Fungus Pseudocercospora Griseola Research Articles

Melaleuca Essential Oil (Melaleuca alternifolia cheel) in the Control of Beans Diseases

Bean cultivation is vital to the global food and economy, especially in Brazil. Facing challenges from diseases that affect production, it is crucial to seek new strategies to maintain productivity and sustainability. Melaleuca alternifolia, known as the tea tree due to its medicinal properties, has little explored potential in controlling diseases in bean plants. The objective of this work was to evaluate the effectiveness of tea tree essential oil in controlling diseases in bean cultivation. In vitro tests were carried out to evaluate bacterial growth, at concentrations of (0.0%, 0.05%, 0.1%, 0.5%, 1% and 2%). And antibiogram with the bacteria Xanthomonas axonopodis pv. phaseoli, in different concentrations (0.0%, 0.05%, 0.1%, 0.5%, 1%, 2% and 3%). For the fungus Pseudocercospora griseola, sporulation tests were carried out, using direct and indirect methods, at concentrations of (0.0%, 0.05%, 0.1%, 0.5%, 1%, 2%, and 3%). Furthermore, for the fungus Colletotrichum lindemuthianum, mycelial growth tests were carried out with the same concentrations. The experiments took place in vivo, with a completely randomized statistical design, involving five replications per treatment and concentrations varying from (0.0%, 0.05%, 0.1%, 0.5%, 1% and 2%). Disease incidence was assessed using a diagrammatic scale, disease severity, Area under the Disease Progress Curve (AACPD) and Area under the Incidence Progress Curve (AACPI). Melaleuca Essential Oil (EO) inhibited the development of fungi and bacteria in in vitro tests starting at 0.5%. In vivo, Melaleuca Essential Oil (EO) showed a significant reduction in the incidence and severity of the disease from 0.5% in both fungi and bacteria. Melaleuca EO can be an effective alternative for disease control in bean cultivation.

A review of Pseudocercospora griseola in common bean ( Phaseolus vulgaris L.) in Africa

Abstract Angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola , is one of the most economically important diseases that limits the productivity of common beans. P. griseola has great variability which explains the large number of existing races and the complexity of genetic resistance. This review was carried out to discuss and document on the diversity of P. griseola in Africa , and the pathogenic variability of pathotypes against different bean varieties and lines. Diversified pathotypes were identified from different common bean-growing countries. About 12 pathotypes were identified from 45 isolates in Uganda. Similarly, about 44 pathotypes were characterized from 100 isolates in Kenya. Pathotypes 61:63 and 63:63 were the most aggressive identified pathotypes in different African countries. Many reports indicated that Andean isolates infect mostly Andean genotypes, while Mesoamerican isolates infect both Andean and Mesoamerican genotypes. The resistances of major commercial varieties and bean lines are breaking down and were found to be susceptible. Hence, multiple resistance breeding should be done for broken commercial varieties and bean lines using the potential identified gene source of landraces U00292, U0074, U351 and U1–9 from Uganda, genotype KKR IL05/Red 40 from Kenya and variety SER125/SER119 from Ethiopia.

Pseudocercospora griseola, the causal agent of common bean angular leaf spot: Strain characterization and sensitivity to fungicides

AbstractAngular leaf spot (ALS), an important disease of common bean (Phaseolus vulgaris), is caused by the fungus Pseudocercospora griseola. This pathogen has a wide genetic variability and, therefore, poses a challenge to integrated disease management. The use of resistant cultivars is difficult; hence, the application of fungicides has been a common practice in common bean cultivation. P. griseola strains were morphophysiologically characterized and their sensitivity to common fungicides used to control ALS was studied. The strains were evaluated for sporulation capacity and a representative sample of 34 strains was bioassayed to determine their sensitivity to commercial concentrations of five fungicides, namely pyraclostrobin, mancozeb, pyraclostrobin + metconazole, chlorothalonil and tebuconazole. Another sample of 29 strains was studied for conidial germination and dimensions. Sporulation capacity ranged from 0.88 to 27.67 × 104 conidia/ml and germination percentage ranged from 39% to 72%. The large differences among strains suggest a wide genetic variability among the strains. A wide variability in aggressiveness of P. griseola was observed, which has consequences for breeding programmes aimed at resistance. The behaviour of pathogen strains differed in every fungicide evaluated, even in a population that has not been under selection pressure in the field. These results confirm the need for further studies and may guide future research with this pathogen.

