Yellow Mosaic Virus Research Articles

Characterization and Detection of Yellow Vein Disease of Okra (<em>Abelmoschus esculentus</em> (L.) Moench) in Sri Lanka

Begamoviruses transmitted by whitefly (Bemisia tabaci Genn, Family Aleyrodidae) cause severe damage to crop plants showing varying symptoms in different crop species. Okra Yellow Vein Mosaic Virus (OYVMV) is one of the most devastating diseases reported in okra cultivation worldwide. In this study, OYVMV disease severity and incidence of three recommended okra varieties were evaluated in field conditions at three different locations; Gannoruwa, Mahailuppalama and Angunakolapalasse. Similar disease symptoms were observed in Mahailuppallama and Angunakolapalasse. In Gannoruwa late infection caused lesser disease incidence and severity. Statistical analysis showed significant difference in severity and incidence of OYVMV among varieties as well as locations. MI 7 and MI 5 showed significantly high disease severity than Haritha while location Mahailluppallama showed significantly high disease severity followed by Angunakolapalasse. Diseased samples collected from these three locations and two additional locations i.e. Kilinochchi and Vauniya were subjected to PCR amplification with different begamovirus specific primers to identify the cross infection with other begamovirus diseases. All symptomatic samples collected from different locations showed positive results for OYVMV specific primer while none of the diseased samples showed positive results for Chili leaf curl virus, Tomato leaf curl virus, Okra leaf curl virus and Okra leaf curl crinkle virus disease specific primers. This study revealed that there is location and variety effect on OYVMV disease incidence and in these locations tested okra varieties were not cross infected with other tested viruses. Sequence analysis has to be done to identify genetic diversity of okra YVMV in different locations.

Nucleotide sequencing and an improved diagnostic for screening okra (Abelmoschus esculentus L.) genotypes for resistance to a newly described begomovirus in India

ABSTRACTTen okra (Abelmoschus esculentus L.) plants showing distinct yellow vein mosaic disease (YVMD) symptoms were collected from different fields in Karnataka State, India. The genomic DNA of the isolated viruses was amplified, cloned, and sequenced. Sequence analysis revealed that the DNA-A-like sequences of all ten isolates were identical. Sequence analysis of a representative virus isolate (OYSK2) with other begomovirus sequences available in GenBank showed ≥90% sequence identity with Bhendi yellow vein Maharashtra virus (BYVMaV; EU482411) and ≤89% homology with full-length Bhendi yellow vein mosaic virus (BYVMV) infecting okra on the Indian subcontinent. These results suggested that a new strain of BYVMaV was present in all ten samples collected from the field. A source of resistance to BYVMaV and naturally present virus isolates causing YVMD was identified by screening okra genotypes under artificial and natural inoculation conditions, respectively. None of the genotypes tested showed complete immunity to BYVMaV. However, the okra genotypes ‘Tulasi’ and ‘Trisha’ were only moderately susceptible under glasshouse and field conditions. The new begomovirus strain could be detected by dot-blot hybridisation using a non-radioactive DNA probe in the virus samples collected from both symptomless and symptomatic okra plants.

Evaluation of advance lines of soybean for resistance to major diseases under natural field condition

Root rot/Charcoal rot, <italic>Alternaia</italic> leaf spot, Bacterial pustule and Yellow Mosaic Virus are important one disease in Vidarbha region of Maharashtra. Thirty advance lines of soybean were screened for these diseases in protected and un-protected condition under natural field conditions and results revealed that four entries viz.NRC-94, JS-20-69, JS 20-71 and KDS- 699 were shown Resistant High Yield (R-HY) reaction to disease complex while NRC-92, KDS 705, KDS-378 and JS 20-41 exhibit Susceptible High Yield Tolerance (S-HY (T)) reaction to disease complex. Only one entry (SL-958) initiates Resistant Low Yield (R-LY) reaction. Rest of the tested advance lines showed Susceptible Low Yield (S-LY) reaction.

Validation of CYR-1 marker linked with yellow mosaic virus resistance in black gram (Vigna mungoL. Hepper)

The inheritance of yellow mosaic virus (YMV) resistance was studied in blackgram using the molecular marker and F2 population derived from the cross Keonjhar Local(susceptible) × OBG-31(resistant). Assuming Mendelian inheritance, almost perfect fit to a ratio of 3S: 1R in segregating population suggested a single recessive gene controlling YMV resistance in V. mungo. The presence of recessive gene was further confirmed by the linked DNA marker of 1236 bp named ‘CYR1’. Amplification of CYR1 marker from the genomic DNA of phenotypic resistant individuals from segregating F2 populations and F3 families revealed a tight linkage between this marker with the YMV resistance.

