Bean Common Mosaic Virus Strains Research Articles

Nanoparticles of Chitosan and Bougainvillea Leaf Extract: Characterization and Its Application to Control Bean common mosaic virus strain Blackeye Cowpea

Kitosan dan ekstrak kasar daun bugenvil diketahui mampu mengendalikan beberapa virus tanaman termasuk Bean common mosaic virus strain Blackeye Cowpea (BCMV-BlC). Untuk mengurangi penggunaan bahan baku dan peningkatan keefektifan juga stabilitasnya, kedua bahan perlu disintesis menggunakan teknologi nanpopartikel (NP). Penelitian bertujuan menyintesis nanopartikel kitosan, ekstrak daun bugenvil, dan kombinasinya menggunakan modifikasi metode gelasi ionik, mengarakterisasi NP dan mengevaluasi potensi NP untuk mengendalikan BCMV-BlC pada tanaman indikator Chenopodium amaranticolor. Nanopartikel kitosan (Kit-NP), ekstrak daun bugenvil (EDB-NP), dan kombinasinya (KEDB-NP) berhasil disintesis dengan rata-rata ukuran partikel berturut-turut sebesar 99.72, 163.68, dan 221.42 nm berdasarkan pengamatan di bawah transmission electron microscope (TEM) dan berbentuk bola (sferis) berdasarkan hasil analisis scanning electron microscope (SEM). Hasil analisis fourier transform infrared (FTIR), KEDB-NP menunjukkan gugus fungsi berturut-turut hidroksil, alkena, amina, cincin aromatik, dan senyawa alifatik organohalogen. Daun C. amaranticolor yang diberi perlakuan Kit-NP, EDB-NP, KEDB-NP dan juga non-NP pada konsentrasi 100-800 ppm sebelum inokulasi virus menunjukkan jumlah rata-rata lesio lokal nekrotik (LLN) nyata lebih rendah dibandingkan kontrol tanaman sakit tanpa perlakuan dan tidak berbeda nyata antarkonsentrasi. Perlakuan NP dan non-NP sebelum inokulasi virus secara nyata memperpanjang periode inkubasi dan menekan pembentukan LLN dengan keefektifan 67.5%–100% dibandingkan dengan aplikasi setelah inokulasi virus. Di antara konsentrasi yang diuji, konsentrasi NP antara 100 dan 300 ppm yang diaplikasikan sebelum penularan virus menunjukkan paling efektif dalam menghambat pembentukan LLN. Sintesis EDB-NP, Kit-NP, dan KEDB-NP menggunakan sangat sedikit bahan baku, namun keefektifannya sebanding dengan bentuk non-NPnya dalam mengendalikan infeksi BCMV.

Screening of Bean Genotypes Against Bean Common Mosaic Virus (BCMV) by Artificial Inoculation and Molecular Confirmation

Bean mosaic virus (BCMV) is a widespread plant pathogen that causes significant bean yield losses in several bean-growing regions worldwide. The use of resistant common bean varieties to BCMV is considered the most efficient and feasible approach to control its effects. Numerous genes and molecular markers associated with resistance to these pathogens have been discovered and used extensively in breeding studies around the world. Screening bean genotypes for resistance to these viruses is a critical step in developing resistant varieties. The goals of the study are to identify virus sources in the region and artificially inoculate Lake Van basin bean genotypes with BCMV. The recovered BCMV strain NL-4 was inoculated with 45 bean cultivars, most of which originated from the Lake Van basin in Turkey. Differentiation between resistant and susceptible was based on visual symptoms, and of the 45 genotypes, 29 were found to be resistant to NL-4, while 16 genotypes were susceptible (8 of them moderately susceptible and 8 of them highly susceptible).

A novel study on bean common mosaic virus accumulation shows disease resistance at the initial stage of infection in Phaseolus vulgaris.

