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Resistance Genes (resistance + gene)
Kinds of Resistance Genes Selected AbstractsCharacterization of Wheat Random Amplified Polymorphic DNA Markers Associated with the H11 Hessian Fly Resistance GeneJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2006Dhia Bouktila Abstract In Tunisia, the Hessian fly Mayetiola destructor Say is a major pest of durum wheat (Triticum durum Desf.) and bread wheat (T. aestivum L.). Genetic resistance is the most efficient and economical method of control of this pest. To date, 31 resistance genes, designated H1,H31, have been identified in wheat. These genes condition resistance to the insect genes responsible for virulence. Using wheat cultivars differing for the presence of an individual Hessian fly resistance gene and random amplified polymorphic DNA (RAPD) analysis, we have identified a polymorphic 386-bp DNA marker (Xgmib1-1A.1) associated with the H11 Hessian fly resistance gene. Blast analysis showed a high identity with a short region in the wild wheat (T. monococcum) genome, adjacent to the leaf rust resistance Lr10 gene. A genetic linkage was reported between this gene (Lr10) and Hessian fly response in wheat. These data were used for screening Hessian fly resistance in Tunisian wheat germplasm. Xgmib1-1A.1-like fragments were detected in four Tunisian durum and bread wheat varieties. Using these varieties in Hessian fly breeding programs in Tunisia would be of benefit in reducing the damage caused by this fly. (Managing editor: Li-Hui Zhao) [source] Identification of Two Blast Resistance Genes in a Rice Variety, DiguJOURNAL OF PHYTOPATHOLOGY, Issue 2 2004X. W. Chen Abstract Blast, caused by Magnaporthe grisea is one of most serious diseases of rice worldwide. A Chinese local rice variety, Digu, with durable blast resistance, is one of the important resources for rice breeding for resistance to blast (M. grisea) in China. The objectives of the current study were to assess the identity of the resistance genes in Digu and to determine the chromosomal location by molecular marker tagging. Two susceptible varieties to blast, Lijiangxintuanheigu (LTH) and Jiangnanxiangnuo (JNXN), a number of different varieties, each containing one blast resistance gene, Piks, Pia, Pik, Pi - b, Pi - kp, Pi - ta2, Pi - ta, Pi - z, Pi - i, Pi - km, Pi - zt, Pi - t and Pi-11, and the progeny populations from the crosses between Digu and each of these varieties were analysed with Chinese blast isolates. We found that the resistance of Digu to each of the two Chinese blast isolates, ZB13 and ZB15, were controlled by two single dominant genes, separately. The two genes are different from the known blast resistance genes and, therefore, designated as Pi-d(t)1 and Pi-d(t)2. By using bulked segregation method and molecular marker analysis in corresponding F2 populations, Pi-d(t)1 was located on chromosome 2 with a distance of 1.2 and 10.6 cM to restriction fragment length polymorphism (RFLP) markers G1314A and G45, respectively. And Pi-d(t)2 was located on chromosome 6 with a distance of 3.2 and 3.4 cM to simple sequence repeat markers RM527 and RM3, respectively. We also developed a novel strategy of resistance gene analogue (RGA) assay with uneven polymerase chain reaction (PCR) to further tag the two genes and successfully identified two RGA markers, SPO01 and SPO03, which were co-segregated toPi-d(t)1 and Pi-d(t)2, respectively, in their corresponding F2 populations. These results provide essential information for further utilization of the Digu's blast resistance genes in rice disease resistance breeding and positional cloning of these genes. [source] Antimicrobial-resistant faecal Escherichia coli in wild mammals in central Europe: multiresistant Escherichia coli producing extended-spectrum beta-lactamases in wild boarsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2010I. Literak Abstract Aims:, To determine the presence of antibiotic-resistant faecal Escherichia coli in populations of wild mammals in the Czech Republic and Slovakia. Methods and Results:, Rectal swabs or faeces collected during 2006,2008 from wild mammals were spread on MacConkey agar and MacConkey agar containing 2 mg l,1 of cefotaxime. From plates with positive growth, one isolate was recovered and identified as E. coli. Susceptibility to 12 antibiotics was tested using the disk diffusion method. Resistance genes, class 1 and 2 integrons and gene cassettes were detected in resistant isolates by polymerase chain reaction (PCR). Extended-spectrum beta-lactamases (ESBL) were further characterized by DNA sequencing, macrorestriction profiling and determination of plasmid sizes. Plasmid DNA was subjected to EcoRV digestion, transferability by conjugation and incompatibility grouping by multiplex PCR. The prevalence of resistant isolates was 2% in small terrestrial mammals (rodents and insectivores, nE. coli = 242), 12% in wild ruminants and foxes (nE. coli = 42), while no resistant isolates were detected in brown bears (nE. coli = 16). In wild boars (Sus scrofa) (nE. coli = 290), the prevalence of resistant isolates was 6%. Class 1 and 2 integrons with various gene cassettes were recorded in resistant isolates. From wild boars, five (2%, nrectal smears = 293) multiresistant isolates producing ESBL were recovered: one isolate with blaCTX-M-1 + blaTEM-1, three with blaCTX-M-1 and one with blaTEM-52b. The blaCTX-M-1 genes were carried on approx. 90 kb IncI1 conjugative plasmids. Conclusions:, Antibiotic-resistant E. coli occured in populations of wild mammals in various prevalences. Significance and Impact of the Study:, Wild mammals are reservoirs of antibiotic-resistant E. coli including ESBL-producing strains which were found in wild boars. [source] A Kindling Model of Pharmacoresistant Temporal Lobe Epilepsy in Sprague,Dawley Rats Induced by Coriaria Lactone and Its Possible MechanismEPILEPSIA, Issue 4 2003Ying Wang Summary: ,Purpose: The aim of this study was to develop a new animal model of pharmacoresistant temporal lobe epilepsy (TLE) by repeated intramuscular injection of Coriaria lactone (CL) at subthreshold dosages and to explore the mechanisms that might be involved. Methods: Healthy male Sprague,Dawley rats (n = 160) were randomized into four groups during the kindling process: three groups (n = 50 for each group) received CL injection at subthreshold dosages (1.25, 1.5, and 1.75 mg/kg, respectively), and ten received normal saline (NS) injection as a control group. The maximal human adult dosage of carbamazepine (CBZ), valproate (VPA), and phenytoin (PHT) was administered as monotherapy to different groups of kindled rats for 1 month (n = 20 for each group). Changes in EEG recording, seizure number, intensity (expressed as grade 1,5 according to Racine stage), and duration, including spontaneous