Identification of sources of resistance to race 63-63 of Pseudocercospora griseola in common bean lines

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.

Marker‐assisted backcrossing for disease resistance and agronomic traits in Carioca beans

AbstractAngular leaf spot, a disease caused by the fungus Pseudocercospora griseola, can lead to yield losses of up to 70% in the common bean (Phaseolus vulgaris) crop. Due to the quantitative character of angular leaf spot, a cultivar with high resistance depends on the presence of several resistance loci. In the present study, a marker‐assisted backcrossing approach was used involving an Andean donor parent (AND 277) and a Mesoamerican recurrent parent (IAC‐Milênio). For marker‐assisted backcrossing in the BC1F1 genotypes, 15 molecular markers previously mapped for angular leaf spot resistance loci were used, and selection was performed by genotypes grouped with the donor parent in discrimination analysis of principal components. Through molecular selection, 42% of the BC2F3 families selected for the Carioca grain ideotype showed high resistance to angular leaf spot under controlled conditions of infection. Two lines resistant under natural conditions and tolerant to Fusarium wilt (Fusarium oxysporum f. sp. phaseoli J. B. Kendr. & W. C. Snyder) were selected for the competition trial. The lines selected, AM138 and AM167, showed superiority to the recurrent cultivar for six of the eight agronomic traits, including resistance to Race 65 of Colletotrichum lindemuthianum slow grain darkening, early maturity, and lighter grain color. Both advanced lines will be included in the value for cultivation and use trials; and as Carioca lines with resistance of Andean origin, they can be widely used as sources of resistance in breeding programs to overcome problems related to inter‐gene pool crosses.

Efficiency of a recurrent selection method to achieve resistance of common beans to Pseudocercospora griseola in a short period

ABSTRACT The angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola, is one of the most notable diseases of common beans (Phaseolus vulgaris). The most effective strategy to control ALS is quantitative disease resistance provided by major and minor genes. One breeding strategy for obtaining lines with durable resistance to P. griseola is a recurrent selection that aims to gradually assemble favorable alleles. In this study, common beans were artificially inoculated with P. griseola and grown in a greenhouse under a recurrent selection program that aims to accelerate the breeding cycle and assimilate resistant conferring genes per generation. From the initial population, three cycles of evaluation, selection, and intercross were carried out in a greenhouse and the most resistant plants were phenotypically selected. Plants at the V2 stage were inoculated with an isolate of P. griseola, race 63-63. Selected plants were transplanted into pots and intercrossed to reap the next cycle of selection. Progenies obtained from the base population (C0) and subsequent cycles (CI, CII, and CIII) were assessed for the degree of the symptoms for ALS under greenhouse and field conditions. The rate of genetic progress per breeding cycle was - 14.8% and - 5.3% for the plants grown in greenhouse and field, respectively. Artificial inoculation with P. griseola allowed three recurrent selection cycles per year, signifying a promising method to obtain ALS-resistant common bean lines in a short period.

Antagonistic activity of rhizobacteria in the inhibition of the fungus Pseudocercospora griseola (Sacc.)