Accurate and early diagnosis of bean common mosaic virus (BCMV) in Phaseolus vulgaris tissues is critical since the pathogen can spread easily and have long-term detrimental effects on bean production. The use of resistant varieties is a key factor in the management activities of BCMV. The study reported here describes the development and application of a novel SYBR Green-based quantitative real-time PCR (qRT-PCR) assay targeting the coat protein gene to determine the host sensitivity to the specific NL-4 strain of BCMV. The technique showed high specificity, validated by melting curve analysis, without cross-reaction. Further, the symptoms development of twenty advanced common bean genotypes after mechanical BCMV-NL-4 infection was evaluated and compared. The results showed that common bean genotypes exhibit varying levels of host susceptibility to this BCMV strain. The YLV-14 and BRS-22 genotypes were determined as the most resistant and susceptible genotypes, respectively, in terms of aggressiveness of symptoms. The accumulation of BCMV was analyzed in the resistant and susceptible genotypes 3, 6, and 9days following the inoculation by the newly developed qRT-PCR. The mean cycle threshold (Ct) values showed that the viral titer was significantly lower in YLV-14, which was evident in both root and leaf 3days after the inoculation. The qRT-PCR thus facilitated an accurate, specific, and feasible assessment of BCMV accumulation in bean tissues even in low virus titers, allowing novel clues in selecting resistant genotypes in the early stages of infection, which is critical for disease management. To the best of our knowledge, this is the first study of a successfully performed qRT-PCR to estimate BCMV quantification.

Characterization of Bean common mosaic virus strain blackeye cowpea mosaic infecting cowpea (Vigna unguiculata (L.) Walp.) in Egypt

Characterization of Bean common mosaic virus strain blackeye cowpea mosaic infecting cowpea (Vigna unguiculata (L.) Walp.) in Egypt

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.

The first report of bean common mosaic virus (BCMV) infection of African yam bean (Sphenostylis stenocarpa) in Nigeria

African yam bean (Sphenostylis stenocarpa) is an underutilized crop that has the potential to contribute to sustainable food security. In October 2021, more than 90% African Yam Bean (AYB) plants showed typical virus symptoms of mosaic and necrosis in the grain legumes field of the Institute of Agricultural Research and Training (IAR&T), Nigeria. Subsequently, leaf samples were collected and tested by ELISA and PCR to identify the virus species. Anti-BCMV and anti-potyvirus antibodies both gave positive results when symptomatic leaves were tested, and PCR using primers designed to the coat protein gene of BCMV amplified a band of the expected size (469bp). The sequence of the PCR product was deposited in GenBank with the accession No. OL763314. The nucleotide sequence of the coat protein gene had 99% identity with BCMV isolate TN2 (KY044818). The identities of the nucleotide and amino acid sequence of the partial CP gene of the isolated virus relative to those of other potyviruses were 82.96-99.12% and 87.33-100%,, respectively. Phylogenetic analyses of the partial CP-nucleotide sequences grouped the isolate from this study (BCMV-IART-AYB) and BCMV-TN2 in the same cluster with other BCMV strains of the peanut stripe (PSt) and the blackeye cowpea (BlC) strains. In this study, we identified Bean commom mosaic virus (BCMV) infecting AYB for the first time in Nigeria and show that it has high nucleotide and amino acid identity with an Isolate of cowpea-infecting BCMV in India and China respectively than isolate in Nigeria.

Registration of the slow‐darkening pinto common bean cultivar ‘Wildcat’

