Bean Common Mosaic Necrosis Virus Research Articles

Characterization of a New, Country Bean (Lablab purpureus) Lineage of Bean Common Mosaic Necrosis Virus.

Country bean (Lablab purpureus, family Fabaceae) is grown in subsistence agriculture in Bangladesh as a multipurpose crop for food, animal feed, and green manure. This study was undertaken to investigate the genetic diversity of bean common mosaic necrosis virus (BCMNV, genus Potyvirus, family Potyviridae) in country beans. Leaf samples from country beans showing yellowing, vein banding, and mosaic symptoms were collected during field surveys between 2015 and 2019 cropping seasons from farmers' fields in different geographic regions. These samples were tested by serological and molecular diagnostic assays for the presence of BCMNV. Virus-positive samples were subjected to high-throughput Illumina sequencing to generate near-complete genomes of BCMNV isolates. In pairwise comparisons, the polyprotein sequences of BCMNV isolates from Bangladesh showed greater than 98% identities among themselves and shared less than 84% sequence identity at the nucleotide level with virus isolates reported from other countries. In the phylogenetic analysis, BCMNV isolates from Bangladeshi country beans formed a separate clade from virus isolates reported from common beans in other countries in the Americas, Africa, Europe, and from East Timor. Grow-out studies showed seed-to-seedling transmission of BCMNV, implying a possible seedborne nature of the virus in country beans.

Registration of ‘USDA Diamondback’ slow‐darkening pinto bean

AbstractThe 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.

Release of multiple virus and bruchid resistant Mesoamerican bean germplasm lines PR1303‐129 and PR1743‐44

AbstractPR1303‐129 (Reg. no. GP‐317, PI 702998) and PR1743‐44 (Reg. no. GP‐318, PI 702999) are multiple virus‐ and bruchid‐resistant common bean (Phaseolus vulgaris L.) germplasm lines developed and released cooperatively by the University of Puerto Rico Agricultural Experiment Station, the USDA‐ARS, the Instituto Dominicano de Investigaciones Agropecuarias y Forestales, the Instituto de Ciencia y Tecnología Agrícola, and Zamorano University. The black bean PR1303‐129 and small dark red bean PR1743‐44 combine resistance to Bean common mosaic virus (BCMV), Bean common mosaic necrosis virus (BCMNV), Bean golden yellow mosaic virus (BGYMV) and the common bean weevil [Acanthoscelides obtectus (Say)] with partial resistance to the Mexican bean weevil [Zabrotes subfasciatus (Boheman)]. Marker‐assisted selection was used to identify the presence of the bgm‐1 gene and the SW12 quantitative trait locus (QTL) for BGYMV resistance and the I and bc‐3 genes for resistance to BCMV and BCMNV. The parents of PR1303‐129 and PR1743‐44 were reported to possess the I gene for resistance to BCMV. Greenhouse inoculations were used to confirm the presence of the bc‐3 gene. Lines were screened in the laboratory and field for resistance to bruchids. Mean seed yields of PR1303‐129 and PR1743‐44 in six trials conducted in Puerto Rico were comparable to the check cultivar ‘Verano’. The release of these germplasm lines should contribute to the development of Mesoamerican cultivars for Central America and the Caribbean with enhanced levels of resistance to viral diseases and pests.

The alleles bc-ud and bc-ur (previously bc-4 gene), representing coding mutations within Vps4 AAA+ ATPase ESCRT protein, interact with other genes to condition resistance to BCMV and BCMNV in common bean.

Bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV) have a damaging impact on global common bean (Phaseolus vulgaris L.) cultivation, causing potential yield losses of over 80%. The primary strategy for controlling these viruses is through host plant resistance. This research aimed to identify and validate structural variations for the bc-ud gene as revealed by long-read sequencing, develop an efficient DNA marker to assist selection of bc-ud in snap and dry beans, and examine the interactions between the bc-ud allele and other BCMV resistance genes. A gene (Phvul.005G125100) model on chromosome Pv05, encoding a vacuolar protein-sorting 4 (Vps4) AAA+ ATPase endosomal sorting complexes required for transport (ESCRT) protein, was identified as the best candidate gene for bc-ud. An 84-bp repetitive insertion variant within the gene, exhibited 100% co-segregation with the bc-ud resistance allele across 264 common bean accessions. The 84-bp repetitive insertion was labeled with an indel marker IND_05_36225873 which was useful for tracking the bc-ud allele across diverse germplasm. A different single nucleotide polymorphism variant within the same candidate gene was associated with the bc-4 gene. Segregation in F2 populations confirmed bc-ud and bc-4 were alleles, so bc-4 was renamed bc-ur to fit gene nomenclature guidelines. The interactions of bc-ud and bc-ur with other resistance genes, such as bc-1 (receptor-like kinase on Pv03) and bc-2 (Vps4 AAA+ ATPase ESCRT protein on Pv11), validated gene combinations in the differential "host groups" effective against specific BCMV/BCMNV "pathogroups." These findings increase our understanding of the Bc-u locus, and enhance our ability to develop more resilient bean varieties through marker-assisted selection, reducing the impact of BCMV and BCMNV.

