Bean Golden Yellow Mosaic Virus Research Articles

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.

Release of tepary bean cultivar ‘USDA Fortuna’ with improved disease and insect resistance, seed size, and culinary quality

AbstractTepary bean (Phaseolus acutifolius A. Gray) is a viable and nutritious alternative to common bean (P. vulgaris L.) in areas with excessively high temperatures and/or chronic drought. Tepary bean is a traditional crop of the Tohono O'odham Indians of the Sonoran Desert in the Southwest United States and Mexico, as well as other Indigenous peoples of the United States, Mexico, and Central America. Despite its potential for broad applications for reduced water‐input agriculture or for hot, semi‐arid, marginal production zones, tepary bean remains an orphan crop. ‘USDA Fortuna’ (Reg. no. CV‐352, PI 698459) is an improved tepary bean cultivar with enhanced seed size, seed quality, tolerance to Bean golden yellow mosaic virus, and resistance to local strains of rust in Puerto Rico. It has leafhopper pest resistance, common bacterial blight resistance, and moderate resistance to powdery mildew. USDA Fortuna is a high‐yielding tepary bean with an attractive black speckled seed color and a quick cooking time. This cultivar was developed cooperatively by the USDA‐ARS, the University of Puerto Rico, Zamorano University, the Instituto Dominicano de Investigaciones Agropecuarias y Forestales (IDIAF) of the Dominican Republic, Quisqueya University of Haiti, the National Seed Service of Haiti, Instituto Nacional de Innovación y Transferencia en Tecnología Agropecuaria (INTA) of Costa Rica, and Iowa State University.

NAC Candidate Gene Marker for bgm-1 and Interaction With QTL for Resistance to Bean Golden Yellow Mosaic Virus in Common Bean.

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 Tm-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. Tm-shift assay markers were generated for MAS of the QTL, but their effectiveness requires further validation.

Registration of PR1572‐19 and PR1572‐26 pinto bean germplasm lines with broad resistance to rust, BGYMV, BCMV, and BCMNV

AbstractCommon bean rust, Bean golden yellow mosaic virus (BGYMV), Bean common mosaic virus (BCMV), and Bean common mosaic necrosis virus (BCMNV) are devastating diseases of dry bean (Phaseolus vulgaris L.) in Central America and the Caribbean. The development of dry bean cultivars with enhanced levels of genetic resistance to these and other diseases is an important goal of the University of Puerto Rico (UPR) and other dry bean breeding programs in Central America and the Caribbean. PR1572‐19 (Reg. no. GP‐308, PI 692976) and PR1572‐26 (Reg. no. GP‐307, PI 692975) are multiple virus‐ and rust‐resistant pinto bean germplasm lines adapted to the humid tropics that were developed and released cooperatively in 2019 by the UPR Agricultural Experiment Station, the Instituto Dominicano de Investigaciones Agropecuarias y Forestales, and the USDA–ARS. Both PR1572‐19 and PR1572‐26 possess the bgm‐1 gene for resistance to BGYMV, the I and bc‐3 loci that provide broad resistance to all strains of BCMV and BCMNV in the United States and the Caribbean, and the Ur‐3 and Ur‐11 loci that confer comprehensive resistance to all known races of the bean rust pathogen. PR1572‐26 also has the SW12 quantitative trait locus marker associated with resistance to BGYMV. PR1572‐19 and PR1572‐26 produced mean seed yields similar to the check cultivar ‘Santa Fe’ in trials conducted in Puerto Rico and mean seed yields comparable to the pinto cultivar ‘La Paz’ in the Cooperative Dry Bean Nursery conducted in Puerto Rico. Both lines should serve as useful sources of resistance to BGYMV, BCMV, BCMNV, and bean rust for common beans of the Durango race that includes the pinto and great northern market classes.

