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Bacterial brown spot (BBS) caused by Pseudomonas syringae pv. syringae (Pss), common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli (Xap) and Xanthomonas fuscans subsp. fuscans (Xff), and halo bacterial blight (HBB), caused by Pseudomonas syringae pv. phaseolicola (Psph), are major bacterial diseases that severely affect common bean yields and global food security. Andean-origin dry beans, representing large-seeded market classes, are particularly susceptible. Using 140,325 SNPs, a multi-locus GWAS was conducted on subsets of the Andean diversity panel (ADP) phenotyped for BBS in South Africa, CBB in Puerto Rico, South Africa, and Zambia, and HBB in South Africa, through natural infection, artificial inoculation, or both. Twenty-four QTL associated with resistance were identified: nine for BBS, eight for CBB, and seven for HBB. Four QTL intervals on Pv01, Pv03, Pv05, and Pv08 overlapped with BBS and HBB resistance. A genomic interval on Pv01, near the fin gene, which determines growth habit, was linked to resistance to all three pathogens. Different QTLs were detected for BBS and CBB resistance when phenotyped under natural infection versus artificial inoculation. These results underscore the importance of combining phenotyping methods in multi-GWAS to capture the full genetic spectrum. Previously recognized CBB resistance QTL SAP6 and SU91 and HBB resistance QTL HB4.2, and HB5.1, were observed. Other common (MAF >0.25) and rare (MAF <0.05) resistance QTL were also detected. Overall, these findings enhance the understanding and utilization of bacterial resistance present in ADP for the development of common beans with improved resistance. [ABSTRACT FROM AUTHOR]

'Kikatiti' pinto bean (Phaseolus vulgaris L.) (Reg. no. CV‐361, PI 705149) was developed by the dry bean breeding program at the University of Nebraska, Agricultural Research Division, and submitted for release in 2021 by the Sokoine University of Agriculture in Morogoro as an upright indeterminate pinto bean with high yield potential and multiple disease resistance across bean production environments in Tanzania. Kikatiti was officially released in 2024 by the National Seed Committee. Kikatiti is an F7:8 derived line developed using the pedigree breeding method in Nebraska. The exceptional performance of Kikatiti in Tanzania was first identified by evaluation of the Durango Diversity Panel (DDP), which consisted of 200 accessions in on‐station trials conducted in Arusha and Mbeya. Kikatiti was identified as accession DDP‐094 (advanced breeding line NE2‐09‐3). Kikatiti yielded 1584 kg ha−1 across 5 years of trials in Tanzania and matured in 89 days. Kikatiti is resistant to bean rust conferred by the Ur‐3 and Ur‐11 genes, resistant to all strains of Bean common mosaic virus and Bean common mosaic necrosis virus conferred by the I and bc‐3 genes, moderately resistant to common bacterial blight conferred by the SAP6 quantitative trait locus, avoids white mold disease due to its upright architecture, and is moderately susceptible to angular leaf spot disease. Kikatiti has large seed size (35.9 g 100 seeds−1), and in on‐farm trials, farmers ranked Kikatiti above local pinto cultivars for its performance and market potential. Kikatiti has the potential to expand pinto bean production across East Africa. Core Ideas: Kikatiti pinto bean has superior productivity in Tanzania.Kikatiti pinto possesses an effective combination of resistance genes to combat bean rust disease in East Africa.Kikatiti pinto possesses an effective combination of resistance genes to combat Bean common mosaic necrosis virus.Farmers ranked Kikatiti above local pinto cultivars for performance and market potential in on‐farm trials. [ABSTRACT FROM AUTHOR]