AbstractSlow‐darkening pinto common bean (Phaseolus vulgaris L.) cultivar ‘Wildcat’ (Reg. no. CV‐345, PI 698190) was released by the University of Nebraska dry bean breeding program in 2018. It was bred for adaptation to western Nebraska growing conditions and enhanced resistance to bean rust, common bacterial blight (CBB), and Bean common mosaic virus (BCMV). The yield of Wildcat was comparable to conventional and slow‐darkening pinto bean cultivars grown in Nebraska from 2015 to 2020. During the 2017 Western Regional Bean Trial, 2017 Midwest Regional Performance Nursery, and 2018 Cooperative Dry Bean Nursery, Wildcat had a higher seed yield than ‘Twin Falls’, ‘Nez Perce’, ‘Black Foot’, ‘Montrose’, ‘Buster’, ‘ND‐Palomino’, and ‘La Paz’ at some locations. Wildcat has the Ur‐11 gene that confers resistance to all but one known bean rust race and carries the Indel NDSU_IND_11_48.459.896 marker tagging the Ur‐11 locus. Wildcat also has the SAP6 sequence characterized amplified region (SCAR) marker linked to a major CBB resistance quantitative trait locus, with an intermediate CBB rating (5.0) under field conditions at western Nebraska in 2020. Wildcat also carries the single dominant I gene that confers resistance to all non‐necrotic strains of BCMV and the SW13 SCAR marker linked to the I gene for resistance to BCMV. Wildcat has white flowers, blooms 46 d after planting, and is a full‐season bean, maturing 93 d after planting. The seed size of Wildcat, 43.3 g 100 seeds–1 on average, was significantly larger than current conventional and slow‐darkening pinto beans.

Registration of ‘White Pearl’ great northern common bean cultivar with upright plant architecture and high yield

AbstractGreat northern common bean (Phaseolus vulgaris L.) cultivar ‘White Pearl’ (Reg. no. CV‐343, PI 698189) was developed by the dry bean breeding program at the University of Nebraska and released in 2018. It was bred specifically for adaptation to western Nebraska growing conditions and for upright plant architecture, high yield, and enhanced resistance to bean rust, common bacterial blight (CBB), and Bean common mosaic virus (BCMV). Seed yield of White Pearl was comparable and slightly higher than other great northern cultivars in on‐station trials conducted in Nebraska and did not differ significantly in yield from ‘Aries’ and ‘Matterhorn’ in regional trials. Seed size (100‐seed weight) of White Pearl was larger than ‘Marquis’, ‘Orion’, ‘Gemini’, ‘Beryl‐R’, and Aries in trials grown in Nebraska. White Pearl carries the sequence characterized amplified region (SCAR) marker SAP6 linked to a major quantitative trait locus (QTL) for resistance to CBB. White Pearl had a CBB disease rating of 6.0 (intermediate) under field conditions at the Scottsbluff and Mitchell Ag Labs in 2020. White Pearl also has the Ur‐3 gene for resistance to bean rust and carries the SS68 Kompetitive Allele Specific polymerase chain reaction (KASP) and SK14 SCAR markers linked to the Ur‐3 locus. It also contains the single dominant hypersensitive I gene that confers resistance to all non‐necrotic strains of BCMV and the SW13 SCAR marker linked to the I gene. White Pearl has bright white seed, blooms 46 d after planting, and is a midseason bean, maturing 89 d after planting.

Identification of stable resistant donors against necrosis inducing strain of bean common mosaic virus in common bean (Phaseolus vulgaris L.)

Most of the commercially approved cultivars of Phaseolus vulgaris were susceptible to bean common mosaic virus (BCMV) which results in severe reduction in yield. In the present study, a total of 350 common bean genotypes were screened under natural epiphytotic conditions and artificial inoculation during 2016–2017, 2017–2018 and 2018–2019. Only eleven genotypes viz., EC400445, EC400414, ET4515B, EC540173, IC360831, BD9116291, EC31084, EC541703, ET8409, IC340947 and IC356024 were found stable resistant. The BCMV infection was confirmed through reverse-transcription polymerase chain reaction using coat protein gene amplification. The amplified region was sequenced and analyzed. Percent identity of BCMV-K with reported BCMV strains from different parts of world and based on nucleotide sequence ranged between 94% and 99.70% and maximum identity (99.70%) is observed with the strains of Uttar Pradesh (MT265069) and Himachal Pradesh (FJ387162, EU492546). The identified resistant sources from this study could be utilized as donors to develop BCMV resistant common bean cultivars.

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.

