Bean Yellow Mosaic Virus Research Articles

Identification of SSR Markers Linked to Mung Bean Yellow Mosaic Virus Resistance in Blackgram (Vigna mungo (L.) Hepper) Using Bulked Segregant Analysis in F2:3 Population

Aims: In blackgram (Vigna mungo (L.) Hepper), mung bean mung bean yellow mosaic virus (MYMV) disease causes severe yield reduction. MAS (Marker Assisted Selection) can be used to improve the selection efficiency for MYMV resistance. Hence the present study was carried out to use bulked segregant analysis (BSA) and simple sequence repeat (SSR) marker validation tests to find the simple sequence repeat (SSR) markers associated to MYMV resistance in the blackgram segregating population, (F2:3) of ADT 3 x IC343856. Study Design: F2:3 generated 60 single plants of ADT 3 x IC343856 were raised with regular rows of MYMV susceptible check variety CO 5 to draw white flies and thus to improve MYMV infection under field screening. To identify the SSR markers associated to MYMV resistance, bulk segregant analysis and marker validation tests were conducted. Place and Duration of Study: The experiment was carried out at Department of Genetics and Plant Breeding, VOC Agricultural College and Research Institute, Killikulam, Tamil Nadu Agricultural University, India from 2020 to 2022. Methodology: The F2:3 mapping population of the cross, ADT 3 x IC 343856 was used for BSA using 50 simple sequence repeat (SSR) markers for mung bean mung bean yellow mosaic virus (MYMV) resistance studies in blackgram. Results: Four markers viz., CEDG008, CEDG271, VM6 and CEDG264 exhibited polymorphism between the parents. The F2:3 segregants were raised along with their parents and check variety CO 5 was raised as infector rows to ensure the disease incidence in the population. An equal number of two extreme genotypes (10 resistant and 10 susceptible respectively) were pooled to form the bulks. Among the four polymorphic markers studied, CEDG 008 was able to differentiate resistant and susceptible bulks and their corresponding individuals (120 bp and 110 bp respectively). From the previous reports, it has been confirmed that CEDG 008 is a potential marker for MYMV resistance studies in different genetic backgrounds.

Bacillus siamensis strain B30 as a biocontrol agent for enhancing systemic resistance and mitigating bean yellow mosaic virus infestation in faba bean plants

Bacillus siamensis strain B30 as a biocontrol agent for enhancing systemic resistance and mitigating bean yellow mosaic virus infestation in faba bean plants

Characterization of the virome in broad bean: First detection of Potyvirus phaseoluteum and Orthotospovirus impatiensnecromaculae in Montecillo, Texcoco, Mexico

Background / Objective. In broad bean (Vicia faba) crops established in Montecillo, Texcoco, State of Mexico, 100% of plants were observed with viral symptoms consisting of mosaic, mottling, leaf curling, wilting and a notable decrease in plant development. These symptoms led to a significant reduction in seed yield and quality. In this context, the present study was carried out with the objective of identifying the viral species associated with these symptoms. Materials and Methods. The experimental strategy consisted of extraction of total RNA from leaves showing the aforementioned symptoms, followed by next-generation sequencing. Results. In the results, the complete genomes of Orthotospovirus impatiensnecromaculae (before impatiens necrotic spot virus) and two isolates of the Potyvirus phaseoluteum (before bean yellow mosaic virus) were obtained. The phylogenetic analysis revealed that the isolate of O. impatiensnecromaculae (INSV CPMEX) shows significant divergences from those previously reported in other plant species. On the other hand, the two P. phaseoluteum isolates (BYMV CP1MEX and BYMV CP2MEX) proved to be different from each other, being related to isolates reported in Sudan and Iran. Conclusion. This result suggests considerable genetic diversity among the viruses associated with viral symptoms in faba bean crops in the region, which underlines the importance of accurate identification for the management and control of these viral infections.

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.

Foliar Application of Rhizobium leguminosarum bv. viciae Strain 33504-Borg201 Promotes Faba Bean Growth and Enhances Systemic Resistance Against Bean Yellow Mosaic Virus Infection.

