Zucchini yellow mosaic virus Populations from East Timorese and Northern Australian Cucurbit Crops: Molecular Properties, Genetic Connectivity, and Biosecurity Implications

Zucchini Yellow Mosaic Virus (ZYMV) as a Serious Biotic Stress to Cucurbits: Prevalence, Diversity, and Its Implications for Crop Sustainability

Zucchini yellow mosaic virus (ZYMV) is a severe threat to cucurbit crops worldwide, including Pakistan. This study was pursued to evaluate the prevalence, geographic distribution, and molecular diversity of ZYMV isolates infecting cucurbits in Pakistan's Pothwar region. Almost all the plant viruses act as a biotic stress on the host plants, which results in a yield loss. These viruses cause losses in single-infection or in mixed-infection cucurbit crops, and we have found a number of mixed-infected samples belonging to the Curubitaceae family. Serological detection of the tested potyviruses in the collected cucurbit samples revealed that ZYMV was the most prevalent virus, with a disease incidence (DI) at 35.2%, followed by Papaya ringspot virus (PRSV) with an incidence of 2.2%, and Watermelon mosaic virus (WMV) having an incidence as little as 0.5% in 2016. In the year 2017, a relatively higher disease incidence of 39.7%, 2.4%, and 0.3% for ZYMV, WMV, and PRSV, respectively, was recorded. ZYMV was the most prevalent virus with the highest incidence in Attock, Rawalpindi, and Islamabad, while PRSV was observed to be the highest in Islamabad and Jhelum. WMV infection was observed only in Rawalpindi and Chakwal. Newly detected Pakistani ZYMV isolates shared 95.8-97.0% nucleotide identities among themselves and 77.1-97.8% with other isolates retrieved from GenBank. Phylogenetic relationships obtained using different ZYMV isolates retrieved from GenBank and validated by in silico restriction analysis revealed that four Pakistani isolates clustered with other ZYMV isolates in group IIb with Chinese, Italian, Polish, and French isolates, while another isolate (MK848239) formed a separate minor clade within IIb. The isolate MK8482490, reported to infect bitter gourd in Pakistan, shared a minor clade with a Chinese isolate (KX884570). Recombination analysis revealed that the recently found ZYMV isolate (MK848239) is most likely a recombinant of Pakistani (MK848237) and Italian (MK956829) isolates, with a recombinant breakpoint between 266 and 814 nucleotide positions. Local isolate comparison and recombination detection may aid in the development of a breeding program that identifies resistant sources against recombinant isolates because the ZYMV is prevalent in a few cucurbit species grown in the surveyed areas and causes heavy losses and economic damage to the agricultural community.

Protective and Curative Activities of Paenibacillus polymyxa against Zucchini yellow mosaic virus Infestation in Squash Plants

The use of microbial products as natural biocontrol agents to increase a plant's systemic resistance to viral infections is a promising way to make agriculture more sustainable and less harmful to the environment. The rhizobacterium Paenibacillus polymyxa has been shown to have strong biocontrol action against plant diseases, but its antiviral activity has been little investigated. Here, the efficiency of the culture filtrate of the P. polymyxa strain SZYM (Acc# ON149452) to protect squash (Cucurbita pepo L.) plants against a Zucchini yellow mosaic virus (ZYMV, Acc# ON159933) infection was evaluated. Under greenhouse conditions, the foliar application of the culture filtrate of SZYM either in protective or curative treatment conditions enhanced squash growth, reduced disease severity, and decreased ZYMV accumulation levels in the treated plants when compared to the non-treated plants. The protective treatment group exhibited the highest inhibitory effect (80%), with significant increases in their total soluble carbohydrates, total soluble protein content, ascorbic acid content, and free radical scavenging activity. Furthermore, a considerable increase in the activities of reactive oxygen species scavenging enzymes (superoxide dismutase, polyphenol oxidase, and peroxidase) were also found. In addition, the induction of systemic resistance with a significant elevation in the transcriptional levels of polyphenolic pathway genes (CHS, PAL, and C3H) and pathogenesis-related genes (PR-1 and PR-3) was observed. Out of the 14 detected compounds in the GC-MS analysis, propanoic acid, benzenedicarboxylic acid, tetradecanoic acid, and their derivatives, as well as pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) were the primary ingredient compounds in the ethyl acetate extract of the SZYM-culture filtrate. Such compounds may act as elicitor molecules that induce systemic resistance against viral infection. Consequently, P. polymyxa can be considered a powerful plant growth-promoting bacterium (PGPB) in agricultural applications as well as a source of bioactive compounds for sustainable disease management. As far as we know, this is the first time that P. polymyxa has been shown to fight viruses in plants.