Incidence and severity of bean common mosaic disease and resistance of popular bean cultivars to the disease in western Kenya

AbstractThe common bean (Phaseolus vulgaris) is a high protein crop and the main legume in the cropping system of western Kenya. Despite its importance, common bean yields are low (<1.0 t/ha) and declining. Bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV) are the most common and most destructive viruses and can cause a yield loss as high as 100%. In Kenya, a limited number of cultivars and exotic genotypes with resistance to BCMV and BCMNV strains have been reported. This study sought to determine the distribution and screen popular cultivars for resistance to the viruses. In October 2016 and May 2017, two diagnostic surveys for bean common mosaic disease (BCMD) were conducted in seven counties of western Kenya namely Bungoma, Busia, Homa Bay, Nandi, Vihiga, Kakamega and Siaya. Leaf samples showing virus‐like symptoms were collected and analysed by ELISA. Sixteen popularly grown bean cultivars together with cowpea (Vigna unguiculata), soybean (Glycine max), green grams (Vigna radiata) and groundnut (Arachis hypogaea) were planted in a greenhouse in a completely randomized block design with three replicates. The plants were inoculated with BCMNV isolate at 3‐leaf stage. Data were taken weekly for 3 weeks on type of symptoms expressed and number of plants infected. In total, 270 bean farms were visited. Symptoms of mosaic, downward curling, local lesions, stunting or a combination of these were observed during both surveys. Mean virus incidence was higher in the short rain season (50.2%) than in the long rain season (35.6%). The mean BCMD severity on a scale of 0–3 was highest (2.3) in Kakamega County and lowest (0.5) in Siaya. On variety resistance tests to BCMNV isolate, 10 bean cultivars were susceptible, four tolerant and two resistant. BCMNV is widely distributed across counties probably because of use of uncertified seeds by farmers and inoculum pressure from seed and aphid vector. For improved yields of common bean, farmers should be advised to plant certified seeds for all legumes in the cropping system.

Поширення вірусу звичайної мозаїки квасолі з насінням phaseolus vulgaris cv Червона Шапочка

Досліджено ефективність двох штамів р. Bacillus, B. subƟlis 16 and B. pumilus 11, проти хвороб ячменю ярого, що спричиняються грибом Bipolaris sorokiniana (Sacc.) Shoemaker. Встановлено, що антагоністична активність залежить як від стійкості сорту, так і від штаму бактерії. Суттєве зниження розвитку темно-бурої плямистості листків відмічали на найбільш сприйнятливому до хвороби сорті ячменю Нащадок у разі обробки рослин суспензією клітин штаму B. subƟlis 16. За внесення в ризосферу ячменю бактеріальних суспензій обох штамів відмічене суттєве зниження розвитку звичайної кореневої гнилі на сприйнятливому до хвороби сорті ячменю ярого Сяйво, що, проте, не супроводжувалося збільшенням маси проростків. Суттєвий приріст біомаси коренів і проростків при обробці бактеріальними інокулянтами відмічали на сортах із середньою стійкістю до хвороби: Себастьян і Антей.

A New Strain of Bean Common Mosaic Virus From Lima Bean (Phaseolus lunatus): Biological and Molecular Characterization.

Lima bean (Phaseolus lunatus) is a popular cultivated legume vegetable grown in the United States for dry bean or canned bean production. In 2017, two symptomatic P. lunatus plants exhibiting mosaic, vein banding, and growth retardation were collected in a public garden in Honolulu, HI. Both samples contained bean common mosaic virus (BCMV), and the two BCMV isolates were subjected to biological characterization on a panel of 11 differential cultivars of common bean (P. vulgaris), and to molecular characterization through whole genome sequencing. Both samples contained nearly identical BCMV sequences, named BCMV-A1, which, in turn, were 93% identical to the peanut stripe virus strain of BCMV. BCMV-A1 induced an unusually severe systemic necrosis in cultivar 'Dubbele Witte', and pronounced necrotic or chlorotic reaction in inoculated leaves of five other bean differentials. BCMV-A1 was able to partially overcome resistance alleles bc-1 and bc-2 expressed singly in common bean, inducing no systemic symptoms. Phylogenetic analysis of the BCMV-A1 sequence, and distinct biological reactions in common bean differentials suggested that BCMV-A1 represented a new lima bean strain of BCMV. In 2017, two BCMV isolates were collected in Idaho from common bean, and based on partial genome sequences were found 99% identical to the BCMV-A1 sequence. The data suggest that the lima bean strain of BCMV may have a wider circulation, including common bean as a host. This new strain of BCMV may thus pose a significant threat to common bean production.