Molecular identification and sequence analysis of bipartite Begomovirus infecting Horsegram legume in India

The molecular diversity of Begomovirus infecting Horsegram yellow Mosaic viruses (HgYMV1 and HgYMV2), from two main horsegram growing farms near Bangalore, Karnataka State, South India was investigated. The viral DNA was amplified from horsegram plants exhibiting mild and severe symptoms by polymerase chain reaction, and complete genome of the HgYMV were identified by their sequence analysis. Isolates of HgYMV1 and HgYMV2 were found to be associated with severe symptom phenotype from HgYMV. HgYMV was most closely related to Mungbean yellow mosaic indian viruse (MYMIV) and Mungbean yellow mosaic virus (MYMV) at 81.8 to 84.8 % nucleotide identity, based on DNA-A and DNA-B component sequences. HgYMV was distantly related to Dolicos yellow mosaic virus from Asia (DoYMV-Ban and DoYMV-DB) and partially to Cowpea golden mosaic virus from Nigeria (CPGMV-[NG]) at 64 and 62 % DNA nucleotide identity. Analysis of the DNA-B sequence of HgYMV revealed a DNA-B component identical to those of Bean golden yellow mosaic virus BGYMV isolates described. Furthermore, the DNA-B component for extant BGYMV isolates and strains were also the closest relatives for the HgYMV1 DNA-B components at 48.7 % nucleotide identity. Therefore, HgYMV could be considered to be a new species of the genus Begomovirus (family Geminiviridae). Keywords: Begomovirus, Horsegram, yellow Mosaic viruses , DNA sequencing

Begomoviruses infecting common beans (Phaseolus vulgaris L.) in production areas in Cuba

Viral diseases caused by begomoviruses are economically important for their depressing impact on common bean production in Cuba. Mayabeque is a Cuban province where this crop is significantly grown and affectations by Bean golden yellow mosaic virus (BGYMV) have been detected in the last 30 years. Integrated pest management (IPM) programs in this crop have allowed controlling the disease for a long time. However, in prospections of the last years, an increase of the incidence of various yellowing symptoms typical of begomoviruses has been observed in common bean production areas. DNA was extracted from leaf samples taken from symptomatic plants. Non-radioactive nucleic acid hybridization and a specific PCR assay were used to detect BGYMV, Common bean severe mosaic virus, Common bean mottle virus, and Tobacco leaf curl Cuba virus. Of the 218 bean plants sampled, 89.5 % was positive to BGYMV; the presence of the rest of the begomovirus species was between 3 and 4% (3.08% of CBMoV, 3.08% of TbLCCuV and 4.32% of CBSMV). The viral DNA from some samples was analyzed by rolling circle amplification (RCA), by restriction fragment length polymorphism analysis using restriction enzymes, and by cloning and sequencing of the viral components. The DNA sequences from BGYMV isolates showed 98% of identity with the isolates reported in Cuba in 2003. The infection by Tobacco leaf curl Cuba virus (TbLCCuV) was confirmed also in fields in the Cuban western region. This is the first work where the DNA-B of TbLCCuV is identified. These studies will help to strengthen phytosanitary surveillance and management programs implemented in the country to control the whitefly-begomovirus complex in this economically important crop.

Identificación de líneas recombinantes de frijol negro opaco resistentes a BCMV, BCMNV y BGYMV mediante marcadores moleculares


 
 