Investigating the interactions of endornaviruses with each other and with other viruses in common bean, Phaseolus vulgaris

BackgroundPlant viruses of the genus Alphaendornavirus are transmitted solely via seed and pollen and generally cause no apparent disease. It has been conjectured that certain plant endornaviruses may confer advantages on their hosts through improved performance (e.g., seed yield) or resilience to abiotic or biotic insult. We recently characterised nine common bean (Phaseolus vulgaris L.) varieties that harboured either Phaseolus vulgaris endornavirus (PvEV1) alone, or PvEV1 in combination with PvEV2 or PvEV1 in combination with PvEV2 and PvEV3. Here, we investigated the interactions of these endornaviruses with each other, and with three infectious pathogenic viruses: cucumber mosaic virus (CMV), bean common mosaic virus (BCMV), and bean common mosaic necrosis virus (BCMNV).ResultsIn lines harbouring PvEV1, PvEV1 and PvEV2, or PvEV1, PvEV2 plus PvEV3, the levels of PvEV1 and PvEV3 RNA were very similar between lines, although there were variations in PvEV2 RNA accumulation. In plants inoculated with infectious viruses, CMV, BCMV and BCMNV levels varied between lines, but this was most likely due to host genotype differences rather than to the presence or absence of endornaviruses. We tested the effects of endornaviruses on seed production and seedborne transmission of infectious pathogenic viruses but found no consistent relationship between the presence of endornaviruses and seed yield or protection from seedborne transmission of infectious pathogenic viruses.ConclusionsIt was concluded that endornaviruses do not interfere with each other’s accumulation. There appears to be no direct synergy or competition between infectious pathogenic viruses and endornaviruses, however, the effects of host genotype may obscure interactions between endornaviruses and infectious viruses. There is no consistent effect of endornaviruses on seed yield or susceptibility to seedborne transmission of other viruses.

Exploring I, bc-12 and bc-3 Gene Locus in Promising Common Bean Lines

Common beans (Phaseolus vulgaris L.), known as the "poor man's meat", is an internationally important legume crop that appeals to farmers as well as consumers. Many biotic stressors such as bean common mosaic virus (BCMV), bean common mosaic necrosis virus (BCMNV) cause significant yield and quality losses in common bean. The most efficient and cost-effective way to lessen of these factors is to develop resistant cultivars. Local genotypes have been cultivated in many areas for years and have varied distinguishing characteristics as a result of spontaneous mutations. Identifying bean germplasm harboring gene sources is critical for developing resistant cultivars against BCMV and BCMNV. For this purpose, a total of 43 promising common bean lines selected from local genotypes cultivated across various regions of Türkiye were subjected to screening using diverse molecular markers (ROC11, SBD-5 and SW-13) to investigate gene sources associated with BCMV and BCMNV. The findings revealed that 21 lines had both I and bc-12 gene locus. In addition, the bc-12+bc-3 gene loci were discovered to be present in the 8 common bean lines. The combination of I+bc-3 resistance genes, which guarantees immune reaction to BCMV and BCMNV, was found in only one line; YLV-32. These gene sources can be evaluated in marker-assisted breeding to develop modern cultivars resistant to BCMV and BCMNV by breeders.

Genetic variation in a tepary bean (Phaseolus acutifolius A. Gray) diversity panel reveals loci associated with biotic stress resistance.

Tepary bean (Phaseolus acutifolius A. Gray), indigenous to the arid climates of northern Mexico and the Southwest United States, diverged from common bean (Phaseolus vulgaris L.), approximately 2 million years ago and exhibits a wide range of resistance to biotic stressors. The tepary genome is highly syntenic to the common bean genome providing a foundation for discovery and breeding of agronomic traits between these two crop species. Although a limited number of adaptive traits from tepary bean have been introgressed into common bean, hybridization barriers between these two species required the development of bridging lines to alleviate this barrier. Thus, to fully utilize the extant tepary bean germplasm as both a crop and as a donor of adaptive traits, we developed a diversity panel of 422 cultivated, weedy, and wild tepary bean accessions which were then genotyped and phenotyped to enable population genetic analyses and genome-wide association studies for their response to a range of biotic stressors. Population structure analyses of the panel revealed eight subpopulations and the differentiation of botanical varieties within P. acutifolius. Genome-wide association studies revealed loci and candidate genes underlying biotic stress resistance including quantitative trait loci for resistance to weevils, common bacterial blight, Fusarium wilt, and bean common mosaic necrosis virus that can be harnessed not only for tepary bean but also common bean improvement.

