Chickpea chlorotic dwarf virus (CpCDV; genus Mastrevirus, family Geminiviridae) is one of the most important legume‐infecting viruses with a wide host range and geographic distribution in Africa and ...Asia. In Iran, CpCDV is common in chickpea (Cicer arietinum), but there is limited information about diversity and infections in plants of other legume species. In the current study, a total of 1671 leaf samples from different pulse crops with symptoms were collected in nine provinces of Iran, and the CpCDV infection status was tested by PCR and/or rolling circle amplification (RCA), resulting in the detection of CpCDV in samples of chickpea, lentil (Lens culinaris) and faba bean (Vicia faba) from different regions. Sequence analysis of complete genomes of 18 isolates recovered by digestion of RCA products revealed infection with isolates of the strains CpCDV‐A and CpCDV‐F in chickpea, lentil and faba bean. Phylogenetic analysis showed that the Iranian isolates of CpCDV were closely related to previously sequenced isolates of CpCDV‐A and CpCDV‐F. To the authors' knowledge, this is the first report of CpCDV‐F in Iran. Using agroinoculation with infectious clones for one isolate each of CpCDV‐A and CpCDV‐F, infectivity was confirmed in both faba bean and chickpea, with plants developing leaf curling and/or yellowing. Both infectious clones also successfully infected Nicotiana benthamiana resulting in mild yellowing and intensive leaf curling for CpCDV‐A, and dark‐green mosaic, dwarfing and mild leaf curling for CpCDV‐F.
Two begomovirus-associated alphasatellites were isolated from okra and a malvastrum plant (Malvaceae) in Cameroon. The complete nucleotide sequences of the okra- and malvastrum-infecting ...alphasatellites were 1375 and 1416–1418 nucleotides, respectively, and both exhibited features characteristic of other alphasatellites. Based on pairwise sequence comparisons, these previously undescribed alphasatellites are members of distinct species in the genera
Colecusatellite
and
Gosmusatellite
and have been tentatively named “pepper yellow vein Mali alphasatellite” and “cotton leaf curl Gezira alphasatellite3”, respectively. Taken together with previous studies, alphasatellites endemic to Cameroon appear to be more diverse and infect plants of many more species and families than currently recognized.
Fruit constitutes a strong sink organ and thus accumulates infecting viruses, but there is limited information about the infection process of viruses in fruit. Tomato yellow leaf curl virus (TYLCV, ...genus Begomovirus, family Geminiviridae) is one of the most important viruses affecting the production of tomato fruit. Using real‐time quantitative PCR, TYLCV was shown to accumulate with increasing titres in early developing tomato fruit tissues from anthesis until 21 days post‐anthesis. In situ hybridization demonstrated that TYLCV DNA and transcripts of the coat protein gene localized specifically to the phloem tissue of young fruit as well as sepals and petals. Embryos of developing seeds were also found to be infected. Expression of a host histone H4 gene was used as a marker for S‐phase and the gene was also found to be expressed in phloem cells of young tomato fruit. The results indicate that TYLCV is transported to developing tomato fruit, where the virus titre gradually increases because of movement and probably also due to virus replication. In this study, the accumulation and localization of TYLCV in early developing tomato fruit are monitored for the first time.
Potato tuber necrosis in the form of spraing symptoms is caused by infection with Potato mop‐top virus (PMTV) or Tobacco rattle virus (TRV); spraing has become more important in the Swedish potato ...crop production. In this study, the presence in Sweden of three potato‐infecting viruses associated with necrotic symptoms in tubers was demonstrated: PMTV, TRV and Tobacco necrosis virus (TNV). This study shows that both PMTV and TRV are frequent in Swedish potato fields. PMTV was found in all Swedish counties, except the two most northern ones. TRV was present at several locations in southern and up to the central parts of Sweden. Both viruses were found further north than observed in earlier surveys. PMTV and TRV were analysed in tubers with spraing symptoms and it was not possible to decide visually if the symptoms were caused by either PMTV or TRV. Furthermore, a high occurrence of symptomless tuber infections was observed for several potato cultivars. A unique observation from this study was a mixed infection of both PMTV and TRV in tubers of cv. Berber, where no visual differences on symptom development were detectable for these tubers compared to single infections. During the survey, tubers of cv. Melody were found to display necrotic symptoms in the skin that are characteristic for the ABC disease. This suggested infection by TNV, which also could be confirmed.
