H. Lecoq

French National Institute for Agricultural Research, Lutetia Parisorum, Île-de-France, France

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Publications (91)155.38 Total impact

  • G Romay · H Lecoq · C Desbiez
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    ABSTRACT: Begomoviruses represent one of the most damaging virus groups on many important crops worldwide. In Venezuela, the begomovirus Melon chlorotic mosaic virus (MeCMV) is the major constraint for melon and watermelon production. MeCMV has been associated with the satellite Melon chlorotic mosaic alphasatellite (MeCMA). Full-length genome sequencing of 20 and 35 isolates of MeCMV and MeCMA, respectively, were carried out to estimate their genetic variability. Furthermore, mechanical transmission assays of MeCMV alone or in conjunction with MeCMA were performed. Genetic variation was low among MeCMV isolates which exhibited 97 to 100% nucleotide identity for the DNA-A component and 95 to 100% for the DNA-B component. Alphasatellite isolates were highly variable ranging from 86.5 to 100%. MeCMV isolates were phylogenetically related to begomoviruses belonging to the Squash leaf curl virus (SLCV) clade, while MeCMA isolates were clustered in two subgroups related to alphasatellites from the New World (Cuba and Brazil). MeCMV has a host range restricted to cucurbit species and two experimental hosts: Nicotiana benthamiana and Nicotiana clevelandii. MeCMV can be mechanically transmitted with up to 100% efficiency in melon. The physiological stage of the inoculated organ (cotyledon or leaf) represents a key factor for inoculation efficiency. This result provides a simple and reliable inoculation method to develop extensive screening for MeCMV resistance sources. In addition, the complex MeCMV+MeCMA was mechanically transmitted to melon, N. benthamiana and N. clevelandii plantlets and successfully back-transmitted. To our knowledge, this finding is the first evidence of sap transmission for a begomovirus-satellite complex.This article is protected by copyright. All rights reserved.
    No preview · Article · Dec 2014 · Plant Pathology
  • Gustavo Romay · H. Lecoq · C. Desbiez
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    ABSTRACT: Cucurbit crops are cultivated throughout the world. Melon (Cucumis melo L.), cucumber (Cucumis sativus L.), watermelon (Citrullus lanatus (Thumb.) Mat. et Nak.), squash and pumpkin (Cucurbita spp) are the major crops. In Latin America and the Caribbean islands (LAC) cucurbits are consumed as a part of the daily diet since pre-Columbian times, when some species such as Cucurbita pepo L., Cucurbita moschata Duch. and Cucurbita maxima Duch. were domesticated by American Indians. In LAC, cucurbit crops have become export commodities and a source of income for several countries, in addition to their role in local consumption. The increase of area devoted to cucurbit crops and the intensification of production has led to the emergence of severe viral epidemics that threaten the sustainability of these cultures. This paper reviews the cucurbit viruses described in the region and their impact. In addition, the potential of different measures to control the most frequent cucurbit viruses in LAC is discussed.
    No preview · Article · Jul 2014 · JOURNAL OF PLANT PATHOLOGY
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    ABSTRACT: In Venezuela, cucurbit viruses have been associated with important yield losses. Therefore, an extensive survey was conducted to determine the major cucurbit viruses in this country. Leaf samples from 284 cucurbit plants exhibiting virus-like symptoms were collected mainly in 2009–2010 from several states of Venezuela. They were assessed for viral infection by polymerase chain reaction (PCR) for Melon chlorotic mosaic virus (MeCMV) and reverse transcriptase (RT)-PCR for Papaya ringspot virus (PRSV), Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Cucumber mosaic virus (CMV), Squash mosaic virus (SqMV) and Cucurbit aphid-borne yellows virus (CABYV). The most common virus in cucurbit fields, MeCMV, was present in 65·8% of samples. Its associated alphasatellite was found in 78% of samples positive for MeCMV. PRSV, ZYMV and WMV were found with different prevalence: 34·2, 32·4 and 1·1% respectively. CMV was also detected (6·7%) but SqMV and CABYV were not found. Single infections were more frequent than mixed infections (56·4 and 38·6%, respectively). For ZYMV, comparison and phylogenetic analyses of either polymerase and coat protein (NIb-CP) partial sequences or CP complete sequences revealed a low genetic diversity within Venezuelan isolates. Thirty-four ZYMV isolates were used for serological and biological analysis. Thirteen monoclonal antibodies showed a major group of isolates spread in several states and two groups located in Zulia only. Venezuelan ZYMV isolates showed biological variability on cucurbit cultivars susceptible, tolerant or resistant to ZYMV. Resistance to ZYMV in cucumber appears potentially durable, whereas resistance or tolerance in zucchini and melon may be easily overcome.
    Full-text · Article · Feb 2014 · Plant Pathology
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    ABSTRACT: Zucchini yellow mosaic virus (ZYMV, genus Potyvirus) causes important crop losses in cucurbits worldwide. In France, ZYMV epidemics are sporadic but occasionally very severe. This contrasts with Watermelon mosaic virus (WMV, genus Potyvirus) which causes regular and early epidemics. Factors influencing ZYMV epidemiology are still poorly understood. In order to gain new insights on the ecology and epidemiology of this virus, a 5-year multilocation trial was conducted in which ZYMV spread and populations were studied in each of the 20 plot/year combinations and compared with WMV. Search for ZYMV alternative hosts was conducted by testing weeds growing naturally around one plot and also by checking ZYMV natural infections in selected ornamental species. Although similar ZYMV populations were observed occasionally in the same plot in two successive years suggesting the occurrence of overwintering hosts nearby, only two Lamium amplexicaule plants were found to be infected by ZYMV of 3459 weed samples that were tested. The scarcity of ZYMV reservoirs contrasts with the frequent detection of WMV in the same samples. Since ZYMV and WMV have many aphid vectors in common and are transmitted with similar efficiencies, the differences observed in ZYMV and WMV reservoir abundances could be a major explanatory factor for the differences observed in the typology of ZYMV and WMV epidemics in France. Other potential ZYMV alternative hosts have been identified in ornamental species including begonia. Although possible in a few cases, exchanges of populations between different plots located from 500m to 4km apart seem uncommon. Therefore, the potential dissemination range of ZYMV by its aphid vectors seems to be rather limited in a fragmented landscape.
    No preview · Article · Jan 2014 · Virus Research
  • G Romay · H Lecoq · C Desbiez
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    ABSTRACT: In recent years, three new potyviruses have been described in the papaya ringspot virus (PRSV) cluster. In addition, two types of PRSV are recognized, type W, infecting cucurbit plants, and type P, infecting papaya and also cucurbits. A third type, PRSV-T, was also partially described in Guadeloupe. Complete genome sequencing of four PRSV-T isolates showed that this virus is a related virus that is distinct from PRSV, and the name zucchini tigré mosaic virus (ZTMV) is proposed, in reference to the typical symptoms observed in zucchini squash. Eleven other viral isolates from different geographic origins were confirmed as ZTMV isolates using the complete sequence of the cylindrical inclusion (CI) coding region, whereas pairwise sequence similarities in the coat protein (CP) coding region did not unambiguously distinguish ZTMV isolates from PRSV isolates. The use of the CI coding region for species demarcation appears more suitable than the CP coding region for closely related viruses. Principal coordinates analysis based on the biological behavior of the viral isolates studied clustered PRSV-P, PRSV-W and ZTMV isolates into three different groups. Therefore, ZTMV is different from PRSV in its molecular and biological properties.
