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ABSTRACT: In Arabidopsis thaliana Columbia (Col-0) plants, the restriction of Tobacco etch virus (TEV) long-distance movement involves at least three dominant RTM (restricted TEV movement) genes named RTM1, RTM2, and RTM3. Previous work has established that, while the RTM-mediated resistance is also effective against other potyviruses, such as Plum pox virus (PPV) and Lettuce mosaic virus (LMV), some isolates of these viruses are able to overcome the RTM mechanism. In order to identify the viral determinant of this RTM-resistance breaking, the biological properties of recombinants between PPV-R, which systemically infects Col-0, and PPV-PSes, restricted by the RTM resistance, were evaluated. Recombinants that contain the PPV-R coat protein (CP) sequence in an RTM-restricted background are able to systemically infect Col-0. The use of recombinants carrying chimeric CP genes indicated that one or more PPV resistance-breaking determinants map to the 5' half of the CP gene. In the case of LMV, sequencing of independent RTM-breaking variants recovered after serial passages of the LMV AF199 isolate on Col-0 plants revealed, in each case, amino acid changes in the CP N-terminal region, close to the DAG motif. Taken together, these findings demonstrate that the potyvirus CP N-terminal region determines the outcome of the interaction with the RTM-mediated resistance.
Molecular Plant-Microbe Interactions 11/2009; 22(10):1302-11. · 4.43 Impact Factor
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ABSTRACT: A complex, polygenic resistance to Plum pox virus (PPV) was previously described in a wild peach-related species, Prunus davidiana clone P1908. In the current study, an analysis of quantitative trait loci (QTL) was performed on an F2 population comprising 99 individuals obtained by selfing the F1 individual #40 of an interspecific cross between susceptible nectarine cv. Summergrand and the resistant P. davidiana clone P1908. Six QTL were identified using both parametric and non-parametric methods of detection, individually explaining 5–28% of the phenotypic variance. The total phenotypic variation explained ranged from 29 to 58%. Alignment of the genetic map of the F2 cross with the P. davidiana parent map showed consistency of QTL over generations, with three of the six QTL co-localizing at the 1-LOD interval and another one at the 2-LOD interval. Two of the QTL were mapped onto linkage group one, where resistance to PPV was previously mapped in apricot. Development and mapping of new microsatellite markers linked to candidate genes revealed a striking co-localization of three of the detected QTL with gene copies coding for eukaryotic translation initiation factors eIF4E and eIF(iso)4G. As co-localization of one QTL with candidate gene eIF(iso)4E was previously reported in the F1 population, the results reported here strongly reinforce the idea that components of the eukaryotic translation initiation complex are correlated with resistance to PPV in P. davidiana P1908.
Plant Pathology 01/2009; 58(3):425 - 435. · 2.13 Impact Factor
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ABSTRACT: Plum pox virus (PPV) is a potyvirus that causes sharka disease in infested stone fruit trees (Prunus species, peach, apricot, plum). In apricots, the resistance is controlled by a major quantitative trait locus that explains
up to 70% of the phenotypic variance; it is localised in the upper part of linkage group 1. In this report, we transformed
candidate genes that mapped in the region of the apricot resistance locus into polymerase chain reaction markers (SSCP and
SSR) and tested for their co-localisation with the major PPV resistance locus in related and unrelated populations. Three
populations of F1 and F2 individuals issued from crosses between the PPV-resistant cultivar ‘Stark Early Orange’ or ‘Goldrich’
and three susceptible parents were used in this study. Molecular-marker data were collected to determine the linkage relationship
between the PPV resistance locus in apricots and markers that target candidate disease-resistance genes. In addition, SSR
markers linked to resistance-gene candidates were mapped to positions flanking the PPV resistance locus in different apricot
populations. Therefore, we demonstrate that this strategy helps to saturate the major genomic region controlling resistance
to PPV in apricot with valuable co-dominant markers.
Tree Genetics & Genomes 01/2008; 4(2):359-365. · 2.34 Impact Factor
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ABSTRACT: Plum pox virus (PPV) belongs to the genus Potyvirus that contains the largest number of virus species infecting plants. Its virus genome has been extensively characterised and sequenced. However, few data are available on its interactions with woody host plants. We therefore focused, in the past 4 years, both on the cellular and molecular aspects of the compatible and incompatible Prunus/PPV interactions. GFP (Green fluorescent protein)-tagged PPV and in situ hybridisation were used to compare the localization of viral particles in stems and leaves of susceptible and resistant apricot cultivars. In parallel, molecular tools were developed through the cloning and characterization of polymorphic, homologous resistance genes and of candidate genes involved in the expression of Prunus/PPV interactions. Candidate genes are currently used to target genomic regions involved in resistance or susceptibility and to identify molecular markers indispensable for further marker assisted selection for resistance to sharka disease.
