Yellow Mosaic Disease Research Articles

Detecting Tomato Leaf Curl New Delhi Virus Causing Ridge Gourd Yellow Mosaic Disease, and Other Begomoviruses by Antibody-Based Methods.

The incidence and severity of begomovirus diseases have been increasing around the world recently, and the ridge gourd [Luffa acutangula (Roxb.) L.] is the latest example of a crop that has become highly susceptible to the outbreak of the tomato leaf curl New Delhi virus (ToLCNDV, genus Begomovirus) in India. Accurate diagnosis of causal agents is important in designing disease management strategies. In this study the coat protein (CP) gene from a ToLCNDV-Rg ridge gourd isolate was used to produce polyclonal antibodies (ToLCNDV-Rg-CP-PAb) in a rabbit. The antibodies successfully detected a 30.5 kDa ToLCNDV-Rg-CP in extracts of symptomatic ridge gourd leaf samples by several assays, such as Western Blotting (WB), Dot Immuno Binding Assay (DIBA), Direct Antigen Coating Enzyme Linked Immuno Sorbent Assay (DAC-ELISA), Immuno Capture Polymerase Chain Reaction (IC-PCR), and Immuno Capture Loop-Mediated Isothermal Amplification (IC-LAMP) assays. However, none of the negative samples tested positive in either of the detection methods. Among all the methods tested, the immunocapture assay, IC-LAMP, was the most sensitive in detecting ToLCNDV-Rg. Furthermore, antibodies generated in this study also detected other commonly occurring begomoviruses in South India, such as tomato leaf curl Palampur virus and squash leaf curl China virus in cucurbits. Together, ToLCNDV-Rg-CP-PAb can be used for detecting at least three species of begomoviruses infecting cucurbits. The obtained antibodies will contribute to monitoring disease outbreaks in multiple crops.

Parent genome contribution and its relationship with grain yield in backcross‐derived lines of soybean (Glycine max)

AbstractIntrogression of yellow mosaic disease (YMD) resistance and effect of recurrent parent genome (RPG) on grain yield was studied in 84 soybean genotypes from four populations namely, F2:7, BC1F6, BC2F5 and BC3F4 derived from cross JS335 x SL525. It was observed that in F2:7, BC1F6, BC2F5 and BC3F4 derived lines, RPG contribution was 42.5%, 54.9%, 66.4% and 77.6%, respectively, which is significantly less than expected values. Linkage drag from donor parent with YMD resistance gene may be a possible reason for such deviations. Average grain yield per plant in F2:7, BC1F6, BC2F5 and BC3F4 generations was observed as 13.0, 14.3, 14.9 and 16.1 g, respectively. It was observed that genotypes with more than 80% RPG observed to have both YMD resistance and good yield potential. Graphical genotyping (GGT) analysis revealed that maximum RPG was recovered in chromosomes 8 and 10 and maximum introgression occurred in chromosomes 6 and 19. Our results demonstrated that RPG was positively associated with yield as evident from yield increase with increase in RPG.

Detection and Classification of Yellow Mosaic Disease in Vigna mungo using Convolutional Neural Network Deep Learning Models

The yield of the black gram crop is negatively impacted by Yellow Mosaic Disease (YMD). Both quantity and quality of the black gram suffer significantly from this disease. Accurate diagnosis, flawless identification, and early detection guide the grower for proper and timely management of the disease. Deep learningbased pre-trained models have revolutionized the classification and identification of plant leaf disease in recent times. In the present study yellow mosaic disease of black gram has been classified using four deep learning models namely; DarkNet-19, SqueezeNet, AlexNet, and GoogLeNet. A total of 1100 images were collected from field experiments for each of three classes namely healthy, moderate and susceptible plants. During the field investigation, datasets with images of three classes; healthy, moderate, and susceptible were collected, pre-processed, and augmented to create a set of 1100 images of each class. Seventy percent of the images were used for the training of the models and thirty percent of the images were used for validation. The results obtained for different deep learning architectures DarkNet-19, SqueezeNet, AlexNet, and GoogLeNet showed validation accuracy and loss scores of 96.09, 60.74, 94.41, and 93.85%, and 0.2319, 0.6923, 0.2429 and 0.1399, respectively. For the YMD classification in blackgram, DarkNet-19 showed the highest accuracy and SqueezeNet showed the lowest accuracy.

