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Thierry Langin - One of the best experts on this subject based on the ideXlab platform.
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resistance to Colletotrichum Lindemuthianum in phaseolus vulgaris a case study for mapping two independent genes
Theoretical and Applied Genetics, 2008Co-Authors: Valerie Geffroy, Michel Dron, Mireille Sevignac, Paul Billant, Thierry LanginAbstract:Anthracnose, caused by the hemibiotrophic fungal pathogen Colletotrichum Lindemuthianum is a devastating disease of common bean. Resistant cultivars are economical means for defense against this pathogen. In the present study, we mapped resistance specificities against 7 C. Lindemuthianum strains of various geographical origins revealing differential reactions on BAT93 and JaloEEP558, two parents of a recombinant inbred lines (RILs) population, of Meso-american and Andean origin, respectively. Six strains revealed the segregation of two independent resistance genes. A specific numerical code calculating the LOD score in the case of two independent segregating genes (i.e. genes with duplicate effects) in a RILs population was developed in order to provide a recombination value (r) between each of the two resistance genes and the tested marker. We mapped two closely linked Andean resistance genes (Co-x, Co-w) at the end of linkage group (LG) B1 and mapped one Meso-american resistance genes (Co-u) at the end of LG B2. We also confirmed the complexity of the previously identified B4 resistance gene cluster, because four of the seven tested strains revealed a resistance specificity near Co-y from JaloEEP558 and two strains identified a resistance specificity near Co-9 from BAT93. Resistance genes found within the same cluster confer resistance to different strains of a single pathogen such as the two anthracnose specificities Co-x and Co-w clustered at the end of LG B1. Clustering of resistance specificities to multiple pathogens such as fungi (Co-u) and viruses (I) was also observed at the end of LG B2.
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the plant nitrogen mobilization promoted by Colletotrichum Lindemuthianum in phaseolus leaves depends on fungus pathogenicity
Journal of Experimental Botany, 2007Co-Authors: Virginie Tavernier, Richard Laugé, Thierry Langin, Sandrine Cadiou, Karine Pageau, Michele Reisdorfcren, Celine MasclauxdaubresseAbstract:Nitrogen plays an essential role in the nutrient relationship between plants and pathogens. Some studies report that the nitrogen-mobilizing plant metabolism that occurs during abiotic and biotic stress could be a 'slash-and-burn' defence strategy. In order to study nitrogen recycling and mobilization in host plants during pathogen attack and invasion, the Colletotrichum Lindemuthianum/Phaseolus vulgaris interaction was used as a model. C. Lindemuthianum is a hemibiotroph that causes anthracnose disease on P. vulgaris. Non-pathogenic mutants and the pathogenic wild-type strain were used to compare their effects on plant metabolism. The deleterious effects of infection were monitored by measuring changes in chlorophyll, protein, and amino acid concentrations. It was shown that amino acid composition changed depending on the plant-fungus interaction and that glutamine accumulated mainly in the leaves infected by the pathogenic strain. Glutamine accumulation correlated with the accumulation of cytosolic glutamine synthetase (GS1 alpha) mRNA. The most striking result was that the GS1 alpha gene was induced in all the fungus-infected leaves, independent of the strain used for inoculation, and that GS1 alpha expression paralleled the PAL3 and CHS defence gene expression. It is concluded that a role of GS1 alpha in plant defence has to be considered.
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Nonpathogenic strains of Colletotrichum Lindemuthianum trigger progressive bean defense responses during appressorium-mediated penetration.