The pinto bean (Phaseolus vulgaris L.) cultivar 'USDA Diamondback' (Reg. no. CV‐353, PI 698822) was released by the USDA‐ARS in 2022 as a high‐yielding cultivar with an upright architecture and the slow‐darkening seed coat trait. It was bred for tolerance to multiple abiotic stresses in a "purgatory" plot purposely managed to have compacted soil, low soil fertility, and intermittent drought conditions. Conversely, selection for high yield potential was conducted in non‐stress trials with tillage, irrigations, and fertilizers applied for optimal production. USDA Diamondback exhibits wide adaption to production regions across the United States, as evidenced by an average seed yield of 3808 kg ha−1 across 14 location‐years in the Cooperative Dry Bean Nursery. Virus testing and resistance gene–linked markers indicate USDA Diamondback has a three‐gene combination (bc‐ud, bc‐1, and bc‐3) that confers durable resistance to all known strains of Bean common mosaic virus and Bean common mosaic necrosis virus. A similar combination of pathogen and marker testing indicated that USDA Diamondback possesses the Ur‐3 and Ur‐6 genes for resistance to bean rust. The seed size, appearance, and canning quality characteristics of USDA Diamondback meets the industry standards for packaging and processing. Core Ideas: USDA Diamondback was bred for high yield potential under both favorable and stressful environments.USDA Diamondback has the slow‐darkening trait that maintains seed coat brightness during prolonged storage.USDA Diamondback has above‐average canning quality.USDA Diamondback is resistant to all known strains of Bean common mosaic virus and Bean common mosaic necrosis virus. [ABSTRACT FROM AUTHOR]

Whitemold (WM) is a major disease in common bean (Phaseolus vulgaris L.), and its complex quantitative genetic control limits the development of WM resistant cultivars. WM2.2, one of the nine meta-QTL with a major effect on WM tolerance, explains up to 35% of the phenotypic variation andwas previously mapped to a large genomic interval on Pv02. Our objective was to narrow the interval of thisQTL using combined approach of classic QTL mapping and QTL-based bulk segregant analysis (BSA), and confirming those results with Khufu de novo QTL-seq. The phenotypic and genotypic data from two RIL populations, 'Raven'/I9365-31 (R31) and 'AN-37'/PS02-029C-20 (Z0726-9), were used to select resistant and susceptible lines to generate subpopulations for bulk DNA sequencing. The QTL physical interval was determined by considering overlapping interval of the identified QTL or peak region in both populations by three independent QTL mapping analyses. Our findings revealed that meta-QTL WM2.2 consists of three regions, WM2.2a (4.27-5.76 Mb; euchromatic), WM 2.2b (12.19 to 17.61 Mb; heterochromatic), and WM2.2c (23.01-25.74 Mb; heterochromatic) found in both populations. Gene models encoding for gibberellin 2-oxidase 8, pentatricopeptide repeat, and heat-shock proteins are the likely candidate genes associated with WM2.2a resistance. A TIR-NBS-LRR class of disease resistance protein (Phvul.002G09200) and LRR domain containing family proteins are potential candidate genes associated with WM2.2b resistance. Nine gene models encoding disease resistance protein [pathogenesis-related thaumatin superfamily protein and disease resistance-responsive (dirigent-like protein) family protein etc] found within theWM2.2c QTL interval are putative candidate genes. WM2.2a region is most likely associated with avoidance mechanisms while WM2.2b and WM2.2c regions trigger physiological resistance based on putative candidate genes. [ABSTRACT FROM AUTHOR]

Beet curly top virus (BCTV), which is synonymous with curly top virus (CTV), causes significant yield loss in common bean (snap and dry beans) cultivars and several other important crops. Common bean cultivars have been found to be resistant to CTV, but screening for resistance is challenging due to the cyclical nature of epidemics and spotty feeding by the leafhopper that vectors the virus. We used an SNP dataset for the Snap Bean Association Panel (SnAP) agroinoculated with CTV-Logan (CA/Logan) strain to locate the Bct gene region to a 1.7-Mb interval on chromosome Pv07 using genome-wide association study (GWAS) analysis. Recombinant lines from the SnAP were used to further narrow the Bct region to a 58.0-kb interval. A missense SNP (S07_2970381) in candidate gene Phvul.007G036300 Exonuclease V (EXO5) was identified as the most likely causal mutation, and it was the most significant SNP detected by GWAS in a dry bean population (DBP) naturally infected by the CTV-Worland (Wor) strain. Tmshift assay markers developed for SNP S07_2970381 and two linked SNPs, S07_2970276 and S07_2966197, were useful for tracking different origins of the Bct EXO5 candidate gene resistance to CTV in common bean. The three SNPs identified four haplotypes, with haplotype 3-1 (Haplo3-1) of Middle American origin associated with the highest levels of CTV resistance. This SNPhaplotype assay will enable breeders to track resistance sources and to develop cultivars with better CTV resistance. [ABSTRACT FROM AUTHOR]

