<div>Background: Cowpea [Vigna unguiculata (L) Walp.] is one of the Paraguayan rural families&rsquo; main crops, serving as an essential protein and carbohydrate source. Cowpea aphid borne mosaic virus (CABMV) and cowpea severe mosaic virus (CPSMV) were identified infecting cowpea plants. Disease control caused by both viruses is difficult because there is no information about local cowpea resistant cultivars and vector control is not practical. 
 
Methods:&nbsp;In the present work, sixteen cowpea genotypes/cultivars were mechanically inoculated with local isolates of CABMV and CPSMV to identify resistant genotypes/cultivars that can be used in breeding programs. Virus infections were determined by symptoms expression and confirmed by PTA-ELISA. 
 
Result:&nbsp;Genotypes Arroz rojo (V. angularis), TVu 379, TVu 382, TE94-256-2E and TE97-309G-9 were resistant to CABMV. Genotypes Arroz rojo (V. angularis), CNCX-698-128F, TVu 379, TVu 382, TVu-3961, TE97-309G-9 and TE97-309G-3 were resistant to CPSMV. Overall, this study showed that local cowpea cultivars do not offer any resistance to virus infection and the need for resistant germplasms for cowpea breeding programs in the country.</div>

​​Screening Cowpea Genotypes for Resistance to Cowpea Aphid Borne Mosaic Virus (CABMV) and Cowpea Severe Mosaic Virus (CPSMV) in Paraguay

Background:&nbsp;Tobacco mosaic virus (TMV) stands as a highly studied virus and consequently, its features and composition are extensively understood. It has been found to induce diverse infections in numerous plant species, with tobacco leaves being notably affected, showing mottled browning. Presently, the sole available method to control its spread is by removing infected plants. Understanding codon use bias is crucial as it could play a pivotal role in molecular interventions aimed at halting the virus&rsquo;s replication and multiplication, thereby helping to contain its propagation. 
 
 
Methods: Currently, the research focuses on assessing codon bias within six genes related to the replicase/coat protein of TMV, namely TMVgp1, TMVgp2, TMVgp3, TMVgp4, TMVgp5 and TMVgp6. To conduct this analysis, various methods such as relative dinucleotide abundance, relative synonymous codon usage (RSCU), neutrality plot and parity rule 2 (PR2) plot were employed. 
 
 
Result: All of the identified genes had a modest codon bias, according to the study on codon usage, as well as the function of mutation pressure in gene TMVgp3 and natural selection in genes TMVgp1, TMVgp2, TMVgp4, TMVgp5 and TMVgp6. The Research into codon use bias showed that the TMV virus&rsquo;s chosen genes are subjected to naturally occurring selection as well as mutational pressure.

Analysis of Codon Usage Bias of Six Genes of Replicase/Coat Protein of Tobacco Mosaic Virus

<div>Background: Whitefly is one of the most destructive sucking pest in the tropical and subtropical regions of the world and causing significant crop losses directly by sucking sap from the plants and indirectly through the transmission of viral diseases specifically caused by the genus Begomovirus. The Begomovirus species viz., Mungbean yellow mosaic India virus (MYMIV) and Mungbean yellow mosaic virus (MYMV) are causing yellow mosaic virus disease in soybean, which is transmitted by whiteflies. The disease accounts to 30-70 per cent yield loss and increases up to 80 - 100 per cent during severe incidence. Hence, there is a need for development of integrated pest management strategies against disease and whiteflies, for this the knowledge on virus-vector relationship is required. But, the studies on biological relationship of yellow mosaic virus disease and whitefly in soybean are scarce. At this juncture, considering the importance of disease in soybean, the present investigation was carried out to know the virus -vector relationship of the YMV and whitefly in soybean. 
 
Methods: The experiment on virus-vector relationship of yellow mosaic virus and whitefly in soybean was conducted at Department of Entomology, College of Agriculture, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during 2016-17. The data on number of whiteflies per plant, acquisition and inoculation access feeding period and pre and post starvation period required for effective transmission of virus was recorded. 
 