Evaluation of Common Bean Cultivars Resistance to the Bean Common Mosaic Necrosis Virus in Western Kenya

The common bean (Phaseolus vulgaris), is a high protein crop and the main legume in the cropping system of western Kenya. Despite its importance, common bean yields are low (<1.0 t/ha) and declining. Bean Common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) are the most common and most destructive and can cause a yield loss as high as 100%. In Kenya, limited cultivars and exotic genotypes with resistance to BCMV and BCMNV strains have been reported. Reports indicate BCMNV being a widespread virus compared to BCMV in western Kenya. This study therefore, sought to screen popular cultivars for resistance to the virus. Sixteen popularly grown bean cultivars together with cowpea (Vigna unguiculata), soybean (Glycine max) and groundnut (Arachis hypogaea) were planted in a green house in a completely randomized block design with three replicates. The plants were inoculated with BCMNV Enzyme Linked Immunosorbent Assay (ELISA) positive isolate at 3-leaf stage. Data was taken weekly for 3 weeks on type of symptoms expressed and number of plants infected. Ten bean cultivars were susceptible, 4 tolerant and 2 resistant. For improved yields of common bean, farmers should be advised to plant certified seeds for all legumes in the cropping system.

A bean common mosaic virus (BCMV)-resistance gene is fine-mapped to the same region as Rsv1-h in the soybean cultivar Suweon 97.

In the soybean cultivar Suweon 97, BCMV-resistance gene was fine-mapped to a 58.1-kb region co-localizing with the Soybean mosaic virus (SMV)-resistance gene, Rsv1-h raising a possibility that the same gene is utilized against both viral pathogens. Certain soybean cultivars exhibit resistance against soybean mosaic virus (SMV) or bean common mosaic virus (BCMV). Although several SMV-resistance loci have been reported, the understanding of the mechanism underlying BCMV resistance in soybean is limited. Here, by crossing a resistant cultivar Suweon 97 with a susceptible cultivar Williams 82 and inoculating 220 F2 individuals with a BCMV strain (HZZB011), we observed a 3:1 (resistant/susceptible) segregation ratio, suggesting that Suweon 97 possesses a single dominant resistance gene against BCMV. By performing bulked segregant analysis with 186 polymorphic simple sequence repeat (SSR) markers across the genome, the resistance gene was determined to be linked with marker BARSOYSSR_13_1109. Examining the genotypes of nearby SSR markers on all 220 F2 individuals then narrowed down the gene between markers BARSOYSSR_13_1109 and BARSOYSSR_13_1122. Furthermore, 14 previously established F2:3 lines showing crossovers between the two markers were assayed for their phenotypes upon BCMV inoculation. By developing six more SNP (single nucleotide polymorphism) markers, the resistance gene was finally delimited to a 58.1-kb interval flanked by BARSOYSSR_13_1114 and SNP-49. Five genes were annotated in this interval of the Williams 82 genome, including a characteristic coiled-coil nucleotide-binding site-leucine-rich repeat (CC-NBS-LRR, CNL)-type of resistance gene, Glyma13g184800. Coincidentally, the SMV-resistance allele Rsv1-h was previously mapped to almost the same region, thereby suggesting that soybean Suweon 97 likely relies on the same CNL-type R gene to resist both viral pathogens.

Dynamic transcriptome profiling of Bean Common Mosaic Virus (BCMV) infection in Common Bean (Phaseolus vulgaris L.).

