Anthracnose In Common Bean Research Articles

Molecular detection of Colletotrichum lindemuthianum in bean seed samples

Abstract: Colletotrichum lindemuthianum is the causal agent of anthracnose in common bean, and infected seeds are the most typical propagation form of the disease. Thus, using common bean seeds free of C. lindemuthianum is crucial to managing this pest, as well as employing fast and accurate detection techniques to ensure high seed quality. In this study, both conventional and quantitative PCR techniques (cPCR and qPCR) were used for the detection and quantification of C. lindemuthianum in samples of common bean seeds. For that, seeds were inoculated by exposing them to fungal colonies for different periods of time, 0 h, 36 h, 72 h, 108 h and 144 h, each period corresponding to an inoculum potential. Then, they were mixed with healthy seeds, so incidences of 0.25%, 0.50%, 1%, 10%, and 100% of seeds with different inoculum potentials were obtained, in samples of 400 seeds. Both cPRC and qPCR techniques were effective in detecting the fungus. With the cPCR method, the highest sensitivity was recorded in those samples with 10% inoculated seeds with inoculum potential P36. On the other hand, with the qPCR technique, the highest sensitivity in detecting the fungus was observed in samples with 0.25% inoculated seeds with inoculum potential P36.

The common bean COK-4 and the Arabidopsis FER kinase domain share similar functions in plant growth and defence.

Receptor-like kinases are membrane proteins that can be shared by diverse signalling pathways. Among them, the Arabidopsis thaliana FERONIA (FER) plays a role in the balance between distinct signals to control growth and defence. We have found that COK-4, a putative kinase encoded in the common bean anthracnose resistance locus Co-4, which is transcriptionally regulated during the immune response, is highly similar to the kinase domain of FER. To assess whether COK-4 is a functional orthologue of FER, we expressed COK-4 in the wild-type Col-0 and the fer-5 mutant of Arabidopsis and evaluated FER-associated traits. We observed that fer-5 plants show an enhanced apoplastic and stomatal defence against Pseudomonas syringae. In addition, the fer-5 mutant shows reduced biomass, smaller guard cell size, greater number of stomata per leaf area, fewer leaves, faster transition to reproductive stage and lower seed weight per plant than the wild-type Col-0. Except for the stomatal complex length and number of stomata, COK-4 expression in fer-5 lines partially or completely rescued both defence and developmental defects of fer-5 to the wild-type level. Notably, COK-4 may have an additive effect to FER, as the expression of COK-4 in Col-0 resulted in enhanced defence and growth phenotypes in comparison with wild-type Col-0 plants. Altogether, these findings indicate that the common bean COK-4 shares at least some of the multiple functions of the Arabidopsis FER kinase domain, acting in both the induction of plant growth and regulation of plant defence.

Gene/QTL discovery for Anthracnose in common bean (Phaseolus vulgaris L.) from North-western Himalayas.

Common bean (Phaseolus vulgaris L.) is one of the most important grain legume crops in the world. The beans grown in north-western Himalayas possess huge diversity for seed color, shape and size but are mostly susceptible to Anthracnose disease caused by seed born fungus Colletotrichum lindemuthianum. Dozens of QTLs/genes have been already identified for this disease in common bean world-wide. However, this is the first report of gene/QTL discovery for Anthracnose using bean germplasm from north-western Himalayas of state Jammu & Kashmir, India. A core set of 96 bean lines comprising 54 indigenous local landraces from 11 hot-spots and 42 exotic lines from 10 different countries were phenotyped at two locations (SKUAST-Jammu and Bhaderwah, Jammu) for Anthracnose resistance. The core set was also genotyped with genome-wide (91) random and trait linked SSR markers. The study of marker-trait associations (MTAs) led to the identification of 10 QTLs/genes for Anthracnose resistance. Among the 10 QTLs/genes identified, two MTAs are stable (BM45 & BM211), two MTAs (PVctt1 & BM211) are major explaining more than 20% phenotypic variation for Anthracnose and one MTA (BM211) is both stable and major. Six (06) genomic regions are reported for the first time, while as four (04) genomic regions validated the already known QTL/gene regions/clusters for Anthracnose. The major, stable and validated markers reported during the present study associated with Anthracnose resistance will prove useful in common bean molecular breeding programs aimed at enhancing Anthracnose resistance of local bean landraces grown in north-western Himalayas of state Jammu and Kashmir.