The bean yellow mosaic virus (BYMV) is one of the most serious economic diseases affecting faba bean crop production. Rhizobium spp., well known for its high nitrogen fixation capacity in legumes, has received little study as a possible biocontrol agent and antiviral. Under greenhouse conditions, foliar application of molecularly characterized Rhizobium leguminosarum bv. viciae strain 33504-Borg201 to the faba bean leaves 24 h before they were infected with BYMV made them much more resistant to the disease while also lowering its severity and accumulation. Furthermore, the treatment promoted plant growth and health, as evidenced by the increased total chlorophyll (32.75 mg/g f.wt.) and protein content (14.39 mg/g f.wt.), as well as the improved fresh and dry weights of the plants. The protective effects of 33504-Borg201 greatly lowered the levels of hydrogen peroxide (H2O2) (4.92 µmol/g f.wt.) and malondialdehyde (MDA) (173.72 µmol/g f.wt.). The antioxidant enzymes peroxidase (1.58 µM/g f.wt.) and polyphenol oxidase (0.57 µM/g f.wt.) inhibited the development of BYMV in plants treated with 33504-Borg201. Gene expression analysis showed that faba bean plants treated with 33504-Borg201 had higher amounts of pathogenesis-related protein-1 (PR-1) (3.28-fold) and hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase (4.13-fold) than control plants. These findings demonstrate the potential of 33,504-Borg201 as a cost-effective and eco-friendly method to protect faba bean plants against BYMV. Implementing this approach could help develop a simple and sustainable strategy for protecting faba bean crops from the devastating effects of BYMV.

Metatranscriptome and small RNA sequencing revealed a mixed infection of newly identified bymovirus and bean yellow mosaic virus on peas

Peas (Pisum sativum L.) are widely cultivated in temperate regions and are susceptible hosts for various viruses across different families. The discovery and identification of new viruses in peas has significant implications for field disease management. Here, we identified a mixed infection of two viruses from field-collected peas exhibiting virus-like symptoms using metatranscriptome and small RNA sequencing techniques. Upon identification, one of the viruses was determined to be a newly isolated and discovered bymovirus from peas, named “pea bymovirus 1 (PBV1)". The other was identified as a novel variant of bean yellow mosaic virus (BYMV-HZ1). Subsequently, mechanical inoculation and RT-PCR assays confirmed that both viruses could be inoculated back onto peas and tobaccos, showing mixed infection by PBV1 and BYMV-HZ1. To our knowledge, this is the first isolation of a bymovirus from pea and the first documented case of mixed infection of peas by PBV1 and BYMV-HZ1 in China.

Physio-biochemical and nutritional alterations in faba bean due to bean yellow mosaic virus infection

Physio-biochemical and nutritional alterations in faba bean due to bean yellow mosaic virus infection

Evaluation of Integrated Pest Management Practices against the Incidence of White Fly and Bean Yellow Mosaic Virus (BYMV) in Rajmash (Phaseolus vulgaris L.)

Evaluation of Integrated Pest Management Practices against the Incidence of White Fly and Bean Yellow Mosaic Virus (BYMV) in Rajmash (Phaseolus vulgaris L.)

First report of saffron latent virus in Crocus sativus from Hungary.