Development of improved genotypes for extra early maturity, higher yield and Mungbean Yellow Mosaic India Virus (MYMIV) resistance in soybean (Glycine max)

Context Breeding for early maturity and higher yield is the principal objective in genetic improvement of Indian soybean. Yellow Mosaic Disease caused by Mungbean Yellow Mosaic India Virus (MYMIV) causes 80% yield loss in soybean. Aims This study aimed to develop early maturing, MYMIV resistant and high yielding soybean genotypes for enhancing soybean production and expanding the land area under cropping. Methods MYMIV resistance was introgressed from G. soja in to a widely adaptable cultivar JS 335 through a series of four generations of backcrosses and by evaluating derived progeny against MYMIV at a disease hot spot. Key results An extra-early maturing (71 days) genetic stock called NRC 252 was developed, which can be a potential gene donor in breeding for early maturing soybean varieties. Introgression lines YMV 1, YMV 2, YMV 11 and YMV 16 with MYMIV resistance and higher yield performance over recurrent parent and other check varieties were identified and characterised. Biplot analysis, assessing the main effect of genotype and the interaction of genotype with environment, revealed an ideal genotype with respect to 100-seed weight and grain yield that was also promising under sugarcane-soybean intercropping system in spring season. Conclusions Alleles from wild type soybean could improve yield attributing traits and MYMIV resistance in cultivated soybean. Improved genotypes such as YMV 1, YMV 2, YMV 11 and YMV 16 were found superior to the recurrent parent JS 335 as well as other check varieties. Implications The genotypes developed in the present study will help in reducing the damage caused by MYMIV disease and expansion of the area of soybean cultivation through intercropping with sugarcane.

Molecular identification of begomovirus associated with yellow mosaic disease of soybean crop from Madhya Pradesh

Molecular identification of begomovirus associated with yellow mosaic disease of soybean crop from Madhya Pradesh

Performance of black gram varieties to mungbean yellow mosaic disease at different sowing dates under spring and summer condition in western terai of Nepal

A field experiment was conducted at Grain Legumes Research Program (GLRP), Khajura, Banke, Nepal during spring and summer season 2019 to elucidate the effect of date of sowing and blackgram varieties on mungbean yellow mosaic disease severity and yield. The experiment was conducted in 2 factorial randomized complete block design with 3 replications. Factor A comprised date of sowing (S1= 5th April 2019, S2= 20th April 2019, S3= 5th May 2019, S4= 20th May 2019, S5= 25th July 2019, S6= 10th August 2019, S7= 25th August 2019 and S8= 10th September 2019) and factor B (Variety): V1= Khajura Mas 1 and V2= Rampur Mas. Disease severity was scored in 1-6 scale. Results revealed that mean values for days to disease appearance, disease score and grain yield in spring season sowing was 26 days, 3.72 and 635 kg/ha, whereas for summer season sowing was 14 days, 5.04 and 185 kg/ha. Among the date of sowing, April 5th sown crop recorded minimum mean disease score (3.1) with highest yield (719 kg/ha). Whereas, September 10th sown crop recorded maximum mean disease score (5.1) with lowest yield (174 kg/ha). Black gram varieties showed significant response to mean disease score and yield at early sowing condition but when the sowing date was delayed, there was no significant response of varieties to mean disease score and yield. The contribution of regression (R2 =0.791) and (R2 = 0.655) for spring season and summer season indicate that 79% and 65% of the blackgram yield would be affected by disease for the respective season. Therefore, it is better to sow blackgram in early season to escape mungbean yellow mosaic disease and minimize yield loss.

