Book Review

To study the variability and to identify the species of Begomovirus associated with yellow mosaic disease of blackgram in Andhra Pradesh, India, infected blackgram samples were collected from six districts belonging to three regions of Andhra Pradesh. The total DNA was isolated by modified CTAB method and amplified with coat protein gene-specific primers (RHA-F and AC abut) resulting in 900?bp gene product. The PCR products were cloned, sequenced and deposited in GenBank. The sequence analysis of six clones showed that the size of amplified CP gene of YMV was 920?bp. Based on nucleotide sequence identity of six isolates representing three regions of Andhra Pradesh, the isolates from Rayalaseema and Telangana region are the same variant of YMV (>99.5% identity) and isolate from coastal Andhra is another variant of YMV (>95.4%) when compared with other region isolates. Comparison of CP gene sequence of YMV-TPT isolate with 27 other isolates in database revealed more than 93.2 and 86.2% identity with MYMIV isolates and less than 80 and 64% identity with MYMY isolates that originate from Indian sub-continent and South-East Asia at nucleotide and amino acid level, respectively. Phylogenetic tree based on CP gene sequences of six isolates with other isolates from GenBank formed unique cluster with MYMIV. Hence the YMV infecting blackgram in Andhra Pradesh is caused by MYMIV rather than MYMY as reported in Tamil Nadu which is adjoining state in southern India.     

Understanding the inheritance of mungbean yellow mosaic virus (MYMV) resistance in mungbean (<Emphasis Type="Italic">Vigna radiata</Emphasis> L. Wilczek)

Mungbean, Vigna radiata, third in the series of important pulse crops, still suffers from yield loss due to mungbean yellow mosaic disease caused by mungbean yellow mosaic virus (MYMV). Hence, studies on plant-microbe interaction are necessary for understanding the inheritance of resistance. This study concentrated on identification of linked molecular markers for MYMV resistance and to find the genetic inheritance of MYMV resistance in mungbean. A total of 413 germplasm entries in a MYMV hot spot area (Vamban) were subjected to natural field infection and 13 selected resistant lines were subjected to Agrobacterium infection using strains harboring partial genome of two different MYMV isolates, VA221 and VA239. Among the resistant lines, KMG189 showed strain-specific resistance to VA221 and had no symptoms during field trials. Ninety F₂ genotypes were developed from the cross made between KMG189 (MYMV-resistant) and VBN(Gg)2 (MYMV-susceptible), segregated in the Mendelian single cross ratio 3S:1R; susceptibility of all the F₁s to MYMV suggested that the MYMV resistance in mungbean is governed by a single recessive gene. Two SCAR markers CM9 and CM815 were developed through bulk segregant analysis, and the linkage analysis proved CM815 SCAR marker to be linked at 5.56 cM with MYMV resistance gene and SCAR CM9 had nil recombination percentage, suggesting it to be very closely linked to the MYMV resistance gene. SCAR marker CM9 was present in chromosome number 3 of mungbean suggesting novel loci for virus resistance in mungbean. The identified loci can be used for developing varieties resistant to MYMV in mungbean.     

Involvement of Volatile Substances in Systemic Resistance of Barley Against Erysiphe graminis f. sp. hordei Induced by Pruning of Leaves

Horsegram yellow mosaic disease was shown to be caused by a geminivirus; horsegram yellow mosaic virus (HYMV). The virus could not be transmitted by mechanical sap inoculation. Leaf dip and purified virus preparations showed geminate virus particles, measuring 15-18 * 30 nm. An antiserum for HYMV was produced and in enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) tests HYMV was detected in leaf extracts of fieldinfected bambara groundnut, french bean, groundnut, limabean, mungbean, pigeonpea and soybean showing yellow mosaic symptoms. Bemisia tabaci fed on purified HYMV through a parafilm membrane transmitted the virus to all the hosts listed above but not to Ageratum conyzoides, okra, cassava, cowpea, Croton bonplandianus, Lab-lab purpureus, Malvastrum coromandalianum and tomato. No reaction was obtained in ELISA and ISEM tests between HYMV antibodies and extracts of plants diseased by whitefly-transmitted agents in India such as A. conyzoides yellow mosaic, okra yellow vein mosaic, C. bonplandianus, yellow vein mosaic, M. coromandalianum yellow vein mosaic, tomato leaf curl and cassava mosaic. HYMV was also not found to be related serologically to bean golden mosaic, virus.     