Bulletin OEPP/EPPO Bulletin 11/2006; 36(2):346 - 349.
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ABSTRACT: 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 PPV-PS 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.
Molecular Plant-Microbe Interactions 06/2006; 19(5):541-9. · 4.43 Impact Factor
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ABSTRACT: The Sharka disease caused by the potyvirus Plum pox virus (PPV) is one of the most serious viral diseases affecting stone fruit trees. The study of PPV/Prunus interaction under greenhouse controlled conditions is space, time, labor consuming. While the PPV/Prunus interactions are now quite well known at the whole plant level, few data however are available on the interactions between the virus and the Prunus host plants at the cellular level. Using a green fluorescent protein (GFP)-tagged M type PPV strain, combined to an in vitro inoculation procedure, we developed a novel tool to track PPV invasion in Prunus persica (peach) cv. GF305 and Prunus armeniaca (apricot) cv. Screara susceptible hosts. Different graft combinations were performed using in vitro-maintained healthy or GFP-tagged PPV infected 'GF305' and 'Screara'. Contact for 30 days in grafts between the inoculum and the genotype to be tested were found sufficient to allow the systemic spread of the recombinant virus: fluorescence from GFP-tagged PPV could easily be detected in the entire plant under a binocular microscope allowing quick and reliable sorting of infected plants. Using a fluorescence stereomicroscopy or confocal microscopy, GFP could also be observed in stem cross-sections especially in epidermis and pith cells. In vitro grafting inoculation with GFP-tagged PPV provides a new and powerful tool to facilitate mid-term virus maintenance. Moreover, this tool will be of special importance in the study of PPV infection dynamics in Prunus, allowing as well precise observations of cellular events related to PPV/Prunus interactions.
Journal of Virological Methods 12/2005; 129(2):125-33. · 2.01 Impact Factor
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ABSTRACT: The genetically anchored physical map of peach is a valuable tool for identifying loci controlling economically important traits in Prunus. Breeding for disease resistance is a key component of most breeding programs. The identification of loci for pathogen resistance in peach provides information about resistance loci, the organization of resistance genes throughout the genome, and permits comparison of resistance regions among other genomes in the Rosaceae. This information will facilitate the breeding of resistant species of Prunus. A candidate gene approach was implemented for locating resistance loci in the genome of peach. Candidate genes representing NBS-LRR, kinase, transmembrane domain classes, as well as, pathogen response (PR) proteins and resistance-associated transcription factors were hybridized to a peach BAC library and mapped by using the peach physical map database and the Genome Database for Rosaceae (GDR). A resistance map for Prunus was generated and currently contains 42 map locations for putative resistance regions distributed among 7 of the 8 linkage groups.
Theoretical and Applied Genetics 12/2005; 111(8):1504-13. · 3.30 Impact Factor
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ABSTRACT: Plum pox virus (PPV), the causative agent of sharka disease in Prunoideae, is one of the most serious problems affecting stone fruit production in Europe and America. Resistance to PPV was previously described in a Prunus davidiana clone, P1908, and introduced into peach (Prunus persica) genotypes. Genetic resistance to PPV displays a complex pattern of quantitative inheritance. An analysis of quantitative trait loci (QTLs) for resistance was performed on an F1 interspecific peach population obtained from a cross between the susceptible nectarine cultivar Summergrand and P. davidiana. The hybrids were graft-inoculated with PPV in duplicate following a classical procedure. The incidence of infection was evaluated four times, over two vegetative cycles, by symptom observation and enzyme-linked immunoadsorbent assays (ELISA). Restriction of systemic downward movement of the PPV virus was also evaluated by testing the susceptible rootstocks. Using both analysis of variance and non-parametric tests, six genomic regions involved in PPV resistance were detected. Depending on the scoring data considered, between 22 and 51% of the phenotypic variance could be explained by the quantitative model. One QTL, located in the distal region of linkage group 1, maps in a genomic region that is syntenic to the location of a resistance gene previously identified in the apricot cv. Goldrich. Some QTLs appeared to be temporally specific, reflecting the environmental dependence of PPV-resistance scoring. Candidate gene fragments were amplified by PCR, isolated and mapped on the peach interspecific linkage map. We report here the co-localization of three analogues of virus resistance genes with two distinct genomic regions linked to PPV resistance in P. davidiana.