Research Article Selection of resistance sources to common bean anthracnose by field phenotyping and DNA marker-assisted screening

The main goal of this work was to select resistance sources to common bean anthracnose by field phenotyping and DNA marker-assisted screening. Fifty-five common bean genotypes, including differential varieties, characterized resistance sources, elite lines, cultivars and controls, were evaluated in a field inoculation trial and screened with SCAR markers linked to resistance genes that are important in Brazil. The field trial was carried out in Santo Antonio de Goias, GO, Brazil, during the fall/winter growing season of 2014, using artificial inoculation with a mixture of six races of Colletotrichum lindemuthianum, selected based on their high virulence and prevalence in Brazil. Amplification reactions with the SCAR markers previously identified as linked to important anthracnose resistance genes on Brazil followed standard procedures. Twenty-eight of the 58 genotypes were resistant to anthracnose (mean severity score ≤ 3.5). Ten of these 28 resistant genotypes stood out because they presented a mean anthracnose severity score of 1.0. Four of the six SCAR markers tested shown to be useful for the assisted selection of their respective target genes (SH18 and SAS13 for Co-42, SAB03 for Co-5, and SAZ20 for Co-6). Two carioca seeded elite lines were highlighted by the phenotypic and molecular screening: K10 (Co-34, Co-42, Co-5 and Co-6) and K13 (Co-4²). The phenotypic and molecular characterization of candidate resistance sources to common bean anthracnose based on their disease reaction in field inoculation trials and on the analysis with molecular markers linked to resistance genes has shown to be a useful strategy. These results aid in the selection of donor parents and resistant lines to be preferably explored by common bean breeding programs in Brazil.

High-resolution mapping reveals linkage between genes in common bean cultivar Ouro Negro conferring resistance to the rust, anthracnose, and angular leaf spot diseases.

Co-segregation analysis and high-throughput genotyping using SNP, SSR, and KASP markers demonstrated genetic linkage between Ur-14 and Co-3 4 /Phg-3 loci conferring resistance to the rust, anthracnose and angular leaf spot diseases of common bean. Rust, anthracnose, and angular leaf spot are major diseases of common bean in the Americas and Africa. The cultivar Ouro Negro has the Ur-14 gene that confers broad spectrum resistance to rust and the gene cluster Co-3 4 /Phg-3 containing two tightly linked genes conferring resistance to anthracnose and angular leaf spot, respectively. We used co-segregation analysis and high-throughput genotyping of 179 F2:3 families from the Rudá (susceptible)×Ouro Negro (resistant) cross-phenotyped separately with races of the rust and anthracnose pathogens. The results confirmed that Ur-14 and Co-3 4 /Phg-3 cluster in Ouro Negro conferred resistance to rust and anthracnose, respectively, and that Ur-14 and the Co-3 4 /Phg-3 cluster were closely linked. Genotyping the F2:3 families, first with 5398 SNPs on the Illumina BeadChip BARCBEAN6K_3 and with 15 SSR, and eight KASP markers, specifically designed for the candidate region containing Ur-14 and Co-3 4 /Phg-3, permitted the creation of a high-resolution genetic linkage map which revealed that Ur-14 was positioned at 2.2cM from Co-3 4 /Phg-3 on the short arm of chromosome Pv04 of the common bean genome. Five flanking SSR markers were tightly linked at 0.1 and 0.2cM from Ur-14, and two flanking KASP markers were tightly linked at 0.1 and 0.3cM from Co-3 4 /Phg-3. Many other SSR, SNP, and KASP markers were also linked to these genes. These markers will be useful for the development of common bean cultivars combining the important Ur-14 and Co-3 4 /Phg-3 genes conferring resistance to three of the most destructive diseases of common bean.

