Common Bean Cultivars Research Articles

Morpho–Molecular Characterization of Brazilian Common Bean Landraces Varieties and Commercial Cultivars

This study aimed to characterize forty genotypes (31 landrace varieties and nine commercial cultivars) of common bean (Phaseolus vulgaris L.) morphologically and molecularly. Morphological descriptors were evaluated during seedling, flowering, physiological maturation and post-harvest stages. Ten microsatellite markers were used for molecular screening. The markers were analyzed according to the number of alleles per locus, the allele frequency per locus and the polymorphism in content (PIC). Genetic distances and cluster analysis were performed using Bayesian inference and the UPGMA method. All black beans evaluated have anthocyanin in the cotyledons, hypocotyls and stems, and their flowers are purple. For the growth habit, 50% of the evaluated genotypes belong to type III, and at the physiological maturation stage, yellow color is predominant in the pods (85%). Through the genetic dissimilarity, three groups were observed for the likelihood reason, and five groups were observed through the UPGMA method, a strong indication of the wide genetic diversity among the evaluated genotypes. All genotypes from the Andean center of origin were grouped into the same cluster.

Euschistus heros: Economic injury level and economic threshold of early maturing carioca common bean cultivar

Early maturing common-bean cultivars lack information referring to Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae) feeding damage assessment. This information is pertinent towards establishing economic threshold for an integrated pest management program. The aim of this study was to analyze the relationship, between the density of stink bugs and the degree of injuries towards the pod and grain production, quantity and quality, of the IPR Curió cultivar. The experiments were conducted during two seasons at the IDR-Paraná in Londrina, Paraná, in field conditions. The experimental design was randomized blocks with five repetitions. The treatments were: 0 (control); 1; 2; 3; 4; 5 E. heros m-1. The evaluated variables were number of grained and flat pods; healthy, damaged and aborted grain mass; grain yield. The economic injury level (EIL), economic threshold (ET) and spraying efficiency influence on the ET were calculated. The total number of grained pods was not affected. More than three brown stink bugs, during the summer season, significantly increases flat pod output. The rainy season resulted in greater aborted grains. Increasing E. heros densities, during the summer season, significantly reduces the healthy grain output. The damaged grain mass doubles at higher than one E. heros population densities. The total grain mass produced was not affected. During the summer season, each E. heros reduces 11% of healthy grain output, and during the rainy season 6%. During the summer season was 1.50 of E. heros m-1 and for the rainy season 1.00 E. heros m-1. The spraying efficiency should directly affect the EIL, modifying the value, thus better resembling the field conditions.

Path analysis for quality traits and minerals in common bean based on data from multi‐environment experiments

AbstractThe number of experiments to be used in path analysis to enhance the efficacy of indirect selection for fast‐cooking common bean (Phaseolus vulgaris L.) lines has not yet been defined. This study sought to break down the correlation coefficient into direct and indirect effects for quality traits and mineral concentration based on data acquired from multi‐environment experiments. Additionally, the study proposed to establish the minimum number of experiments required for path analysis aiming at indirect selection for fast cooking in common bean. Four experiments were conducted in which various quality traits and the concentration of seven minerals were analyzed across 25 common bean cultivars. Variance and path analyses were applied to data from individual experiments and combinations of two, three, and four experiments. Significant cultivar × experiment interaction effects were found for most evaluated traits. The traits exerting the greatest direct effects on cooking time varied across the four experiments. Data from individual experiments were highly variable, resulting in low ability to identify promising traits for indirect selection. However, data from two, three, and four experiments had lower variability and therefore provided a greater ability to identify traits with the greatest direct and indirect effects on cooking time. Mass of 100 grains and calcium concentration emerged as promising traits for indirect selection to achieve fast cooking in common bean. Using data from two experiments allows for an effective interpretation of path analysis results for quality traits and mineral concentration in common bean.

A single-nucleotide polymorphism in PvPW1 encoding β-1,3-glucanase 9 is associated with pod width in Phaseolus vulgaris L.

