Search

Cherry virus A (CVA) is a member of the Capillovirus genus (2). It was discovered serendipitously during cloning of the little cherry agent (2) and has since been shown to be relatively widespread in sweet and sour cherry (Prunus cerasus and P. avium) (2,3). It is currently unclear whether CVA is associated with any specific symptoms in these hosts. Although it can be transmitted by grafting and thus propagated in peach, it has not been reported to naturally infect any host other than cherry. Using a degenerate reverse transcription-polymerase chain reaction (RT-PCR) technique targeting a conserved region of the RNA-dependent RNA polymerase (RdRp) and allowing the amplification of members of the Trichovirus, Capillovirus, and Foveavirus genera of filamentous plant viruses (1), a number of symptomatic Prunus spp. germplasm were evaluated. Among these, a cv. Mirabelle dorée accession (Prunus domestica var. insititia P332) of French origin exhibited severe symptoms of rosetting, severe leaf and fruit deformation, and yellow mosaic occasionally turning necrotic. RT-PCR conducted on symptomatic samples produced an amplification product of the expected size (362 bp) in several independent experiments. Sequencing of these products yielded a single sequence (GenBank Accession No. AY792509) with 88.1% nucleotide identity and 93.2% amino acid identity with the type strain of CVA (2). Presence of a CVA isolate was independently confirmed using a CVA-specific PCR assay directly on the original plum material or following experimental transmission by grafting on several new hosts including apricot (P. armeniaca cv. Priana) and plum (P. domestica cv. Prune d'Ente). To our knowledge, this is the first report of natural infection of CVA in plum. The symptoms observed in the infected plum are reminiscent of those caused by severe Prune dwarf virus (PDV) strains. Infection by PDV was confirmed using a PDV-specific PCR assay. The contribution, if any, of CVA to the symptoms observed remains to be evaluated. These findings suggest that the possible presence of CVA in noncherry Prunus spp. hosts should be taken into consideration by quarantine and certification programs. References: (1) X. Foissac et al. Acta Hortic. 550:3743, 2001. (2) W. Jelkmann. J. Gen. Virol. 76:2015, 1995. (3) M. J. Kirby et al. Plant Pathol. 50:6, 2001.

Este artículo analiza el trasfondo simbólico de la motivación figurativa del ciruelo en la lengua china, y las huellas de dicha semiótica en el léxico figurativo y los fraseologismos, todo ello desde una perspectiva linguo-cultural, siguiendo la Teoría Cognitiva del Lenguaje Figurado de Dobrovol'skij y Piirainen (2005). El ciruelo ha tenido siempre un lugar especial en la cultura china, conllevando un significado social y cultural especial, y transmite unos simbolismos específicos de China, reflejando normas mora-les, creencias, costumbres, etc. La interpretación correcta de estas expresiones figurativas requiere un conocimiento sobre su origen y el trasfondo cultural que subyace tras ellas., This paper aims at analyzing the symbolic background of the figurative motivation of the plum in Chinese and the traces of this semiotics in the figurative lexicon, idioms and proverbs. From a linguo-cultural perspective, it bases on the Cognitive Theory of Figurative Language of Dobrovol'skij and Piirainen (2005). The plum has always played an important role in Chinese culture, bearing special social and cultural connotations, and serves as specific symbols, reflecting moral norms, beliefs, customs, etc. The correct understanding of these figurative expressions requires some knowledge about their origin and the cultural background that underlies them., Cet article vise à analyser le contexte symbolique de la motivation figurative de la prune en chinois et les traces de cette sémiologie dans le lexique figuratif et la phraséologie. D'un point de vue linguistique et culturel, il s'appuie sur la théorie cognitive du langage figuratif de Dobrovol'skij et Piirainen (2005). Le prunier a toujours eu une place privilégiée dans la culture chinoise, comme porteur de significations sociales et culturelles particulières, chargées d’un symbolisme spécifiquement chinois, reflétant des normes morales, des croyances, des coutumes, etc. La bonne compréhension de ces expressions figurées nécessite des connaissances sur leur origine et le contexte culturel qui les soustend.