Virus Diseases of Cereal and Oilseed Crops in Australia: Current Position and Future Challenges

This review summarizes research on virus diseases of cereals and oilseeds in Australia since the 1950s. All viruses known to infect the diverse range of cereal and oilseed crops grown in the continent's temperate, Mediterranean, subtropical and tropical cropping regions are included. Viruses that occur commonly and have potential to cause the greatest seed yield and quality losses are described in detail, focusing on their biology, epidemiology and management. These are: barley yellow dwarf virus, cereal yellow dwarf virus and wheat streak mosaic virus in wheat, barley, oats, triticale and rye; Johnsongrass mosaic virus in sorghum, maize, sweet corn and pearl millet; turnip yellows virus and turnip mosaic virus in canola and Indian mustard; tobacco streak virus in sunflower; and cotton bunchy top virus in cotton. The currently less important viruses covered number nine infecting nine cereal crops and 14 infecting eight oilseed crops (none recorded for rice or linseed). Brief background information on the scope of the Australian cereal and oilseed industries, virus epidemiology and management and yield loss quantification is provided. Major future threats to managing virus diseases effectively include damaging viruses and virus vector species spreading from elsewhere, the increasing spectrum of insecticide resistance in insect and mite vectors, resistance-breaking virus strains, changes in epidemiology, virus and vectors impacts arising from climate instability and extreme weather events, and insufficient industry awareness of virus diseases. The pressing need for more resources to focus on addressing these threats is emphasized and recommendations over future research priorities provided.

Genetic Diversity of Potyviruses Associated with Tulip Breaking Syndrome

Tulip breaking is economically the most important viral disease of modern-day tulip growing. It is characterized by irregular flame and feather-like patterns in the flowers and mosaic on the foliage. Thirty-two leaf samples were collected from cultivated tulip plants showing tulip breaking syndrome from Hungary in 2017 and 2018. Virus identification was performed by serological (ELISA) and molecular (RT-PCR) methods. All samples proved to be infected with a potyvirus and evidence was provided that three potyvirus species could be identified in the samples: Lily mottle virus (LMoV), Tulip breaking virus (TBV) and Rembrandt tulip-breaking virus (ReTBV). Recombination prediction accomplished with Recombination Detection Program (RDP) v4.98 revealed potential intraspecies recombination in the case of TBV and LMoV. Phylogenetic analyses of the coat protein (CP) regions proved the monophyletic origin of these viruses and verified them as three different species according to current International Committee on Taxonomy of Viruses (ICTV) species demarcation criteria. Based on these results, we analyzed taxonomic relations concerning potyviruses associated with tulip breaking syndrome. We propose the elevation of ReTBV to species level, and emergence of two new subgroups in ReTBV.