Serological Studies on Mung Bean Yellow Mosaic Virus

Particles of mung bean yellow mosaic virus (MYMV) were purified by a method that yields up to 3 mg per kg of systemically infected Phaseolus vulgaris“Top Crop” and used to prepare antiserum. MYMV antiserum prepared gave a single precipitin line and had a titre of 1/512 with homologous virus in gel double-diffusion tests. MYMV was shown to be serologically related to other whitefly-transmitted viruses, bean golden mosaic virus, tobacco leaf curl virus and cassava latent virus.     

Bücherbesprechung (Book Reviews)

Abstract

A field experiment was conducted during 2002 – 2003 and 2003 – 2004 to study the impact of controlling the insect vector, Whitefly, of yellow mosaic virus on the performance of green gram grown under rainfed lowland rice fallow situation. Insecticide, Imidachloprid 12.5 kg a.i./ha, was applied at 15- and 30-days growth to four green gram varieties, direct-sown under residual soil moisture conditions after the harvest of kharif rice. Results showed crops under YMV-management achieved 65.67% more seed yield producing 11.68 q/ha, which was significantly higher than the crops under no YMV management (7.05 q ha^?1). Plants which had been treated with insecticide were found to be less affected (8.50%) by YMV compared to those which had no treatment (20.10%). Varieties PDM 54 and PDM 11 emerged as superior, producing significantly higher seed yields, 12.73 and 11.69 q/ha respectively; while Pusa vishal (8.21 q ha^?1) and Pusa 105 (7.85 q ha^?1) produced moderately compared with the local variety (6.31 q ha^?1). In addition, PDM 54 and PDM 11 showed relatively more resistance against YMV infestation recording 5.23% and 6.01% infected plants.     

Cloning, restriction mapping and phylogenetic relationship of genomic components of MYMIV from Lablab purpureus

The present work describes cloning of genomic components of whitefly transmitted geminivirus infecting Lablab purpureus syn. Dolichos lablab (commonly known as Dolichos bean or Hyacinth bean). The genome characterization using PCR with geminiviral degenerate primers and DNA sequencing were used to describe the bipartite virus associated with yellow mosaic disease of Dolichos lablab. Full-length DNA-A and DNA-B clones were obtained. The DNA-A sequence analysis showed that the isolate was similar to other Mungbean yellow mosaic India virus (MYMIV) isolates reported earlier. The nucleotide sequence analysis of the full-length DNA-A of virus isolate revealed more than 97% homology with Mungbean yellow mosaic India virus-[Cowpea] (AF481865), while the DNA-B also showed >95% homology with MYMIV-[Cp] (AF503580) and MYMIV-[Sb] (AY049771). The phylogenetic analysis of present isolate showed close relationship to legume geminiviruses. The nucleotide sequence analysis showed presence of six open reading frames (ORFs) in DNA-A, with 2 ORFs aligned in sense and 4 ORFs in antisense orientation. Similarly, DNA-B contained two open reading frames (ORFs), one in sense and another in antisense orientation.     

Screening and identification of random amplified polymorphic DNA (RAPD) markers linked to mungbean yellow mosaic virus (MYMV) resistance in mungbean (Vigna radiata (L.) Wilczek)

Bulk segregant analysis (BSA) and random amplified polymorphic DNA (RAPD) techniques were used to analyse the F2 individuals of susceptible VBN (Gg) 2 × resistant KMG 189 to screen and identify the molecular marker linked to mungbean yellow mosaic virus (MYMV) resistant gene in mungbean. Two DNA bulks namely resistant bulks and susceptible bulks were setup by pooling equal amount of DNA from five randomly selected plants of each disease response. A total of 72 random sequence decamer oligonucleotide primers were used for RAPD analysis. Primer OPBB 05 (5′-GGGCCGAACA-3′) generated OPBB 05 260 fragment in resistant parent and their bulks but not in the susceptible parent and their bulks. Co segregation analysis was performed in resistant and susceptible F2 individuals, it confirmed that OPBB 05 260 marker was tightly linked to mungbean yellow mosaic virus resistant gene in mungbean.     