Rapid, Sensitive and Simultaneous Detection of Two Wheat RNA Viruses Using Reverse Transcription Recombinase Polymerase Amplification (RT-RPA).

In China, wheat yellow mosaic disease is mostly caused by wheat yellow mosaic virus (WYMV) and Chinese wheat mosaic virus (CWMV). If wheat is co-infected with these two viruses, it can cause severe yellow mosaic symptoms and yield losses. Early detection of viruses is crucial for preventing disease in the field. In this study, we optimized a sensitive, specific reverse transcription recombinase polymerase amplification (RT-RPA) detection method for two viruses, WYMV and CWMV. Two sets of primers were designed based on the capsid protein (CP)-encoding genes of the two viruses, and the reaction conditions were determined. The RT-RPA method, which amplified the target amplicon by a handheld reaction mixture for 20 min, was more sensitive than PCR-CP in the detection of WYMV. Finally, the RT-RPA method was performed on 110 randomly selected field samples, demonstrating its applicability to samples from different regions and specificity for co-infected samples. This study not only describes an improved method for detecting WYMV and CWMV using RT-RPA but also demonstrates the potential of this method, which could be applied under field conditions.

Management of Whitefly, Bemisia tabaci (Genn.) and Yellow Mosaic Virus Disease Infesting Blackgram, Vigna mungo (Linn)

Background: Pulse crops have a unique position in sustainable crop production as they provide highly nutritive food and keep the soil alive as well as productive. They play an important role in the Indian agriculture economy being the major source of protein in Indian dietary. Due to its more luxurious growth and more vegetative canopy, number of insect pests and diseases attack from seedling to maturity stage especially sucking pests like whitefly (Bemisia tabaci Genn.), which is the vector of the drastic disease, yellow mosaic virus disease (YMD) and cause losses ranging from 30-80% per cent. Methods: The field experiment on the management of whitefly and yellow mosaic disease (YMD), was conducted by integrating different combination of insecticides and yellow sticky trap during Kharif, 2018 and 2019 at instructional farm of VBKVK, Udaipur. Seven treatments comprising of different combinations of seed treatments at the time of sowing, foliar spray at 30 and 45 DAG and yellow sticky traps were evaluated. Result: Among the different treatments, seed treatment with Imidacloprid 600 FS @ 5 ml/kg, first foliar spray of Diafenthuron 50 WP @ 0.1% and second foliar spray with Acetamiprid 20 SP @ 0.5 g/l at 30 and 45 DAS respectively + yellow sticky trap resulted in significantly less YMD incidence (18.91%) and the minimum mean whitefly population and highest seed yield of blackgram. The above treatment was followed by seed treatment with Imidacloprid 600 FS @ 5 ml/kg and two foliar spray of Acetamiprid 20 SP @ 0.5 g/l at 30 and 45 DAS + yellow sticky trap, which recorded 20.31% disease incidence of YMD and mean whitefly population of (3.77 and 1.44/plant, respectively after first and second spray) and black gram yield of 10.01 q/ha.

Field Screening and Molecular Characterization of Urdbean Genotypes for Yellow Mosaic Disease

Background: Urdbean [Vigna mungo (L.) Hepper] is an important pulse crop in India as well as in South East Asia. It is an excellent source of easily digestible, good quality protein. Mungbean Yellow Mosaic Virus causing Yellow mosaic disease (YMD) is one of the most devastating diseases affecting urdbean production and productivity to a large extent. Identification of resistant genotypes is one of the most important aspects in the management of MYMV diseases. The current study aimed to identify the MYMV resistant urdbean genotypes in order to manage and control the MYMV disease. Methods: In present investigation, a total 100 urdbean genotypes were screened against MYMV under natural field conditions in the augmented design by planting 2 rows of two test entries each alternated with one row of susceptible check. Further, selected genotypes which showed disease free, highly resistant, resistant, moderately resistance and susceptible reaction in field screening were used to tag RAPD markers associated with MYMV resistance in urdbean. Result: Out of 100 genotypes tested, only one genotype, NDU 12-1 was found to be disease free, twenty seven genotypes found to be highly resistance and four genotypes showed resistance consistently for four consecutive seasons (two summer and two Kharif) during 2017-2018. However, four genotypes were found to be superior for seed yield among all the genotypes tested as well as resistant to MYMV. The RAPD analysis clearly grouped all the MYMV resistant genotypes studied in cluster I whereas the susceptible genotypes were clustered together in the cluster II. The present work has successfully identified the MYMV resistant urdbean genotypes which can be used in MYMV resistance breeding programme.