Climate change and plant virus epidemiology

Changes in global climate driven by anthropogenic activities, especially the burning of fossil fuels and deforestation, have been progressively increasing and are projected to intensify. Increasing concentrations of atmospheric carbon dioxide and temperature will have significant consequences for future food production, quality, distribution and security. The epidemiology of plant viruses will be altered in the future as a result of climate change. Elevated atmospheric carbon dioxide, increased temperature, changes to water availability and more frequent extreme weather events will have direct and indirect effects on plant viruses through changes in hosts and vectors. Predicted climatic changes will affect the distribution and survival of plant viruses and their vectors, which are expected to increase in many geographic regions. Furthermore, climate change can affect the virulence and pathogenicity of plant viruses, consequently increasing the frequency and scale of disease outbreaks. Thus, greater understanding of plant virus epidemiology is needed to better anticipate challenges ahead and to develop effective and robust control strategies that will aid in securing global food production for the future.

Host plant affiliations of aphid vector species found in a remote tropical environment

The Ord River Irrigation Area (ORIA) produces annual crops during the dry season (April to October), and perennial crops all-year-round, and is located in tropical northwestern Australia. Sandalwood plantations cover 50 % of the ORIA's cropping area. Aphids cause major crop losses through transmission of viruses causing debilitating diseases and direct feeding damage. During 2016-2017, in both dry and wet seasons a total of 3320 leaf samples were collected from diverse types of sites on cultivated and uncultivated land and 1248 (38 %) of them were from aphid-colonized plants. In addition, aphids were found at 236 of 355 sampling sites. The 62 plant species sampled came from 23 families 19 of which contained aphid-colonized species. Aphid hosts included introduced weeds, Australian native plants, and volunteer or planted crop plants. Six aphid species were identified by light microscopy and CO1 gene sequencing, but there was no within species nucleotide sequence diversity. Aphis nerii, Hysteroneura setariae, Rhopalosiphum maidis and Schoutedenia ralumensis each colonized 1-3 plant species from a single plant family. A. craccivora colonized 14 species in five plant families. A. gossypii was the most polyphagous species colonizing 19 species in 11 plant families. A. gossypii, A. craccivora, A. nerii and S. ralumensis were found in both wet and dry seasons. Because of A. craccivora's prevalence and high incidences on understory weeds and host trees, sandalwood plantations were important reservoirs for aphid spread to wild and crop plant hosts growing in cultivated and uncultivated land. Alternative hosts growing in rural bushland, irrigation channel banks, vacant or fallow land, and orchard plantation understories also constituted significant aphid reservoirs. This study provides new knowledge of the ecology of aphid vector species not only in the ORIA but also in tropical northern Australia generally. It represents one of relatively few investigations on aphid ecology in tropical environments worldwide.

Epidemiology of Zucchini yellow mosaic virus in cucurbit crops in a remote tropical environment

In the remote Ord River Irrigation Area (ORIA) in tropical northwest Australia, severe Zucchini yellow mosaic virus (ZYMV) epidemics threaten dry season (April-October) cucurbit crops. In 2016-2017, wet season (November-March) sampling studies found a low incidence ZYMV infection in wild Cucumis melo and Citrullus lanatus var. citroides plants, and both volunteer and garden crop cucurbits. Such infections enable its persistence in the wet season, and act as reservoirs for its spread to commercial cucurbit crops during the dry season. Tests on 1019 samples belonging to 55 species from 23 non-cucurbitaceous plant families failed to detect ZYMV. It was also absent from wild cucurbit weeds within sandalwood plantations. The transmission efficiencies of a local isolate by five aphid species found in the ORIA were: 10 % (Aphis craccivora), 7% (A. gossypii), 4% (A. nerii), and 0% (Rhopalosiphum maidis and Hysteroneura setariae). In 2016-2017, in all-year-round trapping at five representative sites, numbers of winged aphids caught were greatest in July-August (i.e. mid growing season) but varied widely between trap sites reflecting local aphid host abundance and year. Apart from one localised exception in 2017, flying aphid numbers caught and ZYMV spread in data collection blocks during 2015-2017 resembled what occurred commercial cucurbit crops. When ZYMV spread from external infection sources into melon blocks, its predominant spread pattern consisted of 1 or 2 plant infection foci often occurring at their margins. In addition, when plants of 29 cucurbit cultivars were inoculated with an ORIA isolate and two other ZYMV isolates and the phenotypes elicited were compared, they resembled each other in overall virulence. However, depending upon isolate-cultivar combination, differences in symptom expression and severity occurred, and one isolate caused a systemic hypersensitive phenotype in honeydew melon cvs Estilo and Whitehaven. When the new genomic RNA sequences of 19 Australian isolates were analysed, all seven ORIA isolates fitted within ZYMV phylogroup B, which also included two from southwest Australia, whereas the remaining 10 isolates were all within minor phylogroups A-I or A-II. Based on previous research and the additional knowledge of ZYMV epidemic drivers established here, an integrated disease management strategy targeting ZYMV spread was devised for the ORIA's cucurbit industry.

