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Angular spot caused by Pseudocercospora griseola (Sacc.) Crous & Braun is one of the most common diseases of beans, reducing up to 80% of the harvest if the climatic conditions are favorable. Genetic improvement for resistance to this disease is one of the most effective strategies through one of the most efficient ways to control this disease is the introduction of genetic resistance mediated by selection assisted by molecular markers. Therefore, the objective of this work was to identify bean genotypes ( Phaseolus vulgaris ) with resistance to angular spot in Mexican varieties and lines of black, bay and red beans. For this purpose, eight specific molecular markers of the SCAR type were used and the correlation between the presence of the markers and the resistance of each genotype was determined, measured by inoculation with two strains of the fungus from different physiographic regions under greenhouse conditions. The varieties Negro Comapa, Negro Cotaxtla, Negro Papaloapan, Ouro Negro and the advanced bean lines Negro SEN 56, SEN 26 and SCN 7 were resistant to angular spot, while Bayo Azteca, Bayo INIFAP, the red bean lines SCR 13 and SER 83, as well as the black bean lines SEN 44 and SEN 70, were susceptible. In general, the genotypes with the greatest resistance presented the markers CV542014, SAA19, SM02 and SN02. Although the genetic materials were heterogeneous, these molecular markers considered as associated with genes with additive effects could support the selection of genotypes resistant to P. griseola and the actions of the improvement programs for the obtaining of new resistant varieties. [ABSTRACT FROM AUTHOR]

This study aimed to develop and validate a standard area diagram set (SADs) to estimate the severity of angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola, in the leaflets of common bean plants. For the elaboration of SADs, the minimum and maximum disease severity limits in the leaflets were considered, along with the intermediate levels following linear increments. The SADs had 10 levels of severity as follows: 0.5%, 2.2%, 4.5%, 9.6%, 20.1%, 30.8%, 41.2%, 52.1%, 67.4%, and 77.3%. The validation was performed by 20 raters, 10 inexperienced and 10 experienced in quantifying severities of foliar diseases. The severity estimates were obtained in 150 leaflets displaying different levels of severity without and using the proposed SADs. Accuracy, precision and reliability of the estimates were improved using SADs. The SADs obtained in the present study proved to be adequate to estimate the severity of ALS in the leaflets of common bean plants with the potential of use in any study in which it is crucial to quantify the severity of this foliar disease to discriminate treatments with precision and accuracy. [ABSTRACT FROM AUTHOR]

The common bean (Phaseolus vulgaris L.) is the most important grain legume in the human diet, mainly in Africa and Latin America. Argentina is one of the five major producers of the common bean in the world, and the main cultivation areas are concentrated in the northwestern provinces of this country. Crop production of the common bean is often affected by biotic factors like some endemic fungal diseases, which exert a major economic impact on the region. The most important fungal diseases affecting the common bean in Argentina are white mold caused by Sclerotinia sclerotiorum, angular leaf spot caused by Pseudocercospora griseola, web blight and root rot caused by Rhizoctonia solani, which can cause production losses of up to 100% in the region. At the present, the most effective strategy for controlling these diseases is the use of genetic resistance. In this sense, population study and characterization of fungal pathogens are essential for developing cultivars with durable resistance. In this review we report diversity studies carried out on these three fungal pathogens affecting the common bean in northwestern Argentina, analyzing more than 200 isolates by means of molecular, morphological and pathogenic approaches. Also, the screening of physiological resistance in several common bean commercial lines and wild native germplasm is reviewed. This review contributes to the development of sustainable management strategies and cultural practices in bean production aimed to minimize yield losses due to fungal diseases in the common bean. [ABSTRACT FROM AUTHOR]

The common bean (Phaseolus vulgaris L.) is the most important grain legume in the human diet, mainly in Africa and Latin America. Argentina is one of the five major producers of the common bean in the world, and the main cultivation areas are concentrated in the northwestern provinces of this country. Crop production of the common bean is often affected by biotic factors like some endemic fungal diseases, which exert a major economic impact on the region. The most important fungal diseases affecting the common bean in Argentina are white mold caused by Sclerotinia sclerotiorum, angular leaf spot caused by Pseudocercospora griseola, web blight and root rot caused by Rhizoctonia solani, which can cause production losses of up to 100% in the region. At the present, the most effective strategy for controlling these diseases is the use of genetic resistance. In this sense, population study and characterization of fungal pathogens are essential for developing cultivars with durable resistance. In this review we report diversity studies carried out on these three fungal pathogens affecting the common bean in northwestern Argentina, analyzing more than 200 isolates by means of molecular, morphological and pathogenic approaches. Also, the screening of physiological resistance in several common bean commercial lines and wild native germplasm is reviewed. This review contributes to the development of sustainable management strategies and cultural practices in bean production aimed to minimize yield losses due to fungal diseases in the common bean.

The implementation of molecular tools that help the early selection of genotypes carrying target alleles increases efficiency and reduces the time and costs of breeding programs. The present study aimed the molecular characterization and validation of Single Nucleotide Polymorphism (SNP) targeting disease resistance alleles for assisted selection. A total of 376 common bean lines with contrasting responses for anthracnose and angular leaf spot resistance were used, as well as 149 F2 plants from the cross between BRS Cometa × SEL 1308 (carrying the Anthracnose resistance gene Co-42). Seven of the ten SNP markers evaluated showed potential for assisted breeding: snpPV0025 (Phg-2), snpPV0027 (Phg-5), snpPV0079 (Phg-5), snpPV0046 (Co-u), snpPV0068 (Co-42), snpPV0070 (Co-42) and snpP8282v3-817 (Co-42). Markers snpPV0070 and snpP8282v3-817 showed high efficiency of selection (99.7 and 99.8%, respectively). These markers exhibit great potential to assist in the selection at different stages of the breeding program and may be readily incorporated into marker-assisted selection. [ABSTRACT FROM AUTHOR]