The pinto bean (Phaseolus vulgaris L.), 'USDA Rattler' (Reg. no. CV‐350, PI 693789), was released by the USDA‐ARS in 2021 as a high‐yielding, upright, full‐season cultivar with abiotic stress tolerance. It was bred for broad adaptation to the different bean production regions across the United States by selection for high yield performance under nonstress and multiple stress trials in Washington state. The multiple stress trials included a "purgatory" plot with low fertility, intermittent drought, and soil compaction, and a separate trial which simulated terminal drought. Conversely, the nonstress trials were well watered and fertilized to optimize yield potential. Yield stability is evidenced by the mean seed yield for the breeding line PT11‐13, from which USDA Rattler was selected, numerically exceeding the trial means for 33 of 38 location‐years. Broad adaptation for USDA Rattler is further evidenced by an average seed yield of 4547 kg ha−1 across 10 location‐years in the Cooperative Dry Bean Nursery. Genetic markers as well as pathogen testing indicate USDA Rattler has I and bc‐3 gene combination for durable resistance to all known strains of Bean common mosaic virus and Bean common mosaic necrosis virus. Greenhouse testing with four races of the rust pathogen indicated USDA Rattler is fixed for the Ur‐3 resistance gene but is heterogenous for presence of the Ur‐11 resistance gene. The seed size, appearance, and canning quality characteristics of USDA Rattler meets the industry standards for packaging and processing. Core Ideas: USDA Rattler was bred for high yield potential under both favorable and stressful environments.USDA Rattler performed well in our "purgatory plot" used to select for drought and low soil fertility tolerance.USDA Rattler is resistant to all known strains of Bean common mosaic virus and Bean common mosaic necrosis virus.USDA Rattler is widely adapted to production regions across the United States. [ABSTRACT FROM AUTHOR]

The classic V (violet, purple) gene of common bean (Phaseolus vulgaris) functions in a complex genetic network that controls seed coat and flower color and flavonoid content. V was cloned to understand its role in the network and the evolution of its orthologs in the Viridiplantae. V mapped genetically to a narrow interval on chromosome Pv06. A candidate gene was selected based on flavonoid analysis and confirmed by recombinational mapping. Protein and domain modeling determined V encodes flavonoid 3′5′ hydroxylase (F3′5′H), a P450 enzyme required for the expression of dihydromyricetin-derived flavonoids in the flavonoid pathway. Eight recessive haplotypes, defined by mutations of key functional domains required for P450 activities, evolved independently in the two bean gene pools from a common ancestral gene. V homologs were identified in Viridiplantae orders by functional domain searches. A phylogenetic analysis determined F3′5′H first appeared in the Streptophyta and is present in only 41% of Angiosperm reference genomes. The evolutionarily related flavonoid pathway gene flavonoid 3′ hydroxylase (F3′H) is found nearly universally in all Angiosperms. F3′H may be conserved because of its role in abiotic stress, while F3′5′H evolved as a major target gene for the evolution of flower and seed coat color in plants. [ABSTRACT FROM AUTHOR]