Applied and environmental microbiology, 2005Co-Authors: Claire Veneault-fourrey, Richard Laugé, Thierry LanginAbstract:The fungal bean pathogen Colletotrichum Lindemuthianum differentiates appressoria in order to penetrate bean tissues. We showed that appressorium development in C. Lindemuthianum can be divided into three stages, and we obtained three nonpathogenic strains, including one strain blocked at each developmental stage. H18 was blocked at the appressorium differentiation stage; i.e., no genuine appressoria were formed. H191 was blocked at the appressorium maturation stage; i.e., appressoria exhibited a pigmentation defect and developed only partial internal turgor pressure. H290 was impaired in appressorium function; i.e., appressoria failed to penetrate into bean tissues. Furthermore, these strains could be further discriminated according to the bean defense responses that they induced. Surprisingly, appressorium maturation, but not appressorium function, was sufficient to induce most plant defense responses tested (superoxide ion production and strong induction of pathogenesis-related proteins). However, appressorium function (i.e., entry into the first host cell) was necessary for avirulence-mediated recognition of the fungus.
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The tetraspanin gene ClPLS1 is essential for appressorium-mediated penetration of the fungal pathogen Colletotrichum Lindemuthianum.
Fungal genetics and biology : FG & B, 2005Co-Authors: Claire Veneault-fourrey, Richard Laugé, Denise Parisot, Mathieu Gourgues, Marc-henri Lebrun, Thierry LanginAbstract:Conservation of the molecular mechanisms controlling appressorium-mediated penetration during evolution was assessed through a functional study of the ClPLS1 gene from Colletotrichum Lindemuthianum orthologous to the MgPLS1 from Magnaporthe grisea, involved in penetration peg development. These two plant-pathogenic Pyrenomycetes differentiate appressoria to penetrate into plant tissues. We showed that ClPLS1 is a functional homologue of MgPLS1 in M. grisea. Loss of ClPLS1 function had no effect on vegetative growth, conidiation or on appressorium differentiation and maturation. However, Clpls1::hph mutants are non-pathogenic on either intact or wounded bean leaves, as a result of a defect in the formation and/or positioning of the penetration pore and consequently in the formation of the penetration peg. These observations suggest that the fungal tetraspanins control a conserved appressorial function that could be required for the correct localization of the site where the penetration peg emerges.
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clnr1 the area nit2 like global nitrogen regulator of the plant fungal pathogen Colletotrichum Lindemuthianum is required for the infection cycle
Molecular Microbiology, 2003Co-Authors: Annelaure Pellier, Richard Laugé, Claire Veneaultfourrey, Thierry LanginAbstract:Nitrogen starvation is generally assumed to be encountered by biotrophic and hemibiotrophic plant fungal pathogens at the beginning of their infection cycle. We tested whether nitrogen starvation constitutes a cue regulating genes that are required for pathogenicity of Colletotrichum Lindemuthianum, a fungal pathogen of common bean. The clnr1 (C. Lindemuthianumnitrogen regulator 1) gene, the areA/nit-2 orthologue of C. Lindemuthianum, was isolated. The predicted CLNR1 protein exhibits high amino acid sequence similarities with the AREA and NIT2 global fungal nitrogen regulators. Targeted clnr1- mutants are unable to use a wide array of nitrogen sources, indicating that clnr1 is the C. Lindemuthianum major nitrogen regulatory gene. The clnr1- mutants are non-pathogenic, although few anthracnose lesions seldom occur on whole plantlets. Surprisingly, cytological analysis reveals that the clnr1- mutants are not disturbed from the penetration stage until the end of the biotrophic phase, but that they are impaired during the setting up of the necrotrophic phase. Thus, through CLNR1, nitrogen starvation constitutes a cue for the regulation of genes that are compulsory for this stage of the C. Lindemuthianum infection process. Additionally, clnr1- mutants complemented with the Aspergillus nidulans areA gene are fully pathogenic, indicating that areA is able to activate the C. Lindemuthianum suited genes, normally under the control of clnr1.
Steve Beebe - One of the best experts on this subject based on the ideXlab platform.
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Sources of Resistance to Colletotrichum Lindemuthianum in the Secondary Gene Pool of Phaseolus vulgaris and in Crosses of Primary and Secondary Gene Pools.