    No preview · Article · Aug 2013 · Archives of Virology
  • C Desbiez · C Chandeysson · H Lecoq · B Moury
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    ABSTRACT: The availability of an infectious cDNA clone is a prerequisite for genetic studies on RNA viruses. However, despite important improvement in molecular biology techniques during the last decades, obtaining such clones often remains tedious, time-consuming and rather unpredictable. In the case of potyviruses, cDNA clones are frequently unstable due to the toxicity of some viral proteins for bacteria. The problem can be overcome by inserting introns into the viral sequence but this requires additional steps in the cloning process and depends on the availability of suitable restriction sites in the viral sequence or adjunction of such sites by mutagenesis. Homologous recombination in yeast rather than in vitro restriction and ligation can be used to build infectious clones or other viral constructs. This paper describes how, by using recombination in yeast and fusion PCR, infectious intron-containing clones were obtained within a few weeks for two strains of watermelon mosaic virus (WMV, Potyvirus), whereas previous attempts using "classical" cloning techniques had failed repeatedly. Using the same approach, intronless infectious clones of two other potyviruses, zucchini yellow mosaic virus (ZYMV) and papaya ringspot virus (PRSV), were obtained in less than two weeks.
    No preview · Article · Apr 2012 · Journal of virological methods
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    ABSTRACT: Watermelon mosaic virus (WMV, genus Potyvirus, family Potyviridae) was reported for the first time in France in 1974, and it is now the most prevalent virus in cucurbit crops. In 2000, new strains referred as 'emerging' (EM) strains were detected in South-eastern France. EM strains are generally more severe and phylogenetically distinct from those previously reported in this country and referred as 'classic' (CL) strains. Since 2000, EM strains have been progressively replacing CL strains in several areas where they co-exist. In order to explain this rapid shift in virus populations, the biological properties of a set of 17 CL and EM WMV isolates were compared. No major differences were observed when comparing a limited host range including 48 different plant species or cultivars. Only two species were differential; Chenopodium quinoa was systemically infected by CL and not by EM isolates whereas Ranunculus sardous was systemically infected by EM and not by CL isolates. A considerable variability was observed in aphid transmission efficiencies but this could not be correlated to the CL or EM types. Two subsets of five isolates of each group were used to compare aphid transmission efficiencies from single and double (CL-EM) infections using six different cucurbit and non-cucurbit hosts. EM isolates were generally better transmitted from mixed CL-EM infections than CL isolates and CL transmission rates were significantly lower from double than from single infections. Cross-protection was only partial between CL and EM strains leading to frequent double infections, and only a slight asymmetry was observed in cross-protection efficiencies. Since double infections occur very commonly in fields, the preferential transmission of EM from mixed CL-EM infections could be one of the factors leading to the displacement of CL isolates by EM isolates.
    No preview · Article · May 2011 · Virus Research
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    ABSTRACT: Since their introduction in south-eastern France around 1999, new, 'emerging' (EM) strains of watermelon mosaic virus (WMV) coexist with the 'classic' (CL) strains present for more than 40 years. This situation constitutes a unique opportunity to estimate the frequency of recombinants appearing in the few years following introduction of new strains of a plant RNA virus. Molecular analyses performed on more than 1000 isolates from epidemiological surveys (2004-2008) and from experimental plots (2009-2010), and targeting only recombinants that became predominant in at least one plant, revealed at least seven independent CL/EM or EM/EM recombination events. The frequency of recombinants involving at least one EM parent in the natural populations tested was on the order of 1 %. No new recombinant was detected for more than 1 year, and none but one in more than one location. In tests comparing host range and aphid transmissibility, the new recombinants did not display a better fitness than their 'parental' isolates. No recombinant was detected from artificial mixed infections of CL and EM isolates of various hosts after testing more than 1500 subcultures obtained after single-aphid transmission. These results constitute one of the first estimations of the frequency of recombinants in natural conditions for a plant RNA virus. This suggests that although viable recombinants of WMV are not rare, and although recombination may potentially lead to new highly damaging strains, the new recombinants observed so far had a lower fitness than the parental strains and did not emerge durably in the populations.
    Preview · Article · Apr 2011 · Journal of General Virology
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    C Desbiez · B Moury · H Lecoq
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    ABSTRACT: All viruses are obligatory parasites that must develop tight interactions with their hosts to complete their infectious cycle. Viruses infecting plants share many structural and functional similarities with those infecting other organisms, particularly animals and fungi. Quantitative data regarding their evolutionary mechanisms--generation of variability by mutation and recombination, changes in populations by selection and genetic drift have been obtained only recently, and appear rather similar to those measured for animal viruses.This review presents an update of our knowledge of the phylogenetic and evolutionary characteristics of plant viruses and their relation to their plant hosts, in comparison with viruses infecting other organisms.
    Preview · Article · Mar 2011 · Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases
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    ABSTRACT: We present here the first comprehensive genetic characterization of melon landraces from the humid tropics of southern India. The genetic diversity among 50 melon landraces collected from 3 agro-ecological regions of southern India (6 agro-ecological sub-regions) was assessed by variation at 17 SSR loci, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance, biochemical composition (ascorbic acid, carotenoids, titrable acidity) and mineral content (P, K, Fe, Zn). Differences among accessions were observed in plant and fruit traits. Melon germplasm with high titrable acidity, higher than average amounts of mineral content and resistance to Cucumber mosaic virus, Zucchini yellow mosaic virus, powdery mildew (races 1, 2, 3, 5), Fusarium wilt (races 1, 2), Aphis gossypii and leafminer was recorded in the collection. A high level of genetic variability in melon germplasm was suggested by the SSR analysis. Comparative analysis using SSRs of the genetic variability between Indian melons from north, south, and east regions and reference accessions of melon from Spain, France, Japan, Korea, Iraq, Zambia showed regional differentiation between Indian melon accessions and that Indian germplasm was weakly related to the melon accessions from other parts of the world, suggesting that an important portion of the genetic variability found within this melon collection has not been used yet for the development of new cultivars. Additional collections of acidulus melon germplasm should be made in southern India and adequate management of this important genetic resource is clearly a necessity. Keywords Cucumis melo –Fungi–Genetic variation–Insect–Landraces–Microsatellite–Resistance–Taxonomic relationships–Virus
    No preview · Article · Feb 2011 · Genetic Resources and Crop Evolution