Spatio-temporal Pattern of Okra Yellow Vein Mosaic Virus and its Vector in Relation to Epidemiological Factors

Spatio-temporal pattern of Okra yellow vein mosaic virus as well as its vector whitefly was investigated in relation to epidemiological factors (Maximum and minimum air temperature, relative humidity, rainfall and wind speed) was determined on commercially grown okra varieties i.e. Sabaz pari, Pahuja, Lush green and Pusa sawani. Data recorded on whitefly population and Okra yellow vein mosaic virus disease incidence was graphically plotted to visualize spatio-temporal pattern. Four okra varieties Sabz pari, Pahuja, Pusa sawani and Lush green was sown under RCBD design. Data obtained from vector population and disease incidence was analyzed through ANOVA and three-dimensional graphs to demonstrate spatial and temporal pattern of OYVMV and B. tabaci population in relation to environmental factors. Among four varieties/lines Pusa sawani showed significant correlation with the environmental factors.

Evidence of Economic Heterosis and Genetic Control of Fruit Yield and Yellow Vein Mosaic Virus Disease Severity Traits of Okra

Evidence of Economic Heterosis and Genetic Control of Fruit Yield and Yellow Vein Mosaic Virus Disease Severity Traits of Okra) Ten diverse genotypes of cultivated and wild species were crossed in half diallel fashion to produce 45 F1 hybrids to determine mode of gene action, extent of economic heterosis and dominance effect, and to estimate combining ability for eight quantitative traits. Predictability ratio revealed overwhelming response of non-additive gene action for controlling fruit length, number of fruits per plant, and fruit yield per plant; additive gene effects for days to 50% flowering, while both additive and non-additive genetic control for node number at first flowering, fruit weight, fruit girth, and PDI of YVMV disease. Appropriate breeding strategies for improvement of studied traits are highlighted here. Significant standard heterosis over two commercial hybrids, Shakti and Abantika was comparatively lower in magnitude for fruit yield per plant (4.62 % and 17.59 %, respectively) and higher in magnitude for PDI of YVMV disease (-71.28 % and -72.28 %, respectively). Partial- to overdominance effects were involved in the inheritance of the studied traits. BCO-1 and 11/RES-6 were identified as potential donors for future use. The study could able to identify an outstanding hybrid (BCO-1 × Arka Anamika) having high tolerance both under field and artificial conditions. This hybrid would definitely make a room in okra growing zones of the tropics after critical testing..

Assessment of genetic diversity in Okra(Abelmoschus esculentusL. Moench) for yield and yellow vein mosaic virus incidence

Thirteen diverse genotypes were evaluated to assess the genetic diversity in a randomized block design during 2013–14 for yield and yellow vein mosaic virus (YVMV) incidence in Okra. On the basis of D2 values, the 30 genotypes were clustered into six groups. Cluster II constituted the largest group (11 genotypes) followed by cluster in and cluster VI (5 genotypes each). The cluster IV and V contain 4 genotypes each, whereas only 1 genotypes present in cluster I. The character coefficient of infection alone contributes highest percentage (51%) toward divergence, followed by number of branches per plant (24%), percentage disease incidence (12%). The first six principal components have accounted 84.00% of total variation and percent variation expected were 24.00% (PC1), 19.50% (PC2), 14.30% (PC3), 11.48% (PC4), 7.97% (PC5) and 6.80% (PC6), respectively. The PC1 has positive association with days to first picking, followed by days to first flowering and days to 50% flowering. However, PC1 has negative association for fruits per plant and fruit weight. Therefore, the traits viz., days to first picking, first flowering node and days to first flowering should be given top priority in diverse parent selection for attempting high yielding along with YVMV tolerant hybrids in okra.

Seed-borne nature of a begomovirus, Mung bean yellow mosaic virus in black gram.

The yellow mosaic viruses (YMV) infecting legumes are considered to be the most devastating begomoviruses as they incite considerable yield loss. The yellow discoloration of pods and seeds of infected plants and symptom emergence in the very first trifoliate leaf of the plants in the field were suggestive that the virus may be seed borne, which was investigated in the present study. The distribution of the virus in various parts of the seeds of black gram (Vigna mungo L. Hepper) plants naturally infected in the field was determined by polymerase chain reaction (PCR), Southern blot analysis, and sequencing. Nucleotide sequencing of the PCR amplicons from the seed parts from groups of ten seeds revealed the presence of mung bean yellow mosaic virus (MYMV) in the seed coat, cotyledon, and embryonic axes. The presence of virion particles was confirmed through double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and immunosorbent electron microscopy (ISEM) even in a single whole seed. In confocal microscopy, positive fluorescent signals were obtained using coat protein gene-specific primers in the embryonic axes. However, in the growth tests performed with the same batch of seeds, there was no symptom development in the seedlings though the virus (both DNA A and B components) was detected in 32 % of tested seedlings. In this study, the MYMV was detected in seed coat, cotyledon, and embryo. This study revealed that the MYMV is a seed-borne virus.