The Potyviruses: An Evolutionary Synthesis Is Emerging

In this review, encouraged by the dictum of Theodosius Dobzhansky that "Nothing in biology makes sense except in the light of evolution", we outline the likely evolutionary pathways that have resulted in the observed similarities and differences of the extant molecules, biology, distribution, etc. of the potyvirids and, especially, its largest genus, the potyviruses. The potyvirids are a family of plant-infecting RNA-genome viruses. They had a single polyphyletic origin, and all share at least three of their genes (i.e., the helicase region of their CI protein, the RdRp region of their NIb protein and their coat protein) with other viruses which are otherwise unrelated. Potyvirids fall into 11 genera of which the potyviruses, the largest, include more than 150 distinct viruses found worldwide. The first potyvirus probably originated 15,000-30,000 years ago, in a Eurasian grass host, by acquiring crucial changes to its coat protein and HC-Pro protein, which enabled it to be transmitted by migrating host-seeking aphids. All potyviruses are aphid-borne and, in nature, infect discreet sets of monocotyledonous or eudicotyledonous angiosperms. All potyvirus genomes are under negative selection; the HC-Pro, CP, Nia, and NIb genes are most strongly selected, and the PIPO gene least, but there are overriding virus specific differences; for example, all turnip mosaic virus genes are more strongly conserved than those of potato virus Y. Estimates of dN/dS (ω) indicate whether potyvirus populations have been evolving as one or more subpopulations and could be used to help define species boundaries. Recombinants are common in many potyvirus populations (20%-64% in five examined), but recombination seems to be an uncommon speciation mechanism as, of 149 distinct potyviruses, only two were clear recombinants. Human activities, especially trade and farming, have fostered and spread both potyviruses and their aphid vectors throughout the world, especially over the past five centuries. The world distribution of potyviruses, especially those found on islands, indicates that potyviruses may be more frequently or effectively transmitted by seed than experimental tests suggest. Only two meta-genomic potyviruses have been recorded from animal samples, and both are probably contaminants.

Global Dimensions of Plant Virus Diseases: Current Status and Future Perspectives

Viral diseases provide a major challenge to twenty-first century agriculture worldwide. Climate change and human population pressures are driving rapid alterations in agricultural practices and cropping systems that favor destructive viral disease outbreaks. Such outbreaks are strikingly apparent in subsistence agriculture in food-insecure regions. Agricultural globalization and international trade are spreading viruses and their vectors to new geographical regions with unexpected consequences for food production and natural ecosystems. Due to the varying epidemiological characteristics of diverent viral pathosystems, there is no one-size-fits-all approach toward mitigating negative viral disease impacts on diverse agroecological production systems. Advances in scientific understanding of virus pathosystems, rapid technological innovation, innovative communication strategies, and global scientific networks provide opportunities to build epidemiologic intelligence of virus threats to crop production and global food security. A paradigm shift toward deploying integrated, smart, and eco-friendly strategies is required to advance virus disease management in diverse agricultural cropping systems.