seizures during different interventions, were compared. The expression of P-170, a multiple drug resistance gene (MDR1) encoding P-glycoprotein, was measured in brain samples from different groups of experimental rats by using an image analysis and measurement system (ImagePro-Plus 4.0). Results: A total of 70 (46.7%) rats were fully kindled with a median of 15 (seven to 20) CL injections. Electrocorticogram (ECoG) including hippocampal (EHG) monitoring revealed the temporal lobe origins of epileptiform potentials, which were consistent with the behavioral changes observed. Spontaneous seizures occurred with frequency and diurnal patterns similar to those of human TLE. The antiepileptic drugs (AEDs) tested lacked a satisfactory seizure control. The maximal P-170 expression was in the kindled rats with AED treatment; the next highest was in the kindled rats without AED intervention. Nonkindled SD rats with CL injection also had increased P-170 expression compared with control SD rats. Conclusions: The study provided a simple and stable animal TLE kindling model with pharmacoresistant properties. The pharmacoresistance observed in the kindled rats to CBZ, VPA, and PHT at maximal human adult dosages together with the increased P-170 expression was a distinct feature of this model. This model might be used in further investigations of the mechanisms involved in pharmacoresistant TLE and for developing new AEDs. [source] Absence of residual effects of a defeated resistance gene in poplarFOREST PATHOLOGY, Issue 2 2003K.-S. Woo Summary In a few plant pathosystems, defeated major genes have been shown to contribute to partial resistance to disease. This hypothesis has never been tested before in a forest tree, but pathogenic variation associated with recent hybridization in poplar rust in the Pacific northwest provided an opportunity. An F2 progeny of 256 poplar clones in the field near Corvallis, Oregon, USA, has been monitored for rust severity and infection type since the advent of the new hybrid rust, Melampsora × columbiana, in the mid-1990s. All 256 clones displayed a susceptible infection type in 1997 and again in 2000, and yet variation in uredinial density (i.e. partial resistance) was still observed. To determine which clones possessed a defeated resistance gene, a greenhouse inoculation was performed with an isolate of M. medusae, one of the parents of M. × columbiana. Clones that would have been resistant to M. medusae, prior to the advent of M. × columbiana, were thus identified. The inoculation resulted in a 1 : 1 segregation (,2=0.772; p=0.38) for resistance, indicating the presence of a major gene. However, the F2 clones possessing the defeated resistance gene displayed the same level of partial resistance in the field in both 1997 and 2000 as their full siblings lacking the gene. Résumé Chez quelques pathosystèmes végétaux, il a été montré que le contournement de gènes majeurs de résistance contribue à une résistance partielle envers la maladie. Cette hypothèse n'a encore jamais été testée chez un arbre forestier, mais le changement de pouvoir pathogène associéà l'hybridation récente de la rouille du peuplier dans le nord-ouest des USA en a fourni l'occasion. Une descendance F2 de 256 clones de peuplier a été suivie au champ près de Corvallis, Oregon, USA, pour la gravité de la rouille et le type d'infection, depuis l'apparition du nouvel hybride Melampsora x columbiana, dans les années 1990. Tous les 256 clones se sont montrés sensibles en 1997 et à nouveau en 2000, et une variation dans la densité des urédies (résistance partielle) a aussi été observée. Pour déterminer quels clones présentaient une résistance contournée, des inoculations ont été réalisées en serre avec un isolat de Melampsora medusae originaire du Kentucky. Des clones qui étaient résistants àM. medusae avant l'apparition de M. x columbiana ont ainsi été identifiés. Les inoculations ont abouti à une ségrégation 1 :1 (,2 = 0,772; P = 0,38) pour la résistance, ce qui indique la présence d'un gène majeur. Cependant, les clones F2 possédant le gène de résistance contourné montraient le même niveau de résistance partielle au champ en 1997 et 2000 que leurs plein-frères qui n'avaient pas ce gène. Zusammenfassung Für einige Pflanzen-Pathosysteme wurde gezeigt, dass unwirksam gewordene Haupt-Resistenzgene immer noch zu einer teilweisen Resistenz beitragen. Für Waldbäume wurde diese Hypothese bisher nie überprüft. Dies wurde jetzt im pazifischen Nordwesten möglich, wo der Pappelrost nach einem rezenten Hybridisierungsereignis stark variierte. An den F2-Nachkommenschaften von 256 Pappelklonen, die unter Freilandbedingungen in der Nähe von Corvallis, Oregon, USA wuchsen, wurde nach dem Auftreten des neuen Hybridrostes (Melampsora × columbiana) ab ca. 1990 die Krankheitsintensität und der Infektionstyp registriert. Alle 256 Klone zeigten einen anfälligen Infektionstyp im Jahre 1997 und dann wieder im Jahre 2000. Dabei wurde eine Variation in der Urediendichte (d.h. partielle Resistenz) beobachtet. Um zu bestimmen, welche Klone ein unwirksam gewordenes Resistenzgen besitzen, wurden Inokulationen im Gewächshaus mit einem Isolat von M. medusae, einem Elter von M. × columbiana, durchgeführt. Damit wurden Klone identifiziert, die vor dem Auftreten von M. × columbiana gegen M. medusae resistent waren. Der Infektionsversuch führte zu einer 1:1 Segregation (,2=0,772; P=0,38) für die Resistenz, was auf das Vorliegen eines Hauptgens hinweist. Die F2-Klone, welche dieses überwundene Resistenzgen besitzen, zeigten jedoch unter Feldbedingungen in den Jahren 1997 und 2000 den gleichen Grad einer Teilresistenz wie ihre Vollgeschwister, welchen dieses Gen fehlt. [source] The Helicobacter hepaticus hefA Gene is Involved in Resistance to AmoxicillinHELICOBACTER, Issue 1 2009Clara Belzer Abstract Background:, Gastrointestinal infections with pathogenic Helicobacter species are commonly treated with combination therapies, which often include amoxicillin. Although this treatment is effective for eradication of Helicobacter pylori, the few existing reports are less clear about antibiotic susceptibility of other Helicobacter species. In this study we have determined the susceptibility of gastric and enterohepatic Helicobacter species to amoxicillin, and have investigated the mechanism of amoxicillin resistance in Helicobacter hepaticus. Materials and methods:, The minimal inhibitory concentration (MIC) of antimicrobial compounds was determined by E -test and agar/broth dilution assays. The hefA gene of H. hepaticus was inactivated by insertion of a chloramphenicol resistance gene. Transcription was measured by quantitative real-time polymerase chain reaction. Results:, Three gastric Helicobacter species (H. pylori, H. mustelae, and H. acinonychis) were susceptible to amoxicillin (MIC < 0.25 mg/L). In contrast, three