Pod width influences pod size, shape, yield, and consumer preference in snap beans (Phaseolus vulgaris L.). In this study, we map PvPW1, a quantitative trait locus associated with pod width in snap beans, through genotyping and phenotyping of recombinant plants. We identify Phvul.006G072800, encoding the β-1,3-glucanase 9 protein, as the causal gene for PvPW1. The PvPW1G3555 allele is found to positively regulate pod width, as revealed by an association analysis between pod width phenotype and the PvPW1G3555C genotype across 17 bi-parental F2 populations. 97.7% of the 133 wide pod accessions carry PvPW1G3555, while 82.1% of the 78 narrow pod accessions carry PvPW1C3555, indicating strong selection pressure on PvPW1 during common bean breeding. Re-sequencing data from 59 common bean cultivars identify an 8-bp deletion in the intron linked to PvPW1C3555, leading to the development of the InDel marker of PvM436. Genotyping 317 common bean accessions with PvM436 demonstrated that accessions with PvM436247 and PvM436227 alleles have wider pods compared to those with PvM436219 allele, establishing PvM436 as a reliable marker for molecular breeding in snap beans. These findings highlight PvPW1 as a critical gene regulating pod width and underscore the utility of PvM436 in marker-assisted selection for snap bean breeding.

Residual herbicides applied to common bean cultivars on maize yield in succession

Given the introduction of increasingly productive and early maturing maize cultivars over the past decade, coupled with the restricted availability of herbicides for controlling eudicots weeds in common bean crops, leading producers have resorted to using mixtures of active ingredients. Consequently, there arises a necessity for studies to assess the carryover effects of these mixtures in succession crops. The objective of this study was to evaluate the residual effect of herbicides applied in common bean cultivars on maize, during two cultivation periods. The statistical design was a randomized complete block with four replications. The common bean cultivars BRS Pérola, IPR Tuiuiú, and BRSMG Marte were planted in the summer season 2016/2017 and in the winter season 2017, and subsequently, the maize DKB 390PRO was planted in the winter season and summer season, respectively. The experimental plots were treated with herbicides applied post-emergence, isolated or mixed, at the following rates [g a.i. ha-1]: fomesafen [250]; fomesafen [375]; bentazon + imazamox [600+28]; bentazon + imazamox + fomesafen [(600+28)+125]; and bentazon + imazamox + fomesafen [(600+28)+87.5]; and hand weeding without herbicide. The herbicides did not cause negative effects on maize yield, regardless of the sowing period and common bean cultivar.

Genome-Wide Association for Morphological and Agronomic Traits in Phaseolus vulgaris L. Accessions.

Exploring genetic resources through genomic analyses has emerged as a powerful strategy to develop common bean (Phaseolus vulgaris L.) cultivars that are both productive and well-adapted to various environments. This study aimed to identify genomic regions linked to morpho-agronomic traits in Mesoamerican and Andean common bean accessions and to elucidate the proteins potentially involved in these traits. We evaluated 109 common bean accessions over three agricultural years, focusing on traits including the grain yield (YDSD), 100-seed weight (SW), number of seeds per pod (SDPD), number of pods per plant (PDPL), first pod insertion height (FPIH), plant height (PLHT), days to flowering (DF), and days to maturity (DPM). Using multilocus methods such as mrMLM, FASTmrMLM, FASTmrEMMA, ISIS EM-BLASSO, and pLARmEB, we identified 36 significant SNPs across all chromosomes (Pv01 to Pv11). Validating these SNPs and candidate genes in segregating populations is crucial for developing more productive common bean cultivars through marker-assisted selection.

