Bean Common Mosaic Virus Research Articles

Correction: Identification and molecular validation of Bean Common Mosaic Virus Resistant Donors in Common Bean (Phaseolus vulgaris L.)

Correction: Identification and molecular validation of Bean Common Mosaic Virus Resistant Donors in Common Bean (Phaseolus vulgaris L.)

K-mer genome-wide association study for anthracnose and BCMV resistance in a Phaseolus vulgaris Andean Diversity Panel.

Access to broad genomic resources and closely linked marker-trait associations for common beans (Phaseolus vulgaris L.) can facilitate development of improved varieties with increased yield, improved market quality traits, and enhanced disease resistance. The emergence of virulent races of anthracnose (caused by Colletotrichum lindemuthianum) and bean common mosaic virus (BCMV) highlight the need for improved methods to identify and incorporate pan-genomic variation in breeding for disease resistance. We sequenced the P. vulgaris Andean Diversity Panel (ADP) and performed a genome-wide association study (GWAS) to identify associations for resistance to BCMV and eight races of anthracnose. Historical single nucleotide polymorphism (SNP)-chip and phenotypic data enabled a three-way comparison between SNP-chip, reference-based whole genome shotgun sequence (WGS)-SNP, and reference-free k-mer (short nucleotide subsequence) GWAS. Across all traits, there was excellent concordance between SNP-chip, WGS-SNP, and k-mer GWAS results-albeit at a much higher marker resolution for the WGS data sets. Significant k-mer haplotype variation revealed selection of the linked I-gene and Co-u traits in North American breeding lines and cultivars. Due to structural variation, only 9.1 to 47.3% of the significantly associated k-mers could be mapped to the reference genome. Thus, to determine the genetic context of cis-associated k-mers, we generated draft whole genome assemblies of four ADP accessions and identified an expanded local repertoire of disease resistance genes associated with resistance to anthracnose and BCMV. With access to variant data in the context of a pan-genome, high resolution mapping of agronomic traits for common bean is now feasible.

Characterization of Two Novel Viruses Within a Complex Virome from Flowering Ginger in Hawaii.

Flowering ginger (Alpinia purpurata) is economically and culturally important in Hawaii. In the past decade, a slow decline syndrome has impacted the production of this crop in the state. RNA sequencing analyses and virus indexing surveys were done on samples collected from four of the Hawaiian Islands. Viral sequences corresponding to six viruses were recovered from transcriptomic data from samples with virus-like symptoms. Canna yellow mottle virus (CaYMV, genus Badnavirus) and two novel viruses, Alpinia vein clearing virus (ApVCV, genus Ampelovirus) and Alpinia vein streaking virus (ApVSV, genus Betanucleorhabdovirus), were found at a moderate incidence in diseased plants. Conversely, three other viruses, including the two potyviruses, banana bract mosaic virus and bean common mosaic virus, and a badnavirus, banana streak GF virus, were also found but at a low incidence. Virus detection in potential insect vectors and transmission assays identified the mealybug Planococcus citri as a vector of CaYMV and ApVCV, whereas the aphid Pentalonia caladii was identified as a vector of the novel ApVSV. Both P. citri and P. caladii are common pests of flowering ginger in Hawaii. Transmission of ApVSV was achieved using P. caladii colonies either established in the laboratory or naturally feeding on infected plants, although no transmission was obtained using viruliferous aphids originally reared on taro (Colocasia esculenta). Our study provides insights into the potential association between viral infections and the observed decline symptoms of flowering ginger in Hawaii. However, more definitive studies are needed to link single or mixed viral infections with decline symptoms.

A Genetic Study of Spillovers in the Bean Common Mosaic Subgroup of Potyviruses.