  • No preview · Article · Nov 2010 · Plant Disease
  • B Joannon · C Lavigne · H Lecoq · C Desbiez
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    ABSTRACT: Since 1999, "emerging" (EM) strains of Watermelon mosaic virus (WMV) have been detected in cucurbit crops of southeastern France, probably as a result of recent introductions. Population genetic approaches were used to study the structure of EM isolates in southeastern France and to identify factors involved in their spatial distribution. A population clustering method (SAMOVA) and a maximum-difference algorithm (Monmonier's algorithm) were combined to visualize and quantify barriers to gene flow between populations. Both methods yielded similar results and two main barriers were identified. A North/South oriented barrier may be related to physical obstacles to gene flow (Rhône River, presence of an area with few cucurbit crops). Although the barrier was very strong, some "crossing" events were detected. A second barrier, oriented Northwest to Southeast, was not correlated with obvious geographical features. The two methods used here are complementary and confirm the limited spread of WMV-EM isolates. This approach can be useful in epidemiology studies to characterize the structure of viral populations and identify barriers to gene flow.
    No preview · Article · Sep 2010 · Phytopathology
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    Cecile Desbiez · M Girard · H Lecoq
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    ABSTRACT: A natural mild isolate of Zucchini yellow mosaic virus was found to contain a mutation in the helper component (HC-Pro) within a conserved motif, "CDNQLD", located 12 residues downstream from the "FRNK" motif involved in symptom severity. Introducing the mutation in an infectious cDNA clone of ZYMV resulted in an almost complete absence of symptoms, although viral accumulation was only partially reduced. The FRNK(X)(12)CDNQLD sequence might be part of a larger motif that is conserved in potyviruses and plays a role in symptomatology and/or silencing inhibition.
    Preview · Article · Mar 2010 · Archives of Virology