Plant Disease, 2002Co-Authors: George S. Mahuku, Carlos Jara, César Cajiao, Steve BeebeAbstract:Mahuku, G. S., Jara, C. E., Cajiao, C., and Beebe, S. 2002. Sources of resistance to Colletotrichum Lindemuthianum in the secondary gene pool of Phaseolus vulgaris and in crosses of primary and secondary gene pools. Plant Dis. 86:1383-1387. Use of genetic resistance is the most practical and economic way to manage anthracnose of common bean. Colletotrichum Lindemuthianum, the causal agent of bean anthracnose, is a highly variabile pathogen, and there are no host resistance genes that are effective against all known races of the pathogen. To diversify sources of resistance, we screened the core collection of the secondary gene pool of Phaseolus spp. and interspecific lines derived from simple and complex crosses of primary and secondary genotypes for their resistance to anthracnose. High levels of resistance were observed in the secondary gene pool. None of the 162 accessions tested was susceptible to C. Lindemuthianum. Of the two species composing the secondary gene pool, P. polyanthus displayed higher levels of resistance than P. coccineus, and all accessions tested were resistant. The response of P. coccineus was more variable, with six genotypes showing an intermediate reaction. Among the 75 lines from interspecific crosses, 49 were resistant to the three races (races 6, 15, and 3481) used in this study, and higher levels of resistance were found in lines that had P. polyanthus as one of the parents in the crosses than in the lines derived from P. coccineus. These lines constitute a valuable source of resistance and may aid in the development of stable resistance to anthracnose.
Richard J Oconnell - One of the best experts on this subject based on the ideXlab platform.
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the spore coat of the bean anthracnose fungus Colletotrichum Lindemuthianum is required for adhesion appressorium development and pathogenicity
Physiological and Molecular Plant Pathology, 2007Co-Authors: Sarah L Rawlings, Richard J Oconnell, Jonathan R GreenAbstract:The spores (conidia) of the bean anthracnose fungal pathogen, Colletotrichum Lindemuthianum, adhere to the aerial parts of plants to initiate the infection process. In previous studies we have shown that the Colletotrichum spores are surrounded by a fibrillar spore coat, comprising several major glycoproteins. Previous evidence showed that a monoclonal antibody (UB20) that recognised these glycoproteins was able to inhibit adhesion of spores to a hydrophobic surface. In this paper we have further studied the role of the spore coat in adhesion, germination and fungal development by studying the effects of UB20 and protease treatment of spores. The latter treatment has previously been shown to remove the spore coat. Spores germinate on glass, polystyrene and water agar, however, appressoria only develop on glass or polystyrene, showing a requirement for a hard surface. Removal of the spore coat with protease inhibits adhesion at 30 min, before the secretion of ECM glycoproteins. Protease treatment also inhibits the development of appressoria and reduces pathogenicity on leaves. Incubation of spores with the MAb UB20 inhibits adhesion at 30 min, but does not affect appressorium formation or pathogenicity. The results suggest that an intact spore coat has two functions; it is required for adhesion to a hydrophobic surface and for the detection of a hard surface necessary for appressorium formation. We suggest that contact with a hard surface, rather than adhesion, is the key event leading to appressorium formation. r 2007 Elsevier Ltd. All rights reserved.
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regulation and role of a ste12 like transcription factor from the plant pathogen Colletotrichum Lindemuthianum
Molecular Microbiology, 2007Co-Authors: Joanne Wong Sak Hoi, Richard J Oconnell, Corentin Herbert, Nafees Bacha, Claude Lafitte, Gisele Borderies, Michel Rossignol, Pierre Rouge, Bernard DumasAbstract:In phytopathogenic fungi, STE12-like genes encode transcription factors essential for appressorium-mediated host penetration. However, their regulation and downstream targets are still unknown. In the present study, a STE12-like gene (CLSTE12) from Colletotrichum Lindemuthianum was isolated. We identified a spliced variant whose expression was negatively regulated during early stages of pathogenesis, whereas the correctly spliced mRNA remained expressed up to the penetration step, suggesting distinct roles for these two transcripts. Indeed, the full-length sequence was able to complement a yeast STE12 mutant, whereas overexpression of the transcript variant had a dominant-negative effect on yeast invasive growth and C. Lindemuthianum pathogenicity. To further investigate the downstream genes that could be regulated by CLSTE12, disruption mutants were generated. Phenotypic analyses of the mutants revealed reduced pectinase activity and conidial adhesion to polystyrene. Analysis of cell surface proteins allowed the identification of a major protein, Clsp1p, which was absent from the mutants. Clsp1p belongs to a new family of wall-associated proteins only found in euascomycetous fungi. Overall, these results suggest that the activity of CLSTE12 can be modulated by a regulated alternative splicing mechanism and that this factor is involved in the production of cell surface proteins and host cell wall degrading enzymes.