enterohepatic Helicobacter species (H. rappini, H. bilis, and H. hepaticus) were resistant to amoxicillin (MIC of 8, 16, and 6,64 mg/L, respectively). There was no detectable ,-lactamase activity in H. hepaticus, and inhibition of ,-lactamases did not change the MIC of amoxicillin of H. hepaticus. A H. hepaticus hefA (hh0224) mutant, encoding a TolC-component of a putative efflux system, resulted in loss of amoxicillin resistance (MIC 0.25 mg/L), and also resulted in increased sensitivity to bile acids. Finally, transcription of the hefA gene was not responsive to amoxicillin, but induced by bile acids. Conclusions:, Rodents are frequently colonized by a variety of enterohepatic Helicobacter species, and this may affect their global health status and intestinal inflammatory responses. Animal facilities should have treatment strategies for Helicobacter infections, and hence resistance of enterohepatic Helicobacter species to amoxicillin should be considered when designing eradication programs. [source] Toll-like receptor 3 agonist poly(I:C)-induced antiviral response in human corneal epithelial cellsIMMUNOLOGY, Issue 1 2006Ashok Kumar Summary The objective of this study was to examine the expression of Toll-like receptor 3 (TLR3) by human corneal epithelial cells (HCECs) and to determine whether exposure to the TLR3 agonist polyinosinic-polycytidylic acid [poly(I:C)]induces an antiviral response in these cells. Fluorescence-activated cell sorter (FACS) analysis revealed TLR3 to be constitutively expressed and distributed intracellularly in HCECs. Stimulation of HCECs with the TLR3 agonist poly(I:C) induced the activation of nuclear factor (NF)-,B and production of the proinflammatory cytokine interleukin (IL)-6 and the chemokine IL-8. Upon exposure to poly(I:C), HCECs initiated a potent antiviral response resulting in an increase of interferon (IFN)-, mRNA expression (7-fold). Poly(I:C) stimulation also up-regulated mRNA expression of the antiviral chemokine IFN-, inducible protein 10 (IP10), myxovirus resistance gene A and 2,,5,-oligoadenylate synthetase (5-, 10- and 9-fold, respectively), and secretion of IP10. These responses were also induced by exogenously added type 1 IFNs, but could not be blocked by pretreatment of the cells with anti-TLR3 monoclonal antibody, suggesting that the receptor was not expressed on the cell surface. Furthermore, incubation of HCECs with an endosomal acidification inhibitor, chloroquine, markedly inhibited poly(I:C)-mediated IFN-, expression in HCECs. These results suggest that corneal epithelial cells are important sentinels of the corneal innate immune system against viral infection, and that stimulation of TLR3 can induce the expression of key proinflammatory cytokines and chemokines and antiviral genes that help in the defence of the cornea against viral infection. [source] Characterizing laboratory colonies of western corn rootworm (Coleoptera: Chrysomelidae) selected for survival on maize containing event DAS-59122-7JOURNAL OF APPLIED ENTOMOLOGY, Issue 3 2008S. A. Lefko Abstract Event DAS-59122-7 is a novel transgenic trait designed to protect the roots and yield potential of maize from the insect pest corn rootworm Diabrotica spp. (Col.: Chrysomelidae). The increased pest status of corn rootworm, exceptional efficacy of this trait, and anticipated increases in farm efficiency and grower and environmental safety will drive adoption of this trait. Strong grower acceptance of this trait highlights the importance of science-based and practical resistance management strategies. A non-diapause trait was introgressed into two laboratory colonies of Diabrotica virgifera virgifera collected from geographically distinct locations: Rochelle, IL and York, NE. Both colonies were divided and each reared on maize containing event DAS-59122-7 or its near isoline. Selected and unselected colonies were evaluated for phenotypic change in larval development, injury potential and survival to adulthood during 10 and 11 generations. The F1 generation of both selected colonies displayed increased larval development, survivorship and measurable, but economically insignificant increases in injury potential on DAS-59122-7 maize. Survival rates of 0.4 and 1.3% in F1 generations of both selected colonies corroborate field estimates of survival on DAS-59122-7 maize. Over later generations, total phenotypic variation declined gradually and irregularly. Despite the absence of random mating, the tolerance trait could not be fixed in either population after 10 or 11 generations of selection. An allele conferring major resistance to DAS-59122-7 was not identified in either selected colony. The assessment also concluded that major resistance gene(s) are rare in populations of D. v. virgifera in the United States, and that a minor trait(s) conferring a low level of survival on DAS-59122-7 maize was present. The tolerance trait identified in this study was considered minor with respect to its impact on DAS-59122-7 maize efficacy, and the role this trait may play in total effective refuge for major resistance genes with recessive inheritance is the basis of future work. [source] Construction and Application of Efficient Ac-Ds Transposon Tagging Vectors in RiceJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 11 2009Shaohong Qu Abstract Transposons are effective mutagens alternative to T-DNA for the generation of insertional mutants in many plant species including those whose transformation is inefficient. The current strategies of transposon tagging are usually slow and labor-intensive and yield low frequency of tagged lines. We have constructed a series of transposon tagging vectors based on three approaches: (i) AcTPase controlled by glucocorticoid binding domain/VP16 acidic activation domain/Gal4 DNA-binding domain (GVG) chemical-inducible expression system; (ii) deletion of AcTPase via Cre- lox site-specific recombination that was initially triggered by Ds excision; and (iii) suppression of early transposition events in transformed rice callus through a dual-functional hygromycin resistance gene in a novel Ds element (HPT-Ds). We tested these vectors in transgenic rice and characterized the transposition events. Our results showed that these vectors are useful resources for functional genomics of rice and other crop plants. The vectors are freely available for the community. [source] Characterization of Wheat Random Amplified Polymorphic DNA Markers Associated with the H11 Hessian Fly Resistance GeneJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2006Dhia Bouktila Abstract In Tunisia, the Hessian fly Mayetiola destructor Say is a major pest of durum wheat (Triticum durum Desf.) and bread wheat (T. aestivum L.). Genetic resistance is the most efficient and economical method of control of this pest. To date, 31 resistance genes, designated