The angular leaf spot caused by the fungus Pseudocercospora griseola (Sacc.) is one of the main diseases in bean plants. Considering the losses caused by this disease, rhizobacteria may be an alternative for the manage­ment of this phytopathogen. Thus, this study evaluates the potential of different strains of rhizobacteria in the inhi­bition of the fungus P. griseola (Sacc.). The antagonistic effect of twenty bacterial strains on this phytopathogen was studied using the circle technique. The completely randomized experimental design was used with five repe­titions. Evaluation was performed on the tenth day, when colony diameter was measured and the percentage of growth inhibition (PGI) of the pathogen was calculated. Twelve strains inhibited the mycelial growth of P. griseola (Sacc.), with PGI values above 40% compared to the control. The strain UNIFENAS 03-36 stood out with inhibi­tion percentage of 85.10%.

Phylogeny of Pseudocercospora griseola from Puerto Rico, Central America and Tanzania confirms the existence of an Afro-Andean clade

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.

Identification of resistance sources of common bean (Phaseolus vulgaris L.) to angular leaf spot (Pseudocercospora griseola)

Common bean (Phaseolus vulgaris L.) is the most important edible legume in the world and is an important source of income for farmers and food for millions of families. Angular Leaf Spot (ALS), caused by the fungus Pseudocercospora griseola (Sacc.) Ferraris, is one of the most important diseases in the production of common bean with the potential to cause significant seed yield losses. An effective and environmentally friendly alternative to control this disease is the use of improved varieties that combine resistance genes of Andean and Mesoamerican origin. In this study, the response of 181 bean genotypes (coming from different breeding programs of several countries including the USA, Puerto Rico, Honduras, Ecuador, Colombia, Tanzania, Malawi, and Angola) to two angular spot isolates (races 61:11 and 63:51, prevalent in Isabela and Juana Díaz, Puerto Rico) were evaluated. Many of these genotypes contained resistant genes to different biotic and to abiotic stress. A total of 16 lines were identified to have resistance to both races. The resistant lines include the Andean breeding lines CAL 143, 277 and the Mesoamerican cultivar ‘Ouro Negro’ that possess the resistance genes Phg-5, Phg-1, Phg-3, respectively. This information can help common bean breeding programs to pyramid genes from the Andean and Mesoamerican gene pools to generate varieties with long-lasting resistance to this disease.

Fine-mapping of angular leaf spot resistance gene Phg-2 in common bean and development of molecular breeding tools

Key messageThe Common Bean Angular Leaf Spot Resistance Gene Phg-2 was fine-mapped to a 409-Kbp region, and molecular markers for breeders were developed and validated in field experiments.Common bean (Phaseolus vulgaris L.) is an important food legume in Latin America, Asia and Africa. It is an important source of protein, carbohydrates and micro-minerals, particularly for smallholder farmers. Common bean productivity is affected by angular leaf spot (ALS) disease caused by the pathogenic fungus Pseudocercospora griseola, resulting in significant yield losses, particularly in low-input smallholder farming systems in the tropics. The ALS resistance gene Phg-2, which was found in several highly resistant common bean genotypes, was investigated in crosses between Mesoamerican pre-breeding lines and elite Andean breeding lines. Next-generation sequencing (NGS) data sets were used to design new SNP-based molecular markers. The Phg-2 locus was confirmed to be the major locus providing ALS resistance in these crosses. The locus was fine-mapped to a 409-Kbp region on chromosome 8. Two clusters of highly related LRR genes were identified in this region, which are the best candidate genes for Phg-2. Molecular markers were identified that are closely linked to the Phg-2 resistance gene and also highly specific to the donor germplasm. Marker-assisted selection (MAS) was used to introgress the Phg-2 resistance locus into Andean breeding germplasm using MAB lines. The usefulness of molecular markers in MAS was confirmed in several field evaluations in complex breeding crosses, under inoculation with different ALS pathotypes. This project demonstrates that NGS data are a powerful tool for the characterization of genetic loci and can be applied in the development of breeding tools.