 El frijol negro opaco de acervo mesoamericano se consume y produce en México. Con el objetivo de identificar líneas recombinantes de frijol negro opaco resistentes al virus del mosaico (BCMV), al virus del mosaico y la necrosis (BCMNV) y al virus del mosaico amarillo dorado del frijol (BGYMV), durante 2015 y 2016 se evaluó una colección de 70 genotipos que incluyeron 20 variedades y 50 líneas recombinantes (LR). Las LR derivaron de tres diferentes cruzas: ‘Negro Papaloapan’/SEN-46, ‘Negro Citlali’/XRAV-187-3 y ‘Jamapa Plus’/XRAV-187-3. Los genotipos se inocularon con las cepas BCMNV NL-3 y BGYMV-MX, y se genotipificaron con marcadores moleculares SW13, ENM, SBD5 y SR2 ligados a genes de resistencia I, bc-3, bc12 y bgm-1. Se identificaron 21 LR que tuvieron los genes bgm-1, I, o la combinación I + bc-3 y resistencia de amplio espectro a BCMV, BCMNV y BGYMV. Las LR tuvieron alta proporción de plantas con el gen I. Seis LR que derivaron de la cruza ‘Negro Papaloapan’/SEN-46 y dos de cada una de las cruzas ‘Negro Citlali’/XRAV-187-3 y ‘Jamapa Plus’/XRAV-187-3 tuvieron entre 8% y 92% de plantas con combinación genética I + bc-3 que confiere resistencia a BCMV y BCMNV. Mientras que los genes I y bgm-1, dan resistencia a BCMV y BGYMV, se detectaron en tres LR de la cruza ‘Negro Papaloapan’/SEN-46 y cuatro de ‘Negro Citlali’/XRAV-187-3. Cuatro LR derivadas de la cruza ‘Negro Papaloapan’/SEN-46: ‘Negro Papaloapan’/SEN 46-7-8, ‘Negro Papaloapan’/SEN- 46-7-11, ‘Negro Papaloapan’/SEN-46-7-12 y ‘Negro Papaloapan’/SEN-46-7-13 tuvieron plantas con genes I, bc-3 y bgm-1 con resistencia de amplio espectro a BCMV, BCMNV y BGYMV. La heterogeneidad de LR en proporción de plantas con genes de resistencia, surge la estrategia de selección asistida por marcadores moleculares para homogenizarlas y desarrollar variedades de frijol negro opaco con resistencia a tres virus que afectan la producción de frijol en América Latina.
 
 

Recombinase polymerase amplification applied to plant virus detection and potential implications

Several isothermal techniques for the detection of plant pathogens have been developed with the advent of molecular techniques. Among them, Recombinase Polymerase Amplification (RPA) is becoming an important technique for the rapid, sensitive and cost-effective detection of plant viruses. The RPA technology has the advantage to be implemented in field-based scenarios because the method requires a minimal sample preparation, and is performed at constant low temperature (37–42 °C). The RPA technique is rapidly becoming a promising tool for use in rapid detection and further diagnostics in plant clinics and monitoring quarantine services. This paper presents a review of studies conducted using RPA for detection/diagnosis of plant viruses with either DNA genomes (Banana bunchy top virus, Bean golden yellow mosaic virus, Tomato mottle virus, Tomato yellow leaf curl virus) or RNA genomes (Little Cherry virus 2, Plum pox virus and Rose rosette virus).

Simultaneous Detection of Both RNA and DNA Viruses Infecting Dry Bean and Occurrence of Mixed Infections by BGYMV, BCMV and BCMNV in the Central-West Region of Mexico.

A multiplex reverse transcription polymerase chain reaction (RT-PCR) assay was developed to simultaneously detect bean common mosaic virus (BCMV), bean common mosaic necrotic virus (BCMNV), and bean golden yellow mosaic virus (BGYMV) from common bean leaves dried with silica gel using a single total nucleic acid extraction cetyl trimethyl ammonium bromide (CTAB) method. A mixture of five specific primers was used to amplify three distinct fragments corresponding to 272 bp from the AC1 gene of BGYMV as well as 469 bp and 746 bp from the CP gene of BCMV and BCMNV, respectively. The three viruses were detected in a single plant or in a bulk of five plants. The multiplex RT-PCR was successfully applied to detect these three viruses from 187 field samples collected from 23 municipalities from the states of Guanajuato, Nayarit and Jalisco, Mexico. Rates of single infections were 14/187 (7.5%), 41/187 (21.9%), and 35/187 (18.7%), for BGYMV, BCMV, and BCMNV, respectively; 29/187 (15.5%) samples were co-infected with two of these viruses and 10/187 (5.3%) with the three viruses. This multiplex RT-PCR assay is a simple, rapid, sensitive, and cost-effective method for detecting these viruses in the common bean and can be used for routine molecular diagnosis and epidemiological studies.