English

english

Screening of moth bean (Vigna aconitifolia) core collection against yellow mosaic virus

A core collection of moth bean [Vigna aconitifolia (Jacq) Marechal] germplasm, consisting of 204 lines identified in NAIP project was evaluated for mung bean yellow mosaic virus (MYMV) resistance; most of the lines were totally destroyed by yellow mosaic virus. Out of 204 accessions, 13 exhibited resistance/tolerance to disease in terms of intensity or level of symptoms appearing on individual plants. The susceptible lines could not bear flowers while resistant plants produced reasonable yield. The response of germplasm to MYMV exposed a distinct variation to the disease reaction. No genetic association between qualitative traits (seed color, leaf shape and plant type) and resistance/susceptibility to MYMV was observed in the present study. However, seed yield was significantly reduced with increased disease intensity.

Moth bean germplasm screening against yellow mosaic virus, II. Developmentof moth bean high-yielding seed and fodder cultivars

Moth bean (Vigna aconitifolia (Jacq.) Marechal) susceptibility to yellow mosaic virus (YMV) purged the crop from the farming system. Therefore, genotype-by-environment interaction (GEI) and biplot studies were undertaken to develop YMV-resistant moth bean cultivars from the germplasm. The germplasm was acquired from the National Agricultural Research Centre (NARC), Islamabad and from the farm fields in two provinces, Punjab and Sindh, Pakistan. Two different groups of moth bean genotypes were screened for YMV versus seed yield (11 genotypes) and YMV versus fodder yield (10 genotypes) over three years (2006-2008) in three locations in Pakistan (D.I.Khan Agriculture Research Station (ARS), Serai Naurang ARS, and Karak ARS). In all germplasm, four moth bean lines were identified as highly resistant to YMV with maximum grain (013393-C, 013388) and fodder (DMB-118-E, DMB-118-A) yields across all years and locations. Genotype, environment, GEI, and biplot analysis revealed that two moth bean lines (013393-C and DMB-118-E) showed the lowest YMV scoring (1) and maximum grain (33.40, 29.70, and 33.98 g plant -1 ) and fodder yields (15.30, 17.40, and 15.35 t ha -1 ) compared with susceptible checks, respectively. Keeping in view the genetic potential of YMV-resistance and the high grain and fodder yields of two moth bean lines (013393-C, DMB-118-E), the Provincial Seed Council (PSC) of Khyber Pakhtunkhwa, Pakistan approved the two lines with the highest grain and fodder yields as new moth bean cultivars, naming them Dera Moth and Green Moth, respectively.

Efficacy of integrated disease management (IDM) modules for okra yellow vein mosaic virus in semi arid region of middle Gujarat

A study was conducted during kharif season of the year 2010-11 to evaluate the effectiveness of okra IDM modules on the basis of infestation level of whiteflies and incidence of yellow vein mosaic virus (YVMV) disease of okra. The IDM module I consisting of periodical uprooting and destruction of infected plants up to 40 days and two sprays of dimethoate (0.03 %); IDM module II comprising destruction of infected plants; first spray with azadirachtin (0.03 %) in the form of neem oil followed by second spray with dimethoate (0.03 %) accompanied by monitoring of whiteflies population by installing of yellow sticky traps @ 10 traps/ha as compared to conventional farmers’ practices. The results indicated that minimum mean whiteflies infestation (1.10) and mean disease incidence (2.29) in IDM module II followed by module I (mean whiteflies infestation 1.98 and mean disease incidence 4.06) as compared to conventional farmers’ practices having higher levels of the same (mean whiteflies infestation 4.89 and mean disease incidence 21.04). Higher mean yield (79.33 q/ha) and cost: benefit ratio (3.02) were also realized in the IDM module II followed by module I (mean yield 61.82 q/ha and cost: benefit ratio 2.54) as compared to farmers’ practice (mean yield 46.05 q/ha and cost: benefit ratio 1.92).