In early April of 2018 we sampled asymptomatic autumn flowering Crocus plants (Fig. S1.) in a private collection in Hajdú-Bihar county, Hungary. From each species (Cr. kotschyanus subsp. kotschyanus, Cr. sativus, Cr. speciosus) 200 mg leaf sample was collected from 5 neighboring shoot, which were treated as one sample. ELISA tests were carried out in duplicates using potyvirus-specific MAb PTY1 antibodies (Jordan and Hammond 1991) on the samples (Agdia, Elkhart, IN, USA). A sample was considered positive if the absorbance was at least three times greater than that of the negative control. Only one sample tested positive; the absorbance values of Cr. sativus leaves were 0.013 and 0.014, while the negative controls were 0.002 and 0.003, respectively. The samples were further tested by RT-PCR for potyviruses (Salamon and Palkovics 2005), tomato spotted wilt virus (TSWV) (Nemes and Salánki 2020) and nepovirus subgroup A (Digiaro et al. 2007). Total nucleic acid was extracted with the phenol-chloroform method of White and Kaper (1989), and reverse transcription was carried out with Maxima H Minus First Strand cDNA Synthesis Kit (Thermo Fisher Scientific Baltics UAB, Vilnius, Lithuania) using random hexamer primer. The samples were negative for TSWV and nepovirus subgroup A, but a single PCR product of ~ 1700 nucleotide (nt) was amplified with potyvirus specific primers and cloned into pGEM®-T Easy vector (Promega, Madison, WI, USA). The 1726 nt long insert sequence, including the complete coat protein region was determined and deposited in the NCBI GenBank database (Accession No: OR425160). Digestion of the original PCR products with restriction enzyme SacI yielded only the predicted restriction fragments (364 / 1362 bp), indicating the presence of only a single potyvirus in the infected sample. BLASTn analysis of the CP cistron revealed the highest nt identities to saffron latent virus (SaLV) Iranian isolates (GenBank AccNo.: MN990394 - 85.44%, MN990415 - 85.39% and RefSeq: NC_036802 - 84.05%). For phylogenetic analyses MEGA11 (Tamura et al. 2021) was used. The resulting Maximum Likelihood tree (Fig. S2) showed that all Iranian SaLV isolates grouped together, while the Hungarian isolate is on an adjacent branch, separate from other virus species, and supported with 100% bootstrap values. From these results, it appears that the Hungarian isolate has been separated from the Iranian clade, and has evolved separately as a distinct lineage. We were unable to fulfill Koch's postulates as all available Crocus sativus plants were infected with SaLV. Latent potyvirus infection of Crocus species, by bean yellow mosaic virus (BYMV), iris mild mosaic virus (IMMV), iris severe mosaic virus (ISMV) and turnip mosaic virus (TuMV) has been reported by Grilli Caiola and Faoro (2011). SaLV was first reported from Iran (Parizad et al. 2017), but to our knowledge has never been reported from Europe or from any current EPPO member state. Since Crocus species can be asymptomatic virus reservoirs, it is important that any certification scheme for production should require laboratory tests to prove the health of the plants; or advise growers to keep possible high value susceptible crops such as breeding material and nuclear stocks at a distance from crocuses to mitigate virus transmission between stocks. It is also advisable to grow infected lots far from healthy stocks and protected wild hosts. To our knowledge, this is the first report of SaLV from Hungary and from Europe.

Molecular Detection and Partial Characterization of Coat Protein Gene of Moth Bean Yellow Mosaic Virus (MBYMV) from Northern Karnataka

Background: Moth bean (Vigna aconitifolia (Jaq.) Marechal) is characterized as one of the most drought hardy, short duration, annual legume crop. It is mainly grown in Northern districts of Karnataka. Moth bean crop suffers from many diseases viz., yellow mosaic, bacterial blight, root rot, anthracnose and powdery mildew. Moth bean is targeted by YMV which causes severe damage to grain and fodder yields. Since not much work has been carried out on characterization of moth bean yellow mosaic virus in Northern Karnataka, an attempt was made to partially characterize coat protein gene of Moth Bean Yellow Mosaic Virus (MBYMV). Methods: The total genomic DNA was extracted from leaf tissues of healthy moth bean plants and yellow mosaic virus infected plants utilizing by modified CTAB method. Specific primers for yellow mosaic viruses were tried to amplify coat protein region of MBYMV. Result: Moth bean leaf samples showing yellow mosaic symptoms gave positive results with MYMV specific primer pairs (MYMV-CP-F/MYMV-CP-R) and yielded amplicons of ~1000 bp. The 1000 bp PCR products were directly sequenced and assembled. Phylogenetic tree based on full length coat protein gene sequence of MBYMV with other geminiviruses sequences downloaded from NCBI Genbank formed three major clusters of MYMV, HgYMV and MYMIV. The present MBYMV isolate formed unique cluster with MYMV group.

Assessing the Performance of Latest Greengram Varieties under Improved production Packages in Thiruppur, Tamil Nadu, India

On Farm Testing (OFT) in Mungbean Yellow Mosaic Virus (MYMV) resistant and high yielding greengram varieties was conducted by Krishi Vigyan Kendra, Tamil Nadu Agricultural University, Tirupur in farmers field during kharif 2020. Totally 15 farmers each with one acre were selected in three villages of Pongalur Block in Tirupur district of Tamil Nadu. Critical input viz., seeds of greengram varieties CO 8 and DGG 1 were distributed to the farmers and the varietal performance were assessed along with the existing variety under cultivation VBN 2. The plant physiological parameters viz., plant height, number of nodules / plant and yield attributing parameters such as number of pods / plants, number of branches/plant, Mung bean Yellow Mosaic Virus (MYMV) disease incidence (%), yield (q ha-1) and B:C ratio were recorded. The results revealed that, among the three varieties, Greengram CO 8 was recorded more number of pods (42) and minimum incidence of Mungbean Yellow Mosaic Virus (MYMV) disease incidence of 3.2 per cent resulting in the highest yield of 9.5 q ha-1 followed by DDG 1 with 34 pods/plant, MYMV disease incidence of 7.3 per cent and yield of 8.4 q ha-1 compared to the existing variety VBN 2, which recorded the lowest number of pods (31 Nos.), yield (7.6 q ha-1) with the highest MYMV disease incidence (12.5%). The highest B:C ratio was recorded in greengram variety CO 8 (2.92) which was followed by DDG 1 (2.58). It was concluded that, farmers of Tirupur district in Tamil Nadu were satisfied with cultivation of greengram CO 8 variety due to the lowest disease incidence, higher yield and Benefit Cost Ratio.