Bean common mosaic virus (BCMV) is a major disease in common bean (Phaseolus vulgaris L.). Host plant resistance is the most effective strategy to minimize crop damage against BCMV and the related Bean common mosaic necrosis virus (BCMNV). To facilitate breeding for resistance, we sought to identify candidate genes and develop markers for the bc-2 gene and the unknown gene with which it interacts. Genome-wide association study (GWAS) of the Durango Diversity Panel (DDP) identified a peak region for bc-2 on chromosome Pv11. Haplotype mapping narrowed the bc-2 genomic interval and identified Phvul.011G092700, a vacuolar protein-sorting 4 (Vps4) AAA+ ATPase endosomal sorting complexes required for transport (ESCRT) protein, as the bc-2 candidate gene. The race Durango Phvul.011G092700 gene model, bc-2 [UI111], contains a 10-kb deletion, while the race Mesoamerican bc-2 [Robust] consists of a single nucleotide polymorphism (SNP) deletion. Each mutation introduces a premature stop codon, and they exhibit the same interaction with the pathogroups (PGs) tested. Phvul.005G125100, another Vps4 AAA+ ATPase ESCRT protein, was identified as the candidate gene for the new recessive bc-4 gene, and the recessive allele is likely an amino acid substitution in the microtubule interacting and transport (MIT) domain. The two Vps4 AAA+ ATPase ESCRT proteins exhibit high similarity to the Zym Cucsa.385040 candidate gene associated with recessive resistance to Zucchini yellow mosaic virus in cucumber. bc-2 alone has no resistance effect but, when combined with bc-4 , provides resistance to BCMV (except PG-V) but not BCMNV, and, when combined with bc-u d, provides resistance to BCMV (except BCMV PG-VII) and BCMNV. So instead of different resistance alleles (i.e., bc-2 and bc-2 2), there is only bc-2 with a differential reaction based on whether it is combined with bc-4 or bc-u d , which are tightly linked in repulsion. The new tools and enhanced understanding of this host-virus pathogen interaction will facilitate breeding common beans for resistance to BCMV and BCMNV. [ABSTRACT FROM AUTHOR]

Bean common mosaic necrosis virus (BCMNV) is a major disease in common bean (Phaseolus vulgaris L.). Host plant resistance is the primary disease control. We sought to identify candidate genes to better understand the host-pathogen interaction and develop tools for marker-assisted selection (MAS). A genome-wide association study (GWAS) approach using 182 lines from a race Durango Diversity Panel (DDP) challenged by BCMNV isolates NL-8 [Pathogroup (PG)-III] and NL-3 (PG-VI), and genotyped with 1.26 million single-nucleotide polymorphisms (SNPs), revealed significant peak regions on chromosomes Pv03 and Pv05, which correspond to bc-1 and bc-u resistance gene loci, respectively. Three candidate genes were identified for NL-3 and NL-8 resistance. Side-by-side receptor-like protein kinases (RLKs), Phvul.003G038700 and Phvul.003G038800 were candidate genes for bc-1. These RLKs were orthologous to linked RLKs associated with virus resistance in soybean (Glycine max). A basic Leucine Zipper (bZIP) transcription factor protein is the candidate gene for bc-u. bZIP protein gene Phvul.005G124100 carries a unique non-synonymous mutation at codon 14 in the first exon (Pv05: 36,114,516 bases), resulting in a premature termination codon that causes a nonfunctional protein. SNP markers for bc-1 and bc-u and new markers for I and bc-3 genes were used to genotype the resistance genes underpinning BCMNV phenotypes in the DDP, host group (HG) differentials, and segregating F3 families. Results revealed major adjustments to the current host-pathogen interaction model: (i) there is only one resistance allele bc-1 for the Bc-1 locus, and differential expression of the allele is based on presence vs. absence of bc-u ; (ii) bc-1 exhibits dominance and incomplete dominance; (iii) bc-1 alone confers resistance to NL-8; (iv) bc-u was absent from HGs 2, 4, 5, and 7 necessitating a new gene symbol bc-u d to reflect this change; (v) bc-u d alone delays susceptible symptoms, and when combined with bc-1 enhanced resistance to NL-3; and (vi) bc-u d is on Pv05, not Pv03 as previously thought. These candidate genes, markers, and adjustments to the host-pathogen interaction will facilitate breeding for resistance to BCMNV and related Bean common mosaic virus (BCMV) in common bean. [ABSTRACT FROM AUTHOR]