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production of a cell wall associated endopolygalacturonase by Colletotrichum Lindemuthianum and pectin degradation during bean infection
Fungal Genetics and Biology, 2004Co-Authors: Corentin Herbert, Marietherese Esquerretugaye, Richard J Oconnell, Elodie Gaulin, Vincent Salesses, Bernard DumasAbstract:The bean pathogen Colletotrichum Lindemuthianum expresses two endopolygalacturonase genes, CLPG1 and CLPG2, during interaction with its host plant. However, only CLPG1 was found to be secreted to the extracellular medium during saprophytic growth of the fungus on pectin. To localize CLPG2, a FLAG epitope sequence was inserted in the C-terminal sequence of CLPG2 and the modified gene was introduced into C. Lindemuthianum. Western blot analysis using a FLAG monoclonal antibody allowed the detection of CLPG2 in intracellular protein extracts and in the cell wall fraction, but not in the culture medium. Indirect immunofluorescence microscopy was performed to detect CLPG2 during saprophytic or parasitic growth. According to the expression pattern of CLPG2, it was found that CLPG2 accumulates in the fungal cell wall during growth on pectin medium and during appressorium formation, both in vitro and during interaction with the plant. Pectin degradation was not detected around the infection peg using the monoclonal antibody JIM7, specific for methyl-esterified galacturonan. However, extensive pectin dissolution was observed during the development of secondary hyphae.
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surface characteristics of necrotrophic secondary hyphae produced by the bean anthracnose fungus Colletotrichum Lindemuthianum
European Journal of Plant Pathology, 2001Co-Authors: Sarah E Perfect, Jonathan R Green, Richard J OconnellAbstract:During infection of bean (Phaseolus vulgaris), the hemibiotrophic anthracnose pathogen, Colletotrichum Lindemuthianum, initially produces biotrophic primary hyphae that are large-diameter and entirely intracellular, followed by necrotrophic secondary hyphae that are narrower and either intercellular or intracellular. In the present study, transmission electron microscopy of infected tissues prepared by high-pressure freezing and freeze-substitution showed that secondary hyphae have much thinner cell walls (25–40 nm) than primary hyphae (100–130 nm) and are not surrounded by an extracellular matrix. Immunofluorescence labelling with a panel of monoclonal antibodies showed that glycoproteins which are present on conidia, germ-tubes, appressoria, primary hyphae and mycelium grown in vitro are absent from the surface of secondary hyphae. Chitin, detected with the lectin wheat germ agglutinin, was the only surface component shared by secondary hyphae and the other fungal cell types. The results suggest that the fungal cell surface becomes modified during necrotrophic growth, with none of the glycoproteins associated with earlier stages of the infection process being produced.