H1,H31, have been identified in wheat. These genes condition resistance to the insect genes responsible for virulence. Using wheat cultivars differing for the presence of an individual Hessian fly resistance gene and random amplified polymorphic DNA (RAPD) analysis, we have identified a polymorphic 386-bp DNA marker (Xgmib1-1A.1) associated with the H11 Hessian fly resistance gene. Blast analysis showed a high identity with a short region in the wild wheat (T. monococcum) genome, adjacent to the leaf rust resistance Lr10 gene. A genetic linkage was reported between this gene (Lr10) and Hessian fly response in wheat. These data were used for screening Hessian fly resistance in Tunisian wheat germplasm. Xgmib1-1A.1-like fragments were detected in four Tunisian durum and bread wheat varieties. Using these varieties in Hessian fly breeding programs in Tunisia would be of benefit in reducing the damage caused by this fly. (Managing editor: Li-Hui Zhao) [source] Virulence Frequences of Puccinia triticina in Germany and the European Regions of the Russian FederationJOURNAL OF PHYTOPATHOLOGY, Issue 1 2007V. Lind Abstract From 2001 to 2003, leaf rust was collected in different regions of Germany and the Russian Federation to generate single spore isolates and to study the structure of the pathogen populations by analyses of virulence. The virulence of isolates was tested with 38 near-isogenic lines each carrying a different resistance gene. The analyses of variance revealed significant effects for the frequency of virulent isolates, the regions and most interactions with years and regions, but no significance was found for the effects of years. In Germany, an increase of virulence frequencies was detected for Lr1 and Lr2a while a decrease was found for Lr3a, Lr3bg and Lr3ka. Such clear trends did not occur in Russia which may be due to the great agroclimatic differences between regions. The variance of the frequency of virulent isolates was used to estimate adequate sample sizes for the analysis of regional populations of leaf rust. This procedure resulted in more reliable information about the dynamic processes within the pathogen populations. In 2002 and 2003, all pathotypes in Germany had a combined virulence to Lr1, Lr2a, Lr2b, Lr15, Lr17 and Lr20 supplemented by a few other genes. The complexity of virulence was lower in the most frequent pathotypes. In Russia virulence to the alleles at locus Lr3 was very common. Using detached leaf segments in Germany and Russia it turned out that the most virulent pathotypes carry 34 and 32 virulence genes, respectively. Virulence to Lr9, Lr19, Lr24 and Lr38 was rare or even absent. The use of major genes, not overcome by corresponding virulent pathotypes, may contribute to more durable types of resistance in case they are combined with genes having different effects, e.g. adult plant resistance. [source] Screening for Barley yellow dwarf virus -Resistant Barley Genotypes by Assessment of Virus Content in Inoculated SeedlingsJOURNAL OF PHYTOPATHOLOGY, Issue 6 2006Abstract The content of Barley yellow dwarf virus (BYDV) in roots and leaves of barley seedling plants differing in their level of resistance was assessed by quantitative ELISA 1,42 days after inoculation with the strain of BYDV (PAV). High virus accumulation in roots and low concentration in leaves was characteristic of the period 9,15 days after inoculation. In leaves, the differences in virus content between resistant and susceptible genotypes became significant after 15 days and resistance to virus accumulation was better expressed 30,39 days after inoculation. Roots of resistant materials exhibited evident retardation of virus accumulation and the greatest difference in virus content between resistant and susceptible plants was detected 9 days after inoculation. By these criteria, the selected winter and spring barley cultivars and lines (in total 44 materials) fell in to five groups according to field reactions and the presence or absence of the Yd2 resistance gene. There were highly significant and positive relations between ELISA values and 5-year field data on symptomatic reactions and grain-yield reductions due to infection. Using the described method, resistant and moderately resistant genotypes (both Yd2 and non- Yd2) were significantly differentiated from susceptible genotypes. The possible use of this method in screening for BYDV resistance is discussed. [source] Identification of Two Blast Resistance Genes in a Rice Variety, DiguJOURNAL OF PHYTOPATHOLOGY, Issue 2 2004X. W. Chen Abstract Blast, caused by Magnaporthe grisea is one of most serious diseases of rice worldwide. A Chinese local rice variety, Digu, with durable blast resistance, is one of the important resources for rice breeding for resistance to blast (M. grisea) in China. The objectives of the current study were to assess the identity of the resistance genes in Digu and to determine the chromosomal location by molecular marker tagging. Two susceptible varieties to blast, Lijiangxintuanheigu (LTH) and Jiangnanxiangnuo (JNXN), a number of different varieties, each containing one blast resistance gene, Piks, Pia, Pik, Pi - b, Pi - kp, Pi - ta2, Pi - ta, Pi - z, Pi - i, Pi - km, Pi - zt, Pi - t and Pi-11, and the progeny populations from the crosses between Digu and each of these varieties were analysed with Chinese blast isolates. We found that the resistance of Digu to each of the two Chinese blast isolates, ZB13 and ZB15, were controlled by two single dominant genes, separately. The two genes are different from the known blast resistance genes and, therefore, designated as Pi-d(t)1 and Pi-d(t)2. By using bulked segregation method and molecular marker analysis in corresponding F2 populations, Pi-d(t)1 was located on chromosome 2 with a distance of 1.2 and 10.6 cM to restriction fragment length polymorphism (RFLP) markers G1314A and G45, respectively. And Pi-d(t)2 was located on chromosome 6 with a distance of 3.2 and 3.4 cM to simple sequence repeat markers RM527 and RM3, respectively. We also developed a novel strategy of resistance gene analogue (RGA) assay with uneven polymerase chain reaction (PCR) to further tag the two genes and successfully identified two RGA markers, SPO01 and SPO03, which were co-segregated toPi-d(t)1 and Pi-d(t)2, respectively, in their corresponding F2 populations. These results provide essential information for further utilization of the Digu's blast resistance genes in rice disease resistance breeding and positional cloning of these genes. [source] A highly efficient gene-targeting system for Aspergillus parasiticusLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2008P.