Four lupin species, Lupinus angustifolius, L. albus, L. luteus, and L. mutabilis, are grown as co... more Four lupin species, Lupinus angustifolius, L. albus, L. luteus, and L. mutabilis, are grown as cool-season grain legume crops. Fifteen viruses infect them. Two of these, bean yellow mosaic virus (BYMV) and cucumber mosaic virus (CMV), cause diseases that threaten grain lupin production. Phytosanitary and cultural control measures are mainly used to manage them. However, breeding virus-resistant lupin cultivars provides an additional management approach. The need to develop this approach stimulated a search for virus resistance sources amongst cultivated lupin species and their wild relatives. This review focuses on the progress made in optimizing virus resistance screening procedures, identifying host resistances to BYMV, CMV, and additional viral pathogen alfalfa mosaic virus (AMV), and the inclusion of BYMV and CMV resistance within lupin breeding programs. The resistance types found in different combinations of virus and grain lupin species include localized hypersensitivity, sys...
Biological characteristics of 11 Potato virus S (PVS) isolates from three cultivated potato speci... more Biological characteristics of 11 Potato virus S (PVS) isolates from three cultivated potato species (Solanum spp.) growing in five Andean countries and 1 from Scotland differed in virulence depending on isolate and host species. Nine isolates infected Chenopodium quinoa systemically but two others and the Scottish isolate remained restricted to inoculated leaves; therefore, they belonged to biologically defined strains PVSA and PVSO, respectively. When nine wild potato species were inoculated, most developed symptomless systemic infection but Solanum megistacrolobum developed systemic hypersensitive resistance (SHR) with one PVSO and two PVSA isolates. Andean potato cultivars developed mostly asymptomatic primary infection but predominantly symptomatic secondary infection. In both wild and cultivated potato plants, PVSA and PVSO elicited similar foliage symptoms. Following graft inoculation, all except two PVSO isolates were detected in partially PVS-resistant cultivar Saco, while c...
Potato virus Y (PVY) disrupts healthy seed potato production and causes tuber yield and quality l... more Potato virus Y (PVY) disrupts healthy seed potato production and causes tuber yield and quality losses globally. Its subdivisions consist of strain groups defined by potato hypersensitive resistance (HR) genes and whether necrosis occurs in tobacco, and phylogroups defined by sequencing. When PVY isolate PP was inoculated to potato cultivar differentials with HR genes, the HR phenotype pattern obtained resembled that caused by strain group PVYD isolate KIP1. A complete genome of isolate PP was obtained by high-throughput sequencing. After removal of its short terminal recombinant segment, it was subjected to phylogenetic analysis together with 30 complete nonrecombinant PVY genomes. It fitted within the same minor phylogroup PVYO3 subclade as KIP1. Putative HR gene Nd was proposed previously to explain the unique HR phenotype pattern that developed when differential cultivars were inoculated with PVYD. However, an alternative explanation was that PVYD elicits HR with HR genes Nc and...
We present the first complete Sweet potato virus G (SPVG) genome from sweet potato in East Timor ... more We present the first complete Sweet potato virus G (SPVG) genome from sweet potato in East Timor and compare it with seven complete SPVG genomes from South Korea (three), Taiwan (two), Argentina (one), and the United States (one). It most resembles the genomes from the United States and South Korea.
In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, K... more In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, Kayseri and Niğde. RT-PCR tests, with primers which amplified its coat protein (CP), detected potato virus S (PVS) in 35 samples. Complete CP sequences were obtained from 14 samples. Phylogenetic analysis using non-recombinant sequences of (i) the 14 CP’s, another 8 from Tokat province and 73 others from GenBank; and (ii) 130 complete ORF, RdRp and TGB sequences from GenBank, found that they fitted within phylogroups, PVSI, PVSII or PVSIII. All Turkish CP sequences were in PVSI, clustering within five subclades. Subclades 1 and 4 were in three to four provinces, whereas 2, 3 and 5 were in one province each. All four genome regions were under strong negative selection constraints (ω = 0.0603–0.1825). Considerable genetic variation existed amongst PVSI and PVSII isolates. Three neutrality test methods showed PVSIII remained balanced whilst PVSI and PVSII underwent population expansion. The ...