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spore surface glycoproteins of Colletotrichum Lindemuthianum are recognized by a monoclonal antibody which inhibits adhesion to polystyrene
Microbiology, 1999Co-Authors: Bleddyn H Hughes, Jonathan R Green, Raffaella Carzaniga, Sarah L Rawlings, Richard J OconnellAbstract:Conidia (spores) of Colletotrichum Lindemuthianum, a fungal plant pathogen causing bean anthracnose, adhere to the aerial parts of host plants to initiate the infection process. These spores possess a fibrillar' spore coat' as well as a cell wall. In a previous study a mAb, UB20, was raised that recognized glycoproteins on the spore surface. In this study UB20 was used to localize and characterize these glycoproteins and to investigate their possible role in adhesion. Glycoproteins recognized by UB20 were concentrated on the outer surface of the spore coat and, to a lesser extent, at the plasma membrane/cell wall interface. Extraction of spores with hot water or 0-2% SDS resulted in removal of the spore coat. Western blotting with UB20 showed that a relatively small number of glycoproteins were extracted by these procedures, including a major component at 110 kDa. Biotinylation of carbohydrate moieties, together with cell fractionation, confirmed that these glycoproteins were exposed at the surface of the spores. In adhesion assays, < 90% of ungerminated conidia attached to polystyrene Petri dishes within 30 min. UB20 IgG at low concentrations inhibited attachment in an antigen-specific manner. This suggests that the glycoproteins recognized by this mAb may function in the initial rapid attachment of conidia to hydrophobic substrata. Polystyrene microspheres bound selectively to the 110 kDa glycoprotein in Western blots, providing further evidence that this component could mediate interactions with hydrophobic substrata.
James D Kelly - One of the best experts on this subject based on the ideXlab platform.
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Colletotrichum Lindemuthianum the causal agent of bean anthracnose
Journal of Plant Pathology, 2017Co-Authors: B A Padder, P N Sharma, Halima E Awale, James D KellyAbstract:Common bean (Phaseolus vulgaris L.) is an important constituent of people’s diets especially in developing countries. Dry beans find a suitable position in the culinary items because of their high nutritional value. For instance, rice and bean recipe (Rajmah Chawal) is famous in the northern part of India. Many fungal, viral and bacterial diseases affect the crop and causes heavy losses worldwide. Among the various fungal diseases, bean anthracnose caused by Colletotrichum Lindemuthianum is a serious disease under cool and humid environments. Under favorable conditions, the yield losses may be up to 100 percent. The scientific community across the world has been studying the bean-anthracnose interaction for over 100 years and the information has helped to understand the pathosystem and devise better disease management strategies. Many excellent reviews on anthracnose resistance genes, marker aided breeding and R gene signatures highlight different tactics for disease management. Assembling the substantial literature available on pathogen is necessary for better understanding of the pathogen biology. The present review consolidates this information and provides a comprehensive outline about the detection, pathogenicity genes, pathogenic variability and molecular diversity of C. Lindemuthianum. The importance of the bean genome and availability of SNP markers to dissect the bean-anthracnose interface is also addressed.
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transcriptome profiling of the phaseolus vulgaris Colletotrichum Lindemuthianum pathosystem
PLOS ONE, 2016Co-Authors: B A Padder, Halima E Awale, Kelvin Kamfwa, James D KellyAbstract:Bean (Phaseolus vulgaris) anthracnose caused by the hemi-biotrophic pathogen Colletotrichum Lindemuthianum is a major factor limiting production worldwide. Although sources of resistance have been identified and characterized, the early molecular events in the host-pathogen interface have not been investigated. In the current study, we conducted a comprehensive transcriptome analysis using Illumina sequencing of two near isogenic lines (NILs) differing for the presence of the Co-1 gene on chromosome Pv01 during a time course following infection with race 73 of C. Lindemuthianum. From this, we identified 3,250 significantly differentially expressed genes (DEGs) within and between the NILs over the time course of infection. During the biotrophic phase the majority of DEGs were up regulated in the susceptible NIL, whereas more DEGs were up-regulated in the resistant NIL during the necrotrophic phase. Various defense related genes, such as those encoding PR proteins, peroxidases, lipoxygenases were up regulated in the resistant NIL. Conversely, genes encoding sugar transporters were up-regulated in the susceptible NIL during the later stages of infection. Additionally, numerous transcription factors (TFs) and candidate genes within the vicinity of the Co-1 locus were differentially expressed, suggesting a global reprogramming of gene expression in and around the Co-1 locus. Through this analysis, we reduced the previous number of candidate genes reported at the Co-1 locus from eight to three. These results suggest the dynamic nature of P. vulgaris–C. Lindemuthianum interaction at the transcriptomic level and reflect the role of both pathogen and effector triggered immunity on changes in plant gene expression.