-K. Chang Abstract Aims:, To establish a system that greatly increases the gene-targeting frequency in Aspergillus parasiticus. Methods and Results:, The ku70 gene, a gene of the nonhomologous end-joining (NHEJ) pathway, was replaced by the nitrate reductase gene (niaD) in A. parasiticus RHN1 that accumulates O -methylsterigmatocystin (OMST). The NHEJ-deficient strain, RH,ku70, produced conidia, sclerotia and OMST normally. It had identical sensitivity as RHN1 to the DNA-topoisomerase I complex inhibitor, camptothecin, and the DNA-damaging agent, melphalan. For targeting an aflatoxin biosynthetic pathway gene, adhA, partial restriction enzyme recognition sequences in its flanking regions were manipulated to create homologous ends for integration. Using a linearized DNA fragment that contained Aspergillus oryzae pyrithiamine resistance gene (ptr) marker the adhA -targeting frequency in RH,ku70 reached 96%. Conclusions:, The homologous recombination pathway is primarily responsible for repair of DNA damages in A. parasiticus. The NHEJ-deficient RH,ku70, easy creation of homologous ends for integration, and the ptr -based selection form a highly efficient gene-targeting system. It substantially reduces the time and workload necessary to obtain knockout strains for functional studies. Significance and Impact of the Study:, The developed system not only streamlines targeted gene replacement and disruption but also can be used to target specific chromosomal locations like promoters or intergenic regions. It will expedite the progresses in the functional genomic studies of A. parasiticus and Aspergilllus flavus. [source] Characterization of integrons and antimicrobial resistance genes in clinical isolates of Gram-negative bacteria from Palestinian hospitalsMICROBIOLOGY AND IMMUNOLOGY, Issue 11 2009Amjad I. A. Hussein ABSTRACT Sixty Gram-negative bacterial isolates were collected from Palestinian hospitals in 2006. Thirty-two (53.3%) isolates showed multidrug resistance phenotypes. PCR and DNA sequencing were used to characterize integrons and antimicrobial resistance genes. PCR screening showed that 19 (31.7%) and five (8.3%) isolates were positive for class 1 and class 2 integrons, respectively. DNA-sequencing results for the captured antimicrobial resistance gene cassettes within class 1 integrons identified the following genes: dihydrofolate reductases, dfrA1, dfrA5, dfrA7, dfrA12, dfrA17 and dfrA25; aminoglycoside adenyltransferases, aadA1, aadA2, aadA5, aadA12 and aadB; aminoglycoside acetyltransferase, aac(6,)-Ib; and chloramphenicol resistance gene, cmlA1. ESBL were identified in 25 (41.7%) isolates. The identified ESBL were blaCTX-M-15, blaCTX-M-56, blaOXA-1, blaSHV-1, blaSHV-12, blaSHV-32 and blaTEM-1 genes. Moreover, we characterized the plasmid-mediated quinolone resistance genes, aac(6,)-Ib-cr and qnrB2, which were detected in seven (11.7%) and two (3.3%) isolates, respectively. In this study various types of antibiotic resistance genes have been identified in Gram-negative bacteria from Palestinian hospitals, many of which are reported in the Middle East area for the first time. [source] Functional variation in a disease resistance gene in populations of Arabidopsis thalianaMOLECULAR ECOLOGY, Issue 22 2008T. H. JORGENSEN Abstract Analyses of functional genetic diversity in natural populations may provide important new insights into gene function and are necessary to understand the evolutionary processes maintaining diversity itself. The importance of including diversity within and between local populations in such studies is often ignored although many of the processes affecting genetic diversity act on this scale. Here we examine the molecular diversity in RPW8 (Recognition of Powdery Mildew), a gene conferring broad-spectrum resistance to powdery mildews in Arabidopsis thaliana stock-center accessions. Our eight UK study populations of the weedy A. thaliana were from locations judged to be subject to a minimum of anthropogenic disturbance and potentially long established. The majority of populations comprised considerable variation both in disease phenotype and RPW8 genotype. Although resistant individuals shared a major RPW8 genotype, no single allele was uniquely associated with resistance. It is concluded that RPW8 is an essential component of resistance to powdery mildews in A. thaliana, but not the only genetic factor involved in this process. No signature of selection was detected at RPW8 with a microsatellite multilocus test using an empirical null model. Unlike many previous studies of this model plant species, we found high levels of genetic diversity and relatively low differentiation (FST = 0.31) between populations at 14 microsatellite markers. This is judged to be due to our sampling being aimed at potentially long established populations and highlights the importance of population choice for studies of genetic diversity within this species. [source] World-wide survey of an Accord insertion and its association with DDT resistance in Drosophila melanogasterMOLECULAR ECOLOGY, Issue 8 2004F. CATANIA Abstract Previous work showed that insecticide resistance in Drosophila melanogaster is correlated with the insertion of an Accord -like element into the 5, region of the cytochrome P450 gene, Cyp6g1. Here, we study the distribution of the Accord -like element in 673 recently collected D. melanogaster lines from 34 world-wide populations. We also examine the extent of microsatellite variability along a 180-kilobase (kb) genomic region of chromosome II encompassing the resistance gene. We confirm a 100% correlation of the Accord insertion with insecticide resistance and a significant reduction in variability extending at least 20 kb downstream of the Cyp6g1 gene. The frequency of the Accord insertion differs significantly between East African (32,55%) and nonAfrican (85,100%) populations. This pattern is consistent with a selective sweep driving the Accord insertion close to fixation in nonAfrican populations as a result of the insecticide resistance phenotype it confers. This study confirms that hitchhiking mapping can be used to identify beneficial mutations in natural populations. [source] Transcription activator-like type III effector AvrXa27 depends on OsTFIIA,5 for the activation of Xa27 transcription in rice that triggers disease resistance to Xanthomonas oryzae pv. oryzaeMOLECULAR PLANT PATHOLOGY, Issue 6 2009KEYU GU SUMMARY The transcription activator-like (TAL) type III effector AvrXa27 from Xanthomonas oryzae pv. oryzae (Xoo) strain PXO99A activates the transcription of the host resistance gene Xa27, which results in disease resistance to bacterial blight (BB) in rice. In this study, we show that AvrXa27-activated Xa27 transcription requires host general transcription factor OsTFIIA,5. The V39E substitution in OsTFIIA,5, encoded by the recessive resistance gene xa5 in rice, greatly attenuates this activation in xa5 and Xa27 double homozygotes on inoculation with Xa27 -incompatible strains. The xa5 gene also