Development and validation of protocols for product stewardship in transgenic white clover (Trifolium repens L.): detection of the AMV CP and npt2 transgenes in seeds, herbage and hay

White clover (Trifolium repens L.) is an important pasture legume in temperate areas throughout the world, providing fodder for grazing animals and improving soil fertility via symbiotic nitrogen fixation. However, the persistence and stress tolerance of white clover is affected by several viruses, chiefly Alfalfa mosaic virus (AMV), Clover yellow vein virus (ClYVV) and White clover mosaic virus (WClMV). Efforts to introgress natural forms of virus resistance from other Trifolium spp. into white clover and lucerne (alfalfa) have had only limited success. This has been addressed by developing white clover germplasm exhibiting viral-coat-protein-mediated resistance to AMV and non-transgenic resistance to ClYVV. This report describes PCR-based assays for detecting the transgenes associated with the H6 transformation event in seeds, fresh leaves, air-dried leaves and mixtures of air-dried herbage of white clover and perennial ryegrass (hay). Although further development is required to convert these assays for use in the field, this paper demonstrates the ability to detect these transgenes in a range of agricultural products associated with the commercial use of white clover.

Morphological Characterization and Agronomic Evaluation of Yellow Vein Mosaic Virus Resistant Single Cross Hybrids for Yield and Quality Traits in Okra (Abelmoschus esculentus L. Moench)

Okra (Abelmoschus esculentus L. Moench) is a traditional pod vegetable widely grown in low, medium and high-input systems for domestic and export markets. The economic and ecological sustainability of okra in these systems is under question because of the low-yielding potential, sub-optimal pod quality and susceptibility to biotic and biotic stresses especially the yellow vein mosaic virus (YVMV) of the traditionally cultivated open-pollinated varieties (OPVs) and landraces. Development and use of improved varieties with high yield potential, superior pod quality and resistance to YVMV play an important role in bringing sustainability of okra in these systems. Fifteen single cross hybrids developed by crossing six newly developed inbred lines (RNOYR-14, RNOYR-15, RNOYR-16, RNOYR-17, RNOYR-18 and RNOYR-24), in half-diallel fashion during rainy season 2012, were evaluated along with three local hybrid checks [No. 64 (Mahyco), Avantika (228) (Bioseed) and Shakti (Nunhems)], one OPV check (Arka Anamika) and one OPV cross check for YVMV susceptibility (Pusa Sawani) in a randomized complete block design with three replications during summer 2013 at the Vegetable Research Station, Hyderabad for studying their yield potential, pod quality and resistance to YVMV. All of the 15 single cross hybrids were resistant to YVMV with 0% incidence as against 100% incidence in OPV checks Arka Anamika and Pusa Sawani. On the basis of mean performance, three crosses RNOYR-15 × RNOYR-16, RNOYR-16 × RNOYR-17 and RNOYR-17 × RNOYR-18 were of significantly higher yield potential than the standard check “No. 64”, but of comparable yield potential with other checks “Avantika” and “Shakti”. In addition, these three crosses also of superior pod quality could be exploited for development of commercial hybrid okra. These hybrids would be advantageous for production and quality improvement, trade facilitation and environmental protection.

Mapping of yellow mosaic virus (YMV) resistance in soybean (Glycine max L. Merr.) through association mapping approach.

Yellow Mosaic Virus (YMV) is a serious disease of soybean. Resistance to YMV was mapped in 180 soybean genotypes through association mapping approach using 121 simple sequence repeats (SSR) and four resistance gene analogue (RGA)-based markers. The association mapping population (AMP) (96 genotypes) and confirmation population (CP) (84 genotypes) was tested for resistance to YMV at hot-spot consecutively for 3 years (2007-2009). The genotypes exhibited significant variability for YMV resistance (P < 0.01). Molecular genotyping and population structure analysis with 'admixture' co-ancestry model detected seven optimal sub-populations in the AMP. Linkage disequilibrium (LD) between the markers extended up to 35 and 10 cM with r2 > 0.15, and >0.25, respectively. The 4 RGA-based markers showed no association with YMV resistance. Two SSR markers, Satt301 and GMHSP179 on chromosome 17 were found to be in significant LD with YMV resistance. Contingency Chi-square test confirmed the association (P < 0.01) and the utility of the markers was validated in the CP. It would pave the way for marker assisted selection for YMV resistance in soybean. This is the first report of its kind in soybean.