Molecular characterization of monopartite bhendi (Abelmoschus moschatus) yellow vein mosaic virus and screening of wild okra

Bhendi yellow vein mosaic disease (BYVMD) is the most devastating viral disease of okra (Abelmoschus moschatus ssp. moschatus) which affects yield and quality of the produce in India. The causative agent of BYVMD is begomovirus i.e. bhendi yellow vein mosaic virus (BYVMV) having DNA-A molecule along with betasatellite. Present study was carried out during 2019–21 at research farm of ICAR-National Bureau of Plant Genetic Resources, New Delhi to find out the diversity of begomovirus and its satellite nucleotide sequences derived from wild okra infected samples exhibiting conspicuous symptom of BYVMD using PCR-based detection technique on two wild okra symptomatic samples, viz. EC361170 and EC361148. Full length amplification of BYVMV satellite molecule and partial amplification of DNA-A was carried out using PCR and cloning of both randomly selected samples showed the presence of monopartite BYVMV. In both samples, presence of DNA-A molecule, betasatellite and alphasatellite were noticed. Two year (kharif 2019 and 2021) field screening of 10 accessions of wild okra (Abelmoschus moschatus ssp. moschatus) was carried out at ICAR-NBPGR, New Delhi. Out of 10 accessions, viz. EC360586, EC360794, EC360830, EC360900, EC359730, EC359836, EC359870, EC360351, EC361111 and EC361171 screened, 4 accessions, viz. EC360794, EC360586, EC360830 and EC361171 showed resistant (R) reaction during both the seasons against BYVMD. This is the first study which showed the presence of alpha-satellite molecule of BYVMV from New Delhi region in wild okra along with its resistance source.

Grower’s Guide: A Review for Sustainable Production of Okra (Abelmoschus Esculentus) in West Africa and Other Regions

Abstract: This paper provides detailed information specifically the botany, history, and current statistical report on okra as well as how it is cultivated. Major biotic and abiotic stress factors impeding the production of okra and the sustainability aspect in the production of the crop are discussed. Many reasons for poor growth and development, low yield of okra as well as seed dormancy or okra plant death are mentioned. These include poor quality of seed and some biotic stresses particularly yellow vein mosaic virus (YVMV) and abiotic stresses such as salinity, drought, various water stresses and high moisture content. However, okra as a tropical and subtropical crop is drought-resistant, thus does well under drought conditions. Notwithstanding, high moisture content, salinity, and the yellow vein mosaic virus disease are the major factors affecting the crop. These conditions especially the yellow vein mosaic virus disease reduce okra yield to about 94% depending on the time of infestation after germination. To control the mosaic virus disease, very limited success has been achieved by chemical methods (including the application of neem oil, Acetamiprid, Imidacloprid and Trizophos), which also are not permanent since some resistant cultivar become susceptible with time. Therefore, advance breeding and development of host resistance to viruses and measures to combat salinity are the important strategies against these impeding conditions.