Are duplicated genes responsible for anthracnose resistance in common bean?

The race 65 of Colletotrichum lindemuthianum, etiologic agent of anthracnose in common bean, is distributed worldwide, having great importance in breeding programs for anthracnose resistance. Several resistance alleles have been identified promoting resistance to this race. However, the variability that has been detected within race has made it difficult to obtain cultivars with durable resistance, because cultivars may have different reactions to each strain of race 65. Thus, this work aimed at studying the resistance inheritance of common bean lines to different strains of C. lindemuthianum, race 65. We used six C. lindemuthianum strains previously characterized as belonging to the race 65 through the international set of differential cultivars of anthracnose and nine commercial cultivars, adapted to the Brazilian growing conditions and with potential ability to discriminate the variability within this race. To obtain information on the resistance inheritance related to nine commercial cultivars to six strains of race 65, these cultivars were crossed two by two in all possible combinations, resulting in 36 hybrids. Segregation in the F2 generations revealed that the resistance to each strain is conditioned by two independent genes with the same function, suggesting that they are duplicated genes, where the dominant allele promotes resistance. These results indicate that the specificity between host resistance genes and pathogen avirulence genes is not limited to races, it also occurs within strains of the same race. Further research may be carried out in order to establish if the alleles identified in these cultivars are different from those described in the literature.

Methyl and p-Bromobenzyl Esters of Hydrogenated Kaurenoic Acid for Controlling Anthracnose in Common Bean Plants.

Kaurenoic acid derivatives were prepared and submitted to in vitro assays with the fungus Colletotrichum lindemuthianum, which causes anthracnose disease in the common bean. The most active substances were found to be methyl and p-bromobenzylesters, 7 and 9, respectively, of the hydrogenated kaurenoic acid, which presented a minimum inhibitory concentration (MIC) of 0.097 and 0.131 mM, respectively, while the commercial fungicide methyl thiophanate (MT) presented a MIC of 0.143 mM. Substances 7 (1.401 mM) and 9 (1.886 mM) reduced the severity of anthracnose in common bean to values statistically comparable to MT (2.044 mM). According to an in silico study, both compounds 7 and 9 are inhibitors of the ketosteroid isomerase (KSI) enzyme produced by other organisms, the amino acid sequence of which could be detected in fungal genomes. These substances appeared to act against C. lindemuthianum by inhibiting its KSI. Therefore, substances 7 and 9 are promising for the development of new fungicides.

Mapping and Genetic Structure Analysis of the Anthracnose Resistance Locus Co-1HY in the Common Bean (Phaseolus vulgaris L.).

Anthracnose is a destructive disease of the common bean (Phaseolus vulgaris L.). The Andean cultivar Hongyundou has been demonstrated to possess strong resistance to anthracnose race 81. To study the genetics of this resistance, the Hongyundou cultivar was crossed with a susceptible genotype Jingdou. Segregation of resistance for race 81 was assessed in the F2 population and F2:3 lines under controlled conditions. Results indicate that Hongyundou carries a single dominant gene for anthracnose resistance. An allele test by crossing Hongyundou with another resistant cultivar revealed that the resistance gene is in the Co-1 locus (therefore named Co-1HY). The physical distance between this locus and the two flanking markers was 46 kb, and this region included four candidate genes, namely, Phvul.001G243500, Phvul.001G243600, Phvul.001G243700 and Phvul.001G243800. These candidate genes encoded serine/threonine-protein kinases. Expression analysis of the four candidate genes in the resistant and susceptible cultivars under control condition and inoculated treatment revealed that all the four candidate genes are expressed at significantly higher levels in the resistant genotype than in susceptible genotype. Phvul.001G243600 and Phvul.001G243700 are expressed nearly 15-fold and 90-fold higher in the resistant genotype than in the susceptible parent before inoculation, respectively. Four candidate genes will provide useful information for further research into the resistance mechanism of anthracnose in common bean. The closely linked flanking markers identified here may be useful for transferring the resistance allele Co-1HY from Hongyundou to elite anthracnose susceptible common bean lines.