Screening Common Bean (Phaseolus vulgaris L.) Germplasm for Resistance against Angular Leaf Spot (Pseudocercospora griseola) Disease under Field Condition

Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola is one of the most destructive disease in Latin America and eastern Africa countries. The fungus, P. griseola is highly variable and a diverse sources of resistance genes is required to manage this economically important disease. The use of genetic resistance is the most practical and economic way to manage angular leaf spot of the common bean. Common bean (Phaseolus vulgarise L.) germplasm were screened for resistance against Angular leaf spot (ALS) under field conditions at Wonodogenet and Areka Research farms. Out of 300 common bean accessions evaluated only 14 (4.6%) common bean accessions were resistant to naturally epidemics of angular leaf spot disease under field condition. Therefore, all common bean germplasm that showed resistance reaction can be involved in breeding program for the improvement of the common bean.

English

Common bean (Phaseolus vulgaris) is a rich source of protein, vitamins, and micronutrients and is an important crop for food security throughout Latin America, Asia, and Africa. Among tropical and subtropical regions of the world, where the majority of beans are grown, yield losses due to the pathogenic fungus Pseudocercospora griseola, causing angular leaf spot (ALS), can be as high as 80%. The strategic use of marker-assisted selection (MAS) to pyramid multiple resistance genes into a single genetic background with preferred morphological and cooking characteristics is being implemented by six research groups throughout East Africa that make up the African Bean Consortium (ABC). Identifying unique markers that are polymorphic among multiple parents is a major source of marker attrition. In this study, an illustration of how 22 DNA sequences physically linked to the Phg-2 ALS resistance locus were identified using the PhaseolusGenes marker database and checked for amplification and polymorphism among 16 ABC breeding parents are given. Only three polymorphic markers could be identified following this procedure; one (g796), showed a polymorphism present only in the ALS resistance donor, Mexico 54. The PCR protocol developed to identify the g796 polymorphism was validated among five laboratories. Furthermore, co-segregation analysis of the marker and ALS resistance phenotype in a population of 100 F2 individuals from the cross between French bean (that is, green bean) genotype Amy and ALS resistance donor Mexico 54 showed the marker is genetically linked (3 cM) to the Phg-2 locus, in addition to being physically linked. This study suggests that in the near future, genetic resequencing data of diverse common bean accessions, compiled within an easily accessible database, will facilitate identification of markers for MAS, marker/trait association, and candidate gene identification. Key words: Angular leaf spot resistance, Phaseolus vulgaris, marker-assisted selection.

Leaf and canopy reflectance spectrometry applied to the estimation of angular leaf spot disease severity of common bean crops.

This study is aimed at (i) estimating the angular leaf spot (ALS) disease severity in common beans crops in Brazil, caused by the fungus Pseudocercospora griseola, employing leaf and canopy spectral reflectance data, (ii) evaluating the informative spectral regions in the detection, and (iii) comparing the estimation accuracy when the reflectance or the first derivative reflectance (FDR) is employed. Three data sets of useful spectral reflectance measurements in the 440 to 850 nm range were employed; measurements were taken over the leaves and canopy of bean crops with different levels of disease. A system based in Principal Component Analysis (PCA) and Artificial Neural Networks (ANN) was developed to estimate the disease severity from leaf and canopy hyperspectral reflectance spectra. Levels of disease to be taken as true reference were determined from the proportion of the total leaf surface covered by necrotic lesions on RGB images. When estimating ALS disease severity in bean crops by using hyperspectral reflectance spectrometry, this study suggests that (i) successful estimations with coefficients of determination up to 0.87 can be achieved if the spectra is acquired by the spectroradiometer in contact with the leaves, (ii) unsuccessful estimations are obtained when the spectra are acquired by the spectroradiometer from one or more meters above the crop, (iii) the red to near-infrared spectral region (630–850 nm) offers the same precision in the estimation as the blue to near-infrared spectral region (440–850), and (iv) neither significant improvements nor significant detriments are achieved when the input data to the estimation processing system are the FDR spectra, instead of the reflectance spectra.