Molecular and General Genetics 03/2005; 272(6):680-9. · 2.63 Impact Factor
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ABSTRACT: We developed primers for the amplification of 24 polymorphic nuclear microsatellites in apricot (Prunus armeniaca L.). Thirteen loci originated from three genomic libraries enriched for TC, TG and AAG motifs. Eight loci were developed from three fruit EST (Expressed-Sequence-Tag) libraries and three from a leaf cDNA microsatellite-enriched library. There were up to nine alleles per polymorphic locus in 12 different cultivars. No difference in allele numbers were shown between cDNA and genomic-source loci. Mean expected heterozygosity was 0.65 (range: 0.15–0.87). Mendelian segregation was confirmed for all loci. These markers should be helpful for diversity studies, genome mapping and cultivar identification in apricot and related species.
Molecular Ecology Notes 10/2004; 4(4):742 - 745. · 2.38 Impact Factor
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ABSTRACT: In a previous study, cDNA microsatellite markers were described in apricot (Prunus armeniaca L.). Specific PCR primers were designed to amplify the microsatellite-containing regions from genomic DNA in different Prunus species. In the present work, cDNA microsatellite markers were developed in the hexaploid Prunus domestica L. species and polymorphism was ascertained in a segregating plum population. Co-dominant mendelian segregation of alleles was demonstrated and microsatellite polymorphism displayed up to 6 alleles per SSR locus per individual. Parentage lineage of three full-sib European plum cultivars (cv. Cacanska najbolja, Cacanska rana and Cacanska lepotica) was reconstructed by the analysis of the above nuclear SSR markers, completed by four chloroplastic microsatellite loci. The six most informative nuclear loci enabled discrimination between the three Cacak cultivars and unrelated individuals as well as the previously proposed parents, Wangenheim and Pozegaca. Data obtained support previous evidence that these cultivars originated from the Stanley cultivar. However, SSR analysis finally excluded Wangenheim as the other possible parent. Based on the results obtained with nuclear and chloroplast SSR loci, we propose the origin of those three Cacak cultivars in a cross between Stanley as the mother plant and Ruth gerstetter as the pollinator. Furthermore, we demonstrate the utility of these apricot SSR markers for genotype fingerprinting of the hexaploid plum cultivars.
Molecular Breeding 01/2004; 13(2):135-142. · 2.85 Impact Factor
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ABSTRACT: EST microsatellite markers were developed in apricot (Prunus armeniaca L.) and grape (Vitis vinifera L.). cDNA libraries from either apricot leaves or grape roots were used in an enrichment procedure for GA and CA repeats. The transferability of EST simple sequence repeat (SSR) markers from apricot and grapevine to other related and unrelated species was examined. Overall, grape primers amplified products in most of the Vitaceae accessions while the apricot primers amplified polymorphic alleles only in closely related species of the Rosaceae. In this taxonomic family, ten EST SSR loci were tested, and one single primer pair, PacB22, was amplified across species and sections in the Prunoideae and Maloideae. Sequencing of EST SSR loci in other species and genera confirmed a higher level of conservation in the microsatellite motif and flanking regions in the Vitaceae compared to the Rosaceae. Two distinct fragments of the PacB22 locus amplified across the Malus and Pyrus genera; however, while the coding region was highly conserved, the microsatellite repeat motif was no longer present. The banding pattern was explained by base substitution and insertion/deletion events in the intronic region of PacB22. This study includes the determination of the degree of polymorphism detected among species and genera in two unrelated taxonomic families and the evaluation of the information provided by the microsatellite repeats and the flanking regions.
Theoretical and Applied Genetics 04/2003; 106(5):912-22. · 3.30 Impact Factor
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ABSTRACT: Transgenic Eucalyptus camaldulensis containing both the insecticidal cry3A gene and the bar gene (conferring tolerance to the herbicide glufosinate ammonium) have been produced by Agrobacterium tumefaciens-mediated transformation of seedling explants. Transgenic plants from two lines tested were resistant to first instars of chrysomelid beetles that are important pests of commercial Australian eucalypt plantations. Both lines also exhibit tolerance to the broad-spectrum herbicide Liberty at 6l/ha (1.2kg active ingredient per hectare), twice the field application rate. Transgenic insect- and herbicide-resistant eucalypts like these are likely to provide better insect and weed control options in plantations, particularly during the vulnerable establishment phase, provided that any adverse ecological impacts of releasing transgenic trees into the environment can be assessed and minimized.