Phosphites for the control of anthracnose in common bean

Abstract: The objective of this work was to evaluate the effect of phosphites in the protection of common bean (Phaseolus vulgaris) against anthracnose. Different phosphite formulations were evaluated by quantifying peroxidase and polyphenol oxidase activity, total phenols, and lignin content. The treatments consisted of sprayings, in the V4, R5, and R7 stages, with: the K, Zn, Mn, K+Mn, K+salicyclic acid, and Cu phosphites; salicylic acid; acibenzolar-S-methyl; the fungicide azoxystrobin; besides a control, without sprayings. The area under the disease progress curve was lower in plants that received applications of the K and Mn phosphites, whose values ranged between 74 and 81%, compared with the control. The K, Zn, and K+salicyilic acid phosphites were effective in controlling the disease. In addition, disease severity was lower with the application of the K, Zn, and Mn phosphites than with the control. Enzyme (peroxidases and polyphenol oxidases) activity and levels of soluble phenols were higher in common bean plants treated with the K and Mn phosphites, although no change was detected in the levels of soluble lignin in the same tissue. Phosphite application reduces the severity of the disease, can enhance enzymatic activity, and is an effective alternative for the control of anthracnose in common bean.

Identification of a New Chromosomal Region Involved in the Genetic Control of Resistance to Anthracnose in Common Bean.

Anthracnose caused by Colletotrichum lindemuthianum (Sacc. & Magnus) Lams.-Scrib. is a major disease affecting common bean (Phaseolus vulgaris L.) crops worldwide. Response to five C. lindemuthianum isolates, classified as races 3, 6, 7, 38, and 73, were analyzed in 156 F2:3 families derived from the cross between line SEL1308 and cultivar Michigan Dark Red Kidney (MDRK). SEL1308 was resistant to all five races, while MDRK was susceptible to all except for race 73. Segregation ratio for response to races 3 and 7 indicated that single dominant genes were responsible for the resistance reaction to each race. Recombination between both race-specific genes was observed and no linkage was found with any of the molecular markers tagging Co-genes or clusters previously described. Linkage analyses allowed the location of both genes at the beginning of linkage group (LG) Pv03, a region tentatively named as Co-17. Segregation ratio for response to races 6 and 38 indicated that two dominant and independent genes conferred resistance to these races. Contingency tests and subpopulation analyses suggested the implication of one region on LG Pv08, corresponding to the Co-4 cluster, and the Co-17 region. For reaction to race 73, the most likely scenario was that two dominant and independent genes conferred resistance: Co-1 in MDRK and Co-42 in SEL1308. Results indicated that, in addition to Co-42 , SEL1308 carries resistance genes located at the beginning of LG Pv03, in which no anthracnose resistance genes were previously mapped. In silico analysis revealed the presence of seven genes codifying typical resistance proteins (R-proteins) in the underlying physical position of the Co-17 region.

Field Management of Anthracnose (<i>Colletotrichum lindemuthianum</i>) in Common Bean through Foliar Spray Fungicides and Seed Treatment Bioagents