Nine viruses of the bean common mosaic virus subgroup of potyviruses are major international crop pathogens, but their phylogenetically closest relatives from non-crop plants have mostly been found only in SE Asia and Oceania, which is thus likely to be their "centre of emergence". We have compared over 700 of the complete genomic ORFs of the crop pandemic and the non-crop viruses in various ways. Only one-third of crop virus genomes are non-recombinant, but more than half the non-crop virus genomes are. Four of the viruses were from crops domesticated in the Old World (Africa to SE Asia), and the other five were from New World crops. There was a temporal signal in only three of the crop virus datasets, but it confirmed that the most recent common ancestors of all the crop viruses were before inter-continental marine trade started after 1492 CE, whereas all the crown clusters of the phylogenies are from after that date. The non-crop virus datasets are genetically more diverse than those of the crop viruses, and Tajima's D analyses showed that their populations were contracting, and only one of the crop viruses had a significantly expanding population. dN/dS analyses showed that most of the genes and codons in all the viruses were under significant negative selection, and the few that were under significant positive selection were mostly in the PIPO-encoding region of the P3 protein, or the PIPO protein itself. Interestingly, more positively selected codons were found in non-crop than in crop viruses, and, as the hosts of the former were taxonomically more diverse than the latter, this may indicate that the positively selected codons are involved in host range determination; AlphaFold3 modelling was used to investigate this possibility.

Characterization of bean common mosaic virus isolates infecting three leguminous bean crops from South and Southeast Asia.

Bean common mosaic virus (BCMV) is causing economically important diseases in leguminous crops worldwide. In this study, BCMV isolates from country bean (CB, Lablab purpureus), yard-long bean (YLB, Vigna unguiculata) and rajma bean (RB, Phaseolus vulgaris) collected from Bangladesh, Nepal and Cambodia were characterized. Samples tested positive for BCMV in serological assays were subjected to high-throughput sequencing to generate near full-length genome sequences. In pair-wise comparisons of the polyprotein open reading frame, thirteen BCMV isolates from Bangladesh, Cambodia, and Nepal showed sequence identity of 92.1 to 98.8% at the nucleotide and 94.2 to 99% at the amino acid level among themselves and with corresponding sequences of BCMV reported previously. In phylogenetic analyses using the global BCMV sequences, they segregated into five distinct lineages, with RB isolates from Nepal clustering with US1/NL1-clade of common bean isolates from different countries, YLB isolates aligning with blackeye cowpea strain sequences reported from China, and CB isolates from Nepal and Bangladesh clustering with soybean isolates from China. One YLB isolate from Nepal was identified as a putative recombinant. None of the BCMV sequences aligned with isolates representing the RU1 or PStV clades. In grow-out tests, seed samples from local markets showed 14.3 to 38.1% transmission efficiency rate of BCMV with CB seed lots and from 9.5% to 33.3% with YLB seed lots.

Reverse Transcription-polymerase Chain Reaction (RT-PCR) Based Detection and Identification of Monopartite Bean Common Mosaic Virus in Mungbean

Background: Bean common mosaic virus (BCMV) which belongs to the genus Potyvirus and the family Potyviridae, causes significant yield losses in legumes across the globe. Traditional methods for BCMV detection and diagnosis, such as visual inspection and serological assays, are often time-consuming, labour-intensive and may lack the sensitivity required for early detection. Advances in molecular techniques have made RT-PCR a powerful tool for the accurate detection of BCMV-infected plants. Methods: Three pairs of specific primers that flank the BCMV coat protein and polyprotein gene were designed using the Primer 3web tool to amplify fragments approximately ranging from 191 to 205 bp. The RT-PCR protocol was then standardized, including the optimization of annealing temperatures for all three primers, followed by the sequencing of the amplified PCR products. The, specificity and sensitivity of primer pair BCMV2 were then established. Result: Three pairs of specific primers were designed and RT-PCR protocol was standardized. The sequenced PCR products showed 98.03% to 99.50 % nucleotide similarity with the corresponding sequences of BCMV isolates used in primer designing. Further, the BCMV2 primer pair specifically amplified the target amplicon (200 bp) from the suspected leaf sample and no amplicon was observed when tested against other pathotypes of potyvirus such as BCMNV, BYMV, CABMV, SMV and PeMoV. The designed primer was sensitive enough to detect 0.05% of target cDNA. Additionally, the RT-PCR protocol was validated using field samples collected from Hyderabad, India. ELISA in combination with RT-PCR using the developed specific BCMV primer pair will ensure a foolproof, sensitive and rapid, procedure for diagnosis of BCMV in the quarantine processing of imported germplasm.