Nutritional and phytochemicals analysis of high‐altitude common bean (Phaseolus vulgaris L.) cultivars of Nepal

AbstractThe common bean, Phaseolus vulgaris L., is an important legume grown in all parts of Nepal to supply dietary protein for humans and livestock. They are rich in a variety of bioactive compounds and thus possess health‐promoting effects in the prevention of chronic diseases, including cancer, cardiovascular diseases, obesity, and diabetes. The present study examined the nutritional and proximate composition and screened the bioactive compounds present in beans grown in the high‐altitude regions of Nepal. The analysis of 18 beans indicated the moisture (6.48%–8.83%), crude protein (17.39%–23.54%), carbohydrate (58.74%–66.37%), crude fat (0.78%–1.58%), crude fiber (3.36%–4.75%), total ash (3.33%–4.69%), and total energy (340.24–350.16 kcal/100 g). The results showed that the common beans were also good sources of nutritionally important minerals, including copper (2.72–8.77 mg/kg), calcium (843.86–2763.62 mg/kg), iron (38.93–73.69 mg/kg), magnesium (1540.63–2083.52 mg/kg), sodium (205.91–695.81 mg/kg), potassium (13,560.21–16,957.05 mg/kg), and zinc (19.80–31.00 mg/kg) on a dry weight basis. Quantification of bioactive compounds revealed the highest concentration of total phenolic content (TPC) in the beans from Jumla (5.96 mg GAE/g) than Dolakha and Darchula. However, the total flavonoid content was higher in Dolakha beans (3.47 mgQE/g). The EP‐15‐03FB landrace from Jumla was superior in terms of protein, phytochemical, and TPC. The results of this study will provide valuable information on the nutritional and phytochemical contents of beans and serve as a basis for further utilization of common beans.

Increased absorption and use of nutrients induced by Si is an indicator for tolerance to water deficit in a common bean cultivar cultivated in the field with and without application of K.

Reduced water content in the soil triggers physiological, biochemical, and morphological damage to plants, aggravated by nutritional deficiency. One possible strategy to mitigate this damage comprises the use of silicon (Si). This study investigated whether Si can mitigate the damage caused by water deficit through nutritional mechanisms in bean plants grown under field conditions. Furthermore, it investigated whether the effectiveness of Si is influenced by water availability in the soil and the Si dose supplied. Therefore, two split-plot experiments were carried out: with and without K supply. In both experiments,the treatments comprised a 3 × 4 factorial scheme. Treatments included three water regimes: 80% (no water deficit), 60% (moderate water deficit), and 40% (severe water deficit) of the soil's water retention capacity. Moreover, they comprised four doses of Si supplied via fertigation-0 kg/ha, 4 kg/ha, 8 kg/ha, and 12 kg/ha-arranged in a randomized block design with four replications. The appropriate dose of Si to be applied increased with the severity of the water deficit, with the recommended dose being 6 kg/ha, 7 kg/ha, and 8 kg/ha of Si for adequate water conditions, moderate water deficit, and severe water deficit, respectively.

Purification and Characterization of Proteinaceous Thermostable α-Amylase Inhibitor from Sardinian Common Bean Nieddone Cultivar (Phaseolus vulgaris L.).

The increasing need for new treatments for obesity and diabetes has led to the development of new drugs and food supplements that could reduce carbohydrate absorption. Many starch blockers, based on common bean proteinaceous inhibitors against α-amylase (α-AI), are already present on the market. The extraction and purification of α-amylase inhibitor from a promising common bean cultivar from Sardinia (Nieddone) is described, highlighting the unique value of the Nieddone cultivar, particularly for its inhibitory activity on digestive enzymes and its complete lack of a hemagglutination effect on human red blood cells. The purification of α-AI involved two chromatographic steps (IEC and SEC) and was essential for revealing certain properties of the inhibitor. The purified inhibitor has a tetrameric structure (α2β2) and a molecular weight of approximately 42 kDa, as determined by SEC and SDS-PAGE, confirming it as a lectin-like inhibitor. The identification of the α-AI sequence was obtained by bottom-up high-resolution mass spectrometry, which allowed us to identify a unique peptide from the α chain and six unique peptides from the β chains. α-AI exhibited an optimum temperature of around 40 °C and two pH optima at 5 and 6.5, respectively. Its remarkable stability at high temperatures was measured (approximately 25% of activity retained even after 5 h at 100 °C), whereas the raw extract lost its activity entirely after just 10 min at 90 °C. Thus, the purification process significantly enhances the thermal stability of α-AI. The demonstrated effectiveness of the purified α-AI against the α-amylase enzyme in pigs, humans and insects underscores the protein's potential for treating obesity and diabetes, as well as for managing insect pests.