Molecular characterization of distinct YMV (Yellow mosaic virus) isolates affecting pulses in India with the aid of coat protein gene as a marker for identification

The present study was carried out to find out the variations present in different isolates of yellow mosaic virus (YMV) causing yellow mosaic disease of pulses in southern parts of India. The coat protein gene of YMV was amplified using gene specific and deng universal primers with DNA isolated from YMV infected samples. Further, cloning and DNA sequencing of CP gene was carried out. CP gene decrypt sequences revealed that YMV infected samples of Black gram, Cowpea and Green gram were similar to the MYMV-Tamil Nadu isolates. Whereas the YMV infected sample of Horse gram was found to be similar with HYMV. Hence, in the present study, two distinct YMV infecting pulses in Tamil Nadu (MYMV and HYMV species) were identified and it was observed that there exists considerable genetic variation among these species. In addition, Cowpea crop which was earlier supposed not to be susceptible for YMV infection also showed the presence of this virus similar to the MYMV. Overall, the findings of the present study indicate that the CP region is efficient enough to provide a simple, rapid, and reliable method for early detection of YMV infections in pulses, which would help to develop proper management strategies to control these viruses.

First report of Mesta yellow vein mosaic virus, Cotton leaf curl Multan betasatellite and Cotton leaf curl Multan alphasatellite infecting cotton in Pakistan

First report of Mesta yellow vein mosaic virus, Cotton leaf curl Multan betasatellite and Cotton leaf curl Multan alphasatellite infecting cotton in Pakistan

Genetic Contribution of Wheat Variety Ningmai 9 to Its Derivates

Ningmai 9 is a soft wheat variety with high yield, wide adaption, and resistance to multiple diseases including Fusarium head blight, Yellow mosaic virus, powdery mildew, and sharp eye spots, which serves as a backbone parent in the southern Huaihe River valley. This study aimed to disclose the genetic contribution of Ningmai 9 to its derivates using SSR markers. A total of 471 alleles were detected on 170 SSR loci, with 1–6 alleles per locus and an average of 2.8. The UPGMA cluster analysis showed that Yangmai 18 and Ningmai 9 were clustered together firstly with the smallest genetic disrtance, and Yangfumai 4 and Ningmai 9 were clustered together with the largest genetic distance. Genetic similarity coefficient showed that more than a half of loci transferred from Ningmai 9 to its derived varieties. The percentage of alleles shared between Ningmai 9 and its derived varieties differed greatly among 21 chromosomes, but the average percentage was similar among A, B, and D genomes. Ten markers had the same amplification banding pattern in Ningmai 9 and nine derived varieties, and nine of them were linked to the QTLs or genes associated with important agronomic traits as previous reports. In comparison of genetic background between Ningmai 9 and Ningmai 13(a direct selection line from Ningmai 9), the genetic similarity coefficient was 0.732, suggesting that the genetic back ground of Ningmai 13 is similar to that of Ningmai 9. Genotyping data showed that the markers associated with protein content and resistance to Fusarium head blight in Ningmai 13 were in correspondence with those in Ningmai 9. These results may partially explain the reason for elite agronomic traits of Ningmai 13 similar to Ningmai 9, such as resistance to Fusarium head blight and soft wheat quality.

DIVA-Geographic Information System approaches for assessment of diversity and distribution pattern ofAbelmoschusspecies from Maharashtra, India

Existence of diversity in the native flora assumes importance, in terms of crop improvement, which has led to germplasm exploration and collection missions of the same. A. manihot and A. tetraphyllus, wild relatives of Abelmoschus species possess resistance genes for Yellow Vein Mosaic Virus (YVMV) and powdery mildew; A. moschatus for jassids; A. tuberculatus for fruit borer and A. caillei for drought tolerance with YVMV resistance. Between 2003 and 2009, germplasm exploration and collection missions for Abelmoschus sp., were carried out in the state of Maharashtra, India. A total of 100 accessions consisting of Abelmoschus caillei (1), A. ficulneus (41), A. manihot (25), A. tetraphyllus (9) and A. tuberculatus (24) were collected and conserved. Occurrences of wild Abelmoschus species in different districts along with indigenous collection numbers (IC) were recorded. DIVA-Geographical Information System (GIS) based on the data from spatial objects and their attributes for species richness and diversity index were used for germplasm of wild Abelmoschus species. DIVA-GIS grid maps, generated for species richness and Shannon Diversity Index for Abelmoschus species identified central Maharashtra for collection of diversity on wild okra

Resistance to yellow vein mosaic virus in okra: a review

Okra (Abelmoschus esculentus L. Moench) is an important vegetable grown throughout the world mainly for its immature fruits. Yellow vein mosaic virus (YVMV) transmitted by white fly (Bemisia tabaci Gen.) is the most serious disease of okra affecting both yield and fruit quality. Since the disease cannot be controlled properly by chemical means, the only practical solution of this problem is to develop tolerant/resistant varieties. Much work has been done to determine the inheritance of resistance to YVMV in okra and to identify different sources of resistance. In this review efforts have been made to elucidate the genetics of resistance to YVMV in okra and also to provide complete information regarding sources of resistance.