Registration of ‘AuSable’ navy bean

Abstract‘AuSable’ (Reg. no. CV‐358, PI 705150) navy bean (Phaseolus vulgaris L.), developed by Michigan State University AgBioResearch was released in 2023 as an early‐mid season, disease‐resistant, upright, short‐vine bean cultivar with excellent dry down. AuSable was developed with the pedigree breeding method to the F4 generation followed by pure line selection for disease, agronomic, and quality traits. In 6 years of field trials, AuSable yielded 3073 kg ha−1, flowered in 46 days, and matured in 95 days on average. Plants averaged 45 cm in height, with a lodging resistance score of 1.7 and seed size of 22 g 100 seed−1. AuSable combines high yield potential with early midseason maturity in a navy bean seed type. AuSable has outyielded ‘Merlin’ by 17% across 6 years and matured 3 days earlier. It exhibits uniform dry down equivalent to ‘Vigilant’ and is well adapted to the intensively managed, narrow row, direct‐harvested production systems where beans are typically grown in Michigan and the Upper Midwest. AuSable possesses resistance to Bean common mosaic virus, is resistant to anthracnose races 7 and 73, has shown moderate tolerance to white mold, and was as tolerant to post emergence damping off caused by Rhizoctonia solani as other navy beans. It is susceptible to common bacterial blight. The seed size of AuSable (22 g 100 seed−1) is most similar to ‘Valiant’ and slightly smaller than ‘Liberty’ (23 g 100 seed−1). Seed of AuSable meets industry standards for packaging and canning quality in the navy bean seed class.

Release of ‘Kikatiti’ a multiple disease resistant pinto bean cultivar with superior productivity in Tanzania identified from evaluation of the Durango Diversity Panel

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

Advancing common bean (Phaseolus vulgaris L.) disease detection with YOLO driven deep learning to enhance agricultural AI

Common beans (CB), a vital source for high protein content, plays a crucial role in ensuring both nutrition and economic stability in diverse communities, particularly in Africa and Latin America. However, CB cultivation poses a significant threat to diseases that can drastically reduce yield and quality. Detecting these diseases solely based on visual symptoms is challenging, due to the variability across different pathogens and similar symptoms caused by distinct pathogens, further complicating the detection process. Traditional methods relying solely on farmers’ ability to detect diseases is inadequate, and while engaging expert pathologists and advanced laboratories is necessary, it can also be resource intensive. To address this challenge, we present a AI-driven system for rapid and cost-effective CB disease detection, leveraging state-of-the-art deep learning and object detection technologies. We utilized an extensive image dataset collected from disease hotspots in Africa and Colombia, focusing on five major diseases: Angular Leaf Spot (ALS), Common Bacterial Blight (CBB), Common Bean Mosaic Virus (CBMV), Bean Rust, and Anthracnose, covering both leaf and pod samples in real-field settings. However, pod images are only available for Angular Leaf Spot disease. The study employed data augmentation techniques and annotation at both whole and micro levels for comprehensive analysis. To train the model, we utilized three advanced YOLO architectures: YOLOv7, YOLOv8, and YOLO-NAS. Particularly for whole leaf annotations, the YOLO-NAS model achieves the highest mAP value of up to 97.9% and a recall of 98.8%, indicating superior detection accuracy. In contrast, for whole pod disease detection, YOLOv7 and YOLOv8 outperformed YOLO-NAS, with mAP values exceeding 95% and 93% recall. However, micro annotation consistently yields lower performance than whole annotation across all disease classes and plant parts, as examined by all YOLO models, highlighting an unexpected discrepancy in detection accuracy. Furthermore, we successfully deployed YOLO-NAS annotation models into an Android app, validating their effectiveness on unseen data from disease hotspots with high classification accuracy (90%). This accomplishment showcases the integration of deep learning into our production pipeline, a process known as DLOps. This innovative approach significantly reduces diagnosis time, enabling farmers to take prompt management interventions. The potential benefits extend beyond rapid diagnosis serving as an early warning system to enhance common bean productivity and quality.

