Diversity of banana streak-inducing viruses in Nigeria and Ghana: Twice as many sources detected by immunoelectron microscopy (IEM) than by TAS-ELISA or IC-PCR

Our previous study had shown that some Musa leaf samples with Banana streak symptoms tested negative for Banana streak virus (BSV) in triple antibody-sandwich ELISA (TAS-ELISA). Therefore, in this study 63 additional Musa leaf samples were tested for BSV by TAS-ELISA, immunoelectron microscopy (IEM) and immunocapture polymerase chain reaction (IC-PCR). Sensitivity tests by sap dilution end-point analyses indicated that IC-PCR was considerably more sensitive than IEM fordetecting typical BSV, while IEM proved to be of similar sensitivity as TAS-ELISA. However, when leaf samples of Musa plants, obtained from different farmers’ fields in Nigeria and Ghana and some Nigeriansources maintained in the greenhouse were screened for BSV, more than twice as many samples revealed BSV-like particles by IEM than were detected by TAS-ELISA or IC-PCR. Of the 51 leaf samplesthat were BSV positive in all tests taken together, 48 were positive by IEM, 25 by IC-PCR and only 19 by TAS-ELISA. Upon IEM examination, typical bacilliform BSV-like particles were clearly recognized although in very diverse concentrations. Bacilliform particles deviating in length from the main particle populations or showing an angularly bent morphology were found. Occasionally, in certain samples and with certain antisera the IEM decoration tests revealed mixtures of strongly decorated and weaklydecorated BSV-like particles or bacilliform particles which did not at all react with the antibodies available. This proved, the occurrence, besides the presence of typical BSV, of diverse populations of BSV-like viruses in West Afric

Molecular techniques for pathogen identification and fungus detection in the environment

Many species of fungi can cause disease in plants, animals and humans. Accurate and robust detection and quantification of fungi is essential for diagnosis, modeling and surveillance. Also direct detection of fungi enables a deeper understanding of natural microbial communities, particularly as a great many fungi are difficult or impossible to cultivate. In the last decade, effective amplification platforms, probe development and various quantitative PCR technologies have revolutionized research on fungal detection and identification. Examples of the latest technology in fungal detection and differentiation are discussed here

The Comprehensive Phytopathogen Genomics Resource: a web-based resource for data-mining plant pathogen genomes

The Comprehensive Phytopathogen Genomics Resource (CPGR) provides a web-based portal for plant pathologists and diagnosticians to view the genome and trancriptome sequence status of 806 bacterial, fungal, oomycete, nematode, viral and viroid plant pathogens. Tools are available to search and analyze annotated genome sequences of 74 bacterial, fungal and oomycete pathogens. Oomycete and fungal genomes are obtained directly from GenBank, whereas bacterial genome sequences are downloaded from the A Systematic Annotation Package (ASAP) database that provides curation of genomes using comparative approaches. Curated lists of bacterial genes relevant to pathogenicity and avirulence are also provided. The Plant Pathogen Transcript Assemblies Database provides annotated assemblies of the transcribed regions of 82 eukaryotic genomes from publicly available single pass Expressed Sequence Tags. Data-mining tools are provided along with tools to create candidate diagnostic markers, an emerging use for genomic sequence data in plant pathology. The Plant Pathogen Ribosomal DNA (rDNA) database is a resource for pathogens that lack genome or transcriptome data sets and contains 131 755 rDNA sequences from GenBank for 17 613 species identified as plant pathogens and related genera

Recent Advances on the Multiplex Molecular Detection of Plant Viruses and Viroids