DETEKSI BEGOMOVIRUS PADA BENIH PEPAYA DAN PENGENDALIANNYA DENGAN METODE HOT WATER TREATMENT

Begomovirus is a virus that has been reported as the cause of yellow leaf curl disease on papaya plants in Bengkulu. Incidence of yellow mosaic disease on papaya plants in Bengkulu up to 100% in papaya cultivation centers. So that it strengthens the suspicion of the potential for seed transmission Begomovirus in papaya plants. Seed-borne viruses by Begomovirus are important because : can be a source of initial inoculum in the planted area. Then the control of the virus is carried by the seeds. It is important to suppress the initial source of inoculum in the field. This research aims to Begomovirus detection in papaya seeds was carried out by PCR method using SPG1 . Primer and SPG 2, and control of virus in seeds by controlling Hot Water Treatment. Seed Papaya plants infected with Begomovirus were given hot water treatment which consisted of two treatments temperature is 56℃ for 60 minutes and 58℃ for 40 minutes in a water bath. positive control are seeds that were confirmed positive for begomovirus without Hot Water Treatment (HWT) while the negative control seeds were confirmed negative for begomovirus. The results of this study showed that Begomovirus was not detected at the age of 7 (primary leaves) days after sowing, however detected in plants aged 14 days after sowing (first leaf) using primers universal SPG 1 and SPG 2. After the papaya seeds were treated (HWT with a temperature of 56℃ for 60 minutes and 58℃ for 40 minutes showed negative results in plants aged 7 days after seedlings and 14 days after sowing. This shows that the HWT treatment is able to suppres Begomovirus in papaya seeds.

Changes in soil fungal communities after onset of wheat yellow mosaic virus disease.

Rhizosphere-associated microbes have important implications for plant health, but knowledge of the association between the pathological conditions of soil-borne virus-infected wheat and soil microbial communities, especially changes in fungal communities, remains limited. We investigated the succession of fungal communities from bulk soil to wheat rhizosphere soil in both infected and healthy plants using amplicon sequencing methods, and assessed their potential role in plant health. The results showed that the diversity of fungi in wheat rhizosphere and bulk soils significantly differed post wheat yellow mosaic virus disease onset. The structure differences in fungal community at the two wheat health states or two compartment niches were evident, soil physicochemical properties (i.e., NH4 +) contribute to differences in fungal community structure and alpha diversity. Comparison analysis showed Mortierellomycetes and Dothideomycetes as dominant communities in healthy wheat soils at class level. The genus Pyronemataceae and Solicoccozyma were significantly are significantly enriched in rhizosphere soil of diseased plant, the genus Cystofilobasidium, Cladosporium, Mortierella, and Stephanonectria are significantly enriched in bulk soil of healthy plant. Co-occurrence network analysis showed that the fungi in healthy wheat soil has higher mutual benefit and connectivity compared with diseased wheat. The results of this study demonstrated that the occurrence of wheat yellow mosaic virus diseases altered both fungal community diversity and composition, and that NH4 + is the most important soil physicochemical factor influencing fungal diversity and community composition.

Mutation of barley HvPDIL5-1 improves resistance to yellow mosaic virus disease without growth or yield penalties.

The soil-borne yellow mosaic virus disease, which is caused by the bymoviruses barley yellow mosaic virus (BaYMV) and/or barley mild mosaic virus (BaMMV), seriously threatens winter barley production in Europe and East Asia. Both viruses are transmitted by the soil-borne plasmodiophorid Polymyxa graminis and are difficult to eliminate through chemical or physical measures in the field, making breeding for resistant cultivars the optimal strategy for disease control. The resistance locus rym1/11 was cloned encoding the host factor gene Protein Disulfide Isomerase Like 5-1 (PDIL5-1), whose loss-of-function variants confer broad-spectrum resistance to multiple strains of BaMMV/BaYMV. Most resistance-conferring variants have been identified in six-rowed barley landraces/historic cultivars, and their introgression into modern two-rowed malting cultivars is difficult because PDIL5-1 is located in a peri-centromeric region with suppressed recombination. In this study, we used CRISPR/Cas9 genome editing to modify PDIL5-1 in the BaYMV/BaMMV-susceptible elite malting barley cv. ‘Golden Promise’ and obtained the mutants pdil5-1-a and pdil5-1-b. PDIL5-1 in the pdil5-1-a mutant encodes a protein lacking a cysteine residue, and pdil5-1-b contains a protein-coding frameshift. Both mutants were completely resistant to BaYMV. The knockout mutant pdil5-1-b showed complete BaMMV resistance, while pdil5-1-a showed decreased viral accumulation but no disease symptoms if compared to ‘Golden Promise’. Both PDIL5-1 edited lines, as well as the previously produced EMS-induced pdil5-1 mutant ‘10253-1-5’ in the elite malting barley cv. ‘Barke’ background, displayed no growth or yield penalties in garden experiments or bymovirus-free field trials. Line ‘10253-1-5’ showed improved resistance and yield performance compared to the wild-type and its sibling line when grown in infectious fields. Therefore, genome editing of the host factor gene PDIL5-1 could facilitate the breeding of barley varieties with resistance to bymoviruses.