O feijão e o tomate são culturas de grande relevância no Brasil, e particularmente no estado do Paraná. A mancha angular do feijão e a septoriose do tomate são doenças importantes nestas culturas. Os cultivos de base agroecológica estão ganhando relevância em diferentes partes do mundo, e vêm sendo estimulados no estado do Paraná. A ciência homeopática tem sido divulgada como uma ferramenta para este tipo de agricultura. Os bioterápicos são produzidos segundo a farmacotécnica homeopática, mas não seguem os mesmos princípios de cura da homeopatia. Neste trabalho avaliou-se o controle da mancha angular do feijão e da septoriose do tomate através de dois bioterápicos, denominados Pse02 (Pseudocercospora griseola 02) e Sep01 (Septoria lycopersici 01), produzidos respectivamente com o patógeno do feijão e com folhas doentes de tomate. Foram conduzidos dois experimentos com cada bioterápico em delineamento inteiramente casualizado em casa de vegetação. As dinamizações 0DH, 12DH, 19DH, 20DH, 21DH, 24DH, 30DH do bioterápico Pse02 e as dinamizações 0CH, 9CH, 12CH, 15CH, 17CH, 19CH do bioterápico Sep01 foram pulverizadas na parte aérea e irrigadas no solo em quatro datas diferentes. Em apenas um experimento de cada bioterápico houve efeito significativo de uma dinamização em relação ao controle. Os bioterápicos Pse02 na dinamização 19DH, e Sep01 na dinamização 15CH promoveram redução significativa no tamanho da lesão de mancha angular bem como na severidade e número de lesões de septoriose do tomate em relação ao controle, respectivamente.

Angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola, is one of the most important foliar fungal diseases in common bean (Phaseolus vulgaris L.). The search for new sources of resistance to ALS is a promising activity in common bean breeding programs. In this study, the reaction of 416 germplasm accessions from the Universidade Federal de Lavras (UFLA) to P. griseola (race 63-63, the most important and most aggressive race) was assessed under greenhouse conditions (plants in the V2 stage, fully developed unifoliolate leaves). We identified 102 (24.5%) resistant and 314 (75.5%) susceptible accessions. Among the resistant lines, more than half are Carioca grain type lines. This study characterizes the resistance of a wide collection of common bean genotypes. The identification of new accessions resistant to P. griseola is an important step in common bean breeding programs. These lines can continually be incorporated in backcrosses to obtain cultivars resistant to ALS. [ABSTRACT FROM AUTHOR]

Genetic resistance of common bean (Phaseolus vulgaris L.) against angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola, is conferred by quantitative trait loci (QTL). In this study, we determined the gene content of the major QTL ALS10.1 located at the end of chromosome Pv10, and identified those that are responsive to ALS infection in resistant (CAL 143) and susceptible (IAC-UNA) genotypes. Based on the current version of the common bean reference genome, the ALS10.1 core region contains 323 genes. Gene Ontology (GO) analysis of these coding sequences revealed the presence of genes involved in signal perception and transduction, programmed cell death (PCD), and defense responses. Two putative R gene clusters were found at ALS10.1 containing evolutionary related coding sequences. Among them, the Phvul.010G025700 was consistently up-regulated in the infected IAC-UNA suggesting its contribution to plant susceptibility to the fungus. We identified six other genes that were regulated during common bean response to P. griseola; three of them might be negative regulators of immunity as they showed opposite expression patterns during resistant and susceptible reactions at the initial phase of fungal infection. Taken together, these findings suggest that common bean reaction to P. griseola involves transcriptional modulation of defense genes in the ALS10.1 locus, contributing to resistance or susceptibility depending on the plant-pathogen interaction.

ABSTRACT: Phenotyping for severity of angular leaf spot (ALS) in common bean is important to identify new sources of resistance and select progenies in conventional and molecular marker-assisted breeding. In this study, three phenotyping methods for ALS severity were assessed and its implications in breeding for resistance to Pseudocercospora griseola are discussed. Reaction of 144 common bean lines to P. griseola was evaluated. Three different experiments were conducted in the greenhouse (V2 and V3 stages) and in the field. Common bean lines were inoculated with a mixture of spores of pathogen races 63-63 and 63-23. We observed that 31 %, 7 % and 10 % of lines were resistant in stages V2, V3 and in the field, respectively. Estimates of coincidence index V2-V3, V2-field and V3-field were 68 %, 69 % and 88 %, respectively. Evaluations in V3 stage and in the field were the phenotyping methods more efficient for ALS severity. However, evaluation in V3 stage is impracticable to assess routinely many genotypes in breeding programs. Evaluation in V2 stage may be used to carry out a first screening, especially in the early stages of breeding programs. Moreover, this methodology may be used in association with evaluation of plants in the field to increase genetic gain.

Angular leaf spot (ALS) is a disease that causes major yield losses in the common bean crop. Studies based on different isolates and populations have already been carried out to elucidate the genetic mechanisms of resistance to ALS. However, understanding of the interaction of this resistance with the reproductive stages of common bean is lacking. The aim of the present study was to identify ALS resistance loci at different plant growth stages (PGS) by association and linkage mapping approaches. An BC2F3 inter-gene pool cross population (AND 277 × IAC-Milênio – AM population) profiled with 1,091 SNPs from genotyping by sequencing (GBS) was used for linkage mapping, and a carioca diversity panel (CDP) genotyped by 5,398 SNPs from BeadChip assay technology was used for association mapping. Both populations were evaluated for ALS resistance at the V2 and V3 PGSs (controlled conditions) and R8 PGS (field conditions). Different QTL (quantitative trait loci) were detected for the three PGSs and both populations, showing a different quantitative profile of the disease at different plant growth stages. For the three PGS, multiple interval mapping (MIM) identified seven significant QTL, and the Genome-wide association study (GWAS) identified fourteen associate SNPs. Several loci validated regions of previous studies, and Phg-1, Phg-2, Phg-4, and Phg-5, among the 5 loci of greatest effects reported in the literature, were detected in the CDP. The AND 277 cultivar contained both the Phg-1 and the Phg-5 QTL, which is reported for the first time in the descendant cultivar CAL143 as ALS10.1UC. The novel QTL named ALS11.1AM was located at the beginning of chromosome Pv11. Gene annotation revealed several putative resistance genes involved in the ALS response at the three PGSs, and with the markers and loci identified, new specific molecular markers can be developed, representing a powerful tool for common bean crop improvement and for gain in ALS resistance.