Result: A single viruliferous whitefly was able to transmit virus and ten viruliferous whiteflies per plant were required for cent per cent transmission of virus. The minimum acquisition access and inoculation access feeding periods required for virus transmission was 0.25h (15 min) each; while the 100 per cent virus transmission was recorded with acquisition and inoculation period of 12h, each. The per cent transmission was increased with the increase of acquisition and inoculation periods. The rate of transmission was positively correlated with pre-acquisition starvation period and negatively correlated with post- acquisition starvation period.</div>

<div>Virus Vector Relationship of Yellow Mosaic Virus and Whitefly, Bemisia tabaci (Gennadius) in Soybean</div>

<div>Background: French bean (Phaseolus vulgaris L.), is one of the important legume vegetables grown in India. The disease mung bean yellow mosaic virus (MYMV) limits successful production of beans. MYMV has become an epidemic in bean growing regions, particularly in the tropical and subtropical countries. In summer, the disease is more serious and widely distributed and reported in various countries. The current study is aimed at identification of MYMV and molecular characterization of mung bean yellow mosaic virus in French bean. This study will be helpful for early detection of the virus, so that better preventive measures can be taken to control MYMV. 
 
Methods: The investigations were conducted during 2016-2017, all the agro climatic zones of Karnataka province were surveyed. The coat protein (CP) gene of MYMV was amplified using gene specific primer with DNA isolated from MYMV infected leaves samples in french bean. Polymerase chain reaction products were Sequenced and analysed using a bioinformatic tool.&nbsp; 
 
Result: The CP gene decrypt sequences analysis revealed that the identity and similarity in global alignment for all the obtained sequences ranging from 80.8 to 95.3% with reference to MYMV, whereas for horse gram yellow mosaic virus (HYMV) it ranges from 90.4 to 99.1%. Two distinct yellow mosaic viruses infecting french bean (MYMV and HYMV) were identified and it was observed that there exists considerable genetic variation among these species. Present work showed that the CP region is efficient enough to provide a simple, rapid and reliable method for early detection of MYMV infections in french bean, which would help to develop proper management strategies to control these viruses.</div>

<div>Identification and Molecular Characterization of Mung Bean Yellow Mosaic Virus in French Bean through Coat Protein Gene</div>

Yellow mosaic virus disease is one of the major diseases of soybean in India. Genetic basis of 41 soybean genotypes varying in resistance against yellow mosaic virus was studied using 58 simple sequence repeat primers. A total of 140 alleles with an average of 2.41 alleles per locus were detected, which indicated very narrow genetic base of the genotypes studied. The polymorphic information content varied from 0.00 to 0.754 with an average of 0.357. Unweighted Pair Group Method with Arithmetic Average allocated the genotypes in 2 major clusters separated at 41% similarity with fairly good bootstrap support. Ten unique alleles observed in the study can be used for identification of genotype possessing that particular unique allele. The resistant group comprised of 21 genotypes with similarity coefficient 0.33 to 0.805, of which 20 genotypes were classified in a single sub-cluster. The results presented are of significance with regard to the identification of suitable donor parents for incorporating yellow mosaic resistance into popular soybean varieties. Genetically diverse parents with varying resistance against yellow mosaic virus identified in the study can be used for generating mapping population for the identification of SSR markers closely linked with yellow mosaic virus. &nbsp;&nbsp; &nbsp;

Assessment of genetic diversity of soybean genotypes differing in resistance against yellow mosaic virus using simple sequence repeat markers

<div>Background: In a region of Karnataka, India with a varied type climate PPSMV infection on pigeonpea occurs in a severe form and considered as green plague and one of the most devastating diseases as it appear in severe form resulting in reduction of 100% yield loss transmitted by vector eriophyid mite Aceriacajani Channabasavanna. However, not much systematic and strategic research work being carried out on epidemiology. In spite of various control measures, Sterility Mosaic Disease has continued to be major constraint in pigeonpea production. A lot of variation exists among the genetic background of different varieties in different regions. These variations render it difficult to evolve a common management strategy to control SMD epidemics. Therefore, it is necessary to know the severity of disease and factors associated with disease development which helps in devising suitable management practices. 
 