Registration of PR1146‐138 Yellow Bean Germplasm Line

The yellow bean (Phaseolus vulgaris L.) is an important market class in Haiti. There have been, however, no previous attempts to genetically improve this seed type for the Caribbean. Landrace varieties of yellow beans in Haiti are susceptible to Bean golden yellow mosaic virus (BGYMV) and Bean common mosaic virus (BCMV), which are important dry bean diseases in the region. In addition, leafhopper (Empoasca kraemeri Ross and Moore) can cause significant yield loss, especially when common beans are planted during periods of low precipitation. The development of dry bean cultivars with enhanced levels of resistance to diseases and pests is an important goal of the University of Puerto Rico (UPR) and the National Seed Service in Haiti. PR1146‐138 (Reg. No. GP‐298, PI 675225) is a multiple virus‐ and pest‐resistant bean germplasm line adapted to the humid tropics that was developed and released cooperatively in 2015 by the UPR Agricultural Experiment Station, the USDA‐ARS, and the National Seed Service of the Ministry of Agriculture, Natural Resources and Rural Development of the Republic of Haiti. PR1146‐138 has a yellow seed type with a hue angle of 86.30 and a chroma of 34.68. PR1146‐138 possesses the I locus that confers resistance to BCMV and the bgm‐1 gene for resistance to BGYMV. PR1146‐138 produced a mean seed yield of 2095 kg ha−1 when tested in Puerto Rico and Haiti in seven environments over a 3‐yr period. It has a determinate growth habit and reached harvest maturity from 65 to 70 d after planting. This line should serve as a useful source of resistance to BGYMV, BCMV, and leafhoppers in the improvement of Andean beans for the tropical lowlands.

Evaluation of recombinase polymerase amplification for detection of begomoviruses by plant diagnostic clinics.

BackgroundPlant viruses in the genus Begomovirus, family Geminiviridae often cause substantial crop losses. These viruses have been emerging in many locations throughout the tropics and subtropics. Like many plant viruses, they are often not recognized by plant diagnostic clinics due in large part to the lack of rapid and cost effective assays. An isothermal amplification assay, Recombinase polymerase amplification (RPA), was evaluated for its ability to detect three begomoviruses and for its suitability for use in plant diagnostic clinics. Methods for DNA extraction and separation of amplicons from proteins used in the assay were modified and compared to RPA manufacturer’s protocols. The modified RPA assays were compared to PCR assays for sensitivity, use in downstream applications, cost, and speed.ResultsRecombinase polymerase amplification (RPA) assays for the detection of Bean golden yellow mosaic virus, Tomato mottle virus and Tomato yellow leaf curl virus (TYLCV) were specific, only amplifying the target viruses in three different host species. RPA was able to detect the target virus when the template was in a crude extract generated using a simple inexpensive extraction method, while PCR was not. Separation of RPA-generated amplicons from DNA-binding proteins could be accomplished by several methods, all of which were faster and less expensive than that recommended by the manufacturer. Use of these modifications resulted in an RPA assay that was faster than PCR but with a similar reagent cost. This modified RPA was the more cost effective assay when labor is added to the cost since RPA can be performed much faster than PCR. RPA had a sensitivity approximate to that of ELISA when crude extract was used as template. RPA-generated amplicons could be used in downstream applications (TA cloning, digestion with a restriction endonuclease, direct sequencing) similar to PCR but unlike some other isothermal reactions.ConclusionsRPA could prove useful for the cost effective detection of plant viruses by plant diagnostic clinics. It can be performed in one hour or less with a reagent cost similar to that of PCR but with a lower labor cost, and with an acceptable level of sensitivity and specificity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-016-0504-8) contains supplementary material, which is available to authorized users.

First report of Tobacco leaf curl Cuba virus infecting common bean in Cuba

In Cuba begomoviruses have emerged as one of the major factors limiting production of solanaceous and fabaceous crops. The begomovirus Bean golden yellow mosaic virus affects the major production areas of common bean ( Phaseolus vulgaris )…

Screening metagenomic data for viruses using the e-probe diagnostic nucleic acid assay.