BackgroundBean common mosaic virus (BCMV) is widespread, with Phaseolus species as the primary host plants. Numerous BCMV strains have been identified on the basis of a panel of bean varieties that distinguish the pathogenicity types with respect to the viral strains. The molecular responses in Phaseolus to BCMV infection have not yet been well characterized.ResultsWe report the transcriptional responses of a widely susceptible variety of common bean (Phaseolus vulgaris L., cultivar ‘Stringless green refugee’) to two BCMV strains, in a time-course experiment. We also report the genome sequence of a previously unreported BCMV strain. The interaction with the known strain NL1-Iowa causes moderate symptoms and large transcriptional responses, and the newly identified strain (Strain 2 or S2) causes severe symptoms and moderate transcriptional responses. The transcriptional profiles of host plants infected with the two isolates are distinct, and involve numerous differences in splice forms in particular genes, and pathway specific expression patterns.ConclusionsWe identified differential host transcriptome response after infection of two different strains of Bean common mosaic virus (BCMV) in common bean (Phaseolus vulgaris L.). Virus infection initiated a suite of changes in gene expression level and patterns in the host plants. Pathways related to defense, gene regulation, metabolic processes, photosynthesis were specifically altered after virus infection. Results presented in this study can increase the understanding of host-pathogen interactions and provide resources for further investigations of the biological mechanisms in BCMV infection and defense.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2976-8) contains supplementary material, which is available to authorized users.

Distribution of BCMV strains in Kashmir valley and identification of resistant sources ofPhaseolus vulgaris

Extensive survey of 100 commercial bean growing areas of Kashmir was conducted during kharif 2009 and 2010 indicated only 13 locations to be free from Bean Common Mosaic Virus (BCMV) disease. The disease incidence ranged from 0.50 to 85%. The maximum disease incidence was recorded in Srinagar followed by districts Anantnag and Bandipora, respectively. Confirmation of the association of BCMV with each isolate was made by mechanical transmission, DAC-ELISA and RT-PCR. Evaluation of eighty-five accessions of common bean of diverse origin under controlled glass-house conditions identified R-40, R-155, R-3, B-6, Pencil white, SKAU-B-02, SKAU-B-01, Pointed lady, TO, P1207262, TU, KRC-5, R-14, Jubila, Contender and Monroe accessions to be resistance against all the five strains (NL-1, NL-1n, NL-7, NL-7n and NL-4) of BCMV prevalent in Kashmir.

Bean common mosaic virus Isolate Exhibits a Novel Pathogenicity Profile in Common Bean, Overcoming the bc-3 Resistance Allele Coding for the Mutated eIF4E Translation Initiation Factor.

Resistance against Bean common mosaic virus (BCMV) in Phaseolus vulgaris is governed by six recessive resistance alleles at four loci. One of these alleles, bc-3, is able to protect P. vulgaris against all BCMV strains and against other potyviruses; bc-3 was identified as the eIF4E allele carrying mutated eukaryotic translation initiation factor gene. Here, we characterized a novel BCMV isolate 1755a that was able to overcome bc-2 and bc-3 alleles in common bean. Thus, it displayed a novel pattern of interactions with resistance genes in P. vulgaris, and was assigned to a new pathogroup, PG-VIII. The IVT7214 cultivar supporting the replication of BCMV-1755a was found to have the intact homozygous bc-3 cleaved amplified polymorphic sequences marker and corresponding mutations in the eIF4E allele that confer resistance to BCMV isolates from all other pathogroups as well as to other potyviruses. The VPg protein of 1755a had seven amino acid substitutions relative to VPgs of other BCMV isolates unable to overcome bc-3. The 1755a genome was found to be a recombinant between NL1, US1 (both PG-I), and a yet unknown BCMV strain. Analysis of the recombination patterns in the genomes of NL1 and US1 (PG-I), NY15P (PG-V), US10 and RU1-OR (PG-VII), and 1755a (PG-VIII), indicated that P1/HC-Pro cistrons of BCMV strains may interact with most resistance genes. This is the first report of a BCMV isolate able to overcome the bc-3 resistance allele, suggesting that the virus has evolved mechanisms to overcome multiple resistance genes available in common bean.