Identifying the molecular basis of resistance to pathogens is critical to promote a chemical-free cropping system. In plants, nucleotide-binding leucine-rich repeat constitute the largest family of disease resistance (R) genes, but this resistance can be rapidly overcome by the pathogen, prompting research into alternative sources of resistance. Anthracnose, caused by the fungus Colletotrichum lindemuthianum , is one of the most important diseases of common bean. This study aimed to identify the molecular basis of Co-x , an anthracnose R gene conferring total resistance to the extremely virulent C. lindemuthianum strain 100. To that end, we sequenced the Co-x 58 kb target region in the resistant JaloEEP558 (Co-x) common bean and identified KTR2/3 , an additional gene encoding a truncated and chimeric CRINKLY4 kinase, located within a CRINKLY4 kinase cluster. The presence of KTR2/3 is strictly correlated with resistance to strain 100 in a diversity panel of common beans. Furthermore, KTR2/3 expression is up-regulated 24 hours post-inoculation and its transient expression in a susceptible genotype increases resistance to strain 100. Our results provide evidence that Co-x encodes a truncated and chimeric CRINKLY4 kinase probably resulting from an unequal recombination event that occurred recently in the Andean domesticated gene pool. This atypical R gene may act as a decoy involved in indirect recognition of a fungal effector. [ABSTRACT FROM AUTHOR]

Genetic resistance is the primary means for control of Bean golden yellow mosaic virus (BGYMV) in common bean (Phaseolus vulgaris L.). Breeding for resistance is difficult because of sporadic and uneven infection across field nurseries. We sought to facilitate breeding for BGYMV resistance by improving marker-assisted selection (MAS) for the recessive bgm-1 gene and identifying and developing MAS for quantitative trait loci (QTL) conditioning resistance. Genetic linkage mapping in two recombinant inbred line populations and genome-wide association study (GWAS) in a large breeding population and two diversity panels revealed a candidate gene for bgm-1 and three QTL BGY4.1, BGY7.1, and BGY8.1 on independent chromosomes. A mutation (5 bp deletion) in a NAC (No Apical Meristem) domain transcriptional regulator superfamily protein gene Phvul.003G027100 on chromosome Pv03 corresponded with the recessive bgm-1 resistance allele. The five bp deletion in exon 2 starting at 20 bp (Pv03: 2,601,582) is expected to cause a stop codon at codon 23 (Pv03: 2,601,625), disrupting further translation of the gene. A T m -shift assay marker named PvNAC1 was developed to track bgm-1. PvNAC1 corresponded with bgm-1 across ∼1,000 lines which trace bgm-1 back to a single landrace "Garrapato" from Mexico. BGY8.1 has no effect on its own but exhibited a major effect when combined with bgm-1. BGY4.1 and BGY7.1 acted additively, and they enhanced the level of resistance when combined with bgm-1. T m -shift assay markers were generated for MAS of the QTL, but their effectiveness requires further validation. [ABSTRACT FROM AUTHOR]

Slow‐darkening (SD) pinto beans (Phaseolus vulgaris L.) possess a desirable new trait, conditioned by the recessive sd gene, that slows seed coat darkening under delayed harvest and under storage. The effect sd may have on performance needs investigation. We examined agronomic performance and cooking quality of SD pinto beans. There were 30 (15 SD and 15 regular darkening [RD]) recombinant inbred lines (RILs) from each of two biparental inbred populations. The 60 RILs were tested across three locations in North Dakota and Washington. In addition, advanced SD and RD pinto breeding lines were tested in trials from 2010 to 2012 and in 2018. Across 2010–2012 trials, the "early generation bred" SD pintos, as a group, had significantly lower emergence, increased lodging, less seed yield, and smaller seed size than the RD group. Conversely, in the 2018 trial, "recently bred" SD pinto breeding lines had competitive agronomic performance to RD lines for seed yield, reduced lodging, and increased emergence. Further research on cooking time is warranted given that SD RILs cooked 20% faster than the RD RILs in one population. Overall, SD pintos exhibited slightly better canning quality than RD pintos. Whether raw or cooked, SD pintos were much lighter in color than RD pintos, emphasizing the need to keep them separated as distinct market classes. Breeders should continue to focus on improving agronomic performance for emergence, lodging, seed yield, seed size, and canning quality of SD pinto beans. [ABSTRACT FROM AUTHOR]