Next generation sequencing (NGS) is not used commonly in diagnostics, in part due to the large amount of time and computational power needed to identify the taxonomic origin of each sequence in a NGS data set. By using the unassembled NGS data sets as the target for searches, pathogen-specific sequences, termed e-probes, could be used as queries to enable detection of specific viruses or organisms in plant sample metagenomes. This method, designated e-probe diagnostic nucleic acid assay, first tested with mock sequence databases, was tested with NGS data sets generated from plants infected with a DNA (Bean golden yellow mosaic virus, BGYMV) or an RNA (Plum pox virus, PPV) virus. In addition, the ability to detect and differentiate among strains of a single virus species, PPV, was examined by using probe sets that were specific to strains. The use of probe sets for multiple viruses determined that one sample was dually infected with BGYMV and Bean golden mosaic virus.

First Report of Tomato yellow leaf curl virus in Tomato in Costa Rica.

One of the most important invasive and harmful members of the genus Begomovirus (family Geminiviridae) is the monopartite Tomato yellow leaf curl virus (TYLCV), which is widespread over the world associated with tomato yellow leaf curl disease (TYLCD). Tomato (Solanum lycopersicum) plants infected with TYLCV show upward leaf curling and yellowing. In Latin America, isolates of TYLCV have been reported from Cuba, the Dominican Republic, Mexico and Puerto Rico (1), Guatemala (GenBank Accession No. GU355941), and Venezuela (partial genome sequence DQ302033). In Costa Rica, only isolates of the bipartite begomoviruses Tomato leaf curl Sinaloa virus (TLCSiV) (3) and Tomato yellow mottle virus (KC176780, KC176781) have been reported infecting tomatoes. During a survey conducted in 2012, similar begomovirus-like symptoms (leaf yellowing and upward leaf curling) were observed in tomato plants of five commercial growing areas in the Central Valley (Grecia region) of Costa Rica. In total, 65 tomato samples were randomly collected, 14 from greenhouses and 41 from open fields. Symptoms of upward leaf curling and yellowing were observed in three samples. Total DNA was extracted from collected samples and tested by dot blot hybridization using a probe to the coat protein (CP) gene of a Guatemalan isolate of Bean golden yellow mosaic virus (3). Only the three symptomatic samples tested positive, which represents an incidence of 14% (2 samples) in greenhouses and 2.4% (1 sample) in open field crops. These samples were subjected to rolling circle amplification (RCA) for viral circular genome amplification (2). The amplified products were then digested with MspI restriction endonuclease, which resulted into DNA fragments of 2,320 and 458 bp for all three samples. This suggested infection with a monopartite begomovirus. In order to obtain the full-length clone, the RCA product of two samples (5240 and 5241) was digested with BamHI, and the ~2.8 kb DNA fragment was cloned into pBluescript II SK(+) (Stratagene, La Jolla, CA) vector. After transformation of Escherichia coli DH5α, recombinant plasmids with inserts of expected size were selected and the insert was sequenced by primer walking (Macrogen Inc., Korea). The inserts of three clones from the two samples (CR:5240-16:2012, CR:5240-17:2012, and CR:5241-14:2012) were sequenced (deposited in GenBank as KF533855, KF533856, and KF533857, respectively). Sequences were all 2,781 nt long and shared 100% identity between themselves (1-nt mismatch between CR:5240-16:2012 and CR:5240-17:2012, and CR:5240-16:2012 and CR:5241-14:2012; and 2-nt mismatches between CR:5240-17:2012 and CR:5241-14:2012) and 99% with the sequence of Tomato yellow leaf curl virus-Israel[Japan:Haruno:2005] (TYLCV-IL[JR:Har:05]) (AB192966). These sequences represented full length genomes of isolates of the monopartite begomovirus TYLCV-IL and grouped in a phylogenetic clade (4) that comprised TYLCV-IL isolates reported from Asia (China and Japan) and from Mexico, while more distantly related to the clade comprising TYLCV-IL isolates reported from Central America (Cuba, Guatemala, Puerto Rico) and the United States, suggesting a distinct introduction event in Costa Rica. This is the first report of the presence of TYLCV in Costa Rica, therefore it is imperative to study the incidence and geographical spread of this virus in the country as well as its genetic diversity, since TYLCV infections might lead to significant yield losses, as reported in other countries.