Methods: To study the influence of sowing dates on SMD and vector population under field conditions. A total of twelve sets of sowings were made at different time interval starting from first week of January 2012 to December, 2012. The SMD disease incidence and mite population were recorded in each treatment at fifteen days interval. Under artificial environment, pigeonpea seedlings of variety ICP8863 were raised. Inoculation of virus was done at different stage of plant growth viz., 15, 30, 45, 60, 75, 90 days after sowing. The observation on terminal disease incidence was recorded at 90 DAS to study the impact of host age on SMD. The eight pigeonpea varieties were sown near the SMD infected plot so as to facilitate the movement of vector population under natural conditions to study the reaction of pigeonpea varieties to SMD. Naturally grown weeds present in and around the sterility mosaic screening nursery were collected at weekly interval to see the presence of mites. In a glass house experiment, twenty-three cultivated species of economic importance and three Nicotiana species were sown three replications to see the alternate host for the virus. 
 
Results: The fluctuation in disease incidence and mite population was recorded throughout the year and early stage of crop growth recorded less disease incidence with lower mite population and gradual increase was recorded at later stage of crop growth period. The maximum disease incidence and mite population was recorded in crop sown during month of June and July where mean temperature was 24 to 26oC, RH 67 to 71% and rainfall of 2.13mm. The disease incidence recorded at different months of sowing had a significant positive correlation with mite population. Pigeonpea plants inoculated up to age of 30 days showed complete sterility with 100% disease incidence. The Resistant genotypes recorded less per cent disease incidence and symptom development at 60DAS. Whereas susceptible variety recorded maximum diseases incidence at early stage of crop growth and showed complete sterility. PPSMV and its vector survived on the ratooned pigeonpea plants and its wild relatives Atylosiascaraboeides during off season.</div>

<div>Epidemiological Factors Influencing the Development of Pigeonpea Sterility Mosaic Virus Disease in Pigeonpea</div>

<div style="text-align:justify">Background: Vigna mungo (Blackgram) is the major pulse crop cultivated in the Indian sub-continent. It is highly prone to yellow mosaic disease (YMD), which is widespread problem because all cultivated varieties are susceptible to the YMD in Andhra Pradesh state. The presence of two species of begomovirus i.e. Mungbean yellow mosaic virus (MYMV) and Mungbean yellow mosaic India virus (MYMIV) with YMD was reported in Andhra Pradesh. The current study was aimed to develop simple method of viral dimer clone construction and identifying the resistant blackgram genotypes against two species of begomovirus (MYMV and MYMIV) by agroinoculation technique. 
&nbsp; 
Methods: In this study, we standardize the rolling circle amplification (RCA) based viral dimer clone construction (MYMV DNA-A, MYMV DNA-B and MYMIV DNA-A) and constructed viral dimer clones were used to transform Agrobacterium tumefaciens EHA105 cells through freeze-thaw technique. Sprouted seed method of agroinoculation screening was conducted. 
 
Result: Total 45 blackgram genotypes were screened by sprouted seed method of agroinoculation with two combinations of viral dimeric constructs (MYMV-TPT-A+MYMV-TPT-B and MYMIV-TPT-A+MYMV-TPT-B). Twenty four genotypes offered resistant against MYMV infection and twenty three genotypes were resistant to MYMIV infection. Total 17 genotypes offered resistance to both species of virus (MYMV andMYMIV) associated with YMD.</div>

Construction of Full-length Dimer Clones of Yellow Mosaic Virus and Screening of Blackgram Germplasm using Agroinoculation

<div>Background: The yellow mosaic disease (YMD) creates a major hindrance and known to affect a number of grain leguminous crops in the Indian sub-continent. However, blackgram (Vigna mungo L.) is the most important grain legume crop which is affected widely by this disease. The disease is caused by a single stranded DNA containing begomovirus viz., Yellow mosaic virus (YMV) which is mainly transmitted through whitefly (Bemisia tabaci Genn.). Symptoms include severe patho-physiological alterations characterized by the presence of bright chlorotic yellow patches interspersed with green areas on leaf lamina. The present study was aimed to determine the variability among disease causing agents in six different geographical isolates representing four states viz. Andhra Pradesh, Karnataka, Odisha and Telangana states of southern India during the 2019 rabi season. 
 