causes attenuation in the induction of Xa27 by AvrXa27 expressed in rice. The xa5 -mediated attenuation of Xa27 -mediated resistance to PXO99A is recessive. Intriguingly, xa5 -mediated resistance to xa5 -incompatible strains is also down-regulated in the xa5 and Xa27 double homozygotes. In addition, AvrXa27 expressed in planta shows weak virulence activity in the xa5 genetic background and causes enhanced susceptibility of the plants to BB inoculation. The results suggest that TAL effectors target host general transcription factors to directly manipulate the host transcriptional machinery for virulence and/or avirulence. The identification of xa5 -mediated attenuation of Xa27 -mediated resistance to Xoo provides a guideline for breeding resistance to BB when pyramiding xa5 with other resistance genes. [source] Rust of flax and linseed caused by Melampsora liniMOLECULAR PLANT PATHOLOGY, Issue 4 2007GREGORY J. LAWRENCE SUMMARY Melampsora lini, while of economic importance as the causal agent of rust disease of flax and linseed, has for several decades been the ,model' rust species with respect to genetic studies of avirulence/virulence. Studies by Harold Flor demonstrated that single pairs of allelic genes determine the avirulence/virulence phenotype on host lines with particular resistance genes and led him to propose his famous ,gene-for-gene' hypothesis. Flor's inheritance studies, together with those subsequently carried out by others, also revealed that, in some cases, an inhibitor gene pair and an avirulence/virulence gene pair interact to determine the infection outcome on host lines with particular resistance genes. Recently, avirulence/virulence genes at four loci, AvrL567, AvrM, AvrP4 and AvrP/AvrP123, have been cloned. All encode novel, small, secreted proteins that are recognized inside plant cells. Yeast two-hybrid studies have shown that the AvrL567 proteins interact directly with the resistance gene protein. The molecular basis of Flor's gene-for-gene relationship has now been elucidated for six interacting gene pairs: those involving resistance genes L5, L6, L7, M, P and P2, where both the resistance gene and the corresponding avirulence gene have been cloned. In other inheritance studies it has been shown that M. lini does not possess a (+) and (,) mating system, but may possess a two factor system. Double-stranded (ds) RNA molecules occur in many strains of M. lini: examination of the progeny of one strain that possesses 11 dsRNA molecules revealed that they fall into three transmission units, designated L, A and B. The L unit consists of a single large dsRNA of 5.2 kbp while the A and B units each consist of five dsRNAs in the size range 1.1,2.8 kbp. The three units have different sexual and asexual transmission characteristics. The L unit is encapsidated in a virus-like particle, whereas the other units are not encapsidated. The population and coevolutionary aspects of M. lini on a wild, native Australian host species, Linum marginale, have been extensively investigated. A recent molecular analysis revealed that the M. lini isolates from L. marginale fall into two distinct lineages, one of which is apparently hybrid between two diverse genomes. Isolates in this lineage are largely fixed for heterozygosity, which suggests that sexual recombination does not occur in this lineage. [source] Magnaporthe oryzae isolates causing gray leaf spot of perennial ryegrass possess a functional copy of the AVR1-CO39 avirulence geneMOLECULAR PLANT PATHOLOGY, Issue 3 2006REBECCA PEYYALA SUMMARY Gray leaf spot of perennial ryegrass (Lolium perenne) is a severe foliar disease caused by the ascomycete fungus Magnaporthe oryzae (formerly known as Magnaporthe grisea). Control of gray leaf spot is completely dependent on the use of fungicides because currently available perennial ryegrass cultivars lack genetic resistance to this disease. M. oryzae isolates from perennial ryegrass (prg) were unable to cause disease on rice cultivars CO39 and 51583, and instead triggered a hypersensitive response. Southern hybridization analysis of DNA from over 50 gray leaf spot isolates revealed that all of them contain sequences corresponding to AVR1-CO39, a host specificity gene that confers avirulence to rice cultivar CO39, which carries the corresponding resistance gene Pi-CO39(t). There was also an almost complete lack of restriction site polymorphism at the avirulence locus. Cloning and sequencing of the AVR1-CO39 gene (AVR1-CO39Lp) from 16 different gray leaf spot isolates revealed just two point mutations, both of which were located upstream of the predicted open reading frame. When an AVR1-CO39Lp gene copy was transferred into ML33, a rice pathogenic isolate that is highly virulent to rice cultivar CO39, the transformants were unable to cause disease on CO39 but retained their virulence to 51583, a rice cultivar that lacks Pi-CO39(t). These data demonstrate that the AVR1-CO39 gene in the gray leaf spot pathogens is functional, and suggest that interaction of AVR1-CO39Lp and Pi-CO39(t) is responsible, at least in part, for the host specificity expressed on CO39. This indicates that it may be possible to use the Pi-CO39(t) resistance gene as part of a transgenic strategy to complement the current deficiency of gray leaf spot resistance in prg. Furthermore, our data indicate that, if Pi-CO39(t) can function in prg, the resistance provided should be broadly effective against a large proportion of the gray leaf spot pathogen population. [source] Magnaporthe grisea interactions with the model grass Brachypodium distachyon closely resemble those with rice (Oryza sativa)MOLECULAR PLANT PATHOLOGY, Issue 4 2004ANDREW P. M. ROUTLEDGE SUMMARY Germplasm of Brachypodium distachyon was inoculated with Magnaporthe grisea using either rice- (Guy11) or grass-adapted (FAG1.1.1, PA19w-06, PA31v-01) host-limited forms of the fungus, and interactions with varying degrees of susceptibility and resistance were identified. Ecotype ABR5 was resistant to each M. grisea strain whereas ABR1 was susceptible to all but P31vi-01. Mendelian segregation in ABR1 × ABR5 crosses suggested that a single dominant resistance gene conferred resistance to Guy11. Microscopic analyses revealed that the aetiology of Guy11 fungal development and disease progression in ABR1 closely resembled that of rice infections. In ABR5, Guy11 pathogenesis was first suppressed at 48 h post-inoculation, at the secondary hyphal formation stage and was coincident with cytoplasmic granulation. Resistance to strains PA31v-01 and FAG1.1.1 was associated with a localized cell death with little callose deposition. 