RENDIMIENTO Y ADAPTACIÓN DE LA VARIEDAD DE FRIJOL ‘NEGRO COMAPA’ EN DOS REGIONES DE MÉXICO

El frijol negro (Phaseolus vulgaris L.), de grano opaco y pequeño es de alta demanda en las regiones del centro y sureste de México. El objetivo de esta investigación fue determinar la adaptación y el rendimiento de la nueva variedad de frijol ‘Negro Comapa’ en áreas del trópico húmedo del Golfo y en el altiplano central de México. De 2007 a 2010 se estableció un ensayo de rendimiento de líneas de frijol que incluyó a esta variedad en seis ambientes del Estado de Veracruz (dos bajo temporal o secano, y cuatro bajo condiciones de humedad residual). En 2009 y 2010 también se evaluó en un ensayo nacional de rendimiento, en 13 ambientes de prueba en México: seis en Veracruz, cuatro en Guanajuato, uno en Durango uno en Sinaloa y uno en Chiapas. En el ensayo nacional, además del rendimiento se determinó la reacción de las variedades a las enfermedades que incidieron en forma natural. En los años mencionados, ‘Negro Comapa’ también se evaluó en pruebas de validación en terrenos de agricultores en 10 ambientes de Veracruz, uno en Oaxaca y uno en Chiapas. En ambos ensayos, el conducido en Veracruz y el nacional, ‘Negro Comapa’ mostró un rendimiento promedio de 1287 y 1764 kg ha-1, respectivamente, que superó al de los demás genotipos. En los sitios con presión por enfermedades, ‘Negro Comapa’ resultó resistente al virus mosaico común (BCMV) y a la mancha angular, y tolerante al virus del mosaico amarillo dorado del frijol (BGYMV). En parcelas de validación, el rendimiento promedio de ‘Negro Comapa’ fue 51 % mayor que el testigo del agricultor.

Registration of PR0401‐259 and PR0650‐31 Dry Bean Germplasm Lines

Web blight (WB), caused by Thanatephorus cucumeris (Frank) Donk (anamorph: Rhizoctonia solani Kühn), is an important disease of common bean (Phaseolus vulgaris L.) in the humid tropics. Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Smith) Vauterin et al., and Bean common mosaic virus (BCMV) pose a threat to common bean production throughout the world. The development and release of dry bean cultivars with enhanced levels of resistance to these and other diseases is an important goal of the University of Puerto Rico (UPR) breeding program. PR0401‐259 (Reg. No. GP‐286, PI 663155) and PR0650‐31 (Reg. No. GP‐285, PI 663154) are multiple‐disease‐resistant bean germplasm lines adapted to the humid tropics and were developed and released cooperatively in 2011 by the UPR Agricultural Experiment Station, the USDA‐ARS, and the Escuela Agrícola Panamericana in Honduras. PR0401‐259 is a pink bean line and PR0650‐31 is a black bean line that possess the allele at the I locus that confers resistance to BCMV. Both lines have high levels of resistance to CBB and moderate levels of resistance to WB. PR0401‐259 also has the bgm‐1 gene for resistance to Bean golden yellow mosaic virus. PR0401‐259 and PR0650‐31 produced mean seed yields similar to those of the check varieties ‘Talamanca’ and ‘Amadeus 77’. PR0401‐259 and PR0650‐31 should serve as useful sources of resistance to WB, CBB, and BCMV.

Begomoviruses Associated with Bean Golden Mosaic Disease in Nicaragua.

Begomovirus spp. cause substantial losses in bean crops in tropical and subtropical regions of the Americas. The predominant Begomovirus sp. in Central America associated with golden mosaic symptoms in bean is Bean golden yellow mosaic virus (BGYMV). However, Calopogonium golden mosaic virus was previously found to infect bean crops in the northern region of Costa Rica. The objective of this research was to identify Begomovirus spp. that infect bean plants in different geographical regions of Nicaragua. In all, 126 samples of young bean leaves with symptoms of golden mosaic were collected from eight different regions of Nicaragua. Using DNA hybridization with specific probes, 120 samples tested positive for BGYMV, 14 samples tested positive for Squash yellow mild mottle virus, and 7 samples tested positive for Calopogonium golden mosaic virus. Sequence analysis of polymerase chain reaction-amplified products from three samples (MA-9 Managua, BE-8 Rivas, and SO-9 Granada) also indicated that the symptoms of golden mosaic in bean are associated with viral sequences from three different Begomovirus spp. Management of bean golden mosaic disease must take into account that BGYMV is the predominant virus (95% of the samples) and that 12% of the samples exhibited possible mixed infections or recombination events in the south and central geographical regions of Nicaragua.