Seriously Outbreak of Rice Bacterial Brown Stripe in 2018 in China

Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola is one of the most economically important disease affecting common bean production in Ethiopia. Until now, no information has been generated regarding the pathotype and pathogenic variability and its distribution in Ethiopia. A study was undertaken to characterize the pathotype and virulence variability among 39 P. griseola isolates, ALS pathogen, occurring in Ethiopia. A total of 21 pathotypes (63:63, 63:59, 63:23, 61:51, 56:36, 55:39, 49:7, 48:60, 42:59, 41:10, 34:53, 23:61, 19:33, 17:45, 8:18, 8:0, 4:16, 1:24, 1:10, 16:18. and 4:37) were determined using 12 sets of ALS common bean differentials cultivars. These results revealed the presence of high and diverse pathogenic variability of the pathogen. Among the determined pathotypes 63:59 and 19:33 were the most frequently appeared. And the occurrence of three pathotypes (63:63, 63:59 and 63:23) were confirmed as well as the previous reports in central America and Argentina. This will be the first comprehensive report of P. griseola pathotypes existing in the common bean growing areas of Ethiopia. Except pathotype 8:0 that were compatible with Andean common bean groups, most of the isolates were pathogenic to both Andean and Mesoamerican common bean gene pools. Based on that, the isolates were classified as Mesoamerican origin pathotypes. This specific study provided major information about the pathogenic diversity and determined the pathotype of P. griseola from common bean in Ethiopia.

Common bean reaction to angular leaf spot comprises transcriptional modulation of genes in the ALS10.1 QTL.

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.

Aggressiveness of Pseudocercospora griseola strains in common bean genotypes and implications for genetic improvement.

The fungus Pseudocercospora griseola, the causal agent of angular leaf spot in the common bean (Phaseolus vulgaris L.), exhibits a broad pathogenic variability that complicates the development of resistant cultivars. For breeding programs to successfully obtain common bean cultivars with durable resistance, knowing the aggressiveness of different strains, as well as the mechanisms of genetic resistance, is important. The aims of this study were to study the variation within race 63.63 by evaluating the aggressiveness of different strains, to analyze the genetic resistance of common bean lines to P. griseola, and to ascertain the implications for genetic improvement in obtaining resistance in this pathosystem. Four strains, collected from different locations, were inoculated in three groups of common bean lines in a greenhouse, and the severity of the disease was subsequently evaluated. Statistical analyses were carried out using the diallel method, which provided information on the vertical and horizontal resistance of host plants, in addition to information regarding the aggressiveness of the strains. The aggressiveness of P. griseola differed between the strains of race 63.63. The diallel method proved to be promising for the identification of horizontal and vertical resistance in the common bean-P. griseola pathosystem, with a predominance of horizontal resistance. Gene pyramiding, using marker-assisted selection, may not be the most effective strategy for obtaining durable resistance.

Anastomosis groups and molecular variation in Pseudocercospora griseola.

The fungus Pseudocercospora griseola is the causal agent of angular leaf spot, a common bean (Phaseolus vulgaris L.) disease. The successful development of angular leaf spot-resistant cultivars depends on understanding the levels of variability in pathogen populations. P. griseola shows great pathogenic and genetic variation using inoculation on differential bean cultivars and molecular markers. Nevertheless, how this variability develops is not clearly understood. Parasexuality has been presented as a mechanism used by asexual fungi to increase variation. Hyphal fusion is the first step for the parasexual cycle, and it can be considered an additional trait for population studies. The aim of this study was to identify hyphal fusion (anastomosis) among P. grisola isolates and to evaluate the variability of isolates using analyses of anastomosis groups and RAPD markers. Hyphal anastomosis was observed in all isolates. Three isolates showed 85.0% compatibility and were compatible with 17 isolates. This is the first report of the occurrence of anastomosis between P. griseola isolates. Sixteen anastomosis groups were observed and only one group was formed by five isolates (Pg-01, Pg-02, Pg-07, Pg-08, and Pg-12). There was a large number of anastomosis groups and absence of clustering among isolates for hyphal fusion, demonstrating the existence of genetic variability for loci involved in the control of this trait. High genotypic variability by RAPD markers was detected, but there was no relationship between genotype and anastomosis group. More studies are necessary to elucidate further the process of asexual recombination in this phytopathogen.