In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, K... more In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, Kayseri and Niğde. RT-PCR tests, with primers which amplified its coat protein (CP), detected potato virus S (PVS) in 35 samples. Complete CP sequences were obtained from 14 samples. Phylogenetic analysis using non-recombinant sequences of (i) the 14 CP’s, another 8 from Tokat province and 73 others from GenBank; and (ii) 130 complete ORF, RdRp and TGB sequences from GenBank, found that they fitted within phylogroups, PVSI, PVSII or PVSIII. All Turkish CP sequences were in PVSI, clustering within five subclades. Subclades 1 and 4 were in three to four provinces, whereas 2, 3 and 5 were in one province each. All four genome regions were under strong negative selection constraints (ω = 0.0603–0.1825). Considerable genetic variation existed amongst PVSI and PVSII isolates. Three neutrality test methods showed PVSIII remained balanced whilst PVSI and PVSII underwent population expansion. The ...
High Plains wheat mosaic virus (HPWMoV) causes a serious disease in major wheat-growing regions w... more High Plains wheat mosaic virus (HPWMoV) causes a serious disease in major wheat-growing regions worldwide. We report here the complete or partial genomic sequences of five HPWMoV isolates from Australian wheat samples. Phylogenetic analysis of the nucleotide sequences of the eight genomic segments of these five isolates together with others from Genbank found all eight genes formed two lineages, L1 and L2. L1 contained a single isolate from Colorado in the North American Great Plains Region (GPR), and L2 had two unresolved clusters, A and B, of isolates from Australia and the GPR. A quarter of the L2B isolate sequences of the nucleocapsid gene (RNA3) were recombinant, which is unexpected as little evidence of recombination exists in viruses with negative single-stranded RNA genomes. Phylogenies calculated from the amino acid sequences of HPWMoV’s RNA-dependent RNA-polymerase (RNA1), glycoprotein (RNA2), and nucleocapsid protein (RNA3) showed they were closest to those of Palo Verde ...
The family Apiaceae comprises approximately 3700 species of herbaceous plants, including importan... more The family Apiaceae comprises approximately 3700 species of herbaceous plants, including important crops, aromatic herbs and field weeds. Here we report a study of 10 preserved historical or recent virus samples of apiaceous plants collected in the United Kingdom (UK) import interceptions from the Mediterranean region (Egypt, Israel and Cyprus) or during surveys of Australian apiaceous crops. Seven complete new genomic sequences and one partial sequence, of the apiaceous potyviruses apium virus Y (ApVY), carrot thin leaf virus (CaTLV), carrot virus Y (CarVY) and celery mosaic virus (CeMV) were obtained. When these 7 and 16 earlier complete non-recombinant apiaceous potyvirus sequences were subjected to phylogenetic analyses, they split into 2 separate lineages: 1 containing ApVY, CeMV, CarVY and panax virus Y and the other CaTLV, ashitabi mosaic virus and konjac virus Y. Preliminary dating analysis suggested the CarVY population first diverged from CeMV and ApVY in the 17th century ...
In 1976, a virus with flexuous, filamentous virions typical of the family Potyviridae was isolate... more In 1976, a virus with flexuous, filamentous virions typical of the family Potyviridae was isolated from symptomatic pepino (Solanum muricatum) plants growing in two valleys in Peru’s coastal desert region. In 2014, a virus with similar-shaped virions was isolated from asymptomatic fruits obtained from pepino plants growing in six coastal valleys and a valley in Peru’s Andean highlands. Both were identified subsequently as Wild potato mosaic virus (WPMV) by serology or high-throughput sequencing (HTS). The symptoms caused by two old and seven new isolates from pepino were examined in indicator plants. Infected solanaceous hosts varied considerably in their sensitivities to infection and individual isolates varied greatly in virulence. All seven new isolates caused quick death of infected Nicotiana benthamiana plants and more than half of them killed infected plants of Physalis floridana and S. chancayense. These three species were the most sensitive to infection. The most virulent is...