Screening of wild okra (Abelmoschus esculentus) against yellow vein mosaic and enation leaf curl diseases

Okra yellow vein mosaic (OYVMD) and enation leaf curl diseases (OELCuD) are the most important biotic diseases which cause yield and quality loss in okra (Abelmoschus esculentus (L.) Moench). Therefore, development of viral resistance varieties and lines become important breeding objective worldwide. Wild relatives are the natural source for disease and pest resistance. Hence an experiment was conducted at research farm of ICAR-Indian Agricultural Research Institute, New Delhi during rainy (kharif) season 2020 and for screening of 24 wild genotypes to identify the resistance source for OYVMD and OELCuD diseases of okra. PDI (Percent disease incidence) for OYVMD varied from 3.12–93.72, while PDI for OELCuD ranged from 0.00–83.29. The area under disease progress curve for both the diseases indicated that the rate of disease incidence was in increasing trend with the growth of the crop. Based on the natural epiphytotic screening A. moschatus (IC 141055), A. tetraphyllus (IC 90476-1) and A. caillei (Sikkim) were 3 top most genotypes from different species which showed very less incidence of OYVMD and no incidence of OELCuD. These genotypes were grouped in highly resistant category for both the diseases; other genotypes grouped in this category were A. moschatus (EC 360900), A. tetraphyllus (IC 90515 and IC 470735). These genotypes can be used further for interspecific breeding programme and resistant variety development in okra.

EFFECT OF YELLOW VEIN MOSAIC VIRUS DISEASE OF OKRA ON GROWTH AND PROXIMATE ANALYSIS OF SOME OKRA CULTIVARS IN DUTSIN-MA

The study was conducted on okra, an important food consumed in Dutsin ma, Katsina State, Nigeria. Reports have indicates the effect of viral infections on produce quantity and quality, this study determined and document the effect of yellow vein mosaic virus disease of okra on performance and nutritional composition of some okra cultivars in Dutsin-ma, Sudan Savannah. Seedlings were inoculated with the virus at 1 week post emergence. Each cultivar was evaluated as inoculated (infected) and uninoculated (Healthy) treatments. Percent disease severity of infection (%), yield related parameters and proximate analysis of pod were measured. Data were subjected to independent t test and significance was determined at 5 % level of probability. Percent disease severity was highest in ‘Yar Balla’ (21.3%) as compared to the remaining cultivars. Reductions in plant height (8.8 %), fruit weight (37.6 %) and crude protein were significantly lower in ‘Yar Balla’ and ‘Jikin Mutum’ The present study reveal that the reduction in crude protein as a result of YVMV infection would worsen the protein deficiency problem of the populace who depend on the crop as the cheapest means of obtaining their daily protein and mineral requirement. There is therefore the need to prevent viral infection of vegetable crops in order to ensure high yield and guarantee its nutritive value.