Registration of ‘USDA Rattler’ pinto bean

AbstractThe 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.

The use of colorimetric loop-mediated isothermal amplification assay for naked-eye detection of bean common mosaic virus

Bean common mosaic virus (BCMV), one of the most prevalent viral diseases of common beans, has been intensively studied since its initial identification. In this paper, a one-step colorimetric reverse-transcription loop-mediated isothermal amplification (RT-LAMP) method was performed by designing oligonucleotide primers to amplify the gene encoding the coat protein of BCMV. Positive LAMP reactions were observed with the naked eye using WarmStart 2 × Master Mix from NEB, changing from pink to yellowish if the test is positive. The sensitivity of this method was similar to that of conventional PCR. The method was tested on common bean and another virus, bean common mosaic necrosis virus (BCMNV), and it was shown to specifically detect BCMV and not produce false positive from other RNAs. The RT-LAMP test was quite reliable for the diagnosis of BCMV from infected samples, and the precise, sensitive. The cost analysis showed that the development of a less expensive and efficient RT-LAMP assay for BCMV detection is an important step in expanding testing capacity and improving access to accurate testing in resource-limited settings. The test can be utilized in laboratory and in the field for the diagnosis and monitoring of BCMV, and is the first reported use of RT-LAMP for BCMV detection.

Screening of snap and dry bean (Phaseolus vulgaris L.) genotypes for resistance to Bean common mosaic virus and Bean common mosaic necrosis virus

The most effective control of Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) is achieved by using the seeds of resistant cultivars. During conventional breeding, resistance against BCMV and BCMNV in common bean can be developed by pyramiding the strain-nonspecific dominant I gene with strain-specific recessive (bc-) resistance genes for long-term virus control. In this study, a total of 58 bean genotypes involving registered green and dry bean cultivars, local genotypes, and breeding lines were tested for the presence of known resistance genes. First of all, each genotype was inoculated with the NL-3 strain of BCMNV and the NL-4 strain of BCMV separately, and the plants were evaluated for the symptom appearance and tested by DAS-ELISA to confirm the presence or absence of the virus after three weeks of sap-inoculation. In the last part of the study, the resistance genes in bean genotypes were investigated by SCAR markers of SW-13 linked with the I gene and SBD-5 linked to bc-12. According to the phenotypic and molecular tests, out of 58 common bean genotypes tested, 37 involved the I gene, and seven and three genotypes contained bc-22 and bc-12 genes, respectively.

Bean Common Mosaic Disease: Etiology, Resistance Resource, and Future Prospects

Bean common mosaic disease is one of the most destructive diseases of the common bean, which is one of the most important legumes worldwide. It is caused by two closely related potyviruses: bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV). Both viruses have spread to all the common bean-growing areas worldwide and have become a major challenge in bean production. In this review, we summarized the biology and diversity of BCMV and BCMNV, discussed the current knowledge on the resistance genes of BCMV, and finally pointed out the future prospects for the control of bean common mosaic disease.

Viral metatranscriptomic approach to study the diversity of virus(es) associated with Common Bean (Phaseolus vulgaris L.) in the North-Western Himalayan region of India.

Plant viruses are a major threat to legume production worldwide. In recent years, new virus strains have emerged with increasing frequencies in various legume cropping systems, which demands the development of cutting-edge virus surveillance techniques. In this study, we surveyed the common bean fields of Kashmir valley for virus infection using a total of 140 symptomatic and non-symptomatic leaf samples collected from different locations. The genetic diversity of viruses was examined by high-throughput sequencing (HTS) with three viruses being identified, namely, Bean Common Mosaic Virus (BCMV), Bean Common Mosaic Necrosis Virus (BCMNV), and Clover Yellow Vein Virus (ClYVV). BCMNV and ClYVV are new reports from India. De novo assembly of transcriptome constructed near-complete genomes of these viruses. RT-PCR results confirmed the presence of these viruses with an emerge incidence of 56. 4% for BCMV, 27.1% for BCMNV and 16.4 for ClYVV in the valley. Several samples were found to contain multiple virus infections with BCMV being the most predominant. Recombination events were detected in the genomes of BCMV and ClYVV, but not BCMNV. Phylogenetic and pairwise identity matrix evidence suggests viral import from multiple countries. Our results demonstrate that HTS followed by multiplex PCR assay is a simple, rapid, and reliable approach for simultaneous diagnosis of plant viruses.

