Genetic Variation between Asian and Mediterranean Populations of Cucurbit Aphid-Borne Yellows Virus

Viral symptoms, such as yellowing, leaf deformation, mottling, vein clearing, and reduced yield, were observed in cucurbits in Iran. This study aimed to detect the main suspected causal agent, cucurbit aphid-borne yellows virus (CABYV), in Iran and analyze the genetic diversity among isolates. Two hundred samples were collected from different growing areas between 2019 and 2022. PCR amplification was performed on the P3 and P4 genes. The sequences of 18 Iranian isolates were obtained and deposited in GenBank. Recombination, phylogenetic, and population genetics studies were then carried out for the complete genome and all ORFs sequences, together with other isolates in GenBank. The nucleotide identities of the overlapped ORF3/4 sequences of Iranian isolates were 94.8 to 99.5% among themselves, and with other tested isolates ranging from 94.3 to 99.3%. Phylogenetic trees based on the complete genome and the overlapped ORF3/4 showed two major clades, namely Asian and Mediterranean, and the new isolates from Iran were positioned in both clades. The obtained results also suggest that all the genes and two clades of CABYV populations were under negative selection pressure. Furthermore, rare gene flow between these two clades (FST > 0.33) confirmed the high genetic separation among them

A Survey of Phytopathogenic Fungi and Oomycetes in Riyadh, Saudi Arabia

A survey of phytopathogenic fungi and Oomycetes<br />was conducted in Riyadh, Kingdom of Saudi Arabia during<br />October 2008 – May 2009. Total of 223 samples were collected<br />from four regions; Al-Kharj, Oyaynah, Old Diriyah, and Al Amariyah. Isolation was done using Potato Dextrose Agar<br />(PDA). Infected parts were cut then sterilized in chlorox<br />(10%), then were put in petridish that contain PDA and<br />incubated at 25-27 °C. A total twelve genera of fungi and<br />single genera of Oomycetes were isolated from the infected<br />plants and identifi ed as Fusarium spp., Alternaria spp.,<br />Helmintosphorium (Bipolaris) spp., Sclerotium spp., Rhizoctonia<br />spp., Cladosporium spp., Mauginiella scattae, Erysiphe spp.,<br />Leveillula spp., Macrophomina phaseolina, Ustilago spp.,<br />Ulocladium spp., and Phytium spp

Global Population Structure of Apple Mosaic Virus (ApMV, Genus <i>Ilarvirus</i>)

The gene sequence data for apple mosaic virus (ApMV) in NCBI GenBank were analyzed to determine the phylogeny and population structure of the virus at a global level. The phylogenies of the movement protein (MP) and coat protein (CP) genes, encoded by RNA3, were shown to be identical and consisted of three lineages but did not closely correlate with those of P1 and P2, suggesting the presence of recombinant isolates. Recombination Detection Program (RDP v.4.56) detected significant recombination signal in the P1 region of K75R1 (KY883318) and Apple (HE574162) and the P2 region of Apple (HE574163) and CITH GD (MN822138). Observation on several diversity parameters suggested that the isolates in group 3 had higher divergence among them, compared to isolates in groups 1 and 2. The neutrality tests assigned positive values to P1, indicating that only this region experiencing balanced or contracting selection. Comparisons of the three phylogroups demonstrated high Fixation index (FST) values and confirmed genetic separation and the lack of gene flow among them. Additionally, ±500 bp of partial MP + ‘intergenic region’ + partial CP coding regions of two Turkish isolates from apple and seven from hazelnut were sequenced and determined that their phylogenetic positions fell within group 1 and 3, respectively

Insight into Population Structure and Evolutionary Analysis of the Emerging Tomato Brown Rugose Fruit Virus

A total of 112 symptomatic tomatoes (Solanum lycopersicum L.) and 83 symptomatic pepper (Capsicum spp.) samples were collected in Ankara, Eskişehir, Bartın, and Zonguldak provinces of Turkey during 2020–2021. Six tomatoes and one pepper sample (3.6%) tested positive for tomato brown rugose fruit virus (ToBRFV, genus Tobamovirus) infection by DAS-ELISA and RT-PCR. ToBRFV-positive tomato and pepper plants were removed from greenhouses as soon as possible, and the greenhouses and tools were disinfected completely. Phylogenetic analysis on the complete CP sequences suggested the clustering of 178 GenBank isolates and 7 novel isolates into three groups. A study using DnaSP software showed very low genetic variation among current global ToBRFV isolates. All four ORFs of the virus genome were under strong negative evolutionary constraints, with a ω value range of 0.0869–0.2066. However, three neutrality tests indicated that most populations of the newly identified ToBRFV are currently expanding by assigning statistically significant negative values to them. The very low FST values (0.25 or less) obtained by all comparisons of the isolates from Europe, the Middle East, China, and America concluded that there is no clear genetic separation among currently known isolates from different geographic origins. The divergence time of ToBRFV was estimated to be in the middle of the course of the evolution of 11 tested tobamoviruses. The time to the most recent common ancestors (TMRCAs) of ToBRFV were calculated to be 0.8 and 1.87 with the genetically closest members of Tobamovirus. The results of this study could improve our understanding on the population structure of the emerging ToBRFV