Tomato yellow leaf curl virus (TYLCV; genus Begomovirus; family Geminiviridae) infects mainly plants of the family Solanaceae, and the infection induces curling and chlorosis of leaves, dwarfing of ...the whole plant, and reduced fruit production. Alternatives for direct control of TYLCV and other geminiviruses have been reported, for example, the use of esterified whey proteins, peptide aptamer libraries or artificial zinc finger proteins. The two latter alternatives affect directly the replication of TYLCV as well as of other geminiviruses because the replication structures and sequences are highly conserved within this virus family. Because peptides and proteins offer a potential solution for virus replication control, in this study we show the isolation, biochemical characterization and antiviral activity of a peptide derived from globulins of amaranth seeds (Amaranthus hypochondriacus) that binds to the replication origin sequence (OriRep) of TYLCV and affects viral replication with a consequent reduction of disease symptoms in Nicotiana benthamiana. Aromatic peptides obtained from papain digests of extracted globulins and albumins of amaranth were tested by intrinsic fluorescent titration and localized surface resonance plasmon to analyze their binding affinity to OriRep of TYLCV. The peptide AmPep1 (molecular weight 2.076 KDa) showed the highest affinity value (Kd = 1.8 nM) for OriRep. This peptide shares a high amino acid similarity with a part of an amaranth 11S globulin, and the strong affinity of AmPep1 could be explained by the presence of tryptophan and lysine facilitating interaction with the secondary structure of OriRep. In order to evaluate the effect of the peptide on in vitro DNA synthesis, rolling circle amplification (RCA) was performed using as template DNA from plants infected with TYLCV or another begomovirus, pepper huasteco yellow vein virus (PHYVV), and adding AmPep1 peptide at different concentrations. The results showed a decrease in DNA synthesis of both viruses at increasing concentrations of AmPep1. To further confirm the antiviral activity of the peptide in vivo, AmPep1 was infiltrated into leaves of N. benthamiana plants previously infected with TYLCV. Plants treated with AmPep1 showed a significant decrease in virus titer compared with untreated N. benthamiana plants as well as reduced symptom progression due to the effect of AmPep1 curtailing TYLCV replication in the plant. The peptide also showed antiviral activity in plants infected with PHYVV. This is the first report, in which a peptide is directly used for DNA virus control in plants, supplied as exogenous application and without generation of transgenic lines.
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•The direct control of TYLCV using a peptide from enzymatic digested 11S amaranth globulin is described.•The peptide binds with high affinity to replication origin sequence (OriRep) decreasing the replication rate of TYLCV.•The peptide reduces the replication rate decreasing viral DNA titer with consequently symptoms reduction of TYLCV.•This is the first report using plant-derived peptides to plant DNA virus control without generation of transgenic lines.
Imported tomato fruits infected with Tomato yellow leaf curl virus (TYLCV) were identified on the market in northern Europe using paper‐based FTA Classic Cards (Whatman), polymerase chain reaction ...(PCR) and partial DNA sequence analysis. Trade tomatoes originating from southern Europe, Africa and the Middle East were sampled in Estonia and Sweden, and tested for infection with begomoviruses. Out of 100 batches analysed with five fruits sampled in each batch (58 batches from Estonia and 42 from Sweden), 20 batches were positive (16 from Estonia and four from Sweden). Rolling circle amplification (RCA) and full‐length genome sequence analysis of one isolate collected in Estonia and one isolate in Sweden, revealed highest nucleotide sequence identity at 99% to TYLCV‐IL for the Estonian isolate and at 97% to TYLCV‐Mld for the Swedish isolate. In this study, TYLCV was identified for the first time in imported tomato fruits on the market in northern Europe. FTA cards proved to be an effective means to collect, extract and store begomovirus DNA from tomato fruits and the subsequent molecular analysis.