Common bean anthracnose is a major production constraint in bean growing regions of Ethiopia. This study aimed to determine whether foliar sprays of mancozeb, folpan and mancolaxyl or antagonistic bioagents; Trichoderma harzianum, Trichoderma viride and Pseudomonas fluorescens could reduce anthracnose symptoms and consequently, increase yield and yield components. A total of seven treatments were arranged in a randomized complete block design with three replications. Statistical analysis showed significant differences among treatments. Anthracnose incidence, severity, infected pods per plant and the area under disease progress curve were highest in the control plots compared to the fungicide sprayed and bioagent treated seed plots. The highest percentage of infected pods per plant, 78.9 and 55 were recorded on the control and mancozeb sprayed plots respectively. The highest AUDPC value resulted in the lowest yield of 1.01 t/ha in the control plots compared to a highest yield of 3.33 t/ha from the sprayed plots with folpan and 1.79 t/ha from plots treated with Pseudomonas fluorescens. Relative yield losses of 69.67, 46.25 and 22.82% were recorded from the control, seed treated plots with P. fluorescens and sprayed plots with mancolaxyl respectively. Economic analysis revealed that the highest rate of return of 8,740 was obtained from Pseudomonas fluorescens seed treatment and the highest net benefit; 43,154 on folpan foliar spray treatment. The results of the present study support the novel possibility of using folpan foliar spray and Pseudomonas fluorescens seed treatments to decrease anthracnose symptoms in bean plants and consequently, achieve greater yield.Keywords: Bioagents; Folpan; Pseudomonas fluorescens; Mancolaxyl; seed treatment

The CD1/CD2 marker for specific detection of Colletotrichum lindemuthianum is an iron transporter pseudogene

Colletotrichum lindemuthianum, the causal agent of anthracnose in common bean (Phaseolus vulgaris), is one of the most yield-limiting factors worldwide. Anthracnose affects the quality of pods by inducing black, sunken cankers and can also affect petioles, leaf veins and stems where it induces the typical anthracnose sunken lesions. A few years ago, a duplex PCR method that combines amplification of an ITS rDNA segment (CY1/CY2) together with an uncharacterized RAPD-derived amplicon (CD1/CD2) was developed for specific detection of C. lindemuthianum. This study shows that the CD1/CD2 marker corresponds to a portion of an iron permease (Ftr1) pseudogene in the vicinity of the gene encoding for a polyhydroxyproline-rich protein in Colletotrichum. Discrimination with Colletotrichum orbiculare is due to a 15 nt deletion in the CY1 annealing region. The potential of using this genomic region for phylogenetic analysis of the C. orbiculare species complex and detection of their related species is discussed.

English

Bean anthracnose caused by Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara is one of the most devastating seed-borne diseases of common bean (Phaseolus vulgaris L.) in Ethiopia. The aim of the present investigation was to evaluate the antifungal activities of bioagents and fungicides which can be used to control bean anthracnose. Three fungicides viz., Mancozeb, Folpan and Mancolaxyl, and three bioagents viz., Trichoderma harzianum Rifai, Trichoderma viride Pers. Fr. and Pseudomonas fluorescens Migula, were screened in vitro for their antifungal activities against common bean anthracnose, C. lindemuthianum using the dual culture and microtitre double-dilution techniques. Antagonistic effects of the three bioagents tested by the dual culture method showed highly significant (P<0.01) percentage of inhibition of the mycelia germination of C. lindemuthianum. The highest percentage of inhibition of the mycelia germination (80.39%) was obtained from T. viride, followed by 75.49% from T. harzianum and 40.2% from P. fluorescens. Similarly, highly significant (P<0.01) differences were observed in the radial growth of mycelia of C. lindemuthianum. The highest growth of mycelia (3.4 cm) was measured from the control (C. lindemuthianum), whereas the least (0.67 cm) was obtained from the dual culture containing T. viride. The in vitro assays revealed that all the antagonistic bioagents produced siderophores which were capable of inhibiting mycelia growth of the pathogen. The mancozeb fungicide was found to be fatal to C. lindemuthianum at four different concentrations poisoned on potato dextrose agar medium. Key words: Bio agents, Colletotrichum lindemuthianum, dual culture, fungicides, in vitro, Phaseolus vulgaris.