Dry bean (Phaseolus vulgaris L.) seeds are a major protein, carbohydrate and mineral source in the human diet of peoples in multiple regions of the world. Seed mineral biofortification is an ongoing objective to improve this important food source. The objective of this research was to assess the seed mineral concentration of five macroelements and eight microelements in a large panel (n = 277) of modern race Durango and race Mesoamerica genotypes to determine if variability existed that could be exploited for targeted seed biofortification. Varieties that derive from these races are found in many diets throughout the world. The panel was grown in replicated trials under typical production conditions in the major bean growing regions of the United States and a subset of the panel was also grown in replicated trials at three locations under control and terminal drought conditions. Except for K, seed mineral concentrations were higher for race Mesoamerica genotypes. Significantly higher seed concentrations for the majority of the minerals were observed for white-seeded genotypes and race Durango genotypes with the now preferred indeterminate, upright growth habit. Modern genotypes (since 1997) had equal or increased mineral concentrations compared with older genotypes. Drought affected mineral content differentially, having no effect on the microelement content but increased Co, Fe and Ni concentrations. The correlation of Ca and Mn concentrations suggests that these elements may share seed deposition mechanisms. The high heritability for seed mineral concentration implies that breeding progress can be achieved by parental selection from this panel. [ABSTRACT FROM AUTHOR]

Pseudomonas syringae pv. phaseolicola (Psph) Race 6 is a globally prevalent and broadly virulent bacterial pathogen with devastating impact causing halo blight of common bean (Phaseolus vulgaris L.). Common bean lines PI 150414 and CAL 143 are known sources of resistance against this pathogen. We constructed high-resolution linkage maps for three recombinant inbred populations to map resistance to Psph Race 6 derived from the two common bean lines. This was complemented with a genome-wide association study (GWAS) of Race 6 resistance in an Andean Diversity Panel of common bean. Race 6 resistance from PI 150414 maps to a single major-effect quantitative trait locus (QTL; HB4.2) on chromosome Pv04 and confers broad-spectrum resistance to eight other races of the pathogen. Resistance segregating in a Rojo x CAL 143 population maps to five chromosome arms and includes HB4.2. GWAS detected one QTL (HB5.1) on chromosome Pv05 for resistance to Race 6 with significant influence on seed yield. The same HB5.1 QTL, found in both Canadian Wonder x PI 150414 and Rojo x CAL 143 populations, was effective against Race 6 but lacks broad resistance. This study provides evidence for marker-assisted breeding for more durable halo blight control in common bean by combining alleles of race-nonspecific resistance (HB4.2 from PI 150414) and race-specific resistance (HB5.1 from cv. Rojo). [ABSTRACT FROM AUTHOR]