ABSTRACT In an intensive sun,ey of lentil and chickpea fields and research stationsplots carried ... more ABSTRACT In an intensive sun,ey of lentil and chickpea fields and research stationsplots carried out in the Punjab province of Pakistan in 1997, more than 6505 plant samples were collected and tested by tissue-blot immunoassay (TBIA) for the presence of 14 different viruses. Overall, about one in five plants of lentil was virus infected, 15 % of fields having incidences higher than 50 %. In contrast. incidences of infection were mostly low in chickpea. Pea seed-borne mosaic virus (PSbMV, genus Potyvirus, family Potyviridae) followed by Cucumber mosaic virus (CMV, genus Cucumovirus, family Bromoviridae), both of which are aphid-transmitted and seed-borne in chickpea and lentil, were the most abundant viruses in lentils, and also occurred in chickpea. Chickpea chlorotic dwarf virus (CCDV, genus Mastrevirus, family Geminiviridae), Beer western Yellows virus (BWYV, genus Polerovirus, family Luteoviridae) and 'chickpea luteovirus' (family Luteoviridae) were common in chickpea fields and were present in lentil. Faba bean necrotic yellows virus (FBNYV, genus Nanovirus) was occasionally found in lentil and chickpea fields,and Alfalfa mosaic virus (AMV, genus Alfamovirus, family Bromoviridae) in chickpea fields. Counting plants with virus symptoms greatly underestimatedvirus incidence in lentil crops but was a better guide to virus occurrencein chickpea. Because of associated yield losses, the high incidences of infection in lentils are cause for concern for lentil production. Virus incidence was sometimes sufficient within individual chickpea fields to be of concern.
SUMMARY Protoplasts derived from shoot cultures of potato cv. Cara, which carries immunity gene R... more SUMMARY Protoplasts derived from shoot cultures of potato cv. Cara, which carries immunity gene Rx, supported only limited virus multiplication after inoculation with particles or RNA of isolate DX, a group 3 strain of potato virus X, as compared to similarly inoculated protoplasts of cultivars King Edward and Pentland Ivory which lack Rx. The Cara protoplasts were, however, able to
SummaryBeet ringspot virus (BRSV) isolate IF came from a 1980 bait test on a Scottish soil sample... more SummaryBeet ringspot virus (BRSV) isolate IF came from a 1980 bait test on a Scottish soil sample. Between 1982 and 1984, it was used to study possible BRSV seed transmission in potato (Solanum tuberosum). To encourage flowering, potato scions were graft-inoculated onto tomato plants and these grafted plants were inoculated with IF. Flowers on BRSV-infected potato shoots were self-pollinated and their seeds collected. BRSV was found readily in pollen from these potato flowers, but never detected in any seedlings that grew from their seeds. Thus, although BRSV was present in pollen, no evidence of potato true seed transmission was obtained. In 1985, IF was preserved by freeze-drying and kept thereafter in a historical virus isolate collection. In 2020, it was subjected to high throughput sequencing and a complete genomic sequence was obtained. No recombination was detected in the IF sequence but its RNA1 and RNA2 were major parents of three, and a minor parent of one, recombinant BRS...
Potato virus V (PVV) causes a disease of potato (Solanum tubersosum) in South and Central America... more Potato virus V (PVV) causes a disease of potato (Solanum tubersosum) in South and Central America, Europe, and the Middle East. We report here the complete genomic sequences of 42 new PVV isolates from the potato’s Andean domestication center in Peru and of eight historical or recent isolates from Europe. When the principal open reading frames of these genomic sequences together with those of nine previously published genomic sequences were analyzed, only two from Peru and one from Iran were found to be recombinant. The phylogeny of the 56 nonrecombinant open reading frame sequences showed that the PVV population had two major phylogroups, one of which formed three minor phylogroups (A1 to A3) of isolates, all of which are found only in the Andean region of South America (Peru and Colombia), and the other formed two minor phylogroups, a basal one of Andean isolates (A4) that is paraphyletic to a crown cluster containing all the isolates found outside South America (World). This sugg...