Este artículo analiza el trasfondo simbólico de la motivación figurativa del ciruelo en la lengua china, y las huellas de dicha semiótica en el léxico figurativo y los fraseologismos, todo ello desde una perspectiva linguo-cultural, siguiendo la Teoría Cognitiva del Lenguaje Figurado de Dobrovol'skij y Piirainen (2005). El ciruelo ha tenido siempre un lugar especial en la cultura china, conllevando un significado social y cultural especial, y transmite unos simbolismos específicos de China, reflejando normas mora-les, creencias, costumbres, etc. La interpretación correcta de estas expresiones figurativas requiere un conocimiento sobre su origen y el trasfondo cultural que subyace tras ellas., This paper aims at analyzing the symbolic background of the figurative motivation of the plum in Chinese and the traces of this semiotics in the figurative lexicon, idioms and proverbs. From a linguo-cultural perspective, it bases on the Cognitive Theory of Figurative Language of Dobrovol'skij and Piirainen (2005). The plum has always played an important role in Chinese culture, bearing special social and cultural connotations, and serves as specific symbols, reflecting moral norms, beliefs, customs, etc. The correct understanding of these figurative expressions requires some knowledge about their origin and the cultural background that underlies them., Cet article vise à analyser le contexte symbolique de la motivation figurative de la prune en chinois et les traces de cette sémiologie dans le lexique figuratif et la phraséologie. D'un point de vue linguistique et culturel, il s'appuie sur la théorie cognitive du langage figuratif de Dobrovol'skij et Piirainen (2005). Le prunier a toujours eu une place privilégiée dans la culture chinoise, comme porteur de significations sociales et culturelles particulières, chargées d’un symbolisme spécifiquement chinois, reflétant des normes morales, des croyances, des coutumes, etc. La bonne compréhension de ces expressions figurées nécessite des connaissances sur leur origine et le contexte culturel qui les soustend.

Les nématodes à galles ([i]Meloidogyne[/i] spp.) sont de ravageurs extrêmement polyphages des racines et dont l’impact est très important à l’échelle globale. La stratégie de résistance aux espèces prédominantes [i]M. arenaria[/i], [i]M. incognita[/i] et[i] M. javanica[/i], est une alternative prioritaire chez de nombreuses plantes cultivées confrontées au retrait des nématicides et notamment chez les arbres fruitiers du genre Prunus. Trois gènes majeurs dominants de résistance, Ma (prunier), RMia (pêcher) et RMja (amandier), ont été identifiés et cartographiés dans cet objectif. Le pyramidagede ces trois gènes, par exemple dans des hybrides 3-voies, ouvre la voie à la création de porte-greffe protégés par au moins deux gènes vis-à-vis de chacune des espèces de nématodes précitées. Du fait de l’interaction durable entre ces plantes pérenneset les nématodes, ce pyramidagegarantit la création de matériels dotés d’une durabilité de résistance sans précédent au niveau mondial. La sélection assistée par marqueurs (SAM) du gène Ma,à spectre complet et cloné (famille desTIR-NB-LRRs(TNLs)), est possible grâce à des marqueurs SCAR intragéniques chez la source P.2175. Nous présentons donc ici les résultats des travaux sur les gènes RMia et RMja conduits dans le cadre d’un projet soutenu par le Ministère de l’Agriculture. Une cartographie à haute résolution du gène RMia chez la source Nemared, par marqueurs SSR (simple sequence repeat) et SNP (single nucleotide polymorphism), a été entreprise notamment dans une descendance F2 [Montclar (sensible) x Nemared]. Des marqueurs SNP ont permis de localiser le gène dans un intervalle physique de 92 kb du génome de référence du pêcher Lovell contenant 3 gènes candidats de type TNL. Le gène RMja porté par l’amandier Alnem, dont le marquage fin est en cours à partir de 800 individus de la population F2 [Lauranne (sensible) x Alnem]), a été situé dans un intervalle d’environ 2 Mb contenant également l’orthologue de Ma. L’obtention prochaine de la séquence NGS des parents Lauranne et Alnem permettra d’assurer un marquage à haute résolution de RMja et ainsi de disposer des outils de SAM pour les trois gènes de résistance