Genetic diversity of legume yellow mosaic begomoviruses in Indonesia and Vietnam

High incidences of yellow mosaic symptoms were observed in soybean and yard‐long bean crops in Indonesia in 2009 and in mungbean crops in Vietnam in 2011. All five soybean and 20 yard‐long bean samples from Java, Indonesia, and 15 mungbean samples from Vietnam with symptoms tested positive for begomovirus infection by polymerase chain reaction (PCR) with primer pair PAL1v1978B/PAR1c715H. On the basis of collection location and the nucleotide sequence comparisons of the 1.5 kb begomoviral DNA‐A components amplified, a subset of samples comprising two soybean and six yard‐long bean isolates from Indonesia and five mungbean isolates from Vietnam were taken forward for more detailed examination. Sequence comparison and phylogenetic analysis of the full‐length sequences of all Indonesian and Vietnam isolates alongside other legume‐infecting begomoviruses revealed that all the isolates from Indonesia were Mungbean yellow mosaic India virus (MYMIV) strain‐A, and all from Vietnam were Mungbean yellow mosaic virus (MYMV) strain‐B. To the best of our knowledge, this is the first identification of MYMIV and MYMV associated with yellow mosaic of legumes in Indonesia and Vietnam, respectively. The epidemiological implications and potential consequences of the emergence of legume‐infecting begomoviruses on legume production in these areas of Southeast Asia are discussed.     

Screening of virus specific primers against the Cassava mosaic virus

Abstract

Five different Indian cassava mosaic virus (ICMV) specific primers were used to screen the virus from CMD affected samples collected from the different parts of Tamil Nadu. Out of five specific primers, three were designed to amplify the specific viral genes of ICMV and two were used for detection of ICMV. All primers amplified specific regions of the virus in all samples. The specific primer for amplification of coat protein gene of ICMV amplified 800 bp of coat protein gene from both ICMV and Sri Lankan cassava mosaic virus (SLCMV) infected samples invariably. The specific primer for amplifying movement protein (MP) gene amplified about 900 bp of movement protein gene from all CMD infected cassava samples. Likewise, 800 bp of nuclear shuttle protein (NSP) gene was amplified from all the samples. The primer ICMV A amplified 700 bp of PCR product from mosaic diseased cassava samples. A 300 bp product from DNA A of the virus amplified in all samples using the primer ICMV A₁.     

Differentiation of Yam Virus Isolates Using Symptomatology, Western Blot Assay, and Monoclonal Antibodies

Monoclonal antibodies (mAbs) were prepared against a yam mosaic virus (YMV) isolate from the Côte d'Ivoire. Symptomatology, Western immunoblotting, and ELISA were used to discriminate 69 isolates of YMV originating from different Dioscorea species and from various yam producing areas. These isolates induced two types of symptoms, were of four different electrophoretic mobilities and formed two serogroups. These results suggest that at least six differetit groups of isolates exist, three of which infect the main cultivated species in various geographical areas while two others were from unusual samples in our collection. An isolate from 'Pilimpikou Yam' from Central Burkina Faso was serologically distinct. It is concluded that there is a significant variability among yam virus isolates which is unrelated to the origin of the isolate (geographic or host species). It is suggested that precautions should be taken in order to avoid international exchange of infected material.     