The complete coding sequences were determined for RNA-1 and RNA-2 of five raspberry isolates of Raspberry bushy dwarf virus (RBDV) from Belarus (BY1, BY3, BY8, BY22) and Sweden (SE3). The analysed ...sequences for both RNA-1 and RNA-2 were highly conserved among these isolates. Phylogenetic analyses including available sequences for the CP gene and the MP gene showed that all analysed RBDV isolates from raspberry were closely related. However, there was no strong correlation between the grouping of raspberry isolates in the phylogenetic analyses and their geographical location. In contrast, RBDV isolates showed a host-dependent relationship with isolates from raspberry and grapevine, forming two distinct clades.
Detection of prey DNA-remains in arthropod predators by polymerase chain reaction (PCR) is useful when investigating food webs. In this study we estimated how long after a feeding event it was ...possible to detect mitochondrial COII DNA (331
bp) from an important aphid pest,
Rhopalosiphum padi (Homoptera: Aphididae)
, in spiders of the genus
Pardosa (Araneae: Lycosidae). Following laboratory evaluations we tested spiders collected in spring-sown cereals for aphid predation during two seasons. Aphids were digested rapidly in laboratory-fed predators and the time point when prey DNA could be amplified from 50% of the spiders was estimated to be 3.7
h. A total of 372 field- collected predators were analyzed by PCR and despite low aphid densities many spiders (26% in 2004 and 19% in 2005) tested positive for
R. padi, indicating consumption of at least one aphid within a few hours before capture. The percentage of spiders that tested positive for
R. padi DNA varied considerably between fields and logistic regression analysis revealed that the probability of detecting aphid DNA was significantly influenced by location and year. We conclude that
Pardosa spiders, under certain conditions, frequently feed on
R. padi and deserve special attention in conservation biological control.
Der Nachweis von Beute-DNA bei räuberischen Arthropoden durch Polymerase-Kettenreaktion (PCR) ist eine nützliche Methode bei der Erforschung von Nahrungsnetzen. Hier untersuchten wir an Spinnen der Gattung
Pardosa (Araneae: Lycosidae), wie lange nach der Nahrungsaufnahme DNA der schädlichen Blattlaus
Rhopalosiphum padi (Homoptera: Aphididae) noch nachzuweisen war. Wir benutzten PCR-Primer, die ein 331
bp langes Bruchstück des mitochondrialen COII-Gens von
R. padi vervielfältigen sollten. Nach Vorversuchen im Labor testeten wir in zwei Jahren Spinnen aus Sommergetreidefeldern auf Blattlausspuren. Die Blattlaus-DNA wurde nach Fütterung im Labor schnell verdaut, und der Zeitraum, nach dem noch 50% der Spinnen positiv auf Blattlaus-DNA getestet werden konnten, wurde rechnerisch zu 3.7 Stunden bestimmt. Von den Getreidefeldern sammelten wir 372 Räuber, die mit PCR analysiert wurden. Trotz geringer Blattlausdichten in beiden Jahren wurden viele Spinnen (2004: 26%; 2005: 19%) positiv auf
R. padi-DNA getestet, was den Verzehr von mindestens einer Blattlaus innerhalb weniger Stunden vor dem Einfangen anzeigt. Der Anteil der Spinnen, die positiv auf
R. padi-DNA getestet wurden, variierte beträchtlich zwischen den Feldern, und eine logistische Regressionsanalyse zeigte, dass die Wahrscheinlichkeit Blattlaus-DNA nachzuweisen signifikant von der Örtlichkeit (Betrieb) und dem Jahr beeinflusst wurde. Wir schließen, dass die Spinnen der Gattung
Pardosa unter bestimmten Umständen häufig an
R. padi fressen und daher besondere Beachtung bei der Nützlingsförderung verdienen.
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