Angular leaf spot (ALS) is a disease that causes major yield losses in the common bean crop. Studies based on different isolates and populations have already been carried out to elucidate the genetic mechanisms of resistance to ALS. However, understanding of the interaction of this resistance with the reproductive stages of common bean is lacking. The aim of the present study was to identify ALS resistance loci at different plant growth stages (PGS) by association and linkage mapping approaches. An BC2F3 inter-gene pool cross population (AND 277 × IAC-Milênio – AM population) profiled with 1,091 SNPs from genotyping by sequencing (GBS) was used for linkage mapping, and a carioca diversity panel (CDP) genotyped by 5,398 SNPs from BeadChip assay technology was used for association mapping. Both populations were evaluated for ALS resistance at the V2 and V3 PGSs (controlled conditions) and R8 PGS (field conditions). Different QTL (quantitative trait loci) were detected for the three PGSs and both populations, showing a different quantitative profile of the disease at different plant growth stages. For the three PGS, multiple interval mapping (MIM) identified seven significant QTL, and the Genome-wide association study (GWAS) identified fourteen associate SNPs. Several loci validated regions of previous studies, and Phg-1 , Phg-2, Phg-4 , and Phg-5 , among the 5 loci of greatest effects reported in the literature, were detected in the CDP. The AND 277 cultivar contained both the Phg-1 and the Phg-5 QTL, which is reported for the first time in the descendant cultivar CAL143 as ALS10.1UC. The novel QTL named ALS11.1AM was located at the beginning of chromosome Pv11. Gene annotation revealed several putative resistance genes involved in the ALS response at the three PGSs, and with the markers and loci identified, new specific molecular markers can be developed, representing a powerful tool for common bean crop improvement and for gain in ALS resistance. [ABSTRACT FROM AUTHOR]

Angular Leaf Spot (ALS), caused by the fungus Pseudocercospora griseola, is an important disease of common bean (Phaseolus vulgaris). Previous studies demonstrated that P. griseola and Phaseolus vulgaris have co-evolved, resulting in the classification of the fungus into Middle American and Andean populations that reflect the evolutionary history of the host. However, an unusual group of P. griseola isolates found in Africa, termed Afro-Andean, was previously found to be pathogenic on Middle American cultivars. This study evaluated the diversity of P. griseola isolates from four countries and confirmed the existence of an Afro-Andean clade using molecular methods. A total of 171 P. griseola isolates from Puerto Rico, Honduras, Guatemala and Tanzania were evaluated. Sequence from four nuclear genes (β-tubulin, actin, the internal transcribed spacer (ITS) region of the ribosomal DNA, and the small subunit rRNA gene) were used to construct phylogenetic trees by Bayesian inference. Phylogenetic trees grouped all isolates from Puerto Rico (43), Honduras (25) and Guatemala (14) in the Middle American clade. Of the 89 Tanzanian isolates, 37 were Middle American and 40 Andean, and a third population with 12 isolates was identified as Afro-Andean. Models using isolation with migration estimated that the divergence between Middle American and Andean P. griseola populations occurred approx. 100,000 years ago, and that the Afro-Andean clade is a sister clade of the Andean population that diverged approx. 40,000 years ago. The results provide an understanding of the co-evolution of beans and the ALS pathogen, and help inform current and future bean breeding efforts. [ABSTRACT FROM AUTHOR]

Angular leaf spot (ALS) is one of the most devastating diseases of common bean (Phaseolus vulgaris L.) and causes serious yield losses worldwide. ALS resistance is reportedly pathotype-specific, but little is known about the efficacy of resistance loci against different pathotypes. Here, we report on ALS resistance evaluations of 316 bean lines under greenhouse and field conditions at multiple sites in Colombia and Uganda. Surprisingly, genome-wide association studies revealed only two of the five previously described resistance loci to be significantly associated with ALS resistance. Phg-2 on chromosome eight was crucial for ALS resistance in all trials, while the resistance locus Phg-4 on chromosome 4 was effective against one particular pathotype. Further dissection of Phg-2 uncovered an unprecedented diversity of functional haplotypes for a resistance locus in common bean. DNA sequence-based clustering identified eleven haplotype groups at Phg-2. One haplotype group conferred broad-spectrum ALS resistance, six showed pathotype-specific effects, and the remaining seven did not exhibit clear resistance patterns. Our research highlights the importance of ALS pathotype-specificity for durable resistance management strategies in common bean. Molecular markers co-segregating with resistance loci and haplotypes will increase breeding efficiency for ALS resistance and allow to react faster to future changes in pathogen pressure and composition. [ABSTRACT FROM AUTHOR]

Angular leaf spot (ALS), a fungal disease caused by Pseudocercospora griseola, has a significant impact on bean productivity in Africa, causing up to 80% yield losses. Efforts to breed for ALS resistance are challenged by continuously evolving pathogen races that differ by location. Released bean varieties in Uganda are susceptible to ALS; the few exotic sources of resistance available are not well adapted to local environmental conditions. To overcome these challenges, a study was conducted to understand pathogen variability and identify new sources of ALS resistance for deployment in ALS resistance breeding. Variability in 45 P. griseola pathotypes was elucidated using a set of 12 ALS differential cultivars, random amplified microsatellite markers, and conserved sequences. The differentials and markers defined 12 pathotypes and 30 haplotypes, respectively, which belonged to the Middle American and Andean gene pool groups, each with high variability. Among the 74 bean landraces screened using the 1:6, 17:39, 21:39, and 61:63 P. griseola pathotypes, only U00279 showed consistent resistance to all the four pathotypes. U00297's resistance to pathotype 17:39 was conferred by a single dominant gene, while digenic epistatic gene interactions were responsible for resistance to other pathotypes. The dominant gene in U00297 was independent of resistance genes harbored by documented resistance sources AND277 and G5686. The results revealed high variability in P. griseola and identified a new source of broad ALS resistance. The divergent inheritance patterns of resistance to the different pathotypes indicate the importance of race specificity of the target host plant in breeding for disease resistance. [ABSTRACT FROM AUTHOR]