Zucchini yellow mosaic virus Genomic Sequences from Papua New Guinea: Lack of Genetic Connectivity with Northern Australian or East Timorese Genomes, and New Recombination Findings

Zucchini yellow mosaic virus (ZYMV) isolates were obtained in Papua New Guinea (PNG) from cucumber (Cucumis sativus) or pumpkin (Cucurbita spp.) plants showing mosaic symptoms growing at Kongop in the Mount Hagen District, Western Highlands Province, or Zage in the Goroka District, Eastern Highlands Province. The samples were blotted onto FTA cards, which were sent to Australia, where they were subjected to high-throughput sequencing. When the coding regions of the nine new ZYMV genomic sequences found were compared with those of 64 other ZYMV sequences from elsewhere, they grouped together, forming new minor phylogroup VII within ZYMV's major phylogroup A. Genetic connectivity was lacking between ZYMV genomic sequences from PNG and its neighboring countries, Australia and East Timor; the closest match between a PNG and any other genomic sequence was a 92.8% nucleotide identity with a sequence in major phylogroup A's minor phylogroup VI from Japan. When the RDP5.2 recombination analysis program was used to compare 66 ZYMV sequences, evidence was obtained of 30 firm recombination events involving 41 sequences, and all isolates from PNG were recombinants. There were 21 sequences without recombination events in major phylogroup A, whereas there were only 4 such sequences within major phylogroup B. ZYMV's P1, Cl, N1a-Pro, P3, CP, and NIb regions contained the highest evidence of recombination breakpoints. Following removal of recombinant sequences, seven minor phylogroups were absent (I, III, IV, V, VI, VII, and VIII), leaving only minor phylogroups II and IX. By contrast, when a phylogenetic tree was constructed using recombinant sequences with their recombinationally derived tracts removed before analysis, five previous minor phylogroups remained unchanged within major phylogroup A (II, III, IV, V, and VII) while four formed two new merged phylogroups (I/VI and VIII/IX). Absence of genetic connectivity between PNG, Australian, and East Timorese ZYMV sequences, and the 92.8% nucleotide identity between a PNG sequence and the closest sequence from elsewhere, suggest that a single introduction may have occurred followed by subsequent evolution to adapt to the PNG environment. The need for enhanced biosecurity measures to protect against potentially damaging virus movements crossing the seas separating neighboring countries in this region of the world is discussed.

Genetic Connectivity Between Papaya Ringspot Virus Genomes from Papua New Guinea and Northern Australia, and New Recombination Insights

Isolates of papaya ringspot virus (PRSV) were obtained from plants of pumpkin (Cucurbita spp.) or cucumber (Cucumis sativus) showing mosaic symptoms growing at Zage in Goroka District in the Eastern Highland Province of Papua New Guinea (PNG) or Bagl in the Mount Hagen District, Western Highlands Province. The samples were sent to Australia on FTA cards where they were subjected to High Throughput Sequencing (HTS). When the coding regions of the six new PRSV genomic sequences obtained via HTS were compared with those of 54 other complete PRSV sequences from other parts of the world, all six grouped together with the 12 northern Australian sequences within major phylogroup B minor phylogroup I, the Australian sequences coming from three widely dispersed locations spanning the north of the continent. Notably, none of the PNG isolates grouped with genomic sequences from the nearby country of East Timor in phylogroup A. The closest genetic match between Australian and PNG sequences was a nucleotide (nt) sequence identity of 96.9%, whereas between PNG and East Timorese isolates it was only 83.1%. These phylogenetic and nt identity findings demonstrate genetic connectivity between PRSV populations from PNG and Australia. Recombination analysis of the 60 PRSV sequences available revealed evidence of 26 recombination events within 18 isolates, only four of which were within major phylogroup B and none of which were from PNG or Australia. Within the recombinant genomes, the P1, Cl, NIa-Pro, NIb, 6K2, and 5'UTR regions contained the highest numbers of recombination breakpoints. After removal of nonrecombinant sequences, four minor phylogroups were lost (IV, VII, VIII, XV), only one of which was in phylogroup B. When genome regions from which recombinationally derived tracts of sequence were removed from recombinants prior to alignment with nonrecombinant genomes, seven previous minor phylogroups within major phylogroup A, and two within major phylogroup B, merged either partially or entirely forming four merged minor phylogroups. The genetic connectivity between PNG and northern Australian isolates and absence of detectable recombination within either group suggests that PRSV isolates from East Timor, rather than PNG, might pose a biosecurity threat to northern Australian agriculture should they prove more virulent than those already present.