Survey for Virus Diversity in Common Bean (Phaseolus vulgaris) Fields and the Detection of a Novel Strain of Cowpea polerovirus 1 in Zambia.

The production of common bean (Phaseolus vulgaris L.) is adversely affected by virus-like diseases globally, but little is known about the occurrence, distribution, and diversity of common bean-infecting viruses in Zambia. Consequently, field surveys were conducted during the 2018 season in 128 fields across six provinces of Zambia and 640 common bean leaf tissue samples were collected with (n = 585) or without (n = 55) symptoms. The prevalence of symptomatic fields was 100%, but incidence of symptomatic plants ranged from 32 to 67.5%. Metagenomic analyses of nine composite samples and a single plant sample of interest revealed the occurrence of isolates of Bean common mosaic necrosis virus, Bean common mosaic virus, Cowpea aphid-borne mosaic virus, Peanut mottle virus, Southern bean mosaic virus (SBMV), Cucumber mosaic virus, Phaseolus vulgaris alphaendornavirus 1 (PvEV-1), PvEV-2, Ethiopian tobacco bushy top virus (ETBTV), and a novel strain of Cowpea polerovirus 1 (CPPV1-Pv) of 5,902 nt in length. While CPPV1-Pv was consistently detected in mixed infection with ETBTV and its satellite RNA molecule, based on results of mechanical transmission assays it does not appear to be involved in disease etiology, suggesting that its role may be limited to being a helper virus for the umbravirus. Screening of the survey samples by real-time PCR for the viruses detected by high-throughput sequencing revealed the prevalence of single (65.2% or 417/640) over mixed (1.9% or 12/640) infections in the samples. SBMV was the most frequently detected virus, occurring in ∼29.4% (188/640) of the samples and at a prevalence rate of 58.6% (75/128) across fields. The results showed that diverse virus species are present in Zambian common bean fields and the information will be useful for the management of common bean viral diseases.

Complete Genome Sequence of an Isolate of Passiflora chlorosis virus from Passion Fruit (Passiflora edulis Sims)

We report the first complete genome sequence of an isolate of Passiflora chlorosis virus (PaCV), a member of the Potyviridae family, identified in passion fruit (Passiflora edulis Sims) plants grown in Israel. The assembled genome is 9672 nucleotides long and encodes a 3084 amino acids polyprotein that is predicted to be proteolytically cleaved into 10 mature peptides. Our analysis of the genome sequence shows that PaCV is a distinct species, sharing 68.5% nucleotide sequence identity and 71.5% amino acid sequence identity with isolates of the bean common mosaic necrosis virus (BCMNV), the most closely related virus classified within the genus Potyvirus. Using quantitative PCR, we detected the virus in RNA samples from leaves exhibiting symptoms of infection, with higher levels in clearly chlorotic leaves, but not in those from healthy leaves.

Bean common mosaic necrosis virus

Bean common mosaic necrosis virus

Introduction of foliar disease resistance into bean bruchid resistant genotypes and heritability studies at F2:3

Common bacterial blight (CBB), Bean common mosaic virus (BCMV) and Bean common Mosaic Necrosis Virus (BCMNV) are the most common foliar diseases affecting common bean worldwide. CBB and BCMV/BCMNV are caused by Xanthomonas axonopodis pv. phaseoli and group of Potyviruses respectively, contributing to high yield and quality losses in Tanzania. Chemical control has not been effective or economical on both of these seed borne diseases. Elsewhere, breeding for resistant cultivars have been reported to be effective and a long-term control measure. The objective of this study was to incorporate foliar disease resistance to CBB, BCMV and BCMNV from KT020 into existing bruchid resistant genotype BR 59-63-10.  One way cross was performed under screen-house condition followed F1 advancement to F2 at which F2:3 was screened using SCAR markers i.e SAP6 for QTL-CBB, SW13 for I gene-BCMV and ROC11 for bc-3 gene-BCMNV resistance. Among forty individuals screened, nine derivatives had resistance to all diseases; seventeen had two resistance genes to either of the disease while ten derivatives of APAx KT020 had one resistance gene to either of the diseases.   Results also showed positive correlation between phenotypic score and markers, while in phenotypic studies all individuals had resistance ranging from 1.40 to 3.29 on leaf lesions and 2.14 to 3.30 on pod severity for CBB based on 1-9 CIAT scale. High heritability of reduced infestation explained by 61.1% and 66.8% on leaf and pod symptoms respectively was obtained. Marker screening indicating a reliable procedure for selecting resistant individual using marker assisted selection (MAS).