Population analysis on tomato spotted wilt virus isolates inducing various symptoms on tomato, pepper, and Chenopodium album in Turkey

Molecular identification of tomato spotted wilt virus (TSWV) has been conducted in several surveys in Turkey, but the population structure of the virus in the country remains unknown. During 2019–2020, 227 viral symptomatic tomato (Solanum lycopersicum), pepper (Capsicum annuum), and weeds leaf samples were collected from Ankara, Bartın, Eskisehir, Konya, and Zonguldak provinces. RT-PCR tests confirmed TSWV infection in 99 tomato, pepper, and Chenopodium album samples (43.6%). Phylogenetic analysis based on complete nucleotide sequences of N gene clustered the 23 newly sequenced Turkish isolates and other 281 isolates in NCBI GenBank into three major clades: p202/3WT, Tarquinia, and p105. All tested Turkish isolates were included in either p202/3WT or p105 clade. Global isolates retained high nucleotide and amino acids identity for N gene according to percentage identity analysis. N gene of TSWV was under very strong negative selection pressures, as shown by the very low ω values (<0.15) for all analyzed populations. Three neutrality tests also suggested that these populations are undergoing balancing selection by assigning negative values to most of them. The genetic differentiation and gene flow analysis among three clades demonstrated that they are genetically divergent from each other, but their medium FST values of around 0.5 showed that gene flows among clades are rare. This is the first detailed study on the genetic diversity and population structure of TSWV in Turkey

Comprehensive surveillance and population study on plum pox virus in Ankara Province of Turkey

Ankara Province with its sizeable stone fruits outputs and its geographic location in the middle of Turkey might be one of the diversity centers of plum pox virus (PPV) in the country, yet the epidemiological data from there were rather limited. Multi-year extensive surveillance in all 25 districts of Ankara sampled 8131 Prunus spp. plants to be tested against PPV. DAS-ELISA detected 609 PPV positive samples (7.49%), which were all also confirmed by RT-PCR using two primer pairs to amplify P3-6K1-CI and partial NIb-CP regions. The partial genomes of 80 isolates were sequenced, then the sequences were subjected to phylogenetic and population analyses together with 170 isolates which complete genome sequences available in NCBI GenBank. The phylogenetic study showed that 73 new isolates were PPV-T, six isolates were PPV-M, and one isolate was PPV-D. The subsequent population study confirmed the interesting features of PPV with very high genetic diversities at the species level, thus it should be divided into strains that each retained much lower divergence among isolates. The obtained data also could provide new evidence to separate M, and MIs isolates into two distinct strains. Although previous studies suggested that Turkish isolates have been endemic since a long time ago in the country, the results of demographic analyses of the present study indicated that the expansions of Turkey and Ankara populations were recent, driven by relatively new mutations in their genome

Insight into Population Structure and Evolutionary Analysis of the Emerging Tomato Brown Rugose Fruit Virus

A total of 112 symptomatic tomatoes (Solanum lycopersicum L.) and 83 symptomatic pepper (Capsicum spp.) samples were collected in Ankara, Eski¸sehir, Bartın, and Zonguldak provinces of Turkey during 2020–2021. Six tomatoes and one pepper sample (3.6%) tested positive for tomato brown rugose fruit virus (ToBRFV, genus Tobamovirus) infection by DAS-ELISA and RT-PCR. ToBRFV-positive tomato and pepper plants were removed from greenhouses as soon as possible, and the greenhouses and tools were disinfected completely. Phylogenetic analysis on the complete CP sequences suggested the clustering of 178 GenBank isolates and 7 novel isolates into three groups. A study using DnaSP software showed very low genetic variation among current global ToBRFV isolates. All four ORFs of the virus genome were under strong negative evolutionary constraints, with a ω value range of 0.0869–0.2066. However, three neutrality tests indicated that most populations of the newly identified ToBRFV are currently expanding by assigning statistically significant negative values to them. The very low FST values (0.25 or less) obtained by all comparisons of the isolates from Europe, the Middle East, China, and America concluded that there is no clear genetic separation among currently known isolates from different geographic origins. The divergence time of ToBRFV was estimated to be in the middle of the course of the evolution of 11 tested tobamoviruses. The time to the most recent common ancestors (TMRCAs) of ToBRFV were calculated to be 0.8 and 1.87 with the genetically closest members of Tobamovirus. The results of this study could improve our understanding on the population structure of the emerging ToBRFV