During 1990-92, narrow-leafed lupins (Lupinus angustifolius) cv. Gungurru, were grown in six fiel... more During 1990-92, narrow-leafed lupins (Lupinus angustifolius) cv. Gungurru, were grown in six field experiments in which plots were sown with healthy seed or seed that carried 0.5-5% infection with cucumber mosaic virus (CMV). Seed-infected plants were the primary source for subsequent virus spread by aphids. The rate of CMV spread and the extent of infection in plots depended on the level of infection in the seed sown, the proportion of infected seeds that successfully developed into established plants and the time of arrival and number of aphid vectors. In general, higher seed infection levels, better establishment of seed-infected plants and early aphid arrival favoured greater virus spread, yield loss and infection in the harvested seed. In 1991, in two experiments, late arrival of aphids resulted in minimal CMV spread, no effect on yield and much less infection in the harvested seed than in the seed sown. In the other four experiments, significant yield losses (25-42%) always re...
A selection of potato cultivars and breeding lines was evaluated for presence of resistance to in... more A selection of potato cultivars and breeding lines was evaluated for presence of resistance to infection with potato leafroll virus (PLRV) via viruliferous aphid vectors ( IR) and/or resistance to accumulation of PLRV antigen ( AR) in infected leaf tissue. Cultivars Aracy, Delcora, Omega and Spunta, and breeding lines BR63.15 and B71.240.2 carried both IR and AR , Bismark, Serrana INTA and L/T1 had alone and Delaware had AR alone. The other cultivars tested had neither. Within both the resistant and susceptible classes for AR, the level of PLRV antigen accumulation achieved varied with cultivar. Previous infection with potato virus X (PVX) or potato virus S (PVS) either alone or together did not diminish the expression of IR or AR. However, the presence of PVX sometimes significantly increased the accumulation of PLRV in susceptible cv. Desiree and this effect was most pronounced in mature leaves of older plants. In contrast, presence of PVX in susceptible cv. Desiree did not increa...
SUMMARY Four field trials were done with narrow-leafed lupins (Lupinus angustifolius) in 1988 - 1... more SUMMARY Four field trials were done with narrow-leafed lupins (Lupinus angustifolius) in 1988 - 1989, to examine the effect of sowing seed with 5% and 0.5% cucumber mosaic virus (CMV) infection on subsequent virus spread, grain yield and percentage of infection in harvested seed. A proportion of the CM V-infected seed failed to produce established plants and thus, plots sown with 5% and 0.5% infected seed contained 1.5-2.9% and 0.2-0.3% of seed-infected plants respectively. The rate of virus spread by aphids was faster and resulted in more extensive infection at maturity in plots sown with 5% infected seed than with 0.5% infected seed. In three trials, sowing 5% infected seed resulted in yield losses of 34 - 53% and CMV infection in the seed harvested of 6 - 13%. The spread of CMV infection resulting from sowing 0.5% infected seed did not significantly decrease yield. However, late CMV spread in these plots caused > 1% seed infection. In the fourth trial, which was badly affected by drought, CMV spread only slowly, there was no significant effect of CMV on grain yield and the percentage of infected seed harvested was 3–5 times less than that in the seed sown. When CMV-infected seed was sown at different depths, target depths of 8 and 11 cm decreased the incidence of seed-infected plants by c. 15% and c. 50% respectively compared with sowing at 5 cm. However, in glasshouse tests, treatment with the pre-emergence herbicide simazine failed to selectively cull out seed-infected plants. The field trials were colonised by green peach (Myzus persicae), blue-green (Acyrthosiphon kondoi) and cowpea (Aphis craccivora) aphids. When the abilities of these aphid species and of the turnip aphid (Lipaphis erysimi) in transmitting CMV from lupins to lupins were examined in glasshouse tests, short acquisition access times favoured transmission. With 5–10 min acquisition access times, overall transmission efficiencies were 10.8%, 9.4%, 6.1% and 3.9% for the green peach, cowpea, blue-green and turnip aphids respectively.