Registration of ‘Coral’ pink bean

Abstract‘Coral’ (Reg. no. CV‐359, PI 705151) pink bean (Phaseolus vulgaris L.), developed by Michigan State University AgBioResearch was released in 2022 as a midseason, disease‐resistant, upright short vine bean cultivar with uniform dry down. Coral was developed with the pedigree breeding method to the F4 generation followed by pure line selection for disease, agronomic, and quality traits. Coral combines high yield potential with midseason maturity in a pink bean seed type. Over the span of 6 years of field trials, Coral produced an average yield of 3228 kg ha−1, flowered at 46 days, and matured in 97 days. Plants averaged 48 cm in height, with a lodging resistance score of 1.4, and seed size of 42 g 100 seed−1. Notably, Coral has outperformed ‘Rosetta’ by 8% across the 6‐year trial period and reached maturity 1 day earlier. It is well adapted to the intensively managed, narrow‐row, direct‐harvested production systems where beans are typically grown in Michigan and the Upper Midwest. Coral exhibits resistance to Bean common mosaic virus, is susceptible to anthracnose, has shown tolerance to common bacterial blight, and white mold. Additionally, it demonstrated tolerance to root rot caused by Rhizoctonia solani similar to Rosetta. Seed size of Coral (42 g 100 seed−1) is larger than Rosetta (37 g 100 seed−1). Seed of Coral meets industry standards for packaging and canning quality in the pink bean seed class.

Epidemiology and Management of Bean Common Mosaic Virus (BCMV) in Traditional Phaseolus vulgaris L. Landraces within Protected Geographical Indications

Protected geographical indications (PGIs) share health problems related to plant propagation material. The PGI “Faba de Lourenzá” encompasses a 1660 km2 area in northern Galicia, Spain, renowned for its “Faba Galaica” (FG) and Faba do marisco” (FM) bean cultivars. The lack of certified virus-free seeds poses a challenge. From 2019 to 2023, seeds from 60 lots were tested for BCMV. Plants from several plots were tested periodically to develop disease progress curves (DPCs). Control methods (plots out PGI zone, virus-free seedlings, rogueing, corn borders, and intercropping) were tested. Yields in five plots were used to assess BCMV’s economic impact. Seed lots were 22.3% FG-infected and <5% FM-infected. The transmission rate of BCMV from infected FG plants to their seeds was 25.5 ± 5%, while for FM it was 12 ± 3%. FG yield losses were on average 31.6 ± 4.5%. Combining virus-free seedlings and infected plant removal in plots outside the PGI area proved effective at reducing infection rates; combining with intercropping resulted in the lowest incidence in an FG plot. Farmer training and off-site plot selection to produce healthy sowing beans are key to improving results.

Reduction in vertical transmission rate of bean common mosaic virus in bee-pollinated common bean plants

Vertical transmission, the transfer of pathogens across generations, is a critical mechanism for the persistence of plant viruses. The transmission mechanisms are diverse, involving direct invasion through the suspensor and virus entry into developing gametes before achieving symplastic isolation. Despite the progress in understanding vertical virus transmission, the environmental factors influencing this process remain largely unexplored. We investigated the complex interplay between vertical transmission of plant viruses and pollination dynamics, focusing on common bean (Phaseolus vulgaris). The intricate relationship between plants and pollinators, especially bees, is essential for global ecosystems and crop productivity. We explored the impact of virus infection on seed transmission rates, with a particular emphasis on bean common mosaic virus (BCMV), bean common mosaic necrosis virus (BCMNV), and cucumber mosaic virus (CMV). Under controlled growth conditions, BCMNV exhibited the highest seed transmission rate, followed by BCMV and CMV. Notably, in the field, bee-pollinated BCMV-infected plants showed a reduced transmission rate compared to self-pollinated plants. This highlights the influence of pollinators on virus transmission dynamics. The findings demonstrate the virus-specific nature of seed transmission and underscore the importance of considering environmental factors, such as pollination, in understanding and managing plant virus spread.

Occurrence, distribution, and genetic diversity of faba bean viruses in China.

