Between 2016 and 2018, a study was conducted to evaluate the prevalence and significance of
Potato virus Y
(PVY) present in seed potatoes distributed through garden stores in western Washington. Seed ...potatoes, particularly those exhibiting symptoms of cracking possibly caused by PVY, were purchased and grown-out in greenhouse tests. A relatively high incidence (47% in 2016; 26% in 2017; 29% in 2018) of the collections (15, 31, and 49 seed lots in total, respectively) produced plants that were confirmed by ELISA to be infected with PVY. Seed sold for organic production yielded approximately ten times more PVY infections than seed sold for conventional production. Strain typing revealed infections primarily by PVY
O
, PVY
NTN
, and PVY
N-Wi
. Mixed infections of PVY
O/NTN
and PVY
O/N-Wi
were detected a few times and no new or unusual PVY strains were found. These PVY strain types often were recovered from plants originating from cracked seed tubers, and the incidence of PVY
N-Wi
from cracked tubers increased (22% to 69%) during the study. PVY
N-Wi
remains an important constituent of the region’s PVY strain composition since its first detection in 2011. Garden enthusiasts and organic potato growers need more information about PVY to help mitigate the risk that PVY infected seed tubers could pose to commercial potato production fields.
Potato virus Y (PVY) is a major threat to potato cultivation worldwide. PVY exists as biologically and genetically distinct strains and causes varying degrees of pathogenicity and a wide range of ...symptoms in potato. Knowledge of the nature of PVY strains is essential for breeding PVY resistant cultivars that are durable against a wide range of strains. We report the complete genome of a PVY potato isolate (JK12) characterised from the potato production areas of Jammu and Kashmir, India. Nucleotide sequence comparisons and phylogenetic analysis with known PVY strains revealed that the isolate belongs to the NTN strain of PVY. At the whole genome sequence level, the JK12 isolate shared the highest identity (99.42%) with PVY-NTN strains reported from Germany, followed by those from United Kingdom (99.34%) and Japan (99.33%). Recombination detection analysis identified two recombination break points and JK12 appeared to have originated from a recombination event between a PVY-N strain from Belgium as a major parent and a PVY-O strain from China as the minor parent. Our results suggest possible mutation and recombination could be the basis for the evolution and the subsequent establishment of NTN in this region. Furthermore, a global evolutionary lineage analysis of all the known PVY strains showed relatively low nucleotide diversity among the PVY-NTN strains. Neutrality tests showed that all the genotypes of PVY are undergoing purifying selection suggesting population expansion of PVY. This is the first report of complete genomic characterization of an NTN strain of PVY isolated from commercial potato fields in India. The implications of the emergence of this strain in the Indian context are discussed.
New recombinant strain and genotype of PVY, designated as PVY
NTN-NW and SYR-III, respectively, shared properties with PVY
NTN and PVY
NW has been reported recently. PVY
NTN-NW predominated in potato ...fields in Syria and was able to induce potato tuber necrotic ringspot disease (PTNRD). Due to the rapid spread of the recombinant strains of PVY which might be the case of PVY
NTN-NW, a specific and reliable detection method is an essential step to control this strain and minimize its spread. The shared properties of PVY
NTN-NW and SYR-III with PVY
NTN and PVY
NW, however, complicate their identification involving multiple detection methods. Therefore, a multiplex polymerase chain reaction (PCR), that relies on a combination of previously published and newly designed primers was developed for the detection and identification of PVY
NTN-NW and SYR-III in single or mixed infections with the main PVY strains, PVY
O, PVY
N, PVY
NTN and PVY
NW. In addition, the present PCR assay was able to detect the recombination points in the P1 region enabling the differentiation of the variable genotypes of the recombinant strains PVY
NTN-NW, PVY
NTN and PVY
NW. The reliability of this PCR assay was confirmed using a significant number of well characterized PVY isolates collected from Syria and Japan including those of PVY
NTN-NW, SYR-III, PVY
O, NA-PVY
N, PVY
NW and PVY
NTN.