Host Resistance to Virus Diseases Provides a Key Enabler towards Fast Tracking Gains in Grain Lupin Breeding.

Four lupin species, Lupinus angustifolius, L. albus, L. luteus, and L. mutabilis, are grown as cool-season grain legume crops. Fifteen viruses infect them. Two of these, bean yellow mosaic virus (BYMV) and cucumber mosaic virus (CMV), cause diseases that threaten grain lupin production. Phytosanitary and cultural control measures are mainly used to manage them. However, breeding virus-resistant lupin cultivars provides an additional management approach. The need to develop this approach stimulated a search for virus resistance sources amongst cultivated lupin species and their wild relatives. This review focuses on the progress made in optimizing virus resistance screening procedures, identifying host resistances to BYMV, CMV, and additional viral pathogen alfalfa mosaic virus (AMV), and the inclusion of BYMV and CMV resistance within lupin breeding programs. The resistance types found in different combinations of virus and grain lupin species include localized hypersensitivity, systemic hypersensitivity, extreme resistance, and partial resistance to aphid or seed transmission. These resistances provide a key enabler towards fast tracking gains in grain lupin breeding. Where studied, their inheritance depended upon single dominant genes or was polygenic. Although transgenic virus resistance was incorporated into L. angustifolius and L. luteus successfully, it proved unstable. Priorities for future research are discussed.

Field and agroinoculation screening of national collection of urd bean (Vigna mungo) germplasm accessions for new sources of mung bean yellow mosaic virus (MYMV) resistance.

Yellow mosaic disease (YMD) is a major problem in Urd bean (Vigna mungo L.) in India, which causes huge yield losses. Breeding for wide spectrum and durable Mungbean yellow mosaic virus (MYMV) resistance and cultivating resistant cultivars is the most appropriate and effective approach. However, the task has become challenging with the report of at least two species of the virus, viz., Mungbean yellow mosaic virus (MYMV) and Mungbean yellow mosaic India virus (MYMIV) and their recombinants; the existence of various isolates of these species with varied virulence and rapid mutations noted in the virus as well as in the whitefly vector population. Thus the present study was carried out to identify and characterize novel and diverse sources of YMV resistance and develop linked molecular markers for breeding durable and broadspectrum resistant urdbean cultivars against YMV. Towards this goal, we have screened 998 accessions of urdbean national collection of germplasm against YMD Hyderabad isolate both in a field under the natural level of disease incidence and through agro inoculation in the laboratory using viruliferous clones of the same isolate. Ten highly resistant accessions identified through repeated testing have been characterized in terms of reported linked markers. We attempted to see diversity among the ten resistant accessions reported here using earlier reported resistance-linked SCAR marker YMV1 and SSR CEDG180 marker. SCAR marker YMV1 did not amplify with any of the 10 accessions. But with CEDG180, results suggested that 10 accessions shortlisted through field and laboratory tests do not carry PU31 allele and this shows that it may be likely to carry novel gene(s). Further studies are needed to genetically characterize these new sources.

Influence of meteorological parameters on incidence of mungbean yellow mosaic virus disease in green gram in Assam