L'article original est publié par The American Society of Plant Biologists Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Root-knot nematode (RKN) Meloidogyne species are major polyphagous pests of most crops worldwide, and cultivars with durable resistance are urgently needed because of nematicide bans. The Ma gene from the Myrobalan plum (Prunus cerasifera) confers complete-spectrum, heat-stable, and high-level resistance to RKN, which is remarkable in comparison with the Mi-1 gene from tomato (Solanum lycopersicum), the sole RKN resistance gene cloned. We report here the positional cloning and the functional validation of the Ma locus present at the heterozygous state in the P.2175 accession. High-resolution mapping totaling over 3,000 segregants reduced the Ma locus interval to a 32-kb cluster of three Toll/Interleukin1 Receptor-Nucleotide Binding Site-Leucine-Rich Repeat (LRR) genes (TNL1–TNL3), including a pseudogene (TNL2) and a truncated gene (TNL3). The sole complete gene in this interval (TNL1) was validated as Ma, as it conferred the same complete-spectrum and high-level resistance (as in P.2175) using its genomic sequence and native promoter region in Agrobacterium rhizogenes-transformed hairy roots and composite plants. The full-length cDNA (2,048 amino acids) of Ma is the longest of all Resistance genes cloned to date. Its TNL structure is completed by a huge post-LRR (PL) sequence (1,088 amino acids) comprising five repeated carboxyl-terminal PL exons with two conserved motifs. The amino-terminal region (213 amino acids) of the LRR exon is conserved between alleles and contrasts with the high interallelic polymorphisms of its distal region (111 amino acids) and of PL domains. The Ma gene highlights the importance of these uncharacterized PL domains, which may be involved in pathogen recognition through the decoy hypothesis or in nuclear signaling.

25 Pag., 2 Tabl., 5 Fig. The definitive version is available at: http://www.elsevier.de/jplph, Iron deficiency induces several mechanisms in response to iron shortage in plants. Metabolic changes occur to sustain the increased iron uptake capacity of Fe-deficient plants. We evaluated the metabolic changes of three Prunus rootstocks submitted to iron chlorosis and their different response for tolerance using measurements of metabolites and enzymatic activities. The more tolerant rootstocks Adesoto (Prunus insititia) and GF 677 (Prunus amygdalus × Prunus persica), and the more sensitive Barrier (P. persica × Prunus davidiana) were grown hydroponically in iron sufficient and deficient conditions during two weeks. Sugar, organic and amino acid concentrations of root tips were determined after two weeks of iron shortage by proton nuclear magnetic resonance spectroscopy of extracts. Complementary analyses of organic acids were performed by liquid chromatography coupled to mass spectrometry. The major soluble sugars found were glucose and sucrose. The major organic acids were malic and citric acids, and the major amino acid was asparagine. Iron deficiency increased root sucrose, total organic and amino acid concentrations and phosphoenolpyruvate carboxylase activity. After two weeks of iron deficiency, the malic, citric and succinic acid concentrations increased in the three rootstocks, although no significant differences were found among genotypes with different tolerance to iron chlorosis. The tolerant rootstock Adesoto showed higher total organic and amino acid concentrations. In contrast, the susceptible rootstock Barrier showed lower total amino acid concentration and phosphoenolpyruvate carboxylase activity values. These results suggest that the induction of this enzyme activity under iron deficiency, as previously shown in herbaceous plants, indicates the tolerance level of rootstocks to iron chlorosis. The analysis of other metabolic parameters, such as organic and amino acid concentrations, gives complementary information for selection of genotypes tolerant to iron chlorosis., This work was partly funded by the Spanish-French bilateral cooperation programs (Picasso Program-HF2003-273; Aquitaine- Aragón Aq23 and Aq25) and the Spanish MICINN (Ministerio de Ciencia e Innovación, grants AGL-2005-05533, AGL-2008-00283 and AGL2009-09018). Sergio Jiménez was supported by an I3P fellowship from CSIC/FSE (Consejo Superior de Investigaciones Científicas/ Fondo Social Europeo) and a travel fellowship from DGA/CAI (CA 5/03).

Twelve Arabidopsis accessions were challenged with Plum pox potyvirus (PPV) isolates representative of the four PPV strains. Each accession supported local and systemic infection by at least some of the PPV isolates, but high variability was observed in the behavior of the five PPV isolates or the 12 Arabidopsis accessions. Resistance to local infection or long-distance movement occurred in about 40% of all the accession-isolate combinations analyzed. Except for Nd-1, all accessions showed resistance to local infection by PPV-SoC; in the Landsberg erecta (Ler) accession, this resistance was compromised by sgt1 and rar1 mutations, suggesting that it could be controlled by an R gene-mediated resistance pathway. While most of the susceptible accessions were symptomless, PPV induced severe symptoms on inflorescences in C24, Ler, and Bay-0 as early as 15 days after inoculation. Genetic analyses indicated that these interaction phenotypes are controlled by different genetic systems. The restriction of long-distance movement of PPV-El Amar and of another member of genus Potyvirus, Lettuce mosaic virus, in Col-0 requires the RTM genes, indicating for the first time that the RTM system may provide a broad range, potyvirus-specific protection against systemic infection. The restriction to PPVPS long-distance movement in Cvi-1 is controlled by a single recessive gene, designated rpv1, which was mapped to chromosome 1. The nuclear inclusion polymerase b-capsid protein region of the viral genome appears to be responsible for the ability of PPV-R to overcome rpv1-mediated resistance.