Complete mitochondrial genome sequence of the common bean anthracnose pathogen Colletotrichum lindemuthianum

Colletotrichum lindemuthianum is the causal agent of anthracnose in common bean (Phaseolus vulgaris), one of the most limiting factors for this crop in South and Central America. In this work, the mitochondrial sequence of a Colombian isolate of C. lindemuthianum obtained from a common bean plant (var. Cargamanto) with anthracnose symptoms is presented. The mtDNA codes for 13 proteins of the respiratory chain, 1 ribosomal protein, 2 homing endonucleases, 2 ribosomal RNAs and 28 tRNAs. This is the first report of a complete mtDNA genome sequence from C. lindemuthianum

Management of Anthracnose in Common Bean by Foliar Sprays of Potassium Silicate, Sodium Molybdate, and Fungicide.

This study aimed to determine whether foliar sprays of potassium silicate (KSi), sodium molybdate (NaMo), or a combination of both (KSi + NaMo), with or without the fungicide azoxystrobin (Azox), could reduce anthracnose symptoms and, consequently increase yield. Two two-by-four factorial experiments, consisting of untreated or fungicide treated, as well as sprays of KSi, NaMo, KSi + NaMo, and no spray (control), were arranged in a randomized block design with three replications. Treatments were as follows: treatment 1, KSi spray; treatment 2, NaMo spray; treatment 3, KSi + NaMo spray; treatment 4, Azox spray; treatment 5, Azox + KSi spray; treatment 6, Azox + NaMo spray, treatment 7, Azox + KSi + NaMo spray; and treatment 8, control (no KSi, NaMo, or Azox). The KSi, NaMo, and Azox treatments were sprayed at the rates of 35 g/liter, 90 g/ha, and 120 g a.i./ha, respectively. The KSi was applied at 20, 27, 40, and 55 days after sowing (das). The NaMo was sprayed only at 27 das whereas the fungicide was sprayed at 27, 40, and 55 das. Plants were inoculated with Colletotrichum lindemuthianum at 23 das. Azox reduced the mean area under disease progress curve (AUDPC) by 63% and mean yield was increased by 150%. Similarly, the mean AUDPC was reduced by 29, 14, and 41% with KSi, NaMo, and KSi + NaMo sprays, respectively, while mean yield increased by 13, 20, and 47%, with KSi, NaMo, or KSi + NaMo sprays, respectively. The variables leaf area index (LAI), leaf area index duration (LAD), healthy leaf area duration (HAD), and radiation intercepted (RI) were not affected by KSi spray. The values for the variables LAI, healthy leaf area index (HLAI), LAD, HAD, RI, intercepted radiation of the healthy leaf area, and healthy leaf area absorption were significantly increased as a result of NaMo spray. The results of the present study support the novel possibility of using a foliar spray of KSi in association with NaMo to decrease anthracnose symptoms in bean plants and, consequently, achieve greater yield.

Field Management of Anthracnose (Colletotrichum lindemuthianum) in Common Bean through Fungicides and Bioagents

Common bean anthracnose is a major production constraint in bean growing regions of Ethiopia. This study aimed to determine whether foliar sprays of mancozeb, folpan and mancolaxyl or antagonistic bioagents; Trichoderma harzianum, Trichoderma viride and Pseudomonas fluorescens could reduce anthracnose symptoms and consequently, increase yield and yield components. A total of seven treatments were arranged in a randomized complete block design with three replications. Statistical analysis showed significant differences among treatments. Anthracnose incidence, severity, infected pods per plant and the area under disease progress curve were highest in the control plots compared to the fungicide sprayed and bioagent treated seed plots. The highest percentage of infected pods per plant of 78.9 and 55.0 recorded on the control and mancozeb sprayed plots, respectively. The highest AUDPC value resulted in the lowest yield of 1.01 t/ha in the control plots compared to a highest yield of 3.3 t/ha from the sprayed plots with folpan and 1.8 t/ha from plots treated with Pseudomonas fluorescens. Relative yield losses of 69.7, 46.3 and 22.8% were recorded from the control, seed treated plots with P. fluorescens and sprayed plots with mancolaxyl, respectively. Economic analysis revealed that the highest rate of return of 8,740 was obtained from Pseudomonas fluorescens seed treatment and the highest net benefit value of 43,154 calculated on folpan foliar spray treatment. The results of the present study support the novel possibility of using folpan foliar spray and Pseudomonas fluorescens seed treatments to decrease anthracnose symptoms in common bean and consequently, achieve greater yield.

