxidase activities showed a significant (p < 0.01) negative correlation with %DI. Genotypes with higher pre-infectional peroxidase activity performed better on exposure to Alternaria alternata infection and accumulate enhanced peroxidase activity. Tibrido accumulated highest peroxidase activity while level was lowest in 1621P, which showed highest ALBD incidence. Moreover, genotypes with better resistance to A. alternata infection maintained higher post-infectional peroxidase activity. In resistant (Tibrido) and all moderately resistant genotypes, leaf peroxidase activity raised after inoculation when compared with the pre-inoculation level. I summary, higher pre- and post-infectional peroxidase activity was found to be associated with Alternaria leaf blight resistance. The peroxidase activity can be used as a biochemical tool in marker-assisted screening of tomato germplasm for Alternaria leaf blight resistance.     

玉米种质资源对六种重要病虫害的抗性鉴定与评价

在2003-2005年间,对604份玉米种质进行了抗弯孢菌叶斑病和玉米螟鉴定,筛选出抗弯孢菌叶斑病的材料93份,抗玉米螟材料22份。2006-2009年间,对836份玉米种质进行了抗大斑病、茎腐病、穗腐病和瘤黑粉病的鉴定与评价,筛选出一批高抗和多抗的资源。在836份资源中,对大斑病1、2和N号3个生理小种具有抗性的材料均为50%左右;抗茎腐病材料为41.3%,高抗和抗性种质分别为264和81份;穗腐病高抗和抗性种质分别为5和171份,占比为21.1%;瘤黑粉病高抗和抗性种质各261和14份,占总鉴定材料的32.9%。上述结果表明抗大斑病、茎腐病和瘤黑粉病的种质资源较为丰富。通过对抗性结果进行对比分析,发现不同生态区玉米种质的抗性强弱以及抗性多样性存在明显差异,黑龙江和内蒙古的种质对病虫害的抗性强弱及多样性程度明显高于四川种质。此外,玉米自交系对病虫害的抗性强弱以及多抗性程度高于农家种。     

Construction of a linkage map based on a <Emphasis Type="Italic">Lathyrus sativus</Emphasis> backcross population and preliminary investigation of QTLs associated with resistance to ascochyta blight

A linkage map of the Lathyrus sativus genome was constructed using 92 backcross individuals derived from a cross between an accession resistant (ATC 80878) to ascochyta blight caused by Mycosphaerella pinodes and a susceptible accession (ATC 80407). A total of 64 markers were mapped on the backcross population, including 47 RAPD, seven sequence-tagged microsatellite site and 13 STS/CAPS markers. The map comprised nine linkage groups, covered a map distance of 803.1 cM, and the average spacing between markers was 15.8 cM. Quantitative trait loci (QTL) associated with ascochyta blight resistance were detected using single-point analysis and simple and composite interval mapping. The backcross population was evaluated for stem resistance in temperature-controlled growth room trials. One significant QTL, QTL1, was located on linkage group 1 and explained 12% of the phenotypic variation in the backcross population. A second suggestive QTL, QTL2, was detected on linkage group 2 and accounted for 9% of the trait variation. The L. sativus R-QTL regions detected may be targeted for future intergenus transfer of the trait into accessions of the closely related species Pisum sativum.     

Late blight resistance linkages in a novel cross of the wild potato species Solanum paucissectum (series Piurana)

The cultivated potato, Solanum tuberosum, is affected by a variety of diseases with late blight, caused by Phytophthora infestans, being the most severe. Wild potato species have proven to be a continuing source of resistance, sometimes of an extreme type, to this disease. The present study constructs the first late blight linkage map of a member of series Piurana, S. paucissectum, a tuber-bearing relative of potato, using probes for conserved sequences from potato and tomato. Eight probes mapped to unexpected linkage groups, but syntenic differences with prior maps of potato were not supported by any blocks of rearranged chromosome segments. All 12 linkage groups were resolved and significant associations with late blight resistance were found on chromosomes 10, 11 and 12. A major quantitative trait locus (QTL) on chromosome 11 accounts for more than 25% of the phenotypic variance measured in a field trial. Crossing of S. paucissectum with cultivated potato resulted in very few seeds indicating partial reproductive barriers. Differential reactions of accessions of this potential donor species with simple and complex isolates of P. infestans suggest that it carries major resistance genes that are not those previously described from the Mexican species, S. demissum. However, the additivity of the QTL effects argues for the quantitative nature of resistance in this cross.     