3,3-Diaminobenzidine staining indicated the elicitation of cell death in B. distachyon was preceded by oxidative stress in the interacting epidermal cells and the underlying mesophyll cells. Northern blot hybridization using probes for barley genes (PR1, PR5 and PAL) indicated that each was more rapidly expressed in ABR5 challenged with Guy11 although the B. distachyon defence genes BD1 and BD8 were more quickly induced in ABR1. Such data show that B. distachyon is an appropriate host for functional genomic investigations into M. grisea pathology and plant responses. [source] Early signalling events in the Avr9/Cf-9-dependent plant defence responseMOLECULAR PLANT PATHOLOGY, Issue 1 2000Tina Romeis Resistance of tomato to the leaf mould fungus Cladosporium fulvum is controlled by the interaction between a plant-encoded resistance gene (Cf-9) and pathogen-encoded avirulence (Avr9) gene. Our objective is to understand the underlying molecular mechanisms that transmit the Cf-9/Avr9-dependent pathogen perception event and activate the plant defence response. Our approach toward the understanding of Cf -function is based on the analysis of early Cf-9/Avr9-mediated responses and signalling events. Because Cf-9 transgenically expressed in tobacco retains its specificity and activity to the Avr9 elicitor, signalling experiments were conducted in the heterologous system using these transgenic lines or derived Cf9 tobacco cell cultures. Among the earliest responses to the Avr9/Cf-9 elicitation event were rapid changes in ion-fluxes, the synthesis of active oxygen species (AOS), probably catalysed by a plant NADPH-oxidase, and the transient activation of two MAP kinases. These kinases were identified as WIPK (wounding-induced protein kinase) and SIPK (salicylic-acid induced kinase) from tobacco. Studies with pharmacological inhibitors suggested that the MAP kinases are located in an independent signalling pathway from the Avr9/Cf-9-dependent synthesis of AOS. SIPK and WIPK were involved in pathogen-related elicitation processes as well as in abiotic stress responses. This indicates that the plant defence is triggered via a signalling network that shares components with pathways originating from abiotic environmental stress stimuli. [source] A bidirectional gene trap construct suitable for T-DNA and Ds -mediated insertional mutagenesis in rice (Oryza sativa L.)PLANT BIOTECHNOLOGY JOURNAL, Issue 5 2004Andrew L. Eamens Summary A construct suitable for genome-wide transfer-DNA (T-DNA) and subsequent transposon-based (Ds) gene trapping has been developed for use in rice (Oryza sativa). This T-DNA/Ds construct contains: Ds terminal sequences immediately inside T-DNA borders for subsequent Ds mobilization; promoterless green fluorescent protein (sgfpS65T) and ,-glucuronidase (uidA) reporter genes, each fused to an intron (from Arabidopsis GPA1 gene) to enable bidirectional gene trapping by T-DNA or Ds; an ampicillin resistance gene (bla) and a bacterial origin of replication (ori) to serve as the plasmid rescue system; an intron-containing hygromycin phosphotransferase gene (hph) as a selectable marker or Ds tracer; and an intron-containing barnase gene in the binary vector backbone (VB) to select against transformants carrying unwanted VB sequences. More than a threefold increase over previously reported reporter gene-based gene trapping efficiencies was observed in primary T-DNA/Ds transformant rice lines, returning an overall reporter gene expression frequency of 23%. Of the plant organs tested, 3.3,7.4% expressed either reporter at varying degrees of organ or tissue specificity. Approximately 70% of the right border (RB) flanking sequence tags (FSTs) retained 1,6 bp of the RB repeat and 30% of the left border (LB) FSTs retained 5,23 bp of the LB repeat. The remaining FSTs carried deletions of 2,84 bp inside the RB or 1,97 bp inside the LB. Transposition of Ds from the original T-DNA was evident in T-DNA/Ds callus lines super-transformed with a transposase gene (Ac) construct, as indicated by gene trap reporter activity and rescue of new FSTs in the resulting double transformant lines. [source] Genetic analysis of seedling resistance to Stagonospora nodorum blotch in selected tetraploid and hexaploid wheat genotypesPLANT BREEDING, Issue 2 2009P. K. Singh Abstract Stagonospora nodorum blotch (SNB), caused by Phaeosphaeria nodorum, is a major component of the leaf-spotting disease complex of wheat (Triticum aestivum L.) in the northern Great Plains of North America. This study was conducted, under controlled environmental conditions, to determine the inheritance of resistance to SNB in a diverse set of hexaploid and tetraploid wheat genotypes and to decipher the genic/allelic relationship among the resistance gene(s). Plants were inoculated at the two to three-leaf stages with a spore suspension of P. nodorum isolate Kelvington-SK and disease reaction was assessed 8 days after inoculation based on a lesion-type scale. Tests of the F1 and F2 generations and of F2 : 3 or F2 : 5 families indicated that a single recessive gene controlled resistance to SNB in both hexaploid and tetraploid resistance sources. Lack of segregation in intra-specific and inter-specific crosses between the hexaploid and the tetraploid resistant genotypes, indicated that these genetically diverse sources of resistance possess the same gene for resistance to SNB. Results of this study suggest that the wheat- P. nodorum interaction may follow the toxin model of the gene-for-gene hypothesis. [source] Wheat leaf rust resistance gene Lr59 derived from Aegilops peregrinaPLANT BREEDING, Issue 4 2008G. F. Marais Abstract An Aegilops peregrina (Hackel in J. Fraser) Maire & Weiller accession that showed resistance to mixed leaf rust (Puccinia triticina Eriks.) inoculum was crossed with, and backcrossed to, hexaploid wheat (Triticum aestivum L.). During backcrossing a chromosome segment containing a leaf rust resistance gene (here designated Lr59) was spontaneously translocated to wheat chromosome 1A. Meiotic, monosomic and microsatellite analyses suggested that the translocated segment replaced most of, or the complete, 1AL arm, and probably resulted from centromeric breaks and fusion. The translocation, of which hexaploid wheat line 0306 is the appropriate source material, provided seedling leaf rust resistance against a wide range of South African and Canadian pathotypes. [source] Strong evidence for a fire blight resistance gene of Malus robusta located on linkage group 3PLANT BREEDING, Issue 5 2007A. Peil Abstract Fire blight (FB), caused by the Gram-negative bacterium Erwinia amylovora is a dangerous disease on pome fruit, including apple. The FB-susceptible cultivar ,Idared' was crossed with the resistant wild species clone Malus × robusta 5. A segregating population of 146 progeny has been tested by artificial shoot inoculation for susceptibility to FB. Progeny were infected from 0% to 100% of the shoot length. To identify chromosomal regions or loci responsible for resistance to FB of Malus × robusta 5, a set of microsatellite