Methods: The variability of YMV associated with YMD of blackgram was studied based on molecular characterization of partial DNA-A coat protein gene with subsequent nucleotide sequencing and phylogenetic tree construction. 
 
Result: The synthetic primers designed for the partial DNA-A segment forms a distinct viral gene specific PCR product. The band size corresponding to CP ~704 bp was obtained for MYMV, whereas CP ~500 bp gene band was obtained for MYMIV. Further, phylogenetic analysis based on partial DNA-A gene sequences of six isolates with other isolates from GenBank formed into two unique clusters viz., MYMV and MYMIV. Overall, our study confirming that the begomovirus causing YMD of blackgram in southern India is explored to be as strains of MYMV and MYMIV.</div>

Molecular Variability of Yellow Mosaic Virus (YMV) of Blackgram in Southern India

Background: The virus-distribution and bimodal seed transmission of BCMV in green gram was studied. The Bean common mosaic virus (BCMV) infecting leguminous crops have been found to be the most devastating Potyvirus as they cause considerable yield loss. Emergence of symptom in the first trifoliate leaf stage of the plants under the natural condition confirms that the virus may be seed borne, which has been investigated in the present study.&nbsp; 
 
Methods: The distribution of the virus in various parts of the seeds of mung bean (Vigna radiata) plants naturally infected in the field was determined by ELISA, polymerase chain reaction (PCR) and sequencing.&nbsp; 
 
Result: Nucleotide sequencing of the PCR amplicons from the seed parts from groups of ten seeds revealed the presence of Bean common mosaic virus (BCMV) in the seed coat, cotyledon and embryonic axes. The grow out test performed with the same batch of seeds, there was symptom development after 3 weeks of sowing and the presence of virus was detected in all the seedlings through ELISA test. RT-PCR amplification of viral cDNA from whole seed, seed coat, cotyledons and embryo generated an amplicon of ~1300 with BCMV coat protein gene specific primer. The genomic sequence (GenBank accession No. ON944468) showed highest nucleotide identity of 90-91% sequence similarities with NL-1 strain (KF114860.1) and 94% sequence similarities with MY15-014 strain (MW079241.1) of previously available BCMV- CP virus gene sequence.

Seed Transmission Behaviour of Bean Common Mosaic Virus in Green Gram

Yellow mosaic disease caused by a Begomovirus has become an important production constraint in lima bean cultivation in Karnataka. The begomovirus causes Lima bean Yellow Mosaic Virus (LYMV), was characterized by sequencing the CP and MP genes. Distinct viral gene specific PCR product corresponding to CP and MP gene ~1000 bp and ~900 bp was obtained. The PCR product were sequenced and compared with the reference Begomoviruses sequences from the NCBI blast database. LYMV (GKVK isolate) shared highest nucleotide identity (98%) with Horsegram yellow mosaic virus (HgYMV) of French bean isolate (Accession No. AM932425.1). Phylogenetic analysis of CP and MP gene sequences of LYMV-GKVK isolate showed that LYMV-GKVK clustered with isolates of HgYMV Horsegram and French bean isolates of Tamil Nadu, Srilanka, Karnataka. Based on Nucleotide Identity begomovirus infecting lima bean at Bangalore is to be considered as strain of HgYMV. The disease was also successfully transmitted to French bean and Horsegram when experimentally transmitted using whitefly vector. Therefore, the begomovirus causing yellow mosaic disease of lima bean is considered as strain of HgYMV. Lima bean is infected by Mungbean Yellow Mosaic India Virus (MYMIV) according to earlier reports whereas our study the reports the infection of HgYMV on Lima bean from Karnataka. Thus it is concluded that Lima bean is infected by both MYMIV and HgYMV in different geographical locations.&nbsp;