The Nucleotide Sequence and Genome Structure of Mung Bean Yellow Mosaic Geminivirus

Complete nucleotide sequences of the infectious cloned DNA components (DNA 1 and DNA 2) of mung bean yellow mosaic virus (MYMV) were determined. MYMV DNA 1 and DNA 2 consists of 2,723 and 2,675 nucleotides respectively. DNA 1 and DNA 2 have little sequence similarity except for a region of approximately 200 bases which is almost identical in the two molecules. Analysis of open reading frames revealed nine potential coding regions for proteins of mol. wt. > 10,000, six in DNA 1 and three in DNA 2. The nucleotide sequence of MYMV DNA was compared with that of bean golden mosaic virus (BGMV), tomato golden mosaic virus (TGMV) and African cassava mosaic virus (ACMV). The 200-base region common to the two DNAs of each virus had little sequence similarity, except for a highly conserved 33-36 base sequence potentially capable of forming a stable hairpin structure. The potential coding regions in the MYMV DNAs had counterparts in the BGMV, TGMV and ACMV, suggesting an overall similarity in genome organization, except for absence of 1L3 in MYMV DNA 1. The most highly conserved ORFs, MYMV 1R1, BGMV 1R1, TGMV 1R1 and ACMV 1R1, are the putative genes for the coat proteins of MYMV, BGMV, TGMV and ACMV, respectively. MYMV 1L1 has also a high degree of sequence similarity with BGMV 1L1, TGMV 1L1 and ACMV 1L1.     

侵染落葵的黄瓜花叶病毒分离物CP基因序列分析

通过间接酶联免疫法(ID-ELISA)检测到染病落葵病样中存在黄瓜花叶病毒（Cucumber Mosaic Virus,CMV）。从病叶中提取总RNA,用RT-PCR方法扩增得到657bp的CMV CP基因片断,将扩增产物与T载体连接并进行测序。用DNA MAN将得到的CP基因序列与GenBank收录的黄瓜花叶病毒两亚组部分株系或分离物的CP基因序列进行比较,结果表明该CP基因与CMV亚组Ⅰ、亚组Ⅱ之间的核苷酸序列同源性分别为91.17~95.43%和75.30~75.76%,推导氨基酸序列同源性分别为95.41~97.71%和81.28~81.74%,表明CMV-Ba与亚组Ⅰ同源关系密切。     

Genetic variability of tobacco streak virus in South India based on the analysis of coat protein gene

Tobacco streak virus (TSV), a member of the genus Ilarvirus, family Bromoviridae is an important viral pathogen in peanut and other crops in South India. Fifteen TSV isolates naturally infecting groundnut, sunflower, onion, black gram, green gram, jute, tagetes, calotropis, pumpkin, watermelon and kenaf plants were collected from fields in different regions of Andhra Pradesh, Tamil Nadu and Karnataka. Virus was identified as TSV by direct antigen coating enzyme linked immunosorbent assay using TSV antiserum. The CP gene from each isolate was amplified using TSV coat protein specific primers. About 700 bp product was amplified, cloned, sequenced and determined its length as 717 nucleotides and codes for 239 amino acids. The sequence analysis revealed that the CP gene shared 91–100% and 91–99% sequence identity with TSV at nucleotide and amino acid level, respectively. The phylogenetic relationship based on the nucleotide sequence of these isolates from different geographical regions was also analysed in this study.     

Yellow mosaic virus affects the ion leakage fromVigna aconitifolia

Yellow mosaic virus (YMV) causes a greater loss of electrolytes from infected leaf tissues ofVigna aconitifolia (mothbean). Four highly susceptible entries of mothbean were examined for the pattern of electrolyte loss after virus has invaded the tissues. It was observed that YMV triggered a heavy loss of ions at initial stages of disease development, but the loss receded at advanced stages of infection. Maximal damage to electrolytes occurred at the second stage, showing about 50% infection. The findings are interesting as the present observations on viral disease differ from other plant diseases.     

PROPERTIES AND HOST RANGE OF TURNIP CRINKLE, ROSETTE AND YELLOW MOSAIC VIRUSES

Three isolates of turnip yellow mosaic virus and two other flea-beetle transmitted viruses, turnip crinkle and turnip rosette, have many similar properties: thermal inactivation end-point between 80 and 90° C.; dilution end-point greater than 10^-4; longevity in vitro at about 20° C. at least 30 days. All were transmitted by mechanical inoculation to a wide range of cruciferous host plants, including many weeds. Turnip yellow mosaic virus infected only Reseda odorata outside the Cruciferae , whereas rosette virus infected a few and crinkle virus many non-cruciferous hosts.     