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genetic mapping of the resistance allele co 52 to Colletotrichum Lindemuthianum in the common bean msu 7 1 line
Australian Journal of Crop Science, 2014Co-Authors: Lorenna L Sousa, James D Kelly, Anelise S Cruz, Pedro Soares Vidigal Filho, Veronica A Vallejo, Maria Celeste GoncalvesvidigalAbstract:Anthracnose is a devastating fungal disease of common bean (Phaseolus vulgaris L.), the causal agent of which is Colletotrichum Lindemuthianum. MSU 7-1 is a common bean breeding line that contains the Co-52 and Co-7 anthracnose resistance genes. In this study, phenotypic analyses were conducted in an F2 population derived from the Mexico 222 (S) x MSU 7-1 (R) cross that was inoculated with race 64 of C. Lindemuthianum. Segregation analysis revealed a 3R:1S ratio, indicating that only Co-52 confers resistance to race 64 once the Co-7 gene has been defeated by this race. The molecular marker g12333250, in linkage group Pv07, was linked in coupling phase to Co-52 at a distance of 1.2 cM. The presence or absence of this marker was also determined in the G 2333, TU, H1 and PI 207262 cultivars. It was found that the g12333250 molecular marker was present in G 2333 and absent in the other cultivars. Because the allele and marker are physically linked in a cis configuration, the Co-52 resistance allele present in MSU 7-1 and G 2333 cultivars can be monitored with great efficiency using g12333250. These results will be very useful for breeding programs aimed at developing anthracnose-resistant bean cultivars via marker-assisted selection.
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ribosomal dna polymorphism in Colletotrichum Lindemuthianum
Fungal Biology, 1999Co-Authors: Ricardo Silveiro Balardin, James J Smith, James D KellyAbstract:Genetic divergence among 57 isolates of Colletotrichum Lindemuthianum collected in north, central and south America and The Netherlands was assessed on the basis of PCR-RFLP analysis and sequencing of the nuclear rDNA region of the two internal transcribed spacers (ITS 1 and ITS 2) and the 5.8S rRNA gene. A reproducible 0.58 kb fragment was amplified in all 57 isolates. Races of C. Lindemuthianum formed two groups based on the restriction of the PCR-amplified ITS regions. Group I consisted mainly of Middle American races (65%), whereas 85% of Andean races belonged in group II. Genetic distances calculated from the sequence polymorphism in the rDNA region ranged from 0.2 to 1.8% among 14 isolates of C. Lindemuthianum. The neighbour-joining and parsimony analyses of the sequence data showed no association of any particular ITS genotype with host gene pool, virulence or geographic origin of races. These data suggest that virulence can arise in different geographic areas at different times, independent of genetic background. Molecular polymorphism among isolates of races 7, 17, 31 and 73 collected in different countries was demonstrated by RFLP analysis of the ITS regions. A similar lack of agreement was observed in the sequence data between isolates of race 73 from Mexico and the United States and the Jukes—Cantor genetic distance between the isolates was large (0.9%). These findings support a level of molecular variability within C. Lindemuthianum greater than the variability previously characterized by virulence analysis and suggest independent evolution of specific virulence patterns.