Major-effect QTLs for stem and foliage resistance to late blight in the wild potato relatives <Emphasis Type="Italic">Solanum sparsipilum</Emphasis> and <Emphasis Type="Italic">S. spegazzinii</Emphasis> are mapped to chromosome X

To find out new resistance sources to late blight in the wild germplasm for potato breeding, we examined the polygenic resistance of Solanum sparsipilum and S. spegazzinii by a quantitative trait locus (QTL) analysis. We performed stem and foliage tests under controlled conditions in two diploid mapping progenies. Four traits were selected for QTL detection. A total of 30 QTLs were mapped, with a large-effect QTL region on chromosome X detected in both potato relatives. The mapping of literature-derived markers highlighted colinearities with published late blight QTLs or R-genes. Results showed (a) the resistance potential of S. sparsipilum and S. spegazzinii for late blight control, and (b) the efficacy of the stem test as a complement to the foliage test to break down the complex late blight resistance into elementary components. The relationships of late blight resistance QTLs with R-genes and maturity QTLs are discussed.     

A Rapid and Efficient Method for In Vitro Screening of Taro for Leaf Blight Disease Caused by Phytophthora colocasiae

Taro leaf blight caused by Phytophthora colocasiae presents the single biggest constraint for taro cultivation globally. To accelerate breeding and selection for disease resistance to leaf blight, it is important to develop bioassays which could differentiate resistant and susceptible cultivars efficiently. In this study, thirty taro accessions and four released cultivars were evaluated for resistance to leaf blight using a modified floating leaf disc assay. A novel method for mass production of P. colocasiae zoospores was developed and used as inoculum for the assay. There were significant (P < 0.05) differences among accessions in their response to P. colocasiae infection in the detached leaf assay. The accessions could be efficiently classified into various resistance groups based on a 0–4 score. Also, the assay results were consistent with the field evaluation scores of taro accessions. Thus, this study reports the development of a rapid, simple and repeatable assay that can be used to screen large numbers of taro cultivars for resistance to P. colocasiae.     

Allele-specific CAPS marker in a <Emphasis Type="Italic">Ve1</Emphasis> homolog of <Emphasis Type="Italic">Capsicum annuum</Emphasis> for improved selection of <Emphasis Type="Italic">Verticillium dahliae</Emphasis> resistance

Verticillium wilt (Verticillium dahliae) is an economically important disease for many high-value crops. The pathogen is difficult to manage due to the long viability of its resting structures, wide host range, and the inability of fungicides to affect the pathogen once in the plant vascular system. In chile pepper (Capsicum annuum), breeding for resistance to Verticillium wilt is especially challenging due to the limited resistance sources. The dominant Ve locus in tomato (Solanum lycopersicum) contains two closely linked and inversely oriented genes, Ve1 and Ve2. Homologs of Ve1 have been characterized in diverse plant species, and interfamily transfer of Ve1 confers race-specific resistance. Queries in the chile pepper WGS database in NCBI with Ve1 and Ve2 sequences identified one open reading frame (ORF) with homology to the tomato Ve genes. Comparison of the candidate CaVe (Capsicum annuum Ve) gene sequences from susceptible and resistant accessions revealed 16 single nucleotide polymorphisms (SNPs) and several haplotypes. A homozygous haplotype was identified for the susceptible accessions and for resistant accessions. We developed a cleaved amplified polymorphic sequence (CAPS) molecular marker within the coding region of CaVe and screened diverse germplasm that has been previously reported as being resistant to Verticillium wilt in other regions. Based on our phenotyping using the New Mexico V. dahliae isolate, the marker could select resistance accessions with 48% accuracy. This molecular marker is a promising tool towards marker-assisted selection for Verticillium wilt resistance and has the potential to improve the efficacy of chile pepper breeding programs, but does not eliminate the need for a bioassay. Furthermore, this work provides a basis for future research in this important pathosystem.     

Reassessment of QTLs for Late Blight Resistance in the Tomato Accession L3708 Using a Restriction Site Associated DNA (RAD) Linkage Map and Highly Aggressive Isolates of Phytophthora infestans

Tomato late blight caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary is a major threat to tomato production in cool and wet environments. Intensified outbreaks of late blight have been observed globally from the 1980s, and are associated with migration of new and more aggressive populations of P. infestans in the field. The objective of this study was to reassess late blight resistance in the wild tomato accession L3708 (Solanum pimpinellifolium L.) against pathogens of different aggressiveness. An F_2:3 genetic mapping population was developed using L3708 as the paternal parent. Two isolates of P. infestans, Pi39A and Pi733, were used for inoculation. Pi733 is a highly aggressive genotype that defeats three known late blight resistance genes, Ph-1, Ph-2, and Ph-5t in tomato. In contrast, Pi39A is a less aggressive genotype that defeats only Ph-1. Restriction site Associated DNA Sequencing (RAD-Seq) technology was used to massively sequence 90 bp nucleotides adjacent to both sides of PstI restriction enzyme cutting sites in the genome for all individuals in the genetic mapping population. The RAD-seq data were used to construct a genetic linkage map containing 440 single nucleotide polymorphism markers. Quantitative trait locus (QTL) analysis identified a new disease-resistant QTL specific to Pi733 on chromosome 2. The Ph-3 gene located on chromosome 9 could be detected whichever isolates were used. This study demonstrated the feasibility and efficiency of RAD-Seq technology for conducting a QTL mapping experiment using an F_2:3 mapping population, which allowed the identification of a new late blight resistant QTL in tomato.     