Alternaria solani IA300 induces growth and development in two common bean cultivars

Alternaria solani IA300 induces growth and development in two common bean cultivars

Differential Gene Expression in Contrasting Common Bean Cultivars for Drought Tolerance during an Extended Dry Period.

Common beans (Phaseolus vulgaris L.), besides being an important source of nutrients such as iron, magnesium, and protein, are crucial for food security, especially in developing countries. Common bean cultivation areas commonly face production challenges due to drought occurrences, mainly during the reproductive period. Dry spells last approximately 20 days, enough time to compromise production. Hence, it is crucial to understand the genetic and molecular mechanisms that confer drought tolerance to improve common bean cultivars' adaptation to drought. Sixty six RNASeq libraries, generated from tolerant and sensitive cultivars in drought time sourced from the R5 phenological stage at 0 to 20 days of water deficit were sequenced, generated over 1.5 billion reads, that aligned to 62,524 transcripts originating from a reference transcriptome, as well as 6673 transcripts obtained via de novo assembly. Differentially expressed transcripts were functionally annotated, revealing a variety of genes associated with molecular functions such as oxidoreductase and transferase activity, as well as biological processes related to stress response and signaling. The presence of regulatory genes involved in signaling cascades and transcriptional control was also highlighted, for example, LEA proteins and dehydrins associated with dehydration protection, and transcription factors such as WRKY, MYB, and NAC, which modulate plant response to water deficit. Additionally, genes related to membrane and protein protection, as well as water and ion uptake and transport, were identified, including aquaporins, RING-type E3 ubiquitin transferases, antioxidant enzymes such as GSTs and CYPs, and thioredoxins. This study highlights the complexity of plant response to water scarcity, focusing on the functional diversity of the genes involved and their participation in the biological processes essential for plant adaptation to water stress. The identification of regulatory and cell protection genes offers promising prospects for genetic improvement aiming at the production of common bean varieties more resistant to drought. These findings have the potential to drive sustainable agriculture, providing valuable insights to ensure food security in a context of climate change.

PERFORMANCE OF COMMON BEAN CULTIVARS IN DIFFERENT ENVIRONMENTS AND PLANT POPULATIONS

This study aimed to identify the most suitable plant populations, considering different environmental conditions (locations, growing seasons, and sowing dates), to express the yield potential of common bean cultivars released or in the process of releasing for regions not included in the initial release. Forty-four experiments were carried out from November 2016 to March 2019, encompassing wet, dry, and winter seasons, across the states of Goiás, Minas Gerais and Paraná. Five plant populations established at sowing (12, 18, 24, 30, and 36 plants m⁻²) were compared in a randomized block design with four replications, using the cultivars BRS FC310, BRS FC409, and BRSMG Uai. Across winter season experiments, the BRS FC310 cultivar consistently displayed higher yield than the others at all plant populations. In contrast, the BRSMG Uai cultivar exhibited the highest yield during the wet season. The maximum grain yields of the three cultivars were higher in the wet than in the winter season and obtained with higher plant populations. Cultivars BRS FC310, BRS FC409, and BRSMG Uai maximized grain yield with, respectively, 28.4, 25.4, and 26.2 plants m⁻² at harvest time in the wet season, and 20.4, 14.0, and 15.2 plants m⁻² in the winter season.