Coat Protein Characterization of Mungbean yellow mosaic virus Infecting Blackgram (Vigna mungo L. Hepper) in Tamil Nadu

The Yellow Mosaic Disease is the main constraint for decreased yield in blackgram production. Coat protein gene of Mungbean yellow mosaic virus (MYMV) has been characterized and phylogenetic tree was constructed. The genomic DNA from diseased plants was collected and it was tested for it’s quality and quantity using a Nanodrop. The isolated DNA was subjected to polymerase chain reaction using begomovirus universal primers for preliminary confirmation of the virus. The samples amplified for universal primers were subjected for gene specific amplification using DNA A primers. The DNA A primers resulted in the amplification of the expected size of 1000 bp amplicon. The DNA fragments were sequenced and the sequence results of DNA A were compared with other sequences available in NCBI and it showed higher similarity with Mungbean yellow mosaic virus banglore coat protein gene (accession no: MK409376). The sequence was submitted in NCBI database and accession numbers were obtained. The phylogenetic tree was constructed using mega 11 software by comparing the selected strains with our isolate.

Molecular epidemiology on seasonal variation of yellow mosaic disease incidence in blackgram (Vigna mungo L. Hepper) with its vector Bemisia tabaci.

The yellow mosaic disease (YMD) of blackgram caused by Mungbean yellow mosaic virus has emerged as a serious threat to grain legume production, especially in Southeastern Asia. Seasonal incidence of YMD with its vector population was assessed in three different agroclimatic zones of Tamil Nadu in India for three consecutive cropping seasons namely, Rabi 2018 (October-December), Summer 2019 (March-May), and Kharif 2019 (June-August) at three different time intervals viz., 20, 40, and 60days after sowing (DAS). For all three seasons, disease incidence and whitefly count were recorded for a resistant and susceptible variety of blackgram in fields without any vector control intervention. The highest disease incidence (87%) was observed in the Panpozhi location during the summer season followed by Vamban and Coimbatore locations. The whitefly count was made through both visual count and yellow sticky traps. The whitefly population was highest at 20 DAS and decreased with the increasing age of crop for all the three locations assessed. Molecular epidemiology was analyzed by determining latent infection of mungbean yellow mosaic virus (MYMV) using molecular diagnosis. Latent infection was found to be well pronounced in the Coimbatore location during the Kharif season, where the crop was asymptomatic in both the resistant and susceptible varieties for all the three time periods assessed. The latent infection of MYMV observed in Coimbatore and Vamban ranged from 16.6 to 83.3% in both resistant and susceptible varieties for all three seasons. In Panpozhi, the latent infection of MYMV ranged from 16.6 to 66.6% for the susceptible variety (CO-5) for all three seasons observed. However, in the Panpozhi location, the resistant variety (VBN-8) failed to record any latent infection.

First Report of Chinese Wheat Mosaic Virus that Infects Barley in Japan.