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virulence and molecular diversity in Colletotrichum Lindemuthianum from south central and north america
Phytopathology, 1997Co-Authors: R S Balardin, A M Jarosz, James D KellyAbstract:ABSTRACT Isolates of Colletotrichum Lindemuthianum (138 total) from Argentina, Brazil, the Dominican Republic, Honduras, Mexico, and the United States were characterized into 41 races based on virulence to 12 differential cultivars of Phaseolus vulgaris. These 41 races were categorized into two groups: those found over a wide geographic area and those restricted to a single country. Races 7, 65, and 73 were widespread. Race 73 was the most common (28%). Race 7 was found once in Argentina and Mexico but at a higher frequency in the United States. Race 65 was found repeatedly in Brazil and the United States. Although 39% of the races were detected repeatedly and three races were widespread, no race was isolated from both P. vulgaris gene pools. Phenetic analyses showed no obvious patterns correlated with virulence clusters. No geographic pattern was evident. Molecular polymorphism generated by random amplified polymorphic DNA confirmed the extensive variability in virulence of C. Lindemuthianum. Virulence phenotypes were grouped into 15 clusters. The two largest clusters contained isolates from all the geographic regions sampled. Molecular polymorphism was observed among isolates from races 65 and 73 within and among countries, except among Bra-zilian isolates of race 65. The genetic diversity of C. Lindemuthianum was greatest in Mexico and Honduras. Our data suggest that C. Lindemuthianum may not be highly structured to specific Phaseolus gene pools.
George S. Mahuku - One of the best experts on this subject based on the ideXlab platform.
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Virulence and Molecular Diversity within Colletotrichum Lindemuthianum Isolates from Andean and Mesoamerican bean Varieties and Regions
European Journal of Plant Pathology, 2004Co-Authors: George S. Mahuku, Jhon Jaime RiascosAbstract:Virulence on a standard set of 12 common bean differential varieties, DNA sequence of repetitive-elements (Rep-PCR) and random amplified microsatellites (RAMS) were used to assess the genetic variability of 200 Colletotrichum Lindemuthianum isolates collected from Andean and Mesoamerican bean varieties and regions. High levels of pathotypic (90 pathotypes) and genetic diversity (0.97) were identified among 200 isolates, revealing that C. Lindemuthianum is a highly diverse pathogen. Although a significant number of pathotypes were common to Andean and Mesoamerican regions, many more were only found in the Mesoamerican region. Cluster analysis of virulence and molecular data did not separate isolates into groups that were structured with common bean gene pools. No genetic differentiation ( G _ST=0.03) was apparent between Andean and Mesoamerican isolates of C. Lindemuthianum . The diversity exhibited by C. Lindemuthianum does not appear to cluster according to common bean gene pools, and the high diversity found in the Mesoamerican region seems to indicate that C. Lindemuthianum originated and was disseminated from this region. Due to the high genetic variation exhibited by C. Lindemuthianum , stacking major resistance genes appears to be the best option for developing cultivars with durable anthracnose resistance.
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Sources of Resistance to Colletotrichum Lindemuthianum in the Secondary Gene Pool of Phaseolus vulgaris and in Crosses of Primary and Secondary Gene Pools.
Plant Disease, 2002Co-Authors: George S. Mahuku, Carlos Jara, César Cajiao, Steve BeebeAbstract:Mahuku, G. S., Jara, C. E., Cajiao, C., and Beebe, S. 2002. Sources of resistance to Colletotrichum Lindemuthianum in the secondary gene pool of Phaseolus vulgaris and in crosses of primary and secondary gene pools. Plant Dis. 86:1383-1387. Use of genetic resistance is the most practical and economic way to manage anthracnose of common bean. Colletotrichum Lindemuthianum, the causal agent of bean anthracnose, is a highly variabile pathogen, and there are no host resistance genes that are effective against all known races of the pathogen. To diversify sources of resistance, we screened the core collection of the secondary gene pool of Phaseolus spp. and interspecific lines derived from simple and complex crosses of primary and secondary genotypes for their resistance to anthracnose. High levels of resistance were observed in the secondary gene pool. None of the 162 accessions tested was susceptible to C. Lindemuthianum. Of the two species composing the secondary gene pool, P. polyanthus displayed higher levels of resistance than P. coccineus, and all accessions tested were resistant. The response of P. coccineus was more variable, with six genotypes showing an intermediate reaction. Among the 75 lines from interspecific crosses, 49 were resistant to the three races (races 6, 15, and 3481) used in this study, and higher levels of resistance were found in lines that had P. polyanthus as one of the parents in the crosses than in the lines derived from P. coccineus. These lines constitute a valuable source of resistance and may aid in the development of stable resistance to anthracnose.