International audience

Prunus species express a more or less wide spectrum of resistance to root-knot nematodes (RKN) of the genus Meloidogyne. Among them, sources from Myrobalan plum (P. cerasifera) control all major and minor RKN species tested. In this outbreeding species, the clones P.2175 and P.2980 are heterozygous for the Ma single dominant gene and carry the alleles Ma1 and Ma3, respectively. Each allele confers a high-level resistance to the predominant RKN, M. arenaria, M. incognita and M. javanica and to the Florida isolate of an unknown Meloidogyne sp. which overcomes the resistance from peach and almond sources. The polymorphism of two coupling-phase SCAR markers tightly linked to Ma, SCAL19690 and SCAFLP2202, was evaluated within diverse diploid Prunus accessions. This material belongs to the subgenera Prunophora (Myrobalan and apricot) or Amygdalus (peach, almond and almond-peach) and includes the RKN resistance sources ‘Nemared’, ‘Alnem 1’ and ‘GF.557’. The alleles SCAL19690 and SCAFLP2202 were not present in three apricot cultivars (‘Moniqui’, ‘Luizet’ and ‘Stark Early Orange’) representative of the genetic diversity of this species and they segregated in an interspecific cross between P.2980 and apricot. These results suggest that apricot, reported as resistant to M. arenaria, M. incognita and M. javanica, and the Myrobalan plum might possess two different resistance systems. SCAL19690 and SCAFLP2202 were also absent from all tested Amygdalus material, whatever its resistance to RKN. Eight Myrobalan×Amygdalus segregating progenies including bispecific (P.2175 or P.2980×peach or almond) and trispecific (P.2175 or P.2980×almond-peach) hybrids were tested with the Florida isolate to identify individuals carrying the Ma resistance alleles. Both SCARs were then evaluated for segregation in these progenies to develop marker-assisted selection of Prunus interspecific rootstocks. SCAL19690 and SCAFLP2202 could be clearly detected and their tight linkage to Ma1 and Ma3 was confirmed. Consequently these SCARs appear to be powerful tools to screen for RKN resistance conferred by the Ma gene. They should also facilitate marker-assisted pyramiding of Ma with other resistance genes from the Amygdalus subgenus or from the botanically-related Armeniaca section.

International audience

International audience

International audience

Apricot pseudo-chlorotic leaf spot virus (APCLSV) is a novel, still poorly known Trichovirus in the family Betaflexiviridae. It is most closely related to Apple chlorotic leaf spot virus (ACLSV) (2,4) and infects stone fruit trees of the Prunus genus. Its presence has so far been detected in apricot, plum, Japanese plum, and peach trees in Italy, Spain, France, Hungary, Turkey, Jordan, and Australia (1,2,4). During the summers of 2008 and 2010, leaf samples of old Czech local plum cultivars were obtained from the Holovousy collection and assessed for the presence of viruses belonging to the Capillovirus, Trichovirus, and Foveavirus genera using the polyvalent degenerate oligonucleotides (PDO) nested reverse transcription (RT)-PCR test (3). Following amplification from total RNAs extracts, the amplicons were cloned and several clones were sequenced for each plant sample. In plum (Prunus domestica) cv. Babce, a mixture of amplicons was observed and BlastN and BlastX analyses of the obtained sequences revealed the presence of ACLSV and APCLSV. The 310-bp APCLSV amplicon (GenBank Accession No. JN790294) showed highest identity (82.9% in nucleotide sequence and 97.1% in amino acid sequence) with the Sus2 isolate of APCLSV (4) and clustered with APCLSV isolates in a phylogenetic analysis. APCLSV infection was further confirmed with an APCLSV-specific RT-PCR assay (4), which yielded a product of the expected 205-bp size (GenBank Accession No. JN653070) with closest homology again to the Sus2 APCLSV isolate (83.4 and 94.3% nucleotide and amino acid identity, respectively). To our knowledge, this finding represents the first detection of APCLSV in domestic plums in the Czech Republic, extending our vision of APCLSV diversity and its geographic distribution. For unknown reasons, APCLSV has almost always been reported in mixed infection with ACLSV (1,2,4) and the situation in cv. Babce does not deviate from this trend. This has greatly hindered the analysis of the pathogenicity of APCLSV, a situation further complicated in the current case because the Babce cultivar was also infected by Plum pox virus. References: (1) M. Barone et al. Acta Hortic. 781:53, 2008. (2) T. Candresse et al. Virus and Virus-Like Diseases of Pome and Stone Fruit Trees. A. Hadidi et al., eds. The American Phytopathological Society, St. Paul, MN, 2011. (3) X. Foissac et al. Phytopathology 95:617, 2005. (4) D. Liberti et al. Phytopathology 95:420, 2005.