Factor analysis applied to simultaneous selection for resistance to anthracnose and angular leaf spot

AbstractDiseases such as anthracnose (Colletotrichum lindemuthianum) and angular leaf spot (Pseudocercospora griseola) can occur in common bean and compromise crop production, especially if susceptible cultivars are grown under conditions favorable to these diseases. The most efficient and sustainable alternative for controlling these diseases is the use of resistant cultivars. The identification of sources of resistance and the use of tools that assist in accurate selection of resistant cultivars are crucial to the success of breeding programs. The aim of this study was to characterize 67 carioca common bean cultivars recommended in Brazil regarding reaction to races 65, 73, 81, and 89 of C. lindemuthianum and to races 63‐23 and 63‐63 of P. griseola and to verify the application of factor analysis in the selection of cultivars resistant to both pathogens. The cultivars and resistant controls BRS Esplendor and MAIII.16‐159 were inoculated in a greenhouse in two experiments for each race. Cultivars were assessed for resistance to multiple races of anthracnose and angular leaf spot using artificial inoculation of plants at V2 stage. Factor analysis proved to be a good alternative for accurate selection of resistant cultivars. The percentage of cultivars simultaneously resistant to all races was low (8.95%). The cultivars Rudá R, VC 15, IAC‐Apuã, IAC‐Carioca Pyatã, BRSMG Amuleto, and BRS FC104 selected by factor analysis showed resistance to anthracnose and angular leaf spot. Therefore, these cultivars are potential sources of resistance for incorporation in bean breeding programs.

Genes putatively involved in Phaseolus vulgaris resistance against Xanthomonas phaseoli pv. phaseoli revealed by a genome‐wide association study

AbstractCarioca and black bean groups play a significant role in Latin American common bean (Phaseolus vulgaris) consumption, serving as excellent sources of nutrients. One of the most significant threats for common bean production is common bacterial blight (CBB), a disease caused by the gram‐negative bacteria Xanthomonas phaseoli pv. phaseoli (Xpp) and Xanthomonas citri pv. fuscans (Xcf). An effective method for managing this disease is the use of plant genetic resistance. However, it is not known whether the same or overlapping sets of genes are associated with resistance to both pathogens. This study aimed to identify a repertoire of genes potentially associated with resistance to Xpp and compare it with that previously reported for Xcf. Eighty carioca and black common bean cultivars that had previously been challenged with Xcf were inoculated with a strain of Xpp, and a genome‐wide association study (GWAS) using single‐nucleotide polymorphisms (SNPs) and disease severity data was conducted. Three carioca and three black bean cultivars exhibited high levels of resistance to Xpp. Five SNPs with the highest −log10(p) values unveiled genes coding for diverse putative biochemical functions, including a light‐regulated Lir1 protein, a proton‐dependent oligopeptide transporter family protein, a metallo‐dependent phosphatase‐like protein, a WPP domain‐interacting tail‐anchored protein 2 and a pectin lyase‐like superfamily protein. No overlap between this repertoire of genes with that reported for Xcf was found. These findings provide important insights into genes potentially involved in the P. vulgaris resistance to Xpp and the complexity of the resistance response to CBB.

Genotype by environment interaction and performance stability of common bean (Phaseolus vulgaris L.) cultivars grown in Dawuro zone, Southwestern Ethiopia

Abstract The performance of most crop genotypes varies significantly depending on their genotype–environment interactions. Providing information on high-yielding and well-adapted common bean genotypes in a given environment is crucial for small-holder farmers to boost their productivity. A field trial was conducted at the Gendo and Wara locations over two consecutive seasons to understand genotype–environment interactions on grain yield and to identify and select common bean genotypes that were better adapted and had high yield potential for production. Ten genotypes were evaluated for their performance using a randomized complete block design with three replications. The AMMI and GGE models were used to identify superior genotypes regarding their mean grain yield performance. The AMMI analysis of variance results showed that grain yield was significantly (p ≤ 0.05) influenced by genotype–environment interactions. This shows that genotypes varied in grain yield mean performance across environments, indicating the possibility of selecting suitable genotypes with specific and broad adaptability. The sum of squares factor indicated that grain yield variation was contributed by the genotype (61.0%), followed by the environment (29.80%) and the genotype–environment interaction effect (9.20%) of the total variation. The AMMI and GGE biplot analysis results showed that SER-119 and SER-125 were identified as the best genotypes regarding their mean grain yield performance. Additionally, the genotype selection index analysis result indicated that SER-119 and SER-125 were stable and consistently exhibited high mean performance in all evaluated settings. Therefore, SER-119 and SER-125 are prime candidates for production in various agroecologies suitable for common bean cultivation in Dawuro zones. The use of tools like GGE biplots and AMMI analysis helped visualize the genotype–environment interactions, aiding in the selection of appropriate genotypes for both specific and wide adaptability.