Transcriptome Sequencing Reveals a Complete Genome Sequence of Cowpea Aphid-Borne Mosaic Virus from Passion Fruit in Kenya

Analysis of transcriptome sequencing (RNA-Seq) data revealed a complete Cowpea aphid-borne mosaic virus (CABMV) genome from virus-infected passion fruit in Kenya. We compared it with six complete CABMV genomes, one each from Zimbabwe and Uganda and two each from Brazil and India. The Zimbabwean isolate CABMV-Z was the closest, with 83.0% nucleotide identity.

New Isolates of Sweet potato feathery mottle virus and Sweet potato virus C: Biological and Molecular Properties, and Recombination Analysis Based on Complete Genomes

Sweet potato feathery mottle virus (SPFMV) and Sweet potato virus C (SPVC) isolates were obtained from sweetpotato shoot or tuberous root samples from three widely separated locations in Australia's tropical north (Cairns, Darwin, and Kununurra). The samples were planted in the glasshouse and scions obtained from the plants were graft inoculated to Ipomoea setosa plants. Virus symptoms were recorded in the field in Kununurra and in glasshouse-grown sweetpotato and I. setosa plants. RNA extracts from I. setosa leaf samples were subjected to high-throughput sequencing. New complete SPFMV (n = 17) and SPVC (n = 6) genomic sequences were obtained and compared with 47 sequences from GenBank. Phylogenetic analysis revealed that the 17 new SPFMV genomes all fitted within either major phylogroup A, minor phylogroup II, formerly O; or major phylogroup B, formerly RC. Major phylogroup A's minor phylogroup I, formerly EA, only appeared when recombinants were included. Numbers of SPVC genomes were insufficient to subdivide it into phylogroups. Within phylogroup A's minor phylogroup II, the closest genetic match between an Australian and a Southeast Asian SPFMV sequence was the 97.4% nucleotide identity with an East Timorese sequence. Recombination analysis of the 43 SPFMV and 27 SPVC sequences revealed evidence of 44 recombination events, 16 of which involved interspecies sequence transfers between SPFMV and SPVC and 28 intraspecies transfers, 17 in SPFMV and 11 in SPVC. Within SPFMV, 11 intraspecies recombination events were between different major phylogroups and 6 were between members of the same major phylogroup. Phylogenetic analysis accounting for the detected recombination events within SPFMV sequences yielded evidence of minor phylogroup II and phylogroup B but the five sequences from minor phylogroup I were distributed in two separate groups among the sequences of minor phylogroup II. For the SPVC sequences, phylogenetic analysis accounting for the detected recombination events revealed three major phylogroups (A, B, and C), with major phylogroup A being further subdivided into two minor phylogroups. Within the recombinant genomes of both viruses, their PI, NIa-Pro, NIb, and CP genes contained the highest numbers of recombination breakpoints. The high frequency of interspecies and interphylogroup recombination events reflects the widespread occurrence of mixed SPVC and SPFMV infections within sweetpotato plants. The prevalence of infection in northern Australian sweetpotato samples reinforces the need for improved virus testing in healthy sweetpotato stock programs. Furthermore, evidence of genetic connectivity between Australian and East Timorese SPFMV genomes emphasizes the need for improved biosecurity measures to protect against potentially damaging international virus movements.

First Complete Genome Sequence of Cucurbit aphid-borne yellows virus from Papua New Guinea

Analysis of an RNA-Seq library from cucumber leaf RNA revealed the first complete genome sequence of Cucurbit aphid-borne yellows virus (CABYV) from Papua New Guinea. We compared it with 36 complete CABYV genomes from other world regions. It most resembled the genome of South Korean isolate GS6.