Chinese wheat mosaic virus (CWMV), a member of the genus Furovirus in the family Virgaviridae (Adams et al. 2017), has a positive-sense RNA genome and is transmitted by Polymyxa graminis. CWMV is a causal agent of yellow mosaic disease in winter wheat in China (Guo et al. 2019). CWMV has also been detected in wheat plants in limited areas of the northern Japan (Nagano and Iwate Prefectures) (Fuji et al. 2022; Maeshima et al. 2010; Shirako and Maejima 2008). In preliminary tests using Western blotting with an antiserum raised against CWMV capsid protein (by Dr Y. Shirako, Tokyo University), we detected a furovirus in a breeding line of barley, “Tozan Kawa 111” (Hordeum vulgare L.) (collected in April 2012), grown in an experimental field infested with CWMV and wheat yellow mosaic virus (genus Bymovirus) in Nagano Prefecture. To investigate the infection of barley plants with cereal plant-associated soil-borne viruses, we collected leaf samples of “Tozan Kawa 111” plants (ten plants) showing yellow mosaic symptoms, but with not apparent wilting or stunting (Fig. S1A) in April 2016 (2015/16 growing season). Total RNA was extracted from symptomatic leave samples with TaKaRa RNAiso reagent (TaKaRa Bio) and subjected to reverse transcription polymerase chain reaction (RT-PCR) to detect virus agents. After cDNA synthesis using Moloney murine leukemia virus reverse transcriptase (Thermo Fisher Scientific) with random hexamers, PCR amplification with QuickTaq HS Dye Mix (Toyobo Co.) was conducted using primer sets specific to two furoviruses and three bymoviruses (Fig. S1B) known to infect wheat and/or barley plants in Japan (Tamada and Kondo 2013). RT-PCR analysis detected infection with CWMV in the leaf samples of “Tozan Kawa 111” plants (Fig. S1B), but not the other soil-borne viruses tested. The amplified PCR products (752 and 718 bp for CWMV RNA1 and RNA2, respectively) were purified by Wizard® SV Gel and PCR Clean-Up System (Promega) and subjected to Sanger sequencing to confirm their nucleotide sequences. The virus sequences from PCR amplicons were deposited in GenBank/DDBJ/ENA with accession numbers LC657081 (RNA1) and LC657082 (RNA2). Nucleotide Basic Local Alignment Search Tool (BLASTn) analysis showed that the sequences have 98.7% and 98.8% nucleotide sequence identity with RNA1 of CWMV Japanese northern isolate (accession No, AB299271) and RNA2 of CWMV Nagano-A isolate (AB935554), respectively. Identical sequences were also found in symptomatic wheat leaf samples (“Fukuho Komugi” cultivar) obtained from the same field (Fig. S1B). Rod-shaped particles were observed by transmission electron microscopy (Hitachi H-7650) in symptomatic “Tozan Kawa 111” leaf samples (Fig. S1C). Using reverse transcription loop-mediated isothermal amplification (Fukuta et al. 2013), CWMV was detected in “Tozan Kawa 111” plants in the same field in the 2015/16–2017/18 growing seasons, but not in the 2018/19–2020/21 growing seasons (Fig. S1D). In the 2015/16–2017/18 growing seasons, CWMV was detected in the barley plants (pooled five plant samples) cultivar “Kashima-mugi”, which showed similar yellow mosaic symptoms (Fig. S1D), but not in most of the other barley variants planted in the field. To our knowledge, this is the first report of CWMV field infection in plants other than wheat (Kuhne 2009). Further extensive virus screening in the fields and virus inoculation experiments are necessary to understand the pathology of CWMV in barley and possibly in other cereal crops.

Genomic and Pathogenic Diversity of Barley Yellow Mosaic Virus and Barley Mild Mosaic Virus Isolates in Fields of China and Their Compatibility with Resistance Genes of Cultivated Barley.

Plant viruses transmitted by the soilborne plasmodiophorid Polymyxa graminis constantly threaten global production of cereal crops. Although the yellow mosaic virus disease of barley has been known to be present for a long time in China, the understanding of the diversity of the viral pathogens and their interactions with host resistance remains limited. In this study, we conducted a nationwide survey of P. graminis and the barley yellow mosaic virus (BaYMV) and barley mild mosaic virus (BaMMV) it transmits, followed by genomic and pathogenic diversity analyses of both viruses. BaYMV and BaMMV were found exclusively in the region downstream of the Yangtze River, despite the national distribution of its transmission vector P. graminis. Analysis of the genomic variations of BaYMV and BaMMV revealed an elevated rate of nonsynonymous substitutions in the viral genome-linked protein (VPg), in which most substitutions were located in its interaction surface with the host eukaryotic translation initiation factor 4E (eIF4E). VPg sequence diversity was associated with the divergence in virus pathogenicity that was identified through multiple field trials. The majority of the resistance genes, including the widely applied rym4 and rym5 (alleles of eIF4E), as well as the combination of rym1/11 and rym5, are not sufficient to protect cultivated barley against viruses in China. Collectively, these results provide insights into virulence specificity and interaction mode with host resistance in cultivated barley, which has significant implications in breeding for the broad-spectrum resistance barley varieties.