Molecular Characteristics of Barley Yellow Dwarf Virus-PAS-The Main Causal Agent of Barley Yellow Dwarf Disease in Poland.

Barley yellow dwarf is a threat to cereal crops worldwide. Barley yellow dwarf virus-PAS (BYDV-PAS) was detected for the first time in Poland in 2015, then in 2019. In the spring of 2021, in several locations in Poland, winter wheat and barley plants with dwarfism and leaf yellowing were collected. Reverse transcription-polymerase chain reaction results revealed BYDV presence in 47 samples and excluded wheat streak mosaic virus infections. Next, immuno-captured polymerase chain reactions confirmed only one case of co-infection caused by BYDV and wheat dwarf virus. Moreover, restriction fragment length polymorphism analysis showed that BYDV-PAS was predominant. The preliminary results were confirmed using sequencing. Infected cereal plants originated mainly from northwestern Poland. The complete coding sequence of coat protein (CP) and a fragment of RNA-dependent RNA polymerase (RdRp) genes of 14 Polish isolates were determined and deposited in the GenBank database. The nucleotide and deduced amino acid sequences of local isolates were compared with others reported to date, indicating their high similarity, from 75.4% to 99.5% and from 81.1% to 100% nucleotide sequence identity, in RdRp and CP, respectively. Phylogenetic analysis, based on the CP gene, revealed the presence of 3 main groups. The Polish isolates clustered together within the Ia group.

Duplex-RT-PCR assay for the simultaneous detection and discrimination of Brome mosaic virus and Cocksfoot mottle virus in cereal plants.

Brome mosaic virus (BMV) and cocksfoot mottle virus (CfMV) are pathogens of grass species including all economically important cereals. Both viruses have been identified in Poland therefore they create a potential risk to cereal crops. In this study, a duplex-reverse transcription-polymerase chain reaction (duplex-RT-PCR) was developed and optimized for simultaneous detection and differentiation of BMV and CfMV as well as for confirmation of their co-infection. Selected primers CfMVdiag-F/CfMVdiag-R and BMV2-F/BMV2-R amplified 390 bp and 798 bp RT-PCR products within coat protein (CP) region of CfMV and replicase gene of BMV, respectively. Duplex-RT-PCR was successfully applied for the detection of CfMV-P1 and different Polish BMV isolates. Moreover, one sample was found to be co-infected with BMV-ML1 and CfMV-ML1 isolates. The specificity of generated RT-PCR products was verified by sequencing. Duplex-RT-PCR, like conventional RT-PCR, was able to detect two viruses occurring in plant tissues in very low concentration (as low as 4.5 pg/µL of total RNA). In contrast to existing methods, newly developed technique offers a significant time and cost-saving advantage. In conclusion, duplex-RT-PCR is a useful tool which can be implemented by phytosanitary services to rapid detection and differentiation of BMV and CfMV.

Development of loop-mediated isothermal amplification assay for rapid detection of genetically different wheat dwarf virus isolates.

Wheat dwarf virus (WDV) is considered as one of the most common viruses on cereal crops. Recently, severe outbreaks of WDV have been observed especially on winter wheat in southwestern part of Poland. Moreover, the presence of genetically different WDV-barley-specific and WDV-wheat-specific forms (WDV-B and WDV-W, respectively) was confirmed. In this study, a loop-mediated isothermal amplification assay (LAMP) was developed for the first time for efficient and rapid detection of WDV-B and WDV-W in infected plants. The reaction was performed using a set of three primer pairs: WDVF3/WDVB3, WDVFIB/WDVBIP and WDVLoopF/WDVLoopB specific for coat protein coding sequence. The amplified products were analyzed by direct staining of DNA, gel electrophoresis and real-time monitoring of the amplification curves. The sensitivity of optimized reaction was tenfold higher in comparison with conventional PCR. LAMP assay developed here is a useful and practical method for the rapid detection of different WDV isolates and can be implemented by phytosanitary services.

Detection and discrimination of European isolates of Soil-borne wheat mosaic virus using immunocapture real-time reverse transcription-polymerase chain reaction.

Soil-borne wheat mosaic virus (SBWMV) is a viral pathogen of cereal crops. Although first detected in the United States, it has since been reported in Germany and Poland. To date, two SBWMV strains (Nebraska-like and New-York-like types) have been detected. While the nucleotide sequences of the coat protein (CP) genes from the two strains show only 89% similarity, the deduced amino acid sequences of this region are identical. Therefore, the isolates cannot be differentiated serologically using the double antibody sandwich enzyme-linked immunosorbent assay. An immunocapture real-time reverse transcription-polymerase chain reaction (IC-real-time-RT-PCR) assay was developed for detection and discrimination of SBWMV strains based on the amplification of short CP fragments (∼250bp). The results showed distinct melting curve profiles related to each strain. The primer pairs gave similar melting points, with a Tm of 82.1°C for Nebraska-like and 83.5°C for New-York-like SBWMV strains. This work confirms that IC-real-time-RT-PCR is a valuable technique for rapid detection and discrimination of SBWMV strains.