[EN] Plant viruses are still one of the main contributors to economic losses in agriculture. It has been estimated that plant viruses can cause as much as 50 billion euros loss worldwide, per year. This situation may be worsened by recent climate change events and the associated changes in disease epidemiology. Reliable and early detection methods are still one of the main and most effective actions to develop control strategies for plant viral diseases. During the last years, considerable progress has been made to develop tools with high specificity and low detection limits for use in the detection of these plant pathogens. Time and cost reductions have been some of the main objectives pursued during the last few years as these increase their feasibility for routine use. Among other strategies, these objectives can be achieved by the simultaneous detection and (or) identification of several viruses in a single assay. Nucleic acid-based detection techniques are especially suitable for this purpose. Polyvalent detection has allowed the detection of multiple plant viruses at the genus level. Multiplexing RT polymerase chain reaction (PCR) has been optimized for the simultaneous detection of more than 10 plant viruses/viroids. In this short review, we provide an update on the progress made during the last decade on techniques such as multiplex PCR, polyvalent PCR, non-isotopic molecular hybridization techniques, real-time PCR, and array technologies to allow simultaneous detection of multiple plant viruses. Also, the potential and benefits of the powerful new technique of deep sequencing/next-generation sequencing are described.This work was funded by grant BIO2017-88321-R from the Spanish Direccion General de Investigacion Cientifica y Tecnica (DGICYT) and the Prometeo Program GV2014/010 from the Generalitat Valenciana.Pallás Benet, V.; Sanchez Navarro, JÁ.; James, D. (2018). Recent Advances on the Multiplex Molecular Detection of Plant Viruses and Viroids. Frontiers in Microbiology. 9. https://doi.org/10.3389/fmicb.2018.02087S

Editorial : Plant Viruses, Volume II: Molecular Plant Virus Epidemiology and Its Management

Non peer reviewe

Production of monoclonal and polyclonal antibodies against a Nigerian isolate of banana streak virus

Banana streak virus is serologically and genomically heterogenous worldwide and there has been the need to produce antibodies that can detect all known serotypes of this virus. Antibody production requires purified virus, since BSV titre is low in Musa tissues, there was the need for an efficient method of purifying the virus. We are reporting the first production of two monoclonal antibodies, BSV 3F9/1 and BSV 3D4/2, against an isolate of BSV. Culture fluids of BSV 3F9/1 and BSV 3D4/2 had antibody titres of 1:204,000 and 1:6400, by ELISA, respectively. The two monoclonal antibodies detected all isolates of BSV that were detected by the homologous mouse polyclonal antibodies. Caesium gradient centrifugation reduced yield of BSV during purification. We described a method of purification, which excluded the caesium gradient step and yet increased BSV yield by about 15-fold. The virus preparation obtained by this new method was used to produce BSV-specific mouse and rabbit polyclonal antibodies. These BSV monoclonal antibodies together with the polyclonal antibodies were used for the detection of BSV

Identification and potential use of RAPD markers linked to yam mosaic virus resistance in white yam (Dioscorea rotundata)

Resistance to Yam mosaic virus (YMV) in tetraploid white yam (Dioscorea rotundata) is inherited differentially as a dominant and recessive character. Elite D. rotundata breeding lines with durable resistance to YMV can be developed by pyramiding major dominant and recessive genes using marker assisted selection (MAS). The tetraploid breeding line, TDr 89/01444, is a source of dominant genetic resistance to yam mosaic disease. Bulked segregant analysis was used to search for random amplified polymorphic DNA (RAPD) markers linked to YMV resistance in F1 progeny derived from a cross between TDr 89/01444 and the susceptible female parent, TDr 87/00571. The F1 progeny segregated 1:1 (resistant: susceptible) when inoculated with a Nigerian isolate of YMV, confirming that resistance to YMV in TDr 89/01444 was dominantly inherited. A single locus that contributes to YMV resistance in TDr 89/01444 was identified and tentatively named Ymv-1. Two RAPD markers closely linked in coupling phase with Ymv-1 were identified, both of which were mapped on the same linkage group: OPW18850 (3.0 centiMorgans [cM]) and OPX15850 (2.0 cM). Both markers successfully identified Ymv-1 in resistant genotypes among 12 D. rotundata varieties and in resistant F1 individuals from the cross TDr 93-1 ´ TDr 87/ 00211, indicating their potential for use in marker-assisted selection. OPW18850 and OPX15850 are the first DNA markers for YMV resistance and represent a starting point in the use of molecular markers to assist breeding for resistance to YMV