With worldwide cultivation, the faba bean (Vicia faba L.) stands as one of the most vital cool-season legume crops, serving as a major component of food security. China leads global faba bean production in terms of both total planting area and yield, with major production hubs in Yunnan, Sichuan, Jiangsu, and Gansu provinces. The faba bean viruses have caused serious yield losses in these production areas, but previous researches have not comprehensively investigated this issue. In this study, we collected 287 faba bean samples over three consecutive years from eight provinces/municipalities of China. We employed small RNA sequencing, RT-PCR, DNA sequencing, and phylogenetic analysis to detect the presence of viruses and examine their incidence, distribution, and genetic diversity. We identified a total of nine distinct viruses: bean yellow mosaic virus (BYMV, Potyvirus), milk vetch dwarf virus (MDV, Nanovirus), vicia cryptic virus (VCV, Alphapartitivirus), bean common mosaic virus (BCMV, Potyvirus), beet western yellows virus (BWYV, Polerovirus), broad bean wilt virus (BBWV, Fabavirus), soybean mosaic virus (SMV, Potyvirus), pea seed-borne mosaic virus (PSbMV, Potyvirus), and cucumber mosaic virus (CMV, Cucumovirus). BYMV was the predominant virus found during our sampling, followed by MDV and VCV. This study marks the first reported detection of BCMV in Chinese faba bean fields. Except for several isolates from Gansu and Yunnan provinces, our sequence analysis revealed that the majority of BYMV isolates contain highly conserved nucleotide sequences of coat protein (CP). Amino acid sequence alignment indicates that there is a conserved NAG motif at the N-terminal region of BYMV CP, which is considered important for aphid transmission. Our findings not only highlight the presence and diversity of pathogenic viruses in Chinese faba bean production, but also provide target pathogens for future antiviral resource screening and a basis for antiviral breeding.

Identification and Molecular Validation of Bean Common Mosaic Virus Resistant Donors in Common Bean (Phaseolus vulgaris L.)

Identification and Molecular Validation of Bean Common Mosaic Virus Resistant Donors in Common Bean (Phaseolus vulgaris L.)

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.

Germplasm Screening for Identification of BCMV Resistance Sources from Diverse Cowpea [Vigna unguiculata (L.) Walp.] Germplasm using Serological and Molecular Diagnostics

Background: Bean common mosaic disease (BCMD) caused by Bean common mosaic virus (BCMV) has been regarded as one of the most important seed-borne and aphid vector transmitted destructive disease of cowpea not only affecting its yield but also reducing its grain quality globally. Since the dawn of crop improvement, germplasm served as the source of resistance for various biotic stresses. Currently, host plant resistance is the best, reliable, economic and environmental friendly practice of virus disease management. The objective of this study was to assess the response of diverse cowpea germplasm against BCMV under natural and controlled conditions followed by serological and molecular detection. Methods: In this study, 85 cowpea germplasm accessions and one known BCMV susceptible (C152) and one resistant (CP55) varieties are evaluated for their response to the BCMD in augmented block design (ABD). The reaction of cowpea accessions were assessed using percent disease incidence (PDI). Transmission Electron microscopy (TEM), Direct Antigen Coating-Enzyme-linked Immunosorbent Assay (DAC-ELISA) and Reverse Transcription-Polymerase Chain Reaction (RT-PCR) were used for confirming the BCMV. Result: Natural and controlled condition screening data analysis revealed a significant difference among diverse cowpea germplasm for BCMV diseases incidence. Based on field screening at Ranchi and New Delhi (2019 and 2020) and artificial confirmation. 24 out of 85 accessions were found to be immune and confirmed through DAC-ELISA and RT-PCR. As a consequence these accessions could be a potential new source of disease resistance for BCMV in breeding programs.Further, DAC ELISA of seed coat and Embryo revealed the presence of virus in 5% and 15% of samples tested. Accession IC418505 recorded highest disease incidence (40.0%).

Serological and RT-PCR evaluation of African yam bean (Sphenostylis stenocarpa (Hochst ex. A. Rich) Harms) accessions to viral resistance under field condition

African yam bean (AYB) (Sphenostylis stenocarpa (Hochst ex. A. Rich.) harms) an underutilized legume that produces nutritionally healthy seeds and tubers in some variety. The low yield of the crop is attributed to production constraints such as attacks by pest and disease-causing organisms such as fungi, bacteria and viruses. In this study, one hundred AYB accessions were evaluated for resistance to viral infection. The AYB accessions were planted using a randomized complete block design on the experimental field at the International Institute of Tropical Agriculture (IITA) Ibadan, Nigeria. Viral disease severity was assessed at 10, 12, 14, 16 and 18 weeks after planting (WAP) based on disease symptoms using disease severity index on visual scale of 1–5. Antigen–coated plate enzyme linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction were used to index diseased leaf samples collected from the field. Result from five virus species (Cowpea mild mottle virus, Cowpea mottle virus, Southern bean mosaic virus, Cowpea mosaic virus and Bean common mosaic virus) were detected in few accessions while mixed infections were observed in some accessions. TSs-552, TSs-577, TSs-580, TSs-560 and TSs-600 were devoid of viruses and could be resistant. There were no significant differences at p < 0.05 in the mean disease incidence (DI) of viral diseases. However, at 18 weeks after planting, TSs-604 had the highest (100%) mean DI while TSs-584 had the lowest (13.33%) mean DI. Cluster analysis based on the AUDPC produced 6 main clusters, the clusters revealed grouping patterns in which AYB lines with similar resistance ratings were shown to form unique clusters. The information generated from this study will contribute to the development of strategies in the management of virus diseases infecting AYB.