Sweet potato feathery mottle virus and Sweet potato virus C from East Timorese and Australian Sweetpotato: Biological and Molecular Properties, and Biosecurity Implications

Sweet potato feathery mottle virus (SPFMV) and Sweet potato virus C (SPVC) isolates from sweetpotato were studied to examine genetic connectivity between viruses from Australia and Southeast Asia. East Timorese samples from sweetpotato were sent to Australia on FTA cards. Shoot and tuberous root samples were collected in Australia and planted in the glasshouse, and scions were graft inoculated to Ipomoea setosa plants. Symptoms in infected sweetpotato and I. setosa plants were recorded. RNA extracts from FTA cards and I. setosa leaf samples were subjected to high-throughput sequencing (HTS). Complete genomic sequences (CS) of SPFMV and SPVC (11 each) were obtained by HTS, and coat protein (CP) genes from them were compared with others from GenBank. SPFMV sequences clustered into two major phylogroups (A and B = RC) and two minor phylogroups (EA[I] and O[II]) within A; East Timorese sequences were in EA(I) and O(II), whereas Australian sequences were in O(II) and B(RC). With SPVC, CP trees provided sufficient diversity to distinguish major phylogroups A and B and six minor phylogroups within A (I to VI); East Timorese sequences were in minor phylogroup I, whereas Australian sequences were in minor phylogroups II and VI and in major phylogroup B. With SPFMV, Aus13B grouped with East Timorese sequence TM64B within minor phylogroup O, giving nucleotide sequence identities of 97.4% (CS) and 98.3% (CP). However, the closest match with an Australian sequence was the 97.6% (CS) and 98.7% (CP) nucleotide identity between Aus13B and an Argentinian sequence. With SPVC, closest nucleotide identity matches between Australian and East Timorese sequences were 94.1% with Aus6a and TM68A (CS) and 96.3% with Aus55-4C and TM64A (CP); however neither pair member belonged to the same minor phylogroup. Also, the closest Australian match was 99.1% (CP) nucleotide identity between Aus4C and New Zealand isolate NZ4-4. These first complete genome sequences of SPFMV and SPVC from sweetpotato plantings in the Australian continent and neighboring Southeast Asia suggest at least two (SPFMV) and three (SPVC) separate introductions to Australia since agriculture commenced more than two centuries ago. These findings have major implications for both healthy stock programs and biosecurity management in relation to pathogen entry into Australia and elsewhere.

Two Complete Genome Sequences of Squash mosaic virus from 20-Year-Old Cucurbit Leaf Samples from Australia

We present the first complete Australian Squash mosaic virus (SqMV) genome sequences. We compared the 2 Australian genomes from 20-year-old cucurbit samples with 8 other SqMV genomes. The Australian genomes shared >99.0% nucleotide identities, and their RNA1 and RNA2 sequences most closely resembled isolates Y and Kimbe from Japan, respectively.

Analysis of an RNA-seq Strand-Specific Library Sample Reveals a Complete Genome of Hardenbergia mosaic virus from Native Wisteria, an Indigenous Virus from Southwest Australia

Analysis of an RNA-seq strand-specific library revealed a complete genome of Hardenbergia mosaic virus (HarMV) from RNA extracted from a native wisteria (Hardenbergia comptoniana) plant from southwest Australia. We compared it with eight other complete HarMV genomes. It most resembled (85.8% nucleotide identity) the genome of HarMV isolate MD4-D.

First Complete Squash leaf curl China virus Genomic Segment DNA-A Sequence from East Timor

We present here the first complete Squash leaf curl China virus (SLCCV) genomic segment DNA-A sequence from East Timor. It was isolated from a pumpkin plant. When compared with 15 complete SLCCV DNA-A genome sequences from other world regions, it most resembled the Malaysian isolate MC1 sequence.