Leaf discs of Nicotiana benthamiana plants were transformed with Agrobacterium tumefaciens and transgenic plants expressing plum pox potyvirus (PPV) coat protein (CP) were generated. Homozygous R2 progeny from these plants were inoculated with PPV. Plants were scored for the appearance of symptoms and tested for infection by DAS-ELISA. Various levels of resistance were obtained after an initial stage in which PPV was able to multiply in all the transgenic plants. Within 2–3 weeks after inoculation, the transgenic resistant plants fully recovered from virus infection. Conversely, control and susceptible transgenic lines developed severe symptoms and high virus titres. Prunus domestica (plum) was transformed by inoculating hypocotyl slices with A. tumefaciens containing a binary plasmid which included the NPTII, GUS, and PPV CP genes within its T-DNA region. Transgenic shoots were rooted and established in the glasshouse. Analysis of selected transformants by PCR showed that the engineered foreign genes had been integrated, including that for PPV CP. Histological assays on young leaves of these putative transformants gave a positive reaction. This suggests that all genes transferred are expressed in these transformed plums.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; In the present study, phenotypic variability of 80 plum (Prunus domestica L.) varieties maintained in the French National Plum Collection was evaluated with 19 quantitative traits. In addition, genetic diversity and genetic structure was studied in three plum species (P. domestica L., Prunus cerasifera Ehrh. and Prunus spinosa L.) using chloroplast DNA (cpDNA) markers and five single sequence repeat (SSR) loci. Based on phenotypic traits, some varieties, such as mirabelle plums, grouped together. Bayesian structure analysis was used to identify different genetic groups, whereby damson plums were clearly distinguished from greengage plums. When examining the three species together, a higher level of cpDNA allelic richness was found in P. cerasifera and in P. spinosa than in P. domestica where only five cpDNA haplotypes were detected in the national plum collection, with one main haplotype that accounted for 80% of the varieties studied. P. domestica cpDNA haplotypes tended to group together with P. cerasifera haplotypes whereas most of P. spinosa haplotypes formed a separate cluster. SSR markers were somewhat able to distinguish the three species. These results provide some clues as to the origin of plum and the various plum varieties. Our results also provide useful information for the management of plum genetic resources.

International audience

International audience

International audience

International audience; In Prunus spp., resistance genes to root-knot nematodes (RKN), Meloidogyne arenaria, Meloidogyne incognita, Meloidogyne javanica, and Meloidogyne floridensis, confer either a complete spectrum, e.g., the Ma and Rjap genes in Myrobalan and Japanese plums (subgenus Prunophora), respectively, or a more restricted spectrum, e.g., the RMia gene (M. arenaria + M. incognita) in peach (subgenus Amygdalus). We report here characterization data of the RMja gene from the almond Alnem1, another Amygdalus source. The study of its spectrum is hampered by the inability of almond to be propagated by cuttings; we overcame this problem by using F1 and BC1 crosses with previously genotyped Myrobalan plums that conferred their rooting ability to hybrids for simultaneous evaluation to different RKN. As expected from a homozygous dominant resistance, BC1 progenies of Alnem1 segregated for resistance to M. javanica but were uniformly susceptible to M. incognita and M. floridensis, demonstrating that RMja controlled M. javanica but not M. incognita nor M. floridensis. SSR markers covering the Prunus reference map placed RMja on LG7 in the same region as Ma and Rjap and thus showed its independence from the RMia gene (LG2) of the botanically closer peach. The spectrum of this gene allows the theoretical construction of interspecific rootstocks, Myrobalan plum x (almond x peach), which cumulate RMja with Ma and RMia and are protected from each of the predominant RKN affecting Prunus, i.e., M. arenaria, M. incognita, and M. javanica, by at least two genes. This pyramiding strategy should offer to rootstock material an unprecedented guarantee of durable RKN resistance.