Green gram (Vigna radiata) is one of the most important pulse crops grown in India and abroad bean yellow mosaic virus disease caused by Mung bean yellow mosaic virus has become a major threat in greengram cultivation in Assam. An experiment was conducted in the Experimental field, Department of Plant Pathology, Biswanath College of Agriculture, Assam Agricultural University, Biswanath Chariali during 2021-22, where green gram was sown in five dates starting from 5th September 2021to 3rd October 2021 at 7 days interval to study the effect of meteorological parameters in the incidence of green gram yellow mosaic virus disease, effect on growth and yield parameters so as to find out the best sowing time of the crop as a strategy for managing the disease. During the study, symptoms like, appearance of chlorotic specks along the veins, puckering of leaves, typical mosaic pattern, complete yellowing and drying of the leaves were recorded. Highest whitefly population (12.42 no/plant) was recorded in the crop sown on 19.09.2021 and the lowest (6.24no/plant) was recorded in the 05.9.2021 sown crop. Lowest (40.32%) disease incidence with highest seed yield (4.50 q/ha) was recorded in the crop sown on 05.09.2021, whereas highest (88.25%) disease incidence with lowest yield (2.50 q/ha) was recorded in the crop sown in second fortnight of September (19.09.21). Maximum temperature ranging from 29-33 oC, minimum temperature 13-23 oC with 8-9 bright sunshine hours were found to be conducive for incidence and rapid spread of the disease.

Morphological Screening of Black Gram Genotypes with Reference to Mung Bean Yellow Mosaic Virus

One of the most devastating diseases affecting blackgram productivity in India is mung bean yellow mosaic. It is transmitted by whitefly (Bemisia tabaci). The current investigation was carried out to identify the blackgram genotypes resistant against the Mung bean yellow Mosaic virus (MYMV) through field screening at natural condition. The genotypes were screened using the infector row method. Twelve blackgram genotypes namely VBN-2, VBN-3, VBN-5, VBN-6, VBN-7 VBN-8, VBN-9 VBN-10, VBN-11, ADT-5, ADT-6 and CO-5 were used for screening during summer 2022. The genotypes viz., VBN-6, VBN-10 and VBN-11 were found to be resistant and moderately resistant viz., VBN-4, VBN-5, VBN-7, and VBN-8. It implies that utilization of these genotypes as YMV resistance donors for results in the production of high yielding MYMV resistant varieties through backcrossing or marker assisted backcrossing by introgression of the genes to agronomically potential genotypes that were susceptible to MYMV.

Rhizobium leguminosarum bv. viciae-Mediated Silver Nanoparticles for Controlling Bean Yellow Mosaic Virus (BYMV) Infection in Faba Bean Plants.

The faba bean plant (Vicia faba L.) is one of the world's most important legume crops and can be infected with various viral diseases that affect its production. One of the more significant viruses in terms of economic impact is bean yellow mosaic virus (BYMV). The current study used the molecularly identified Rhizobium leguminosarum bv. viciae strain 33504-Borg1, a nitrogen-fixing bacteria, to biosynthesize silver nanoparticles (AgNPs) to control BYMV disease in faba bean plants. Scanning electron microscopy (SEM), a particle size analyzer (PSA) with dynamic light scattering (DLS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the prepared AgNPs. The DLS, SEM, and TEM analyses revealed that the AgNPs were spherical and rough, with sizes ranging from 13.7 to 40 nm. The FTIR analysis recognized various functional groups related to AgNP capping and stability. Under greenhouse conditions, spraying faba bean leaves with the AgNPs (100 µg/mL) 24 h before BYMV inoculation induced plant resistance and reduced plant disease severity and virus concentration levels. Contrarily, the AgNP treatment enhanced plant health by raising photosynthetic rates, increasing the fresh and dry weight of the faba bean plants, and increasing other measured metrics to levels comparable to healthy controls. Antioxidant enzymes (peroxidase and polyphenol oxidase) inhibited the development of BYMV in the faba bean plants treated with the AgNPs. The AgNPs decreased oxidative stress markers (H2O2 and MDA) in the faba bean plants. The plants treated with the AgNPs showed higher expression levels of PR-1 and HQT than the control plants. The study findings could be used to develop a simple, low-cost, and environmentally friendly method of protecting the faba bean plant from BYMV.

Physical Properties of Potyvirus on Chilli (Capsicum annuum) of Doon Valley in Uttarakhand

A virus is transmitted mechanically in the plant host. Potyviridae is a family of Potyvirus,consisting of a positive-sense RNA genome and filamentous particles. It has a single typeof protein coat. Mostly, this virus is identified in Leguminosae and Solanaceae family. Theplant virus is transmitted by mechanical inoculation and aphids. Chilli, cucurbits, potatoes,peas, tomatoes, and other plants were infected with the bean yellow mosaic virus, pea mosaicvirus, bean yellow mosaic virus, sugarcane mosaic virus, and peanut mosaic virus. Thermalinactivation point, dilution endpoint, longevity in vitro, and longevity in vivo were used toidentify the physical properties of a potyvirus. Several isolates mild and severe were collectedin the chilli plant. The infected plant developed necrotic leaf spots and chlorotic symptoms.