  • No preview · Article · Dec 2009 · Plant Disease
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    ABSTRACT: Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV) are two criniviruses that are emerging worldwide, and induce similar yellowing diseases in tomato crops. While TICV is transmitted only by Trialeurodes vaporariorum, ToCV is transmitted by three whitefly species in two genera Trialeurodes vaporariorum, T. abutilonea and Bemisia tabaci. The efficiency of transmission by T. vaporariorum from plants infected by one virus or by both was compared, and the probability of virus transmission by a single whitefly was derived from group testing experiments. The estimated transmission probabilities ranged from 0·01 to 0·13, and were not significantly different between ToCV and TICV, or between single and mixed infections. Experiments using B. tabaci as a vector and source plants infected by TICV and ToCV did not reveal any functional trans-complementation for transmission of TICV by ToCV, suggesting that if this phenomenon occurs in nature, it is at a very low frequency. Possible reasons why TICV did not establish in southern France while ToCV is now endemic are discussed.
    Full-text · Article · Mar 2009 · Plant Pathology
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    ABSTRACT: Severe symptoms caused by Watermelon mosaic virus (WMV) in zucchini squash leaves and fruits have been observed since 1999 in South-eastern (SE) France. Their appearance correlates with the introduction of new, "emerging" (EM) isolates distant at the molecular level from the "classic" (CL) isolates present for more than 30 years. To understand the origin and spread of EM isolates, a survey was performed between 2004 and 2007. WMV isolates collected were characterized by sequencing part of the polymerase and coat protein coding regions. This revealed the presence of EM isolates in SE France only, whereas CL isolates were widespread throughout the country. Besides, four subgroups of EM isolates were observed in SE France, suggesting multiple introductions. Recombinants between CL and EM groups, which probably arose locally, were observed during the survey. A strong geographic structure that remained stable during the 4 years was observed between different EM isolates. Our results showed that EM isolates did not spread over long distances, but rapidly replaced the pre-existing CL isolates in all sites where both groups occurred.
    No preview · Article · Feb 2009 · Virus Research
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    ABSTRACT: Cucurbit viruses are involved in complex and changing pathosystems in France, with new virus strains or species regularly reported. Zucchini yellow mosaic virus (ZYMV) is an archetypal emerging virus that was reported in France in 1979. It has since caused sporadic but occasionally very severe economic losses and its epidemiology still remains poorly understood. Partial sequencing of the viral genome has been used to characterize ZYMV isolates that occurred over a 29-year period in experimental plots at Montfavet, France (n=227), or that were received through a national survey for cucurbit viruses conducted in France from 2004 to 2007 (n=198). A total of 34 haplotypes were differentiated belonging to five molecular groups, three including isolates already described in France and two corresponding to isolates that emerged in France within the last 5 years. Comparison of haplotypes found at one location during successive years revealed contrasting situations. When they were either the same or closely related haplotypes, this suggested the availability of overwintering hosts, whereas when they belonged to different molecular groups this indicated shifts in viral populations with possible new introductions. The contribution of molecular epidemiology in tracing the origin of ZYMV in the French West Indies is also reviewed.
    No preview · Article · Feb 2009 · Virus Research
  • H. Lecoq · C. Desbiez