International audience

International audience

Plant Genetics and Genomics - Volume 6 (Part IV, chapter 26); International audience

International audience; Cell walls were isolated from flesh and skin of five plum varieties corresponding to three species (Prunus domestica L., Prunus salicina Lindl. and Prunus insititia Lindl.) using the alcohol-insoluble solids (AIS) procedure. Yields varied from 83 to 114 g kg−1 dry weight in the flesh and from 192 to 361 g kg−1 dry weight in the skins. Their main sugars were uronic acid (224–322 mg g−1 AIS), cellulosic glucose (139–170 mg g−1 AIS), galactose and arabinose. Galactose and arabinose ratio were variable between the varieties. The degrees of methylation were high (62–84). The cell walls of the flesh and skin of three of these plums: Golden Japan, Prune Rouge and Reine Claude (two P. salicina and one P. domestica) were extracted using water, chelator (CDTA), dilute alkali, concentrated alkali (4 M NaOH), followed by washing with water. The main fractions were water- and dilute alkali-soluble pectins, with 19–31% and 17–29% yields. The composition of the 4 M NaOH extract was diagnostic of a fucogalactoxyloglucan as the main hemicellulose, representing 3–7% of the plum AIS. Cellulose only accounted for 10–11% of the AIS from flesh and 7–9% of the AIS from skin

International audience

International audience; Originally identified in Bulgaria in 1915, Plum pox virus (PPV) is the most damaging virus of stone fruit trees, including apricot, plum, peach and cherry. PPV steadily spread throughout Europe over the years since its discovery and at the turn of the century (1999-2000) it reached North America (USA and Canada). While many strategies to control the spread of PPV have been undertaken over the decades and many studies have contributed to the characterization of the virus isolates there has been relatively little progress in the development of resistant varieties. With the paucity of natural resistance, transgenic technology, based on the engineering of the virus capsid gene, was investigated as a useful source of resistance. This work identified the C5 plum clone as highly resistant to PPV infection. These findings were supported by detailed molecular studies indicating that post-transcriptional gene silencing (PTGS) is the resistance mechanism with resistance being mediated through the production of small interfering RNA (siRNA). The durability of PPV resistance in C5 (named ‘HoneySweet’) is reflected through more than 10 years of field tests. In total, over 15 years of research with ‘HoneySweet’ have demonstrated that this clone and the resistance mechanism that it represents is: i) an important tool to demonstrate the successful deployment of biotechnology against a quarantine pest; ii) a safe product of biotechnology; and iii) a useful strategy for avoiding the use of pesticides to control natural aphid vectors of PPV. The deregulation of ‘HoneySweet’ in the USA by USDA/APHIS (Federal Register Doc. E7-13649, July 12 2007) and clearance by the U.S. Food and Drug Administration (FDA) corroborate these findings.

International audience

Transgenic C5 cv. Honey Sweet is a clone of Prunus domestica L. transformed with the Plum pox virus coat protein gene (PPV-CP). This transgenic plum displays post-transcriptional gene silencing (PTGS) which makes it highly resistant to PPV infection. To test the effect of heterologous viruses on the efficacy and stability of PTGS against PPV, transgenic C5 trees were graft-inoculated with different combinations of Prunus necrotic ringspot virus (PNRSV), Apple chlorotic leaf spot virus (ACLSV), Prune dwarf virus (PDV) and PPV-D strain. The potential for suppression of the silencing mechanism mediated by these viruses was evaluated. Challenge experiments were performed under greenhouse, nursery and field conditions in Romania and Spain, comprising two different environments, continental and Mediterranean, respectively. Virus infections were evaluated by visual monitoring of symptom and by serological and molecular assays. The engineered resistance to PPV in C5 transgenic plums was stable and was not suppressed by the presence of the challenging heterologous viruses over a three-year experimental period across all trials.