BRS Sublime is a common bean cultivar with carioca grains, high nutritional grain quality, and high yield potential (4667 kg ha-1). It has a normal cycle, upright growth, low loss rates in the mechanical harvest, and is recommended for planting in 19 Brazilian states, in the three main common bean cultivation regions. It is the first cultivar developed in the world with angular leaf spot resistance. [ABSTRACT FROM AUTHOR]

Pseudocercospora griseola is the causal agent of Angular Leaf Spot (ALS), a disease of common bean. Due to its coevolution with beans, two major groups have been defined, “Andean” ( P. griseola f. griseola ) and “Mesoamerican” ( P. griseola f. mesoamericana ). The aim of this study was to characterize the dark pigment, melanin, synthetized by a selected isolate of each genic group of P. griseola when grown on Potato-dextrose broth. P. griseola f. griseola isolate S3b and P. griseola f. mesoamericana isolate T4 produced 1.7 ± 0.6 and 4.1 ± 0.9 mg of melanin per g of dry biomass, respectively. Although both melanins possessed similar UV–visible absorption spectroscopic pattern, P. griseola f. mesoamericana isolate T4 melanin had a lower UV–visible absorption, higher reducing activity and metal chelating ability than melanin from P. griseola f. griseola isolate S3b. However, when the size of the sample was 10 mg S3b melanin had a higher content of free phenolic groups. Furthermore, cell wall polysaccharides modified in melanin the availability of active phenolic groups, which was dependent on the fungal isolate and the size of the sample. Therefore, the amount and chemical features of melanin as well as its deposition in mycelium walls within isolates is different, which might explain the different pigmentation and physiological behaviours of these representatives of the two groups of P. griseola . [ABSTRACT FROM AUTHOR]

This study compared severity of angular leaf spot in common bean lines, based on the healthy and diseased leaf area, andthe graded scale. We used 12 common bean lines in the dry and rainy seasons. Two contiguous experiments were conducted in eachseason, with and without chemical control of the pathogen. We evaluated the percentage of the healthy and diseased leaf area; severitybased on a graded scale and the area under the disease progress curve; and yield. The diseased or healthy leaf area is efficient toevaluate the severity of angular leaf spot with a sample of 20 to 30 leaflets per plot. For all traits, the results of central and borderareas did not differ, indicating that the evaluation of border rows is unnecessary and, finally, the severity assessment of the upper planthalf can discriminate the lines more efficiently.

The objective of the present study was to assess the genetic potential of inbred carioca common bean families from five populations derived from crossings involving elite lines and a disease-resistant line (Rudá- R), and to assess the efficiency of SCAR molecular markers in selecting plants resistant to anthracnose and angular leaf spot, at the time of bulk formation. Plant architecture, yield and grain type were assessed. Significant effect among families within population was observed, suggesting wide genetic variability for the characters assessed. Twenty-six superior families were selected. The families contained the greatest number of markers, identified by SCAR molecular markers in the F4 generation. Eighteen of these families were resistant to the races 65 and 453 of Colletotrichum lindemuthianum and five were resistant to the race 63.23 of Pseudocercospora griseola. Thus selection assisted by SCAR markers, in the F4 generation, was an important tool in common bean br e eding.

O objetivo deste trabalho foi avaliar o efeito de isolados de Bacillus cereus e Pseudomonas putida sobre a severidade da mancha-angular do feijoeiro, em condições de campo. Quatro experimentos foram conduzidos em épocas favoráveis à mancha-angular (Pseudocercospora griseola), com as cultivares Pérola e Ouro Negro. Os experimentos foram realizados em delineamento de blocos ao acaso, com seis repetições. Os tratamentos foram pulverizações sobre as plantas com três estirpes de B. cereus (UFV-172, UFV-101 e UFV-75) e duas estirpes de P. putida (UFV-53 e UFV-Pp), acibenzolar-S-metil, fungicida clorotalonil e controle pulverizado com água, no total de oito tratamentos. Os tratamentos foram aplicados por atomização no filoplano de plantas de feijoeiro, semanalmente, a partir do 15º dia após a emergência até o fim do ensaio. Calculou-se a área abaixo da curva de progresso da mancha-angular do feijoeiro; a doença ocorreu naturalmente. A produção foi avaliada pela massa média de sementes por planta. Os antagonistas foram eficientes em reduzir a severidade da doença, em comparação à testemunha, e obtiveram o mesmo nível de controle do tratamento químico. O menor índice de severidade da doença propiciou melhor produção do que o tratamento controle.

Information about genetic control of plant reaction to pathogens is essential in plant breeding programs focusing resistance. This study aimed to obtain information about genetic control of the angular leaf spot reaction in leaves and pods from common bean (Phaseolus vulgaris L.) line ESAL 686. This line was crossed with cultivars Jalo EEP 558 (resistant), Cornell 49-242 (resistant) and Carioca MG (susceptible). Generations F1, F2 and backcrosses (BC11 and BC21) were obtained. In the dry season (2009), parents and respective populations were evaluated for angular leaf spot reaction under field conditions. Disease severity was evaluated on leaves and pods using diagrammatic scales. Severity scores were obtained and mean and variance genetic components were estimated for both. Segregation of F2 generation was analyzed for some crosses. Different genes control angular leaf spot reaction in leaves and pods. Mean and variance components showed predominance of additive effects. Heritability was high, however, was greater on pods than on leaves which indicated that leaf reaction is more influenced by the environment.