markers (simple sequence repeat, SSRs) was chosen covering all linkage groups of apple. Up to eight different microsatellites were bulked to one mutliplex PCR using four different labels and a fifth label for a size standard. Fifty-nine microsatellite markers out of 72 SSRs were polymorphic. Fifty-four of 66 loci detected could be mapped and were useful for the detection of related resistant loci. Alleles of microsatellites Hi03d06, CH03g07 and CH03e03 originating from the resistant donor M. robusta were associated with resistance to Erwinia amylovora. Up to eighty percent of the phenotypic variation could be explained by the interval spanned by SSRs CH03g07 and CH03e03, indicating the presence of a major resistance gene. All three microsatellites are located on the distal part of linkage group 3, spanning 15 cM. The SSR marker CH03e03 can be regarded as diagnostic marker for FB resistance. Only seven progeny expressing allele b (184 bp) of CH03e03 showed blighted shoot lengths of more than 30% and only nine progeny lacking allele b showed blighted shoot lengths of <30%. By setting a threshold of 30% shoot necrosis for resistance to FB, the 146 individuals segregate into 71 susceptible and 75 resistant plants, and resistance to FB maps 9 cM away from marker CH03e03. [source] Fusarium head blight resistance derived from Lophopyrum elongatum chromosome 7E and its augmentation with Fhb1 in wheatPLANT BREEDING, Issue 5 2006X. Shen Abstract The objective of this study was to assess the effectiveness of Fusarium head blight (FHB) resistance derived from wheatgrass Lophopyrum elongatum chromosome 7E and to determine whether this resistance can augment resistance in combination with other FHB resistance quantitative trait loci (QTL) or genes in wheat. The ,Chinese Spring',Lophopyrum elongatum disomic substitution line 7E(7B) was crossed to three wheat lines: ,Ning 7840', L3, and L4. F2 populations were evaluated for type II resistance with the single-floret inoculation method in the greenhouse. Simple sequence repeat markers associated with Fhb1 in ,Ning 7840' and L4 and markers located on chromosome 7E were genotyped in each population. Marker,trait association was analysed with one-way or two-way analysis of variance. The research showed that, in the three populations, the average number of diseased spikelets (NDS) in plants with chromosome 7E is 1.2, 3.1 and 3.2, vs. NDS of 3.3, 7.2 and 9.1 in plants without 7E, a reduction in NDS of 2.1, 4.1 and 5.9 in the respective populations. The QTL on 7E and the Fhb1 gene augment disease resistance when combined. The effect of the QTL on 7E was greater than that on 3BS in this experiment. Data also suggest that the FHB resistance gene derived from L. elongatum is located on the long arm of 7E. [source] Evaluation of common wheat cultivars for tan spot resistance and chromosomal location of a resistance gene in the cultivar ,Salamouni'PLANT BREEDING, Issue 4 2006W. Tadesse Abstract A total of 50 wheat (Triticum aestivum L.) cultivars were evaluated for resistance to tan spot, using Pyrenophora tritici-repentis race 1 and race 5 isolates. The cultivars ,Salamouni', ,Red Chief', ,Dashen', ,Empire' and ,Armada' were resistant to isolate ASC1a (race 1), whereas 76% of the cultivars were susceptible. Chi-squared analysis of the F2 segregation data of hybrids between 20 monosomic lines of the wheat cultivar ,Chinese Spring' and the resistant cultivar ,Salamouni' revealed that tan spot resistance in ,Salamouni' was controlled by a single recessive gene located on chromosome 3A. This gene is designated tsn4. The resistant cultivars identified in this study are recommended for use in breeding programmes to improve tan spot resistance in common wheat. [source] Field trial of serially passaged isolates of BYDV-PAV overcoming resistance derived from Thinopyrum intermedium in wheatPLANT BREEDING, Issue 3 2006F. Chain Abstract Barley yellow dwarf disease (BYDD) 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 viral species including the species Barley yellow dwarf virus -PAV (BYDV-PAV, family Luteoviridae, genus Luteovirus), frequently found in western Europe. Resistance sources towards BYDD are scarce. Indeed, breeding-resistant genotypes is a long and expensive process. Thus, estimating the durability of the resistance genes before the achievement of selection would be an asset for breeders. One isolate of BYDV-PAV has been serially passaged on two hosts, ,Zhong ZH' and ,TC14', carrying a gene for partial resistance. The resulting viral population showed an increase of the speed of development of the infection in controlled conditions. In this study, these viral populations were evaluated in a 3-year field trial, including a susceptible host, ,Rendezvous', and a host carrying the resistance gene of ,TC14' in a ,Rendezvous' background, to assess the effect of serial passages in field conditions. Results indicate that isolates issued from serial passages on hosts carrying a gene for partial resistance induced increased damage in field conditions when compared with the initial isolate. Yield losses are mainly due to a decrease of the number of kernels per square metre. The interest on using partial resistance gene to control BYDD is discussed. [source] Comparison of a modified assay method for the endopeptidase marker Ep-D1b with the Sequence Tag Site marker XustSSR2001,7DL for strawbreaker foot rot resistance in wheatPLANT BREEDING, Issue 1 2006D. K. Santra Abstract The endopeptidase marker Ep-D1b and Sequence Tag Site (STS) marker XustSSR2001,7DL were reported to be closely associated with the most effective resistance gene (Pch1) in wheat (Triticum aestivum L.) for strawbreaker foot rot [Pseudocercosporella herpotrichoides (Fron) Deighton]. Our objectives were to: (i) develop an efficient assay method for Ep-D1b in wheat; (ii) correlate endopeptidase zymograms to strawbreaker foot rot reactions of various wheat genotypes; and (iii) compare the utility of Ep-D1b and XustSSR2001,7DL for predicting disease response. An improved method of assaying for the Ep-D1b marker using roots from a single seedling was developed, which is a 2.5-fold improvement over the previous method. Thirty-eight wheat genotypes with known reactions to strawbreaker foot rot were analysed for Ep-D1b and the STS marker. Six distinct endopeptidase zymograms were identified among these 38 genotypes tested, and three of these patterns were novel. The endopeptidase marker was 100% accurate for predicting strawbreaker foot rot disease response, whereas the STS marker predicted the correct phenotype with approximately 90% accuracy. The endopeptidase marker Ep-D1b was more effective and was more economical for use in marker-assisted selection strategies for Pch1 in our laboratory compared with the STS marker. [source] | |||||||||||||||||||||||||||||||||||||