Two strains of
Potato virus Y (PVY), the common (PVY
O) and the tobacco veinal necrosis (PVY
N) have been known for decades. More recently, a tuber ringspot necrosis (PVY
NTN), and several ...recombinants of PVY
O and PVY
N (designated here as PVY
N:O) have been described. Further, the PVY
N group of strains have been assigned to two geographical subgroups of European (EU) PVY
N/NTN and the North American (NA) PVY
N/NTN. The evolution of new PVY
N strains, has complicated the diagnosis, which requires a combination of bioassay, serological and molecular assays. To simplify the identification and differentiation of various PVY
N strain groups, a competitive (single antisense and multiple sense primers) reverse transcription-polymerase chain reaction (RT-PCR) was used, making use of minor differences in the variable region part of the PVY genome. Specifically, primers based on small variations in nucleotide stretches of P1 gene permitted a broad range separation of PVY
O and PVY
N groups and the specific detection of strain subgroups. The primer pairs designed for identifying PVY
O, EU-PVY
N/NTN, NA-PVY
N and NA-PVY
NTN are described. Primer pairs can be used in a uniplex (single pair of primer) or multiplex (duplex, tetraplex or pentaplex) competitive RT-PCR, allowing simultaneous testing for any combination of PVY
O, EU-PVY
N/NTN, NA-PVY
N and NA-PVY
NTN.
Outbreaks of a new mating type (A2) of late blight (Phythopthora infestans) and the spread of bacterial wilt (Ralstonia solanacearum) were the most notable events among fungi and bacteria during the ...last 10 to 15 years in the Andes. The emergence of the A2 mating type of P. infestans was probably a result of seed movement from the Northern hemisphere. Black scurf caused by the fungus Rhizoctonia solani spread in Peru and Bolivia causing economic losses estimated at 5 to 10%. A high incidence of common scab on potato tubers, caused by the bacteria Streptomyces scabies was found in some localities in Bolivia. Among the emerging viruses, the NTN strains of PVY have been found in some countries including Peru. Recently, two other viruses have been found spreading in potatoes. One is coded SB26/29 and is transmitted by Russelliana solanicola, the first psyllid vector found for a plant virus. The other emerging virus is coded SB41 and is apparently also new to potatoes. It causes a severe mosaic on the affected plants and the virus is transmitted experimentally only by grafting. Some other viruses of minor importance have also been detected in potatoes.PUBLICATION ABSTRACT
The aim of this work was to correlate the appearance of the symptoms, multiplication and spread of virus after mechanical inoculation of potato (
Solanum tuberosum L.) cultivars showing different ...levels of susceptibility and sensitivity to
Potato virus Y
NTN (PVY
NTN). The potato cultivars used were the resistant cultivar Sante and susceptible cultivars Igor, Pentland squire and Désirée. The spread of the virus PVY
NTN in infected plants was monitored using different methods: DAS-ELISA, tissue printing, immuno-serological electron microscopy and real-time PCR. In all three susceptible cultivars, the virus was detected in the inoculated leaves 4–5 days after inoculation. From there virus spread rapidly, first into the stem, then more or less simultaneously to the upper leaves and roots. Real-time PCR was shown to be very sensitive and enabled viral RNA to be detected in non-inoculated leaves of susceptible cultivar Igor earlier than other methods. Therefore, for exact studies of plant–virus interaction, a combination of methods which detect viruses on the basis of their different properties (coat protein, morphology or RNA) should be used to monitor the spread of viruses.
A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools ...differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVYN strain and six to the PVYO strain. No PVYC was found. Two other isolates reacted serologically like PVYO, but were unable to elicit a hypersensitive response from the Nytbr gene and probably represent the PVYZ group. At the molecular level, these two isolates showed a combination of both PVYO and PVYN and could be recombinants of these strains. Another isolate reacted serologically like PVYO, but induced vein necrosis in tobacco, like PVYN-Wilga. Some PVYN isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVYNTN group. The PVYNTN, PVYN-Wilga and PVYZ groups probably represent pathotypes within strains PVYN and PVYO, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.
A potyvirus known to be an important agent involved in causing a disease of trailing petunias, was identified as being a member of the necrotic strain of potato virus Y (PVY) using a number of ...monoclonal antibodies. The sequence of the coat protein gene for the PVY isolate was determined and when compared with sequences for other PVY strains it was shown to cluster closely with isolates of PVY^sup NTN^ and to have a recombination point present within the coat protein common with other isolates of PVY^sup NTN^. When inoculated onto potato tuber necrotic ringspot disease (PTNRD) susceptible potato cultivars the petunia isolate was found to be capable of causing necrotic tuber symptoms, consistent with those caused by other isolates of PVY^sup NTN^. Due to the number of similarities it is thought the petunia isolate belongs to the PVY^sup NTN^ group of isolates. Out of 24 species of bedding and pot plant crops tested, 19 were shown by mechanical inoculation to be susceptible to PVY, highlighting not only a clear risk to a number of commercially important plant species from PVY^sup NTN^ infected trailing petunias, but also other susceptible crops grown in these areas.PUBLICATION ABSTRACT
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