Objetivou-se no trabalho, selecionar linhagens de feijoeiro comum que reunissem, além da alta produtividade, porte ereto e grãos do tipo Carioca, também a resistência à antracnose e à mancha angular. O material experimental constituiu-se de 143 linhagens oriundas de três famílias segregantes F1:4RC2 {[(G2333 X ESAL 696) X ESAL 696] X CI 140}. Foram conduzidos quatro experimentos em três localidades da região sul de Minas Gerais, avaliando-se a produção, o tipo de grão, o porte e a reação à mancha angular. A reação à antracnose foi determinada a partir de inoculações de plantas jovens de cada linhagem, com as raças 2047 e 1545, mantidas em câmara de nevoeiro por três dias e transferidas para casa de vegetação com irrigação por aspersão, a cada quatro horas. Selecionaram-se quatro linhagens com alta produtividade, porte mais arbustivo, grãos tipo carioca e com resistência à mancha angular (nota até 4). Uma das linhagens selecionada possui o alelo Co-4², outras duas possuem o alelo Co-7 de resistência à antracnose e a última, embora seja suscetível à antracnose, possui resistência à mancha angular (nota 3,97) e maior produtividade de grãos.Aiming to select common bean lines with high grain yield, Carioca grain type, upright plant habit and resistant to anthracnose and angular leaf spot, 143 lines were selected from three families of the cross F1:4RC2 {[(G2333 X ESAL 696) X ESAL 696] X CI 140}. The promising lines were selected based on the agronomical traits in four field experiments, set up in three places in Southern MG State using the square lattice design. The reaction of each line to the anthracnose was evaluated by inoculating the seedlings using the races 1545 and 2047, and kept in humid chamber during three days, and then moved to greenhouse with sprinkle irrigation every four hours. Four lines with high grain yield, upright plant habit, Carioca grain type, and resistance to angular leaf spot (score up to 4) were selected. Among them one of the lines has the Co-4² allele for anthracnose resistance, two lines have the Co-7 allele, and the last one, although susceptible do anthracnose, presented the highest grain yield and angular leaf spot resistance (score 3,97).

O objetivo deste estudo foi a caracterização fenotípica e molecular de 31 genótipos de feijão do tipo carioca, quanto à resistência aos patógenos da antracnose, ferrugem e mancha-angular. Foram realizadas inoculações com 13 patótipos de Colletotrichum lindemuthianum, dois de Uromyces appendiculatus e sete de Pseudocercospora griseola. Na caracterização molecular, foram utilizados cinco marcadores moleculares previamente identificados, ligados a diferentes alelos de resistência aos patógenos. Sete genótipos apresentaram resistência a 12 patótipos de C. lindemuthianum. Nove genótipos apresentaram resistência a cinco patótipos de P. griseola. Dez genótipos foram resistentes aos patótipos de U. appendiculatus. As linhagens VC 2, VC 3 e VC 5, além da Rudá-R (linhagem piramidada com cinco genes que conferem resistência a alguns patótipos de antracnose, ferrugem e mancha-angular), foram as que se destacaram quanto à resistência múltipla aos patógenos acima citados. Foi detectado polimorfismo molecular entre a maioria dos genótipos com a Rudá-R, o que indica a possibilidade de uso dos marcadores moleculares SCARF10, SCARY20, SCARAZ20, SCARH13 e OPX11.The present study aimed at the phenotypic and molecular characterization of 31 genotypes of the carioca-type common bean regarding the resistance to anthracnose, rust and angular leaf spot (ALS) pathogens. Thirteen pathotypes of Colletotrichum lindemuthianum, two of Uromyces appendiculatus and seven of Pseudocercospora griseola were inoculated. In the molecular characterization, five molecular markers, identified in advance, and linked to the different alleles of pathogens' resistance, were used. Seven genotypes showed resistance to 12 pathotypes of C. lindemuthianum. Nine genotypes presented resistance to five pathotypes of P. griseola. Ten genotypes were resistant to the pathotypes of U. appendiculatus. The lines VC 2, VC 3 and VC 5, besides Rudá-R (line pyramided with five genes which confer resistance to some pathotypes of anthracnose, rust and ALS), were the stood out for multiple resistance to the pathogens above described. Molecular polymorphism was detected between the most genotypes with Rudá-R, which indicates the possibility of using the molecular markers SCARF10, SCARY20, SCARAZ20, SCARH13 and OPX11.

Angular leaf spot (Pseudocercospora griseola Crous U, Brown) is one of the most important diseases hindering common bean (Phaseolus vulgaris L.) production in the Great Lakes Region of Africa, including the Democratic Republic of Congo. The disease causes extreme yield losses, estimated at 384.2 tonnes per year, in Sub-Saharan Africa. Little is known about the distribution, severity and incidence of the disease and the effect of agronomic practices and environmental factors on the disease prevalence in the country to facilitate interventions. A field survey was conducted during two crop seasons, February to June and September to January, in two main beans growing zones of eastern DRC namely; sub-humid highland and sub-humid mid altitude at low latitudes, in South and North Kivu, respectively. Severity and incidence of angular leaf-spot and other occurring diseases were assessed on common bean plants in farmers’ fields. Angular leaf spot in these fields had an average severity index (PSI) of 49.9%. PSI was significantly different (P<0.05) between districts and seasons. Using multiple regression analysis, independent variables: growth stage, cropping system, districts and altitude were shown to have significant influence on the observed PSI (P<0.05) with R2 = 96.2%. The highest severity (PSI=59.7%) was observed in Kabare district, and the lowest in Uvira district (PSI=39.5%). Screening of a set of 37 released common bean varieties in DRC using virulent Andean and Mesoamerican isolates identified four resistant bean varieties; ARA 4, COD MLV 059, MLV 224/94B, LSA 144 and Mexico 54. Some of these varieties possess useful traits, in addition to acceptable seed market class, and are hence recommended as suitable parents for ALS resistant variety development and promotion in ALS prone environments. [ABSTRACT FROM AUTHOR]