Breeding Common Bean for Resistance to Diseases: A Review

Diseases cause severe losses (20–100%) to yield and quality of common bean (Phaseolus vulgaris L.) worldwide. Our objectives were to describe major bean disease problems in the Americas and review progress achieved in breeding for resistance. We also describe strategies to integrate genetic improvement for resistance to multiple diseases with cultivar development. Common bacterial blight, halo blight, and bacterial brown spot are the major bacterial diseases. Angular leaf spot, anthracnose, root rots, rust, and white mold are severe fungal diseases. Bean common mosaic virus (BCMV), Bean golden mosaic virus (BGMV), Bean golden yellow mosaic virus (BGYMV), and Beet curly top virus (BCTV) are important viral diseases. Breeding for resistance to one or two diseases at a time is emphasized. Backcross, pedigree, and bulk‐pedigree methods of breeding are used. The use of molecular markers has gradually increased. Substantial progress has been made in breeding and genetics of resistance to most of these diseases; however, improvement in resistance to bacterial brown spot, halo blight, root rots, and web blight has been slow and localized. Furthermore, cultivars with high levels of resistance to one or more quantitatively inherited diseases (e.g., common bacterial blight and white mold) are rare. Breeding strategies for simultaneous and integrated genetic improvement of multiple qualitatively and quantitatively inherited resistances and cultivar development are briefly described.

Inoculation of plants with begomoviruses by particle bombardment without cloning: Using rolling circle amplification of total DNA from infected plants and whiteflies

A new system for inoculation of plants with begomoviral DNA without cloning or the use insect vectors is described. Total DNA extracted from begomovirus-infected plants was amplified by rolling circle amplification (RCA) using the bacteriophage phi29 DNA polymerase, and inoculated to plants by particle bombardment. Infection rates of up to 100% were obtained using this technique. This technique successfully inoculated all the begomoviruses evaluated: five bipartite ( Bean golden yellow mosaic virus, Cabbage leaf curl virus, Squash leaf curl virus, Tomato mottle virus, Watermelon chlorotic stunt virus) as well as one monopartite ( Tomato yellow leaf curl virus). The success of the technique was not dependent upon plant species. Four species from three plant families [ Phaseolus vulgaris (bean), Solanum lycopersicum (tomato), Cucurbita pepo (squash), and Citrullus lanatus (watermelon)], could all be inoculated by this technique. The success of the method was not dependent upon either the type or the age of the source of virus. Infectious DNA was obtained successfully from fresh, freeze-dried or desiccated plant material, from squashes of plant leaves on FTA cards, as well as from the insect vector. Plant material collected and dried as long as 25 years ago yielded infectious DNA by this method. In summary, this method can be used to obtain infectious DNA of single-stranded circular DNA viruses that can be activated for purposes of completing Koch's postulates, for preservation of pure virus cultures, and for many other applications where infectious DNA is required.

Registration of ‘Verano’ White Bean

‘Verano’, Reg. No. CV‐282, PI 653706, a multiple disease resistant white bean (Phaseolus vulgaris L.) cultivar adapted to the humid tropics, was developed and released in 2007 cooperatively by the University of Puerto Rico Agricultural Experiment Station and the USDA‐ARS. Verano has tolerance to high temperature and resistance to Bean golden yellow mosaic virus, a whitefly [Bemisia tabaci (Gennadius)]‐transmitted begomovirus, Bean common mosaic virus, and common bacterial blight [caused by Xanthomonas axonopodis pv. phaseoli (Smith) Dye]. The release and adoption of a high temperature–tolerant cultivar such as Verano will improve yield and seed quality of green‐shelled beans produced in Puerto Rico. Verano possesses traits that may be useful to breeding programs where high temperature, viral diseases, and common bacterial blight limit bean production.