Assessing Aluminum Stress Resilience in Common Bean Roots: Phenotypic, Histochemical, and PvGST/PvPOD Gene Expression Analysis

Common bean (Phaseolus vulgaris L.) is grown in various parts of the world. Aluminum (Al) toxicity poses a significant and widespread challenge in marginal areas with unfavorable soil qualities where common bean is grown. In acidic soils, stable forms of Al dissolve into the soil solution and inhibit root growth and function by injuring the root apex with phytotoxic ions. This leads to the development of a smaller root system, adversely affecting crop yield. In this study, the phenotypic evaluation for relative root elongation of 10 common bean genotypes/cultivars under Al stress (50 µM), the impact of Al toxicity using different histochemical dyes (Evan’s blue and Schiff’s reagent) and the expression levels of PvGST (Glutathione S-transferases) and PvPOD (peroxidase) genes in the root tissues of the most resistant/sensitive common beans under Al stress (50 µM) and control conditions (0 µM) were investigated. The maximum relative root elongation value (71.9%) was found in Önceler-98 cultivar, while the lowest value (14.1%) was obtained from Blksr-19 genotype. Histochemical applications used in the study supported phenotypic results. The cracks at the root tip and high blue color intensity were detected in Schiff’s reagent and Evan’s blue dyes in the Blksr-19, respectively. The expression levels of PvGST and PvPOD genes in the root tissue of the Blksr-19 (Al-sensitive) were highly upregulated at 24 h of Al stress treatment. The results revealed that these genes might be involved in the common bean root tissue's defense mechanism against Al stress for the first time. The findings herein will help plant breeders develop common bean cultivars tolerant to Al toxicity.

Calibration, testing and application of the AquaCrop model for bean crop under irrigation regimes.

Crop growth simulation models relate the soil-water-plant-atmosphere components to estimate the development and yield of plants in different scenarios, enabling the identification of efficient irrigation strategies. The aim of this study was to calibrate crop coefficients for a common bean cultivar (IAPAR 57) and assess the AquaCrop model's efficacy in simulating crop growth under different irrigation regimes (T0 - non-irrigated, T1-fully irrigated, and T2-deficit irrigated) and sowing dates (S1-March 21, S2-April 24, and S3-August 23). Successful calibration was achieved for crop seasons with suitable temperatures to crop growth (S1 and S3). However, during periods with suboptimal temperatures (April 24 season), coupled with reduced irrigation supply (T0 and T2), the AquaCrop model did not appropriately account for the combined effects of thermal and water stresses. Despite adjustments to stress coefficients, this led to an overestimation of crop growth and yield. In long-term simulations, the model successfully replicated the variability of crop water availability over cropping seasons, reflecting the impact of precipitation variations. It recommended irrigation strategies for the study region (irrigate at depletion of 120 and 170% of readily available water for sowing on March 21 and August 24, respectively) to achieve high crop yield (> 2,769kgha-1) and water productivity (1,050 to 1,445kgm-3) with minimal application depths (< 150mm). While acknowledging the need for improvements in thermal stress calculations, the AquaCrop model demonstrates promising utility in studies and applications where water availability significantly influences crop production.

Alterations in Gene Expression during Incompatible Interaction between Amendoim Cavalo Common Bean and Colletotrichum lindemuthianum.