Four lupin species, Lupinus angustifolius, L. albus, L. luteus, and L. mutabilis, are grown as co... more Four lupin species, Lupinus angustifolius, L. albus, L. luteus, and L. mutabilis, are grown as cool-season grain legume crops. Fifteen viruses infect them. Two of these, bean yellow mosaic virus (BYMV) and cucumber mosaic virus (CMV), cause diseases that threaten grain lupin production. Phytosanitary and cultural control measures are mainly used to manage them. However, breeding virus-resistant lupin cultivars provides an additional management approach. The need to develop this approach stimulated a search for virus resistance sources amongst cultivated lupin species and their wild relatives. This review focuses on the progress made in optimizing virus resistance screening procedures, identifying host resistances to BYMV, CMV, and additional viral pathogen alfalfa mosaic virus (AMV), and the inclusion of BYMV and CMV resistance within lupin breeding programs. The resistance types found in different combinations of virus and grain lupin species include localized hypersensitivity, sys...
Biological characteristics of 11 Potato virus S (PVS) isolates from three cultivated potato speci... more Biological characteristics of 11 Potato virus S (PVS) isolates from three cultivated potato species (Solanum spp.) growing in five Andean countries and 1 from Scotland differed in virulence depending on isolate and host species. Nine isolates infected Chenopodium quinoa systemically but two others and the Scottish isolate remained restricted to inoculated leaves; therefore, they belonged to biologically defined strains PVSA and PVSO, respectively. When nine wild potato species were inoculated, most developed symptomless systemic infection but Solanum megistacrolobum developed systemic hypersensitive resistance (SHR) with one PVSO and two PVSA isolates. Andean potato cultivars developed mostly asymptomatic primary infection but predominantly symptomatic secondary infection. In both wild and cultivated potato plants, PVSA and PVSO elicited similar foliage symptoms. Following graft inoculation, all except two PVSO isolates were detected in partially PVS-resistant cultivar Saco, while c...
Potato virus Y (PVY) disrupts healthy seed potato production and causes tuber yield and quality l... more Potato virus Y (PVY) disrupts healthy seed potato production and causes tuber yield and quality losses globally. Its subdivisions consist of strain groups defined by potato hypersensitive resistance (HR) genes and whether necrosis occurs in tobacco, and phylogroups defined by sequencing. When PVY isolate PP was inoculated to potato cultivar differentials with HR genes, the HR phenotype pattern obtained resembled that caused by strain group PVYD isolate KIP1. A complete genome of isolate PP was obtained by high-throughput sequencing. After removal of its short terminal recombinant segment, it was subjected to phylogenetic analysis together with 30 complete nonrecombinant PVY genomes. It fitted within the same minor phylogroup PVYO3 subclade as KIP1. Putative HR gene Nd was proposed previously to explain the unique HR phenotype pattern that developed when differential cultivars were inoculated with PVYD. However, an alternative explanation was that PVYD elicits HR with HR genes Nc and...
We present the first complete Sweet potato virus G (SPVG) genome from sweet potato in East Timor ... more We present the first complete Sweet potato virus G (SPVG) genome from sweet potato in East Timor and compare it with seven complete SPVG genomes from South Korea (three), Taiwan (two), Argentina (one), and the United States (one). It most resembles the genomes from the United States and South Korea.
In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, K... more In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, Kayseri and Niğde. RT-PCR tests, with primers which amplified its coat protein (CP), detected potato virus S (PVS) in 35 samples. Complete CP sequences were obtained from 14 samples. Phylogenetic analysis using non-recombinant sequences of (i) the 14 CP’s, another 8 from Tokat province and 73 others from GenBank; and (ii) 130 complete ORF, RdRp and TGB sequences from GenBank, found that they fitted within phylogroups, PVSI, PVSII or PVSIII. All Turkish CP sequences were in PVSI, clustering within five subclades. Subclades 1 and 4 were in three to four provinces, whereas 2, 3 and 5 were in one province each. All four genome regions were under strong negative selection constraints (ω = 0.0603–0.1825). Considerable genetic variation existed amongst PVSI and PVSII isolates. Three neutrality test methods showed PVSIII remained balanced whilst PVSI and PVSII underwent population expansion. The ...