International audience

A cDNA library covering the complete genome of plum pox virus strain D (PPV D) has been obtained, and an endonuclease restriction map derived from it. This map was superposed on the PPV genomic organisation map, established for a nonaphid transmissible strain of PPV (Maiss et al., 1989). This allowed us to select seven probes, corresponding to different regions on the PPV genome. These probes were tested in a dot-blot hybridization assay for the detection of PPV. Probes of various lengths (0.25 to 1.5 kb) were tested and those measuring at least 0.8 kb (4 of the 7 probes selected) proved to be the most sensitive. The detection limit was of about 5 pg of purified virus per assay. Probes representing non-structural viral protein genes were equally sensitive in detecting both serotypes D and M of PPV. The previously described probe pBPPVl (Varveri et al., 1988), covering the coat protein gene of strain D, was less sensitive, when compared to the above probes, in detecting heterologous strains of PPV. The polyvalence of probes transcribed from non-structural viral protein genes was confirmed by screening isolates of PPV, collected in infected orchards in several Mediterranean countries.

International audience; The reaction of a genetically engineered plum clone (C5) resistant to plum pox virus (PPV) by graft inoculation with the virus was evaluated. The resistance in this clone has been demonstrated to be mediated through post-transcriptional gene silencing (PTGS). A single C5 plant out of 30 plants inoculated with PPV M strain by double chip-budding showed mild diffuse mosaic ‘Sharka’ symptom at the bottom section of the scion. The upper leaves of this PPV-infected C5 plant remained symptomless and the virus was not detected in them by either DAS-ELISA or RT-PCR. An RNA silencing associated small interfering RNA duplex, siRNA (21–26 nt), was detected in non-inoculated C5 plants and in the portions of inoculated C5 plant in which PPV could not be detected. In the PPV-infected portion of the C5 plant and in C6 PPV susceptible plants only the ∼21–22 nt siRNAs was detected. Cytosine-methylation was confirmed in C5 plants both uninfected and showing PPV symptoms. The 25–26 nt siRNA normally present in C5 was absent in PPV-infected C5 tissues confirming the critical role of this siRNA in the resistance of clone C5 to PPV infection. We also show that this PPV infection was limited and transient. It was only detected in one plant at one of four post-dormancy sampling dates and did not appear to affect the overall PPV resistance of the C5 clone.

El impacto ambiental de la liberación al campo de ciruelos europeos (Prunus domestica L.) transgénicos portadores del gen de la proteína de la cápsida (CP) de Plum pox virus (PPV) se ha evaluado durante un periodo de ocho años, en una finca experimental de Liria, Valencia, y los resultados obtenidos se revisan y discuten en este trabajo. La variabilidad molecular de poblaciones de PPV que infectan ciruelos transgénicos se comparó con la de poblaciones de PPV que infectan ciruelos no transgénicos, así como el número y las especies de pulgones (vectores de transmisión del virus) y otros artrópodos que visitaron los dos tipos de árboles del campo experimental. Además, se estudió la posibilidad de que en los ciruelos transgénicos emergieran virus recombinantes (entre el ARNm del transgén y el ARN de un virus infectivo) con propiedades biológicas alteradas y potencialmente peligrosas. Para los ensayos se utilizaron cinco líneas transgénicas de ciruelo europeo (la línea C5 ‘HoneySweet’ resistente a PPV y las líneas C4, C6, PT6 y PT23, susceptibles a PPV) y ciruelos europeos y japoneses (P. salicina Lind) no transgénicos. No se detectaron diferencias entre la variabilidad de las poblaciones de PPV presentes en ciruelos transgénicos y no transgénicos ni en el número y especies de pulgones y otros artrópodos que visitaron ciruelos transgénicos y convencionales. Tampoco se detectaron virus recombinantes viables en las plantas transgénicas después de ocho años de exposición de las mismas a la infección natural por PPV. Los datos indican que el cultivo en campo de ciruelos europeos transgénicos en condiciones mediterráneas no supone ningún riesgo ambiental, en términos de los parámetros estudiados, más allá del ocasionado por el cultivo de ciruelos convencionales.

National audience

International audience

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; The molecular variability of Plum pox virus (PPV) populations was compared in transgenic European plums (Prunus domestica L.) carrying the coat protein (CP) gene of PPV and non-transgenic plums in an experimental orchard in Valencia, Spain. A major objective of this study was to detect recombination between PPV CP transgene transcripts and infecting PPV RNA. Additionally, we assessed the number and species of PPV aphid vectors that visited transgenic and non-transgenic plum trees. Test trees consisted of five different P. domestica transgenic lines, i.e. the PPV-resistant C5 'HoneySweet' line and the PPV-susceptible C4, C6, PT6 and PT23 lines, and non-transgenic P. domestica and P. salicina Lind trees. No significant difference in the genetic diversity of PPV populations infecting transgenic and conventional plums was detected, in particular no recombinant between transgene transcripts and incoming viral RNA was found at detectable levels. Also, no significant difference was detected in aphid populations, including viruliferous individuals, that visited transgenic and conventional plums. Our data indicate that PPV-CP transgenic European plums exposed to natural PPV infection over an 8 year period caused limited, if any, risk beyond the cultivation of conventional plums under Mediterranean conditions in terms of the emergence of recombinant PPV and diversity of PPV and aphid populations.