Anthracnose, caused by the fungus Colletotrichum lindemuthianum, poses a significant and widespread threat to the common bean crop. The use of plant genetic resistance has proven to be the most effective strategy for managing anthracnose disease. The Amendoim Cavalo (AC) Andean cultivar has resistance against multiple races of C. lindemuthianum, which is conferred by the Co-AC gene. Fine mapping of this resistance gene to common bean chromosome Pv01 enabled the identification of Phvul.001G244300, Phvul.001G244400, and Phvul.001G244500 candidate genes for further validation. In this study, the relative expression of Co-AC candidate genes was assessed, as well as other putative genes in the vicinity of this locus and known resistance genes, in the AC cultivar following inoculation with the race 73 of C. lindemuthianum. Gene expression analysis revealed significantly higher expression levels of Phvul.001G244500. Notably, Phvul.001G244500 encodes a putative Basic Helix-Loop-Helix transcription factor, suggesting its involvement in the regulation of defense responses. Furthermore, a significant modulation of the expression of defense-related genes PR1a, PR1b, and PR2 was observed in a time-course experiment. These findings contribute to the development of improved strategies for breeding anthracnose-resistant common bean cultivars, thereby mitigating the impact of this pathogen on crop yields and ensuring sustainable bean production.

Genetic and pathogenic characterization of Rhizoctonia solani AG-4 isolates obtained from common bean

Common bean (Phaseolus vulgaris L.) is the most important grain legume. Crop production of common bean is affected by a number of diseases, such as Rhizoctonia root rot, being detected worldwide. Herein, we aimed to genetically and pathologically characterize Rhizoctonia solani isolates obtained from different provinces in Turkey. Anastomosis groups (AG) and subgroups of isolates were identified based on the sequence analysis of the rDNA-ITS region. The most prevalent subgroup was AG-4 HGIII, according to BLAST analysis and the phylogeny of resultant sequences, followed by AG-4 HGI and AG-4 HGII, respectively. iPBS retrotransposons highly supported the phylogenetic tree and provided a high level of genetic variability among isolates to discriminate AG subgroups. The results indicated that the iPBS DNA marker system based on retrotransposons could be used to discriminate Rhizoctonia isolates relying on AG grouping. The virulence of the pathogen isolates changed from 3.67 to 5 based on the agar-plate assay on the susceptible cv. Gina. The reactions of thirty common bean cultivars were also evaluated against the most aggressive isolate in each subgroup. The reaction assay showed significant differences among both isolates and cultivars; the highest disease severity among cultivars was observed to AG-4 HGI, followed by AG-4 HGIII and AG-4 HGII, respectively. None of the cultivars showed resistance to all AG subgroups. Screening of AGs among the isolates and selecting cultivars are critical to managing Rhizoctonia disease due to the range of host suitability according to AG subgroups.

Identification of QTLs and validation of molecular markers associated with reaction to Fusarium wilt in the common bean cultivar BRS FP403

AbstractFusarium wilt, caused by the fungus Fusarium oxysporum f. sp. phaseoli, is one of the most prevalent diseases in the common bean crop (Phaseolus vulgaris). However, there is little information regarding the genetics of reaction to this disease. Thus, the aims of this study were to estimate genetic parameters, identify quantitative trait loci (QTLs) associated with reaction to Fusarium wilt, and validate the markers identified. A total of 165 progenies of the population BRS FP403 × BRS Horizonte were evaluated. Evaluation was made in 2016 and 2017 in field trials in an area infested with the pathogen in Santo Antônio de Goiás, Brazil. Genotyping of single nucleotide polymorphism and SilicoDArT, where DArT is Diversity Arrays Technology, markers using the DArTseq technology was performed in the F2 generation. Analyses of the phenotypic data indicated the presence of variability among the progenies and the possibility of success from selection, with high estimates of heritability (90%) and gain from selection (37%). A genetic map was obtained with 702 markers and spanned 3069 cM. Five QTLs associated with reaction to Fusarium wilt were identified on five chromosomes. There was interaction between the QTLs and years. Through joint analysis, four QTLs were identified on chromosomes Pv01, Pv02, Pv03, and Pv04, explaining 5.8%–40.5% of the variation. The QTL FOP2.3403H explained 40.5% of phenotypic variation and was stable over the 2 years. From this QTL, two hydrolysis probes were developed for genotyping in a panel of lines for validation. Selection efficiency was over 92%, indicating considerable potential for use in marker‐assisted selection.