Identification of Peanut Green Mosaic Virus Strains in India*

During field surveys, three peanut green mosaic virus isolates differing in symptomatology on groundnut and a few other hosts were collected. Ultrathin sections of infected groundnut leaflets showed cytoplasmic inclusions with pin wheels and scrolls. In enzyme-linked immunosorbent assay they reacted strongly with antisera to peanut green mosaic and soybean mosaic virus antisera, and moderately with adzuki bean mosaic and peanut stripe virus antisera. All isolates also reacted positively with antisera to peanut eye spot, blackeye cowpea mosaic, pea seed-borne mosaic, potato virus Y and tobacco etch viruses, and did not react with antisera to peanut mottle, bean yellow mosaic, bean common mosaic, clover yellow vein and sugarcane mosaic viruses. SDS-PAGE analysis of purified virus preparations of the three isolates showed a single polypeptide with mol. wt. of 34,500 daltons. Based on these results, the three isolates are identified as biologically distinct strains of peanut green mosaic virus.     

RNA/cDNA Hybridization and Infectivity Tests Suggest that Barley Yellow Mosaic Virus Isolate M has a Bipartite Genome

Northern blot analysis with random-primed cDNAs revealed that RNAs 1 and 2 of barley yellow mosaic virus (Ba YMV) isolate M have no extensive base sequence homologies. Both RNAs are needed for infection. RNA 2 is therefore neither a subgenomic nor a, satellite RNA, but rather an essential part of the viral genome. Ba YMV isolate M has thus a bipartite genome.     

韭葱黄条病毒、洋葱黄矮病毒和胡葱黄条病毒六安分离物CP基因克隆及同源性分析

设计特异性引物PCR扩增了六安大蒜病样中的韭葱黄条病毒(Leek yellow stripe virus,LYSV)、洋葱黄矮病毒(Onion yellow dwarf virus,OYDV)和胡葱黄条病毒(Shallot yellow stripe virus,SYSV)的全长CP基因,插入到pGEM-T载体并测序。分别比较3种病毒CP基因种内变异性和种间亲缘关系。结果表明LYSV六安分离物CP基因由864个碱基组成,与Genbank上已报道的68个LYSV不同分离物CP基因的核苷酸序列同源性为76.12%～84.31%;OYDV的CP基因由771个碱基组成,与Genbank上已报道的86个OYDV不同分离物同源性为81.06%～90.40%;SYSV的CP基因由774个碱基组成,与Genbank上已报道的11个SYSV不同分离物CP基因同源性为88.63%～94.32%;从分析结果来看,LYSV的CP基因不同分离物之间变异性较大,OYDV CP变异性不大,SYSV变异性很小;3种病毒都有1个以上的宿主,病毒种内不同宿主分离物之间CP序列差异很小。进化分析显示OYDV和SYSV的CP基因亲缘性较近并成簇,LYSV的CP基因与OYDV和LYSV的CP基因亲缘性较远。     

小西葫芦黄化花叶病毒分离物的3′末端序列多态性研究

研究了来自中国大陆9个小西葫芦黄化花叶病毒（ZYMV）分离物的基因组3′末端核苷酸序列及所推导的外壳蛋白（CP）氨基酸序列以及3′末端非编码区（UTR）序列,并与其它地区所报道的16个ZMYV分离物进行了同源性比较。ZYMV CP基因核苷酸序列具有一定的寄主相关性和地域相关性,但总体上其关联程度不明显;同时,CP氨基酸序列的寄主适应性程度明显高于地域相关性。25个ZYMV分离物的CP氨基酸序列根据其变异程度分为2个区： N端约41个氨基酸为高度变异区,CP核心区和C端氨基酸序列为保守区。研究结果初步揭示了ZYMV作为单链RNA病毒通过与寄主相互作用而表现寄主适应性变异的趋势。