English

Angular Leaf Spot (ALS) caused by the fungus Pseudocercospora griseola and Bean common mosaic and necrosis virus (BCMV/BCMNV) are important diseases of common bean in Tanzania that can cause severe yield reduction when uncontrolled. This study was conducted to incorporate resistant genes for ALS and BCMV/BCMNV diseases into adapted, market class and farmers and consumers preferred bean genotype using Marker assisted selection. The parents Mexico 54 and UBR(25)95 donor of Phg-2 and I/bc-3 genes for ALS and BCMV/BCMNV, respectively were used the recipient being Kablanketi. In selection, SCAR markers SNO2, ROC11 and SW13 linked to Phg-2, bc-3 and I gene, respectively were used. A parallel backcrossing (modified double cross) procedure was used. The F1, F2 and backcrosses from single crosses were characterized. The Chi square values for ALS were 0.081 (P<0.776) and 0.017 (P<0.896) and for BCMNV were 1.609 (P<0.205) and 1.2 (P<0.273) for molecular and phenotypic screening, respectively. The resistance to ALS and BCMNV was found to be monogenic and the genes involved are dominant and recessive, respectively. The heritability of ALS was found to be high (0.772) implying that selection for ALS can be done early in segregating populations. High correlation values, r = 0.741 and 0.624 for ALS and BCMNV, were obtained between phenotypic and molecular data, indicating high reliability for markers. In selection, it was possible to select lines with multiple disease resistances. This work signified the use of MAS for multiple gene screening. Key words: Common bean, Pseudocercospora griseola, marker assisted selection, genotype, inheritance.

Differentially expressed proteins during an incompatible interaction between common bean and the fungus Pseudocercospora griseola

The common bean (Phaseolus vulgaris L.) is the main source of protein and an important source of minerals in several countries around the world. Angular leaf spot, caused by the fungus Pseudocercospora griseola, is one of the major diseases of the common bean. In this work, we used two-dimensional gel electrophoresis and mass spectrometry to analyze alterations in the proteome of common bean leaves challenged with an incompatible race of P. griseola. Twenty-three differentially expressed proteins were detected in leaves of cultivar AND 277 collected at 12, 24 and 48 h after inoculation. The proteins were digested with trypsin and submitted to MALDI-TOF/TOF and MicrOTOF-Q electrospray mass spectrometry. Nineteen of them were identified upon MS/MS fragmentation. Most of these proteins are involved with amino acid metabolism, terpenoid metabolism, phenylpropanoid biosynthesis, antioxidant systems, vitamin and cofactor metabolism, plant–pathogen interaction, carbohydrate metabolism, photosynthesis, or genetic information processing, showing that the interaction in this pathosystem affects different genes from various metabolic pathways and processes.

Characterization of the Angular Leaf Spot Resistance Gene Present in Common Bean Cultivar Ouro Negro

Angular leaf spot (ALS), incited by the fungus Pseudocercospora griseola, is a major disease affecting common bean. Important resistance sources have been identified and characterized: AND 277, BAT 332, Cornell 49-242, MAR-2, and Mexico 54. P. griseola presents high physiological variability. The control of this kind of pathogen requires continuous evaluation, including monitoring and characterization of pathogenic variability, and eventual germplasm introgression of genes in adapted cultivars. Cultivar Ouro Negro is currently being used as an ALS resistance source in Brazil. This work aimed to characterize the ALS resistance gene present in cultivar Ouro Negro in relation to the other five resistance sources. These cultivars were crossed with ‘Ouro Negro’ (allelism tests) and with susceptible cv. Ruda (inheritance studies) and their segregation patterns were evaluated. The inheritance studies and the allelism tests indicate that ‘Ouro Negro’ harbors at least one resistance locus which is distinct from those present in the other resistance sources.