Determination of Genetic Diversity and Screening of BCMV and BCMNV Resistance in Some Bean Genotypes Using Molecular Markers

Fresh bean (Phaseolus vulgaris L.) is an important legume crop in Turkey used as a major source of protein in the human diet. The total fresh bean production of Turkey is estimated at 651,094 tons. Bean production shows a decreasing factor due to various abiotic and biotic factors in Turkey. Among the viruses that infect beans, Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) are the most widespread destructive agents. The main objective of this study was to carry out a diagnostic survey for Bean common mosaic disease (BCMD) in beans, characterize its causal agent, and evaluate host resistance to BCMV and BCMNV. In addition to this, genotypes were tested for the levels of genetic diversity by 58 SSR markers. A total of 123 alleles with a PIC value of ≥0.2 were obtained from 75 bean genotypes. The unweighted NJ dendrogram was created using the scoring data, which demonstrated the molecular genetic relationships among the bean genotypes. SCAR (Sequence Characterized Amplified Region) markers were used to determine the resistant genotypes to BCMV and BCMNV. According to the result, 21 out of 75 genotypes have resistance alleles to both pathogens.

Coding Mutations in Vacuolar Protein-Sorting 4 AAA+ ATPase Endosomal Sorting Complexes Required for Transport Protein Homologs Underlie bc-2 and New bc-4 Gene Conferring Resistance to Bean Common Mosaic Virus in Common Bean.

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[UI 111], 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-ud, provides resistance to BCMV (except BCMV PG-VII) and BCMNV. So instead of different resistance alleles (i.e., bc-2 and bc-22), there is only bc-2 with a differential reaction based on whether it is combined with bc-4 or bc-ud, 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.

Phenotypic and molecular screening of dry bean (Phaseolus vulgaris L.) breeding lines for resistance to bean common mosaic virus and bean common mosaic necrosis virus

Bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV) are among the most economically important virus species infecting common bean. The use of resistant plant cultivars is the most effective way to control these viruses. National dry bean breeding studies have been conducted by seven different governmental agricultural research institutes in Turkey, and advanced breeding lines have been developed by using the selected local dry bean populations and crossing studies. In this study, 204 breeding lines were tested for resistance levels to BCMV and BCMNV. Initially, BCMNV NL-3 and BCMV NL-4 strains were individually sap-inoculated onto the leaves of bean plants belonging to each breeding lines with 10 replications, and the reactions of plants were evaluated for symptomatic appearance of virus infection 21 days after inoculation. Additionally, phenotypic evaluation was confirmed by molecular markers linked to resistance genes. As a result of the study, 153 breeding lines were found to involve the dominant I gene whereas four and five of the tested lines had the recessive genes bc-1² and bc-2², respectively. In conclusion, it was emphasized that these breeding lines could be registered after evaluating them in terms of yield and quality. Also, the use of seeds of the resistant lines to supply the source of virus-resistance in breeding studies and maintaining their seeds at the national genebank were recommended.

An Innate Preference of Bumblebees for Volatile Organic Compounds Emitted by Phaseolus vulgaris Plants Infected With Three Different Viruses

Cucumber mosaic virus (CMV)-infected tomato (Solanum lycopersicum L.) plants emit volatile organic compounds (VOCs) attractive to bumblebees (Bombus terrestris L.), which are important tomato pollinators, but which do not transmit CMV. We investigated if this effect was unique to the tomato-CMV pathosystem. In two bean (Phaseolus vulgaris L.) cultivars, infection with the potyviruses bean common mosaic virus (BCMV) or bean common mosaic necrosis virus (BCMNV), or with the cucumovirus CMV induced quantitative changes in VOC emission detectable by coupled gas chromatography–mass spectrometry. In free-choice olfactometry assays bumblebees showed an innate preference for VOC blends emitted by virus-infected non-flowering bean plants and flowering CMV-infected bean plants, over VOCs emitted by non-infected plants. Bumblebees also preferred VOCs of flowering BCMV-infected plants of the Wairimu cultivar over non-infected plants, but the preference was not significant for BCMV-infected plants of the Dubbele witte cultivar. Bumblebees did not show a significant preference for VOCs from BCMNV-infected flowering bean plants but differential conditioning olfactometric assays showed that bumblebees do perceive differences between VOC blends emitted by flowering BCMNV-infected plants over non-infected plants. These results are consistent with the concept that increased pollinator attraction may be a virus-to-host payback, and show that virus-induced changes in bee-attracting VOC emission is not unique to one virus-host combination.