Incidence, transmission, host range and population dynamics of aphids transmitting bean common mosaic virus of cowpea

Cowpea [Vigna unguiculata (Linn.) Wilczek] is an important pulse crop which belongs to family Fabaceae. Bean Common Mosaic is a major viral disease in cowpea resulting in significant yield losses to a tune of 70 per cent. The results showed that disease was widespread in all the surveyed areas, with the highest average per cent disease incidence being observed in Bagalkote (29.82%) followed by Vijayapur (27.41%), Dharwad (25.47%) and Belagavi district (18.89%). The disease incidence varied from 3.25 per cent to 69.56 per cent among the villages and from 12.94 per cent to 44.80 per cent among the taluks. The host range and transmission studies revealed that BCMV infecting cowpea is readily transmissible by sap, aphids and through seeds. The mechanical transmission was 71.43 per cent, aphid transmission was found to an extent of 54.42 per cent and the seed transmission of BCMV infecting cowpea was 64.00 per cent. The population of aphid (Aphis craccivora) was maximum during the 38th and 39th Standard Meteorological Weeks (SMWs) with the mean value of 92.70 and 81.20, respectively. The aphid population varied at different crop stages. Aphid population build up showed a strong significant negative correlation with rainfall. There was a significant negative correlation with minimum temperature and morning RH.

Molecular Characterization of an Isolate of Bean Common Mosaic Virus First Identified in Gardenia Using Metatranscriptome and Small RNA Sequencing.

Gardenia (Gardenia jasminoides) is a popular and economically vital plant known for its ornamental and medicinal properties. Despite its widespread cultivation, there has been no documentation of plant viruses on gardenia yet. In the present study, gardenia leaves exhibiting symptoms of plant viral diseases were sampled and sequenced by both metatranscriptome and small RNA sequencing. As a consequence, bean common mosaic virus (BCMV) was identified in gardenia for the first time and named BCMV-gardenia. The full genome sequence of BCMV-gardenia is 10,054 nucleotides (nt) in length (excluding the poly (A) at the 3' termini), encoding a large polyprotein of 3,222 amino acids. Sequence analysis showed that the N-termini of the polyprotein encoded by BCMV-gardenia is less conserved when compared to other BCMV isolates, whereas the C-termini is the most conserved. Maximum likelihood phylogenetic analysis showed that BCMV-gardenia was clustered closely with other BCMV isolates identified outside the leguminous plants. Our results indicated that the majority of BCMV-gardenia virus-derived small interfering RNAs (vsiRNAs) were 21 nt and 22 nt, with 21 nt being more abundant. The first nucleotide at the 5' termini of vsiRNAs derived from BCMV-gardenia preferred U and A. The ratio of vsiRNAs derived from sense (51.1%) and antisense (48.9%) strands is approaching, and the distribution of vsiRNAs along the viral genome is generally even, with some hot spots forming in local regions. Our findings could provide new insights into the diversity, evolution, and host expansion of BCMV and contribute to the prevention and treatment of this virus.

Molecular Characteristics of Bean Common Mosaic Virus Occurring in Inner Mongolia, China.

Bean common mosaic virus (BCMV) was detected on common bean (Phaseolus vulgaris) plants showing wrinkled and/or narrow leaves, curling, shrinking and chlorosis of leaves, dwarfing of plants, and mottled pods in Inner Mongolia and named BCMV-22Huhe. Its genome has a size of 10,062 bp and was deposited in GenBank under the accession number OR778613. It is closely related to BCMV-Az (GenBank accession no. KP903372, in China) in the lineage of AzBMV. A recombination event was detected for BCMV-22Huhe among the 99 BCMV isolates published in the NCBI GenBank database, showing that BCMV-CJ25 (MK069986, found in Mexico) was a potential major parent, and the minor parent is unknown. This work is the first description of the occurrence of BCMV in Inner Mongolia, China.