Pseudocercospora griseola, the causal agent of angular leaf spot, has caused serious damage on local bean genotypes in bean greenhouses in Zonguldak, Bartın, and Karabük provinces of Turkey. The disease begins as angular spots on leaves which are followed by quick death of leaves and it causes deep brown wounds on the seeds. Since bean producers use their domestic seeds, infected seeds increase the inoculum source year by year and distribute the disease to close by provinces. Therefore, determination of the inoculum source of angular leaf spot disease agent, P. griseola on the locally cultivated bean genotypes was aimed. For this purpose, seeds with suspected symptoms of the disease and diseased plant debris were collected from the greenhouses where the disease is seen every year and analyzed in the laboratory in 2013. Then trials were established with the diseased seeds planted in uninfected soil and healthy seeds planted in diseased plant debris mixed with uninfected soil. As a result of the experiments, it was determined that angular leaf spot of beans was carried by seeds and diseased plant debris in the Western Black Sea Region. [ABSTRACT FROM AUTHOR]

Angular leaf spot caused by Pseudocercospora griseola is the most destructive disease of common bean (Phaseolus vulgaris L) in the Southern Highlands of Tanzania (SHT). The objectives of this study were to assess the farming system and farmers awareness in the ALS disease prone environments of the SHT. A structured questionnaire was designed to collect information from 238 respondents sampled from Mbeya, Njombe, Iringa and Rukwa regions. Data collected included population demography, production constraints, and indicators of poverty. The results showed that ALS widely occurred in the SHT but farmers were not aware of the disease and sources of inocula. Most of the respondents were poor with average yields of less than 500 kg ha-1. Lack of knowledge on ALS disease and the presence of favorable environmental conditions increased chances of P. griseola proliferation. Therefore, trainings on awareness and intensification of extension services is important. Breeding for durable resistance is an overriding consideration towards increasing bean productivity in the SHT. [ABSTRACT FROM AUTHOR]

This study assessed the influence of resistance inducers in controlling bean diseases. It was evaluated two doses of calcium silicate combined with potassium silicate, acibenzolar-S-methyl (ASM), orthophosphate, manganese phosphite, manganese sulfate, fungicide and water, on the severity, incidence and development of anthracnose and bean plant development. The second experiment evaluated the effect of six foliar treatments (five resistance inducers and water) with and without fungicides on anthracnose and angular leaf spot control and plant yield. Resistance inducing molecules influenced the incidence and severity of anthracnose. Plants treated with ASM, orthophosphate, manganese sulfate and manganese sulfate were down 10.3% the area under the progression of severity curve when compared to the control. There was no effect of calcium silicate supplementation on the anthracnose control and plant development. Plants sprayed with orthophosphate and coffee bark extract showed lower values of area under the curve in the progression of anthracnose incidence when compared to the control. There was no influence of resistance inducers on the severity of anthracnose and angular leaf spot. The use of inducers when combined with fungicides did not provide additional effect on disease control and bean productivity. [ABSTRACT FROM AUTHOR]

Genetic resistance of common bean (Phaseolus vulgaris L.) against angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola, is conferred by quantitative trait loci (QTL). In this study, we determined the gene content of the major QTL ALS10.1 located at the end of chromosome Pv10, and identified those that are responsive to ALS infection in resistant (CAL 143) and susceptible (IAC-UNA) genotypes. Based on the current version of the common bean reference genome, the ALS10.1 core region contains 323 genes. Gene Ontology (GO) analysis of these coding sequences revealed the presence of genes involved in signal perception and transduction, programmed cell death (PCD), and defense responses. Two putative R gene clusters were found at ALS10.1 containing evolutionary related coding sequences. Among them, the Phvul.010G025700 was consistently up-regulated in the infected IAC-UNA suggesting its contribution to plant susceptibility to the fungus. We identified six other genes that were regulated during common bean response to P. griseola; three of them might be negative regulators of immunity as they showed opposite expression patterns during resistant and susceptible reactions at the initial phase of fungal infection. Taken together, these findings suggest that common bean reaction to P. griseola involves transcriptional modulation of defense genes in the ALS10.1 locus, contributing to resistance or susceptibility depending on the plant-pathogen interaction.

Durable resistance, conditioned by minor resistance genes, has been described as more reliable in managing angular leaf spot (ALS) disease in the long term. The aim of this study was to develop a breeding method for durable ALS resistance in common bean and use it to accumulate minor genes into single genotypes. Four genotypes with intermediate resistance to ALS were selected from an initial 182 genotypes and used to generate a double cross segregating population. The F was planted in a nethouse and inoculated with a mixture of races of the ALS pathogen. The genotypes that showed intermediate resistance to ALS were subsequently selected from the F to the F segregating populations. In the F generation resistant plants were selected and the F plants were evaluated, together with the parents and several market class varieties. Data were collected on ALS disease severity, seed yield, days to physiological maturity, seed size, seed colour and growth habit. Ten F advanced lines with enhanced levels of resistance (disease score 1.9-3.2) were selected. These lines had improved resistance when compared to their parents (disease score 4.6-4.8) and market class varieties (disease score 5.4-8.2), which confirmed breeding progress for resistance to ALS. Simultaneous selection was done for seed yield, seed size, farmer preferred seed type and growth habit. The results of the study have shown that it is possible to develop ALS resistant common bean lines through the double cross method, using a mixture of ALS races. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a diagrammatic scale to evaluate angular leaf spot (ALS) severity in primary leaves of common bean. A diagrammatic scale was developed and validated with nine levels of severity: 0 %; 0.1 to 0.5 %; 0.6 to 4.0 %; 4.1 to 7.0 %; 7.1 to 16 %; 16.1 to 26 %; 26.1 to 32 %; 32.1 to 38 % and 38.1 to 60 %. The use of this scale, associated with the early inoculation method, allowed rating of ALS severity in common bean leaves in the V2 stage of development that is, when the primary leaves are fully open. Validation of the scale was performed by 14 Evaluators. These Evaluators estimated the severity in 40 common bean leaves with different levels of severity, previously measured by the software Quant®. The accuracy and precision of each Evaluator were determined by simple linear regression, by comparing between actual severity, measured electronically, and that estimated by the Evaluator. Without the scale, most of the Evaluators overestimated the severity of the disease. With the scale, the Evaluators obtained better levels of accuracy and precision, with absolute errors less than 5 %. The diagrammatic scale proposed proved to be adequate for early performance of the pathogenicity test. [ABSTRACT FROM AUTHOR]