In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, K... more In 2020, 264 samples were collected from potato fields in the Turkish provinces of Bolu, Afyon, Kayseri and Niğde. RT-PCR tests, with primers which amplified its coat protein (CP), detected potato virus S (PVS) in 35 samples. Complete CP sequences were obtained from 14 samples. Phylogenetic analysis using non-recombinant sequences of (i) the 14 CP’s, another 8 from Tokat province and 73 others from GenBank; and (ii) 130 complete ORF, RdRp and TGB sequences from GenBank, found that they fitted within phylogroups, PVSI, PVSII or PVSIII. All Turkish CP sequences were in PVSI, clustering within five subclades. Subclades 1 and 4 were in three to four provinces, whereas 2, 3 and 5 were in one province each. All four genome regions were under strong negative selection constraints (ω = 0.0603–0.1825). Considerable genetic variation existed amongst PVSI and PVSII isolates. Three neutrality test methods showed PVSIII remained balanced whilst PVSI and PVSII underwent population expansion. The ...
High Plains wheat mosaic virus (HPWMoV) causes a serious disease in major wheat-growing regions w... more High Plains wheat mosaic virus (HPWMoV) causes a serious disease in major wheat-growing regions worldwide. We report here the complete or partial genomic sequences of five HPWMoV isolates from Australian wheat samples. Phylogenetic analysis of the nucleotide sequences of the eight genomic segments of these five isolates together with others from Genbank found all eight genes formed two lineages, L1 and L2. L1 contained a single isolate from Colorado in the North American Great Plains Region (GPR), and L2 had two unresolved clusters, A and B, of isolates from Australia and the GPR. A quarter of the L2B isolate sequences of the nucleocapsid gene (RNA3) were recombinant, which is unexpected as little evidence of recombination exists in viruses with negative single-stranded RNA genomes. Phylogenies calculated from the amino acid sequences of HPWMoV’s RNA-dependent RNA-polymerase (RNA1), glycoprotein (RNA2), and nucleocapsid protein (RNA3) showed they were closest to those of Palo Verde ...
The family Apiaceae comprises approximately 3700 species of herbaceous plants, including importan... more The family Apiaceae comprises approximately 3700 species of herbaceous plants, including important crops, aromatic herbs and field weeds. Here we report a study of 10 preserved historical or recent virus samples of apiaceous plants collected in the United Kingdom (UK) import interceptions from the Mediterranean region (Egypt, Israel and Cyprus) or during surveys of Australian apiaceous crops. Seven complete new genomic sequences and one partial sequence, of the apiaceous potyviruses apium virus Y (ApVY), carrot thin leaf virus (CaTLV), carrot virus Y (CarVY) and celery mosaic virus (CeMV) were obtained. When these 7 and 16 earlier complete non-recombinant apiaceous potyvirus sequences were subjected to phylogenetic analyses, they split into 2 separate lineages: 1 containing ApVY, CeMV, CarVY and panax virus Y and the other CaTLV, ashitabi mosaic virus and konjac virus Y. Preliminary dating analysis suggested the CarVY population first diverged from CeMV and ApVY in the 17th century ...
In 1976, a virus with flexuous, filamentous virions typical of the family Potyviridae was isolate... more In 1976, a virus with flexuous, filamentous virions typical of the family Potyviridae was isolated from symptomatic pepino (Solanum muricatum) plants growing in two valleys in Peru’s coastal desert region. In 2014, a virus with similar-shaped virions was isolated from asymptomatic fruits obtained from pepino plants growing in six coastal valleys and a valley in Peru’s Andean highlands. Both were identified subsequently as Wild potato mosaic virus (WPMV) by serology or high-throughput sequencing (HTS). The symptoms caused by two old and seven new isolates from pepino were examined in indicator plants. Infected solanaceous hosts varied considerably in their sensitivities to infection and individual isolates varied greatly in virulence. All seven new isolates caused quick death of infected Nicotiana benthamiana plants and more than half of them killed infected plants of Physalis floridana and S. chancayense. These three species were the most sensitive to infection. The most virulent is...