International audience; The prevalence of PPV-M, PPV-D and PPV-Rec strains has been evaluated in 6 European countries (Bulgaria, Czech Republic, France, Serbia, Slovakia and Slovenia). A total of 547 samples have been collected from peach, apricot and plum trees and were characterised directly by PCR-based typing procedures targeting two genomic regions located upstream and downstream the recombination breakpoint located in the Nib gene shared by all PPV-Rec isolates. PPV-M isolates were found predominant in 4 of the 6 countries whereas PPV-Rec was detected in all countries but one. The genetic diversity and structure of PPV-M populations in Europe were evaluated by sequencing 27 isolates coming from 8 countries. The existence of 2 sub-clusters within the PPV-M group has been evidenced. This structure is apparently correlated with the geographical origin of the isolates.

National audience

International audience

International audience

) is the causal agentof the economically important sharka disease of stone fruit trees. To date, sixstrains of PPV have been recognized (PPV-M, -D, -Rec, -EA, -C, and -W),differing by their serological and molecular properties [1], the PPV-M, -D, and-Rec strains being the most common and widespread. The minor EA (El Amar)strain consists of divergent isolates, so far geographically limited to Egypt. TheoriginalElAmarisolatewaspartiallysequencedintheearly1990s[4]andwaslaterused to produce strain-specific monoclonal antibodies [3]. Recently, the completenucleotide sequence of an isolate belonging the EA strain and deriving from theoriginal isolate was reported [2]; (AM157175). We report here the completedfull-length sequence of the original ElAmar isolate kept in the virus collection ofINRA Bordeaux.This new sequence shows 3.8% divergence from theAM157175sequence, providing evidence for a higher variability within the PPV-EA strainthan in other PPV strains.

Diplôme : DES

Cherry virus A (CVA) has been reported to naturally infect sweet and sour cherry, apricot, peach, and plum but has not been associated with any symptoms. In the spring and summer of 2005, samples were collected in Prunus spp. germplasm collections in Campania (Italy) and analyzed by a polyvalent reverse transcription-polymerase chain reaction (RT-PCR) assay (1). Amplicons were sequenced, revealing CVA infection in seven apricot cultivars (Prunus armeniaca L.), one plum (Prunus domestica L.), and one cherry (Prunus avium L.). CVA sequences (GenBank Accession Nos. DQ445275 to DQ445292) compared among themselves and with databank sequences showed pairwise nucleotide sequence identity levels of 80.3 to 99.6% (86.8 to 100% for amino acid sequences), significantly extending the known variability range of CVA. The presence of CVA was confirmed by hybridization with a CVA-specific probe (P39) (2), targeting region different from that amplified in the polymerase chain reaction assay. All samples containing CVA were found to be in mixed infections with Apple chlorotic leaf spot virus (ACLSV) and Apricot pseudo-chlorotic leaf spot virus (plum, apricot), or ACLSV plus Cherry green ring mottle virus (cherry) so that CVA symptomatology could not be evaluated. To our knowledge, these results constitute the first report of the occurrence of CVA in Italy. They confirm the ability of CVA to naturally infect noncherry Prunus spp. hosts with surprisingly high prevalence levels (6 of 14 and 1 of 6 tested apricot and plum cultivars, respectively). References: (1) X. Foissac et al. Phytopathology 95:617, 2005. (2) W. Jelkmann J. Gen. Virol. 76:2015, 1995.

International audience; Characterization of a seemingly new spherical virus isolated from severely affected plum trees in south-western France indicated that its divided genome is composed of two single-stranded, polyadenylated RNAs of approximately 7.4 and 3.7 kb. Its particles are composed of three coat protein subunits of approximately 23, 23.5, and 24.5 kDa. Partial sequencing of the genomic RNAs indicated that this new virus, tentatively named stocky prune virus (StPV), is distantly related to the two sequenced cheraviruses, cherry rasp leaf virus (CRLV) and apple latent spherical virus (ALSV). StPV should be regarded as a new member in the unassigned genus Cheravirus.

International audience

International audience