Pseudocercospora griseola, the causal agent of angular leaf spot, caused important damage in domestic varieties and was first identified in Çaycuma district of Zonguldak province in Turkey. This pathogen has caused serious damage on local bean genotypes in the province. The disease begins as angular spots on leaves which is followed by quick death of leaves and it causes deep brown wounds on capsules. Since chemical control is not recommended for the disease in Turkey, it causes severe yield and economic losses. Besides, because the producers use domestic seeds, the infected seeds will increase the inoculum source year by year and distribute the disease to close by provinces. With this project, chemical control possibilities of P. griseola that is the causal agent of angular leaf spot in locally grown bean genotypes were investigated. Chemicals were applied as seed treatment and foliar spraying. The trials were carried out in Çaycuma and Gökçebey the district of Zonguldak in 2010, 2011 and 2012. Difenoconazole, Azoxystrobin and Mancozeb showed the highest impact in control of the disease. [ABSTRACT FROM AUTHOR]

The objectives of this study were to identify which method and period of evaluation of angular leaf spot ( ALS) of common bean, caused by the fungal pathogen Pseudocercospora griseola, allow better discrimination among common bean lines derived from seven cycles of recurrent selection for resistance to this pathogen. For that reason, 35 lines of the first seven cycles of the programme were assessed for disease severity on leaves and pods using a rating scale. For leaves, the methods used were severity in field plots ( SF), severity in sampled leaflets ( SS) and percentage of the sampled leaf area with symptoms (% LAS). Leaf assessments were performed at 7, 14, 21, 28, 33 and 41 days after flowering ( DAF), and area under the disease progress curve ( AUDPC) was calculated. On pods, severity was evaluated at 41 DAF. It was observed that the SF using a rating scale is the most efficient method for selection of resistant lines, and the best time period for evaluating the disease is around 33 DAF. [ABSTRACT FROM AUTHOR]

Disease severity assessment by means of a scoring scale, especially for angular leaf spot ( Pseudocercospora griseola) in common bean, is hindered in experiments for assessment of progenies and/or breeding lines due to lack of uniformity of occurrence of the pathogens and segregation within progenies. The purpose of this study was to estimate the efficiency of the use of one plant per plot in assessing the severity of angular leaf spot in experiments for assessment of progenies and/or breeding lines in the common bean crop. To that end, two experimental strategies were used - one of them using one plant per plot and another using a standard size plot (SPP) (2-4-m length rows). The experiments were conducted in the period from November 2011 to May 2012 in the municipalities of Lavras and Lambari, state of Minas Gerais, Brazil. Forty-one lines from the breeding programme of the Universidade Federal de Lavras ( UFLA) and from other research institutions were assessed, which differed in regard to their degree of susceptibility to P. griseola. The lines were assessed in regard to the severity of said disease using a five-degree diagrammatic scale. In all the one plant per plot experiments, severity scores of angular leaf spot from the beginning of its occurrence, and later in intervals ranging from 7 to 12 days, were obtained. In the experiment with the SPP, assessment was made a few days prior to grain harvest. Estimates of the correlations between severity scores and grain yield (GY) were mostly of small magnitude. There was good coincidence between the lines classified as more resistant or more susceptible to the pathogen under the two conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] The bacteria studied have the potential to control fungal and bacterial diseases. [•] The bacteria studied have the potential to control foliar and stem/vascular diseases. [•] The combination of these bacteria diversifies and intensifies the effect that bacteria produce individually. [Copyright &y& Elsevier]

Yield losses due to rust and angular leaf spot (ALS) of snap beans may reach 100% in Eastern Africa. Where susceptible varieties are grown, farmers control these diseases with routine fungicide applications. To determine an optimum application rate and spray schedule for Orius® (tebuconazole 250 g/L), we sprayed 10 mL and 20 mL Orius® per 15 L spray water twice at two trifoliate leaf stage and 50% flowering, and three times at the same stages, with an additional application at pod initiation. In farmers’ fields, we tested the effect of fungicide sprays, use of resistant variety, intercropping, increased plant spacing and farmyard manure on rust and ALS diseases. Application three times of 20 mL Orius® per 15 L spray water reduced rust severity scores by 5.7 and 2.4 in 2010 and 2011, respectively. Lowest rust and ALS severities were observed when a resistant variety, fungicide or farmyard manure was used. Pod yield increments due to disease management ranged between 13% and 242%. Prophylactic fungicide application, use of resistant varieties and farmyard manure can be used to reduce disease severity and improve snap bean quality on smallholder farms. [ABSTRACT FROM PUBLISHER]

Abstract: The present work aimed to study the effect of saccharin and ulvan against rust in artificially inoculated plants and against both rust and angular leaf spot (ALS) in naturally infected bean plants. In the greenhouse, bean plants of cv. Guará (susceptible) and FT-line (rust resistant) at first trifoliate leaf stage were sprayed with saccharin (0.24 mg mL−1) or ulvan (1 or 10 mg mL−1), and inoculated with Uromyces appendiculatus six days after spray. Both compounds provided an intermediary level of protection. They reduced at a similar extent the number, diameter and particularly sporulation of rust pustules in susceptible plants, suggesting that mechanisms of resistance operate at latter stages of fungus colonization. Three follow-up experiments were carried out under natural infection conditions during the spring 2009 and 2010, and summer/autumn 2010. ALS was observed during all three outdoor pot experiments, whereas rust occurred only during the spring 2009 and 2010. Saccharin sprayed every 14 days was able to protect bean plants against rust during the three experiments, whereas significantly reduced ALS only during summer/autumn and spring 2010. On the other hand, ulvan at a reduced dose rate (1 mg mL−1) did not affect significantly the epidemiological development of both diseases. Increase in seed weight was observed when saccharin-treated plants were infected after pre-flowering, but not when rust infection occurred earlier. Possible reasons why such trade-offs can be obtained in certain circumstances are discussed. [Copyright &y& Elsevier]