An Overview of Distribution, Biology and the Management of Common Bean Anthracnose

Bean anthracnose caused by Colletotrichum lindemuthianum (Sacc. & Magn.) is one of the most important seed borne disease of common bean (Phaseolus vulgaris L.) in the world. The disease is prevalent in areas that experience cool and wet weather conditions, causing up to 100% yield loss. Besides infecting Phaseolus vulgaris, Colletotrichum lindemuthianum also attacks other legumes like mung bean (P. aureus), cowpea (Vigna sinensis), and broad bean (Vicia faba). The disease causes symptoms to appear on leaves, stems, pods and seeds. The pathogen can survive in seeds for up to five years, and is also known to overwinter in crop debris. Seed infection is the primary means by which the pathogen spreads. Therefore, the production and the use of certified seeds is one control measure that is effective in dealing with the disease. Fungicidal seed treatment and foliar application as well as cultural and biological methods are very important for bean anthracnose management. Further information on biology and survival of C. lindemuthianum is needed to devise more effective management strategies. In this review attention were given to the biology and management options, with an emphasis on the future research priorities.

Investigating Phenotypic Variability inColletotrichum lindemuthianumPopulations

Colletotrichum lindemuthianum, causal agent of anthracnose in the common bean, has wide genetic variability. Differential bean cultivars and morphological and physiological characteristics were used to analyze 74 isolates of C. lindemuthianum collected in two counties in the state of Minas Gerais, Brazil. Six different races were found, with a predominance of race 65 at both locations. Isolates were classified according to their sensitivities to the fungicide thiophanate-methyl, normally used in the control of common bean anthracnose. In all, ≈10% of isolates were resistant to the fungicide in vitro. Characteristics such as indexes of mycelia growth rate, colony diameter, sporulation capacity, and percentage of germination demonstrated the high genetic variability of C. lindemuthianum. We also observed variation in conidial cytology. The conidia of most isolates showed septa formation after germination, in contrast to septa absence, previously reported in the literature. Sexual and asexual reproduction were evaluated for mechanisms that may contribute in the generation of variability in C. lindemuthianum. Conidial anastomosis tubes were commonly found, indicating that asexual reproduction can help increase variability in this species. Information from this study confirmed high variability in C. lindemuthianum and will guide future studies in basic knowledge and applied technologies.

Mapping of Gene Conferring Resistance to Anthracnose in Common Bean (&lt;I&gt;Phaseolus vulgaris&lt;/I&gt; L.) by Molecular Markers

Mapping of Gene Conferring Resistance to Anthracnose in Common Bean (&lt;I&gt;Phaseolus vulgaris&lt;/I&gt; L.) by Molecular Markers

Common bean lines as potential differential cultivars for race 65 of Colletorichum lindemuthianum.

Colletotrichum lindemuthianum, which is known for its wide diversity in virulence, is the causal agent of anthracnose of common bean (Phaseolus vulgaris). Studies of race characterization using the standard set of 12 differential cultivars have shown the predominance of race 65 in Minas Gerais state (Brazil). However, the presence of genetic variability within race 65 has complicated the development of a durable resistant bean cultivar. Therefore, the objective of this study was to identify common bean lines able to differentiate the variation within race 65 to complement the results of the standard set of differential cultivars. A total of 12 common bean lines adapted to Brazilian conditions and 12 fungal isolates classified as race 65 were used. We now propose a new nomenclature to identify the pathogenic variability of race 65 isolates. Using this methodology, five different reaction patterns were observed, allowing the differentiation of regionally important races that could not be discriminated using the standard set of differential cultivars. Furthermore, our approach makes it possible the identification of new genes and sources of resistance to anthracnose.