ABSTRACT In an intensive sun,ey of lentil and chickpea fields and research stationsplots carried ... more ABSTRACT In an intensive sun,ey of lentil and chickpea fields and research stationsplots carried out in the Punjab province of Pakistan in 1997, more than 6505 plant samples were collected and tested by tissue-blot immunoassay (TBIA) for the presence of 14 different viruses. Overall, about one in five plants of lentil was virus infected, 15 % of fields having incidences higher than 50 %. In contrast. incidences of infection were mostly low in chickpea. Pea seed-borne mosaic virus (PSbMV, genus Potyvirus, family Potyviridae) followed by Cucumber mosaic virus (CMV, genus Cucumovirus, family Bromoviridae), both of which are aphid-transmitted and seed-borne in chickpea and lentil, were the most abundant viruses in lentils, and also occurred in chickpea. Chickpea chlorotic dwarf virus (CCDV, genus Mastrevirus, family Geminiviridae), Beer western Yellows virus (BWYV, genus Polerovirus, family Luteoviridae) and 'chickpea luteovirus' (family Luteoviridae) were common in chickpea fields and were present in lentil. Faba bean necrotic yellows virus (FBNYV, genus Nanovirus) was occasionally found in lentil and chickpea fields,and Alfalfa mosaic virus (AMV, genus Alfamovirus, family Bromoviridae) in chickpea fields. Counting plants with virus symptoms greatly underestimatedvirus incidence in lentil crops but was a better guide to virus occurrencein chickpea. Because of associated yield losses, the high incidences of infection in lentils are cause for concern for lentil production. Virus incidence was sometimes sufficient within individual chickpea fields to be of concern.
SUMMARY Protoplasts derived from shoot cultures of potato cv. Cara, which carries immunity gene R... more SUMMARY Protoplasts derived from shoot cultures of potato cv. Cara, which carries immunity gene Rx, supported only limited virus multiplication after inoculation with particles or RNA of isolate DX, a group 3 strain of potato virus X, as compared to similarly inoculated protoplasts of cultivars King Edward and Pentland Ivory which lack Rx. The Cara protoplasts were, however, able to
SummaryBeet ringspot virus (BRSV) isolate IF came from a 1980 bait test on a Scottish soil sample... more SummaryBeet ringspot virus (BRSV) isolate IF came from a 1980 bait test on a Scottish soil sample. Between 1982 and 1984, it was used to study possible BRSV seed transmission in potato (Solanum tuberosum). To encourage flowering, potato scions were graft-inoculated onto tomato plants and these grafted plants were inoculated with IF. Flowers on BRSV-infected potato shoots were self-pollinated and their seeds collected. BRSV was found readily in pollen from these potato flowers, but never detected in any seedlings that grew from their seeds. Thus, although BRSV was present in pollen, no evidence of potato true seed transmission was obtained. In 1985, IF was preserved by freeze-drying and kept thereafter in a historical virus isolate collection. In 2020, it was subjected to high throughput sequencing and a complete genomic sequence was obtained. No recombination was detected in the IF sequence but its RNA1 and RNA2 were major parents of three, and a minor parent of one, recombinant BRS...
Potato virus V (PVV) causes a disease of potato (Solanum tubersosum) in South and Central America... more Potato virus V (PVV) causes a disease of potato (Solanum tubersosum) in South and Central America, Europe, and the Middle East. We report here the complete genomic sequences of 42 new PVV isolates from the potato’s Andean domestication center in Peru and of eight historical or recent isolates from Europe. When the principal open reading frames of these genomic sequences together with those of nine previously published genomic sequences were analyzed, only two from Peru and one from Iran were found to be recombinant. The phylogeny of the 56 nonrecombinant open reading frame sequences showed that the PVV population had two major phylogroups, one of which formed three minor phylogroups (A1 to A3) of isolates, all of which are found only in the Andean region of South America (Peru and Colombia), and the other formed two minor phylogroups, a basal one of Andean isolates (A4) that is paraphyletic to a crown cluster containing all the isolates found outside South America (World). This sugg...