Bahasa Indonesia

Recently, a mosaic disease was observed on jack bean cultivation in Dramaga, Bogor,West Java. The symptom on infected plants, i.e. combination of pale and dark green area was more obvious on young leaves. Vein banding, leaf malformation, and growth inhibition was also observed in infected plants. The symptom was not very obvious in older leaves. Serological detection gave positive reaction to Bean common mosaic virus (BCMV) antiserum, but reaction was negative when detected using specific primer to coat protein (CP) of BCMV strain black eye by reverse transcription polymerase chain reaction. DNA fragments were successfully amplified by RT-PCR using universal primer of CP gene and degenerated primer for cylindrical inclusion gen (CI) of Potyvirus. DNA analysis showed the highest homology (86.4–91.5%) to several isolates of BCMV-infecting different crops from several countries based on partial sequence of CP, whereas based on partial sequence of CI the highest homology (87.3%) was to BCMV-RU1-P. This is the first report of BCMV infection on jack bean in Bogor, West Java, Indonesia.

First Report of Bean common mosaic virus Infecting Mungbean (Vigna radiata) in China.

Bean common mosaic virus (BCMV) is a member of the genus Potyvirus and one of the numerous viruses that can infect Phaseolus vulgaris. In May of 2013, we planted more than 100 varieties of mungbean in fields and a greenhouse of Nanjing. Mungbean (Vigna radiata (Linn.) Wilczek.) with leaves displaying mosaic and shrinkage typical of viral infection was observed in a greenhouse and a field in Nanjing. About 60% of the varieties can be infected. The symptoms in some sources from Southeast Asian countries and wild germplasm are heavier, while the symptoms are lighter on the local varieties. It can be transmitted to mungbean via aphid or mechanical inoculation, or by seeds. The infected leaves were collected for electron micrograph analysis. Pinwheel inclusion and filamentous virus particles were observed, indicating a Potyvirus infection. To confirm the presence of Potyvirus infection, total RNA was extracted from plants from the greenhouse and field, and RT-PCR was performed using universal Potyvirus primers (Sprimer (+) 5'-GGXAAYAAYAGYGGXCAZCC-3'; X=A, G, C or T, Y=T or C, Z=A or G); M4T (5'-GTTTTCCCAGTCACGAC(T)-3'), which amplify a region of the 3' fragment of the RNA-dependent RNA polymerase of potyviruses (1). The 596-bp sequence was found to be 95% identical to the BCMV isolate HB (GenBank Accession No. KC478389.1). To confirm the presence of BCMV, three leaf samples were randomly collected and all were determined to be positive when subjected to ELISA using BCMV-specific antibodies. The virus infecting mungbean was identified as BCMV and the strain was named BCMV-JAAS (KJ866945). Using gene-specific primers (BCMV-cp-F: 5'-CAAAAGGACAAGGATTGAGGA, BCMV-cp-R: 3'-ACAACAAACATTGCCGTAGC) for the reported coat protein gene in BCMV, a 1,080-bp gene fragment was amplified from the total RNA of the isolate, and subsequent sequence analysis indicated that an 862-bp region contained the complete cp gene that encodes a 228 amino acid protein. The nucleotide sequences of the cp gene from the isolate shared 96% homology with the reported BCMV-HB. The phylogenetic trees based on the CP gene show that BCMV-JAAS (KJ866945) was most closely related to other Chinese BCMV isolates (KF439722.1 and AJ132145.1) followed by Azuki mosaic virus (AB012663.1) and Peanut stripe virus (U34972.1). These results indicate that the virus associated with the mosaic disease in mungbean is an isolate of BCMV. To our knowledge, this is the first report of BCMV infecting mungbean in China. BCMV affects a wide range of legume crops and can spread rapidly, causing serious harm. The discovery could effectively control BCMV and characterize the prevalent BCMV strains. Research utilizing whole-genome sequencing of the mungbean isolate is continuing and is currently being expanded to characterize the genetic diversity of the virus, assisting in the study of the evolution of the virus. Reference: (1) J. Chen and J. P. Chen. Chin. J. Virol. 18:372, 2002.