THE ROLE OF BIOTIC FACTORS IN <i>LUPINUS POLYPHYLLUS </i>LINDL.(FABACEAE)INVASIVENESS LIMITATION

The article presents experimental data on the species composition of fungal and viral pathogens in the conditions of the secondary range of Lupinus polyphyllus . Tobacco mosaic virus, Bean yellow mosaic virus, Bean common mosaic virus and Pea enation mosaic virus were diagnosed on Lupinus polyphyllus for the first time. The issues related to the peculiarities of the adaptability of viruses to invasive plant species are discussed. The preventive role of vectors ( Aphididae ) in the expansion of pathogens and the widening of the spectrum of host plants (susceptible species) is emphasized. Interaction with vectors, including their non-specific species, is one of the mechanisms of virus adaptability, their expansion into new regions and the formation of new pathosystems with invasive plant species. It is concluded that based on the analysis of trophic connections of vectors, it is possible to prognosticate the search for the most effective variants of harmful organisms for the biocontrol of L. polyphyllus .

Farmers’ Perceptions and Knowledge of Country Bean (Lablab purpureus L.) Insect Pests, and Diseases, and Their Management Practices, in Bangladesh

Country bean (Lablab purpureus L.), a popular vegetable in Bangladesh, is severely affected by insect pests and diseases. Farmers’ perceptions of insect pests, diseases, and their management are critical constraints to the establishment of an effective and sustainable pest management approach for this crop. A comprehensive survey was conducted with 300 country bean farmers from six districts of Bangladesh to assess farmers’ perceptions and knowledge of the insect pests and diseases of country bean, and their management practices. The survey results show that country bean farmers have been facing varying pest problems for more than ten years. They could identify eight pests and only one beneficial insect species in their fields, including thrips and jute weevil, as new pests. Among the pests, aphids and pod borers were common in all surveyed areas. More than 80% of farmers said their bean plants were severely affected by bean yellow mosaic virus and white mold diseases. Farmers also mentioned that insect pests and diseases together caused 30–40% yield losses of this crop. About 76% of the farmers solely depended on different chemical pesticides for the production of country bean. Growers frequently used insecticides from the organophosphorus and neonicotinoid groups, and fungicides from the triazole group, to manage pests associated with this crop. Farmers start applying pesticides from the seedling stages, at three-day intervals, maintaining only two- to four-day pre-harvest intervals (PHI). Our findings provide insight into the importance of developing sustainable pest management approaches for country bean production in Bangladesh.

Elimination of coexisting canna yellow mottle virus, bean yellow mosaic virus and cucumber mosaic virus from Canna generalis cv. black knight through in vitro chemotherapy of rhizome explants.

During our previous study, the mixed infection of canna yellow mottle virus (CaYMV), bean yellow mosaic virus (BYMV), and cucumber mosaic virus (CMV) was identified in a Black Knight cultivar of canna exhibiting severe yellow streak and mottling symptoms. Before the development of the virus-free plants, the ability of callogenesis and organogenesis from the ovary, stalk, and rhizome explants was tested on different concentrations and combinations of TDZ, NAA, BAP, and Ads growth regulators. The performance of rhizome explants was above all the explant types and 33.33 ± 1.67 rhizomes (out of 50 placed) showed callus development on ME medium (MS supplemented with 0.8mg/L TDZ and 0.25mg/L NAA) and further on a refined M4 medium (MS supplemented with 4.0mg/L BAP, 1.0mg/L NAA and 50mg/L Ads) produced 4.06 ± 0.16 shoots per explant. The development of virus-free plants was attempted by in vitro chemotherapy using ribavirin. Not only in callogenesis and shoot development but also in the ribavirin treatments, rhizomes developed about 3.78 ± 0.68 shoots per explant on 40mg/L ribavirin in the ME medium. These optimizations suggested that ME medium for callogenesis, M4 medium for shoot development and the treatment of 40mg/L ribavirin for 30days at M4 medium was effective. The elimination of coinfection of all three viruses from rhizome explants of 0.5 cm2 of the Black Knight cultivar was attempted. Consequently, a total of 53.33% of plants free from all three viruses (48 out of the 90 plants developed) were obtained when screened by RT-PCR and PCR for their absence.