During 1990-92, narrow-leafed lupins (Lupinus angustifolius) cv. Gungurru, were grown in six fiel... more During 1990-92, narrow-leafed lupins (Lupinus angustifolius) cv. Gungurru, were grown in six field experiments in which plots were sown with healthy seed or seed that carried 0.5-5% infection with cucumber mosaic virus (CMV). Seed-infected plants were the primary source for subsequent virus spread by aphids. The rate of CMV spread and the extent of infection in plots depended on the level of infection in the seed sown, the proportion of infected seeds that successfully developed into established plants and the time of arrival and number of aphid vectors. In general, higher seed infection levels, better establishment of seed-infected plants and early aphid arrival favoured greater virus spread, yield loss and infection in the harvested seed. In 1991, in two experiments, late arrival of aphids resulted in minimal CMV spread, no effect on yield and much less infection in the harvested seed than in the seed sown. In the other four experiments, significant yield losses (25-42%) always re...
A selection of potato cultivars and breeding lines was evaluated for presence of resistance to in... more A selection of potato cultivars and breeding lines was evaluated for presence of resistance to infection with potato leafroll virus (PLRV) via viruliferous aphid vectors ( IR) and/or resistance to accumulation of PLRV antigen ( AR) in infected leaf tissue. Cultivars Aracy, Delcora, Omega and Spunta, and breeding lines BR63.15 and B71.240.2 carried both IR and AR , Bismark, Serrana INTA and L/T1 had alone and Delaware had AR alone. The other cultivars tested had neither. Within both the resistant and susceptible classes for AR, the level of PLRV antigen accumulation achieved varied with cultivar. Previous infection with potato virus X (PVX) or potato virus S (PVS) either alone or together did not diminish the expression of IR or AR. However, the presence of PVX sometimes significantly increased the accumulation of PLRV in susceptible cv. Desiree and this effect was most pronounced in mature leaves of older plants. In contrast, presence of PVX in susceptible cv. Desiree did not increa...
SUMMARY Four field trials were done with narrow-leafed lupins (Lupinus angustifolius) in 1988 - 1... more SUMMARY Four field trials were done with narrow-leafed lupins (Lupinus angustifolius) in 1988 - 1989, to examine the effect of sowing seed with 5% and 0.5% cucumber mosaic virus (CMV) infection on subsequent virus spread, grain yield and percentage of infection in harvested seed. A proportion of the CM V-infected seed failed to produce established plants and thus, plots sown with 5% and 0.5% infected seed contained 1.5-2.9% and 0.2-0.3% of seed-infected plants respectively. The rate of virus spread by aphids was faster and resulted in more extensive infection at maturity in plots sown with 5% infected seed than with 0.5% infected seed. In three trials, sowing 5% infected seed resulted in yield losses of 34 - 53% and CMV infection in the seed harvested of 6 - 13%. The spread of CMV infection resulting from sowing 0.5% infected seed did not significantly decrease yield. However, late CMV spread in these plots caused > 1% seed infection. In the fourth trial, which was badly affected by drought, CMV spread only slowly, there was no significant effect of CMV on grain yield and the percentage of infected seed harvested was 3–5 times less than that in the seed sown. When CMV-infected seed was sown at different depths, target depths of 8 and 11 cm decreased the incidence of seed-infected plants by c. 15% and c. 50% respectively compared with sowing at 5 cm. However, in glasshouse tests, treatment with the pre-emergence herbicide simazine failed to selectively cull out seed-infected plants. The field trials were colonised by green peach (Myzus persicae), blue-green (Acyrthosiphon kondoi) and cowpea (Aphis craccivora) aphids. When the abilities of these aphid species and of the turnip aphid (Lipaphis erysimi) in transmitting CMV from lupins to lupins were examined in glasshouse tests, short acquisition access times favoured transmission. With 5–10 min acquisition access times, overall transmission efficiencies were 10.8%, 9.4%, 6.1% and 3.9% for the green peach, cowpea, blue-green and turnip aphids respectively.
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