Common bacterial blight (CBB) disease limits dry bean (Phaseolus vulgaris L.) production worldwide. Resistance quantitative trait loci (QTL) from tepary bean (Phaseolus acutifolius A. Gray) have been used to develop dry bean lines with high levels of CBB resistance. This study examines the effects that two QTL from tepary bean BC420 (B) on chromosome Pv06 and SU91 (S) on Pv08 have on agronomic (seed yield and seed weight) and canning quality traits (water uptake, percentage washed drained weight [PWDWT], texture, and visual appearance). Sixteen small white dry bean near-isogenic lines, representing four homozygous genotypes for the BC420 and SU91 QTL BBSS, bbSS, BBss, and bbss, the donor resistant parent Teebus-BC5 (BBSS), and the recurrent susceptible parent 'Teebus' (bbss) were tested in replicated, inoculated and non-inoculated field plots across five environments in South Africa. Plots were inoculated with a mixture of Xanthomonas axonopodis pv. phaseoli and X. fuscans sbsp. fuscans isolates. The BC420 and SU91 QTL did not cause a yield penalty in non-inoculated plots in environments with low to no disease. SU91 provided yield protection under severe disease pressure, and both QTL in combination reduced disease severity score under moderate to high disease pressure. Seed weight was maintained in lines with the QTL under severe to moderate pressure and was unaffected by the QTL in low- to no-disease environments. Water uptake was significantly reduced in genotypes with BC420 (BBSS, BBss) and likely influenced traits measured subsequently: lower PWDWT, firmer texture, and less attractive visual appearance, which contributed to a reduced canning quality overall. Deployment of BC420 and SU91 QTL can be safely recommended for control of CBB, as no agronomic penalty was observed in CBB-free conditions, but canning quality should be closely monitored in lines with BC420 QTL. [ABSTRACT FROM AUTHOR]

White mold, caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease that limits common bean production and quality worldwide. The host-pathogen interaction is complex, with partial resistance in the host inherited as a quantitative trait with low to moderate heritability. Our objective was to identify meta-QTL conditioning partial resistance to white mold from individual QTL identified across multiple populations and environments. The physical positions for 37 individual QTL were identified across 14 recombinant inbred bi-parental populations (six new, three re-genotyped, and five from the literature). A meta-QTL analysis of the 37 QTL was conducted using the genetic linkage map of Stampede x Red Hawk population as the reference. The 37 QTL condensed into 17 named loci (12 previously named and five new) of which nine were defined as meta-QTL WM1.1, WM2.2, WM3.1, WM5.4, WM6.2, WM7.1, WM7.4, WM7.5, and WM8.3. The nine meta-QTL had confidence intervals ranging from 0.65 to 9.41 Mb. Candidate genes shown to express under S. sclerotiorum infection in other studies, including cell wall receptor kinase, COI1, ethylene responsive transcription factor, peroxidase, and MYB transcription factor, were found within the confidence interval for five of the meta-QTL. The nine meta-QTL are recommended as potential targets for MAS for partial resistance to white mold in common bean. [ABSTRACT FROM AUTHOR]

An ideotype breeding strategy to improve an economically important trait is achievable if subcomponent phenotypes most associated with the trait are targeted for selection. The success of this strategy in modern breeding history can be highlighted in dry bean (Phaseolus vulgaris L.), where an enhancement in dry bean production was facilitated in the last 25 yr by replacing Type III prostrate growth habit with Type II upright growth habit. This growth habit leads to disease avoidance and enables cost-effective management practices. To better understand the ideotype breeding trajectory in dry bean, and guarantee further improvements, we characterized 16 traits at three locations using a panel consisting of 122 genotypes with different growth habits. Among the growth habit types, significant differences were detected for seven architectural traits, three seed yield (SY) traits, and one phenological trait. Genetic variance was greater in the Type II genotypes than the Type III genotypes for five of the significant traits, including canopy height (CNH) and SY. Furthermore, in Type II genotypes, moderate narrow-sense heritability was detected for CNH, lodging (LDG), plant length (PL), and stem diameter (STD), suggesting positive gain can be made for growth habit from crosses between Type II genotypes. A network analysis of Type II genotypes revealed these four traits are highly correlated, and suggests possible genetic relatedness among the traits. Breeders often use CNH as a selection criterion, and the positive correlation between this trait and STD suggests a possible anatomical mechanism responsible for the more upright plant types. [ABSTRACT FROM AUTHOR]