QTLs for resistance to powdery mildew in pepper under natural and artificial infections

Epidemics of powdery mildew due to Leveillula taurica is an increasing problem in pepper production areas, particularly in coastal regions or greenhouse cultivation. The highly resistant genitor 'H3' was submitted to genetic analysis and QTL mapping in order to promote the introgression of its oligogenic resistance into large and sweet-fruited cultivars. The doubled-haploid progeny from the cross 'H3' (resistant) by 'Vania' (susceptible) was tested for resistance under both natural field infection and artificial inoculation tests, and QTL detection was compared for those two methods. Seven genomic regions including additive QTLs and epistatic interactions were detected, explaining altogether the major part of genotypic variance. Two genomic regions were common to both the evaluation methods, whereas other QTLs were method-specific, reflecting the environment dependence of powdery mildew epidemics. Orthologies with tomato genomic regions carrying resistance genes to L. taurica and Oidium lycopersicum were revealed by comparative mapping with pepper. Tight linkages between the detected QTLs and virus resistance or fruit color traits in pepper were also shown, which adds to the agronomic importance of these regions in pepper breeding programs.Communicated by G. Wenzel     

DNA markers for Fusarium head blight resistance QTLs in two wheat populations

Genetic resistance to Fusarium head blight (FHB), caused by Fusarium graminearum, is necessary to reduce the wheat grain yield and quality losses caused by this disease. Development of resistant cultivars has been slowed by poorly adapted and incomplete resistance sources and confounding environmental effects that make screening of germplasm difficult. DNA markers for FHB resistance QTLs have been identified and may be used to speed the introgression of resistance genes into adapted germplasm. This study was conducted to identify and map additional DNA markers linked to genes controlling FHB resistance in two spring wheat recombinant inbred populations, both segregating for genes from the widely used resistance source ’Sumai 3’. The first population was from the cross of Sumai 3/Stoa in which we previously identified five resistance QTLs. The second population was from the cross of ND2603 (Sumai 3/Wheaton) (resistant)/ Butte 86 (moderately susceptible). Both populations were evaluated for reaction to inoculation with F. graminearum in two greenhouse experiments. A combination of 521 RFLP, AFLP, and SSR markers were mapped in the Sumai 3/Stoa population and all DNA markers associated with resistance were screened on the ND2603/Butte 86 population. Two new QTL on chromosomes 3AL and 6AS wer found in the ND2603/Butte 86 population, and AFLP and SSR markers were identified that explained a greater portion of the phenotypic variation compared to the previous RFLP markers. Both of the Sumai 3-derived QTL regions (on chromosomes 3BS, and 6BS) from the Sumai 3/Stoa population were associated with FHB resistance in the ND2603/Butte 86 population. Markers in the 3BS QTL region (Qfhs.ndsu-3BS) alone explain 41.6 and 24.8% of the resistance to FHB in the Sumai 3/Stoa and ND2603/Butte 86 populations, respectively. This region contains a major QTL for resistance to FHB and should be useful in marker-assisted selection. Received: 17 August 2000 / Accepted: 16 October 2000     

Mapping of loci from <Emphasis Type="Italic">Solanum lycopersicoides</Emphasis> conferring resistance or susceptibility to <Emphasis Type="Italic">Botrytis cinerea</Emphasis> in tomato

Cultivated tomato (Solanum lycopersicum, syn. Lycopersicon esculentum) is susceptible to the necrotrophic ascomycete and causal agent of gray mold, Botrytis cinerea. Resistance to this fungal pathogen is elevated in wild relatives of tomato, including Solanum lycopersicoides. An introgression line population (IL) containing chromosomal segments of S. lycopersicoides within the background of tomato cv. VF36 was used to screen the genome for foliar resistance and susceptibility to B. cinerea. Based on this screen, putative quantitative trait loci (QTL) were identified, five for resistance and two for susceptibility. Four resistance QTL decreased infection frequency while the fifth reduced lesion diameter. One susceptibility QTL increased infection frequency whereas the other increased lesion diameter. Overlapping chromosomal segments provided strong evidence for partial resistance on chromosomes 1 and 9 and for elevated susceptibility on chromosome 11. Segregation analysis confirmed the major resistance QTL on the long arm of chromosome 1 and susceptibility on chromosome 11. Linkage of partial resistance to chromosome 9 could not be confirmed. The usefulness of these data for resistance breeding and for map-based cloning of foliar resistance to B. cinerea is discussed.