Molecular Breeding 05/2000; 6(3):307-315. · 2.85 Impact Factor
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ABSTRACT: MADS-box genes in plants are a diverse class of transcription factors that are involved in regulating developmental processes, particularly meristem and organ identity during floral development. They are characterized by a highly conserved MADS-box domain of 59 amino acids that binds to specific DNA sequences. We report the characterization of a cDNA clone, ETL (Eucalyptus TM3 Like), from Eucalyptus globulus subspecies bicostata encoding a putative transcription factor of the MADS-box class that is strongly expressed in both vegetative and floral tissues, suggesting that it regulates processes other than floral development. The clone was isolated from a floral bud cDNA library with a probe generated from Eucalyptus genomic DNA by PCR using degenerate primers to the MADS-box of the floral regulatory gene APETALA 1. The ETL cDNA clone encodes a putative protein of 206 amino acids that contains an N-terminal MADS-box and a helical domain of approx. 60 amino acids predicted to form a coiled-coil (K-box). These structural features are characteristic of plant MADS-box proteins. The MADS-box domain contains all the signature residues of a class of MADS-box genes typified by the tomato gene TM3 and overall, ETL shows 56% amino acid identity to TM3. Like TM3, the ETL gene is expressed in both vegetative and reproductive organs, predominantly in root and shoot meristems and organ primordia, as well as in developing male and female floral organs.
Gene 04/1999; 228(1-2):155-60. · 2.34 Impact Factor
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ABSTRACT: Two genes cloned from Eucalyptus globulus, Eucalyptus LeaFy (ELF1 and ELF2), have sequence homology to the floral meristem identity genes LEAFY from Arabidopsis and FLORICAULA from Antirrhinum. ELF1 is expressed in the developing eucalypt floral organs in a pattern similar to LEAFY while ELF2 appears to be a pseudo gene. ELF1 is expressed strongly in the early floral primordium and then successively in the primordia of sepals, petals, stamens and carpels. It is also expressed in the leaf primordia and young leaves and adult and juvenile trees. The ELF1 promoter coupled to a GUS reporter gene directs expression in transgenic Arabidopsis in a temporal and tissue-specific pattern similar to an equivalent Arabidopsis LEAFY promoter construct. Strong expression is seen in young flower buds and then later in sepals and petals. No expression was seen in rosette leaves or roots of flowering plants or in any non-flowering plants grown under long days. Furthermore, ectopic expression of the ELF1 gene in transgenic Arabidopsis causes the premature conversion of shoots into flowers, as does an equivalent 35S-LFY construct. These data suggest that ELF1 plays a similar role to LFY in flower development and that the basic mechanisms involved in flower initiation and development in Eucalyptus are similar to those in Arabidopsis.
Plant Molecular Biology 09/1998; 37(6):897-910. · 4.15 Impact Factor
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ABSTRACT: We report the first case of plastid chimera within the Actinidia genus, where plastid inheritance was believed to be paternal. The heterogeneity of chloroplast DNA observed in the hexaploid Actinidia deliciosa cultivar D uno involves the presence or absence of a particular MspI restriction site in the region between the psbC gene and the tRNA-Ser(UGA) gene. The heterogeneity was first observed using restriction fragment length polymorphism and then confirmed through cloning and sequencing. The analysis of the cloned fragments revealed the presence of two haplotypes: the most frequent type was found in 123 (88.5%) out of a total of 139 colonies screened. Partial sequences of the psbC-trnS fragment from both haplotypes revealed that the polymorphism occurs within the coding region of the psbC gene and consists of a synonymous transition. A contamination-free cross involving D uno as the male parent produced only plants characterized by the most frequent haplotype, indicating either selection bias against the rare type or more likely fixation of the frequent type in tissues leading to the formation of the male gametes. The MspI restriction profiles performed on various tissues suggest that the rarer type is absent from the histogenic layer LII and that D uno is a periclinal plastid chimera.
Journal of Heredity 93(4):293-300. · 2.80 Impact Factor
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ABSTRACT: In compatible interactions between plants and viruses that result in systemic infection, symptom development is a major phenotypic trait. However, host determinants governing this trait are mostly unknown, and the mechanisms underlying it are still poorly understood. In a previous study on the Arabidopsis thaliana¿Plum pox virus (PPV) pathosystem, we showed a large degree of variation in symptom development among susceptible accessions. In particular, Cvi-1 (Cape Verde islands) accumulates viral particules but remains symptomless, Col-0 (Columbia) sometimes shows weak symptoms compared with Ler (Landsberg erecta), which always shows severe symptoms. Genetic analyses of Col × Ler and Cvi × Ler F2 and recombinant inbred line (RIL) populations suggested that symptom development as well as viral accumulation traits are polygenic and quantitative. Three of the symptom quantitative trait loci (QTL) identified could be confirmed in near-isogenic lines, including PSI1 (PPV symptom induction 1), which was identified on the distal part of chromosome 1 in both RIL populations. With respect to viral accumulation, several factors have been detected and, interestingly, in the Col × Ler population, two out of three viral accumulation QTL colocalized with loci controlling symptom development, although correlation analysis showed weak linearity between symptom severity and virus accumulation. In addition, in the Cvi × Ler RIL population, a digenic recessive determinant controlling PPV infection was identified
Molecular Plant-Microbe Interactions 21 (2008) 2.