Abiotic stress tolerance in dry bean (Phaseolus vulgaris L.) is complex. Increased population sizes are contributing to finding QTL conditioning stress response but phenotyping has not kept pace with high throughput genotyping for such studies. Our objectives were to determine effectiveness of 20 most tolerant and 20 most susceptible lines representing phenotypic extremes from a RIL population ('Buster' × 'Roza' [BR]) to facilitate examination of 19 traits for relevance to stress response and to validate existing QTL conditioning stress response. Using phenotypic extremes tested across multiple trials, eight of the 19 traits were clearly associated with drought stress. Pod wall ratio (PW), plant biomass by weight or a visual rating, and greenness index (NDVI) were most associated with seed yield (SY) under stress followed by phenology traits. The phenotypic extreme lines were also useful for validating QTL previously identified in the whole RIL population conditioning SY, seed weight (SW) and days to flower (DF), harvest maturity (HM), and seed fill (DSF). New QTL were identified for biomass, PW, and NDVI which co-segregated with major QTL for seed yield SY1.1BR and SY2.1BR. The preliminary finding of NDVI 1.1BR supports aerial imaging in larger genetic populations geared toward QTL analysis of stress response. In summary, phenotypic extremes helped sort through traits relevant to stress response in the Buster × Roza RIL population and verified the effect of two major QTL in response to terminal drought. [ABSTRACT FROM AUTHOR]

Dry beans (Phaseolus vulgaris L.) of the Andean gene pool, including red mottled, kidney, cranberry, and yellow seed types are important in Africa and the Americas. Andean dry bean breeding gains have lagged behind those of Mesoamerican beans. This difference may result from a narrower genetic base in the Andean gene pool and reduced breeding efforts. The objective of this research was to establish, genotype, and phenotype a panel of bean germplasm to be used for Andean dry bean breeding. An Andean diversity panel (ADP) was assembled, consisting of 396 accessions and including important cultivars, breeding lines, and landraces that originate mostly from Africa, the Caribbean, and North and South America. The panel was genotyped using the Illumina BARCBean6K_3 SNP BeadChip. The population contained two subgroups: Andean and Mesoamerican bean germplasm. The ADP was comprised of 349 Andean, 21 Mesoamerican, and 26 Andean-Mesoamerican admixed accessions. Most admixed lines came from Africa (12 accessions) and the Caribbean (five accessions). Association mapping was conducted for determinacy. Significant single-nucleotide polymorphism (SNP) trait associations were found on chromosome Pv01, with the most significant SNP marker being 3.1 kb from the Terminal Flower 1 PvTFL1y gene. The ADP was evaluated for numerous traits in field trials in the United States and Africa. Variability was found for resistance to rust, angular leaf spot and common bacterial blight diseases; tolerance to low soil fertility; cooking time; and other traits that can be used to improve Andean bean germplasm for Africa and the Americas. [ABSTRACT FROM AUTHOR]

Terminal and intermittent drought limits dry bean (Phaseolus vulgaris L.) production worldwide. Tolerance to drought exists but is difficult to breed for because of inconsistent expression across environments. Our objective was to identify quantitative trait loci (QTL) conditioning yield in a recombinant inbred line (RIL) population with consistent expression across multiple drought-stress environments. We tested 140 RILs from 'Buster' pinto (susceptible)/'Roza' pink (tolerant) for yield under multiple stresses (intermittent drought, compaction, and low fertility) across 3 yr and terminal drought across four location-years. A genetic linkage map (953 cM) was generated using single nucleotide polymorphism (SNP) markers. Two majoreffect QTL were detected on Pv01 and Pv02. The Pv01 QTL, defined by the closest marker SNP50809 (47.7 Mb), explained up to 37% of the phenotypic variance for seed yield under multiple stress (including intermittent drought) and was consistently expressed each year. The Pv02 QTL, nearest SNP40055 (11.8 Mb), was detected under drought stress (R2 = 33%) in addition to multiple stress (R2 = 17-23%). Phenological traits cosegregated with the yield QTL and affirmed the importance of phenological plasticity in adaptation to drought stress. Late maturity contributed to increased yield under multiple and nonstress and early maturity to increased yield under terminal drought. Given major and consistent effect, further investigation of the potential for the Pv01 and Pv02 QTL in breeding for multiple abiotic stress and drought tolerance in dry bean is warranted. [ABSTRACT FROM AUTHOR]