    No preview · Article · Dec 2008
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    ABSTRACT: A study was conducted to better understand the population structure of Zucchini yellow mosaic virus (ZYMV), a severe virus affecting cucurbit crops worldwide, in Tunisia and to estimate whether the use of resistant cultivars may provide durable control. Analysis of the polymerase and coat protein (NIb-CP) partial sequences of 83 isolates collected in the three main cucurbit-growing areas in Tunisia showed that ZYMV grouped into two distinct clusters within ZYMV molecular group A. An important variability was observed in the MREK motif of the P3 protein, a motif associated with tolerance breaking in ZYMV-tolerant zucchini squash cultivars. Interestingly, significant differences were found in the distribution of the MREK variants in the two clusters defined by the partial NIb-CP sequences, MREK and MKEK sequences being more common in cluster 1 and cluster 2, respectively. When combining NIb-CP and P3 sequence information, ZYMV molecular variability was shown to be significantly higher in the Cap Bon region than in the Bizerte area. An important biological variability was observed in a subset of 23 isolates regarding symptomatology in susceptible or resistant cucurbits. Some isolates overcame ZYMV tolerance or resistance in zucchini squash and melon, but not in cucumber. Three serotypes were differentiated using a set of 13 monoclonal antibodies (MAbs). Seven parameters characterizing the 23 isolates, including molecular, serological and biological properties, were used for a multiple component analysis (MCA). This analysis revealed that symptom intensity of a given isolate was similar in different susceptible cucurbit hosts, suggesting similar degrees of aggressiveness in different hosts.
    Full-text · Article · Aug 2008 · Plant Pathology
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    Preview · Article · Jul 2008 · Plant Pathology

Publication Stats

2k Citations
155.38 Total Impact Points

Institutions

  • 1992-2009
    • French National Institute for Agricultural Research
      • Pathologie Végétale
      Lutetia Parisorum, Île-de-France, France
    • University of California, Davis
      • Department of Plant Pathology
      Davis, California, United States