The objective of the present study was to assess the genetic potential of inbred carioca common bean families from five populations derived from crossings involving elite lines and a disease-resistant line (Rudá- R), and to assess the efficiency of SCAR molecular markers in selecting plants resistant to anthracnose and angular leaf spot, at the time of bulk formation. Plant architecture, yield and grain type were assessed. Significant effect among families within population was observed, suggesting wide genetic variability for the characters assessed. Twenty-six superior families were selected. The families contained the greatest number of markers, identified by SCAR molecular markers in the F4 generation. Eighteen of these families were resistant to the races 65 and 453 of Colletotrichum lindemuthianum and five were resistant to the race 63.23 of Pseudocercospora griseola. Thus selection assisted by SCAR markers, in the F4 generation, was an important tool in common bean breeding. [ABSTRACT FROM AUTHOR]

nthracnose, rust and angular leaf spot caused by Colletotrichum lindemuthianum, Uromyces appendiculatus and Pseudocercospora griseola, respectively, are economically important diseases affecting the common bean production in Brazil. The BIOAGRO/UFV bean breeding program developed Rudá-R, a dry bean line with 'carioca' seed type, containing the following disease resistance genes: Co- 4, Co- 6 and Co- 10 (anthracnose); Ur- ON (rust) and Phg- 1 (angular leaf spot). To transfer this combination of disease resistance genes present in Rudá-R to a black-seeded bean, a backcrossing program aided by molecular markers was conducted, involving Rudá-R (donor genitor) and Diamante Negro (recurrent genitor). Forty black-seeded BCF lines were obtained with combinations of at least three markers linked to the indicated disease resistance genes. The lines were evaluated for resistance to the three mentioned pathogens. Eight of the lines were homozygous and resistant to all four evaluated races of C. lindemuthianum, but susceptible to race 2047. Four of the lines were homozygous and resistant to two races of U. appendiculatus. Twenty of the lines were homozygous and resistant to the two races of P. griseola tested. Grain yield of the BCF lines was evaluated during the 'winter' season of 2006 and the 'dry' season of 2007. All lines had statistically equal or higher yields than Rudá-R and Diamante Negro. Lines were identified that not only were high yielding but also resistant to the three pathogens tested. These lines are potential genotypes for further testing and for release as new black common bean varieties. [ABSTRACT FROM AUTHOR]

The genetic progress (GP) was evaluated after eight cycles of recurrent selection for resistance to angular leaf spot in common bean and indirect gain for yield and grain type. The base population (Cycle-0) was obtained from the diallel cross of seven lines with carioca grain and ten resistance sources. To obtain Cycle I, the most resistant S0 plants of Cycle 0 were intercrossed. The same procedure was adopted in the subsequent cycles. GP for resistance to the pathogen was estimated by the overall average of the progenies of each cycle in comparison with control Carioca MG and for productivity in comparison to the controls Carioca MG and Pérola. Lines of the first six cycles were used for grain type. No GP was detected for resistance to angular leaf spot. However, the indirect yield gain was 2.3% and 2.5% in the selection for grain type, with values similar to those obtained by direct selection for these traits. [ABSTRACT FROM AUTHOR]

Pseudocercospora griseola (Sacc.) Crous & Braun is a widespread fungal phytopathogen that is responsible for angular leaf spot in the common bean (Phaseolus vulgaris L.). A number of fungal phytopathogens have been shown to harbour mycoviruses, and this possibility was investigated in populations of Pseudocercospora griseola. The total nucleic acid extracts of 61 fungal isolates were subjected to agarose gel electrophoresis. Small fragments (800-4800 bp) could be identified in 42 of the samples. The presence of dsRNA in isolate Ig838 was confirmed by treatment of total nucleic acid with DNase, RNase A, and nuclease S1. Transmission electron microscopy revealed the presence of viral-like particles 40 nm in diameter in the mycelia of 2 fungal isolates, namely 29-3 and Ig838. The transmission of dsRNA by means of conidia was 100% for isolate 29-3, but there was loss of 1-6 fragments of dsRNA in monosporic colonies of isolate Ig848. Cycloheximide treatment failed to inhibit the mycovirus in isolate 29-3, but proved efficient in the elimination of the 2.2, 2.0, 1.8, 1.2 and 1.0 kb fragments in 2 colonies of isolate Ig848. The occurrence of a mycovirus in Pseudocercospora griseola was demonstrated for the first time in the present study. Pseudocercospora griseola (Sacc.) Crous & Braun est un phytopathogène fongique répandu qui cause la maladie des taches anguleuses du haricot (Phaseolus vulgaris L.). Puisqu’un certain nombre de phytopathogènes fongiques sont porteurs de mycovirus, cette possibilité a été examinée chez Pseudocercospora griseola. Des extraits d’acides nucléiques totaux de 61 isolats fongiques ont été soumis à une électrophorèse sur agarose. Des petits fragments (800-4800 pb) ont pu être identifiés chez 42 des isolats. La présence d’ARN db dans l’isolat Ig838 a été confirmée par un traitement des acides nucléiques totaux à la DNase, à la RNase A et à la nucléase S1. La microscopie électronique à transmission a révélé la présence de particules virales de 40 nm de diamètre dans le mycélium de 2 isolats fongiques, soit 29-3 et Ig838. La transmission de l’ARN db par l’intermédiaire de conidies était de 100 % chez 29-3, mais de 1-6 fragments d’ARN db étaient perdus dans les colonies monosporiques de Ig848. Un traitement à la cycloheximide n’a pu inhiber le mycovirus dans l’isolat 29-3, mais s’est montré efficace pour éliminer les fragments de 2,2, 2,0, 1,8, 1,2 et 1,0 kb dans 2 colonies de l’isolat Ig848. La présence d’un mycovirus chez Pseudocercospora griseola a été ici démontrée pour la première fois. [ABSTRACT FROM AUTHOR]