Papers by Gregory Dechamp-guillaume
Plant Nutrition, 2001
ABSTRACT Tomato plants were grown in soilless culture under controlled conditions. At the 6/8 lea... more ABSTRACT Tomato plants were grown in soilless culture under controlled conditions. At the 6/8 leaf stage, plants were transferred to a calcium deficiency medium. Four days later, the protein profile of calcium deficient leaves differed when compared to control leaves. The induction of two proteins (27.0 kDa and 71.4 kDa) appeared only in the young leaves of calcium deficient plants. These proteins could be related to stress proteins shown with biotic or abiotic stresses.
TAG Theoretical and Applied Genetics, 1998
Genetic variability for partial resistance to bacterial leaf streak in barley, caused by Xanthomo... more Genetic variability for partial resistance to bacterial leaf streak in barley, caused by Xanthomonas campestris pv. hordei, was investigated in 119 doubledhaploid lines (DH) developed by the Hordeum bulbosum method from the F progeny of the cross between two cultivars, 'Morex' (resistant) and 'Steptoe' (susceptible). Two experiments were undertaken in a randomized complete block design with three replicates, in a controlled growth chamber. Twenty seeds per replicate were planted in plastic containers (60;40;8 cm) containing moistened vermiculite. At the two-leaf stage seedlings were inoculated with an Iranian strain of the pathogen. Genetic variability was observed among the 119 DH lines for partial resistance to the disease. Some DH lines were significantly more resistant than 'Morex' (resistant parent) to bacterial leaf streak. Genetic gain in percentage of resistant parent for 5% of the selected DH lines was significant (47.70% and 33.72% in the first and the second experiment, respectively). A QTL analysis of bacterial leaf streak resistance showed that three QTLs were detected on chromosomes 3 and 7. Multilocus allelic effects of the three QTLs account for almost 54% of the mean difference between the parents and nearly 30% of the phenotypic variation of the trait in the mean experiment. The resistance locus on chromosome 3, near ABG377, apprears to be a major gene.
TAG Theoretical and Applied Genetics, 2002
Partial resistance to downy mildew (Plasmopara halstedii) and to black stem (Phoma macdonaldii) i... more Partial resistance to downy mildew (Plasmopara halstedii) and to black stem (Phoma macdonaldii) in sunflower were investigated under natural field infection and a controlled growth chamber respectively. Genetic control for resistance to the diseases was determined in recombinant inbred lines (RILs) and their two parents, 'PAC-2' and 'RHA-266.' The experiments were undertaken in a randomized complete block design with two replications, in a field severely infected by downy mildew and in a controlled growth chamber with plants inoculated with an agressive French isolate of P. macdonaldii. Each replication consisted of three rows, 4.6-m long, giving 48 plants per RIL or parent in the field and 15 plants in the growth chamber. Genetic variability was observed among the RILs for resistance to both diseases. When 10% of the selected RILs were compared with the mean of the two parents genetic gain was significant for partial resistance to the diseases. Four putative QTLs for resistance to downy mildew on linkage groups 1, 9 and 17 were detected using composite interval mapping. The QTLs explained 54.9% of the total phenotypic variance. Major QTLs (dmr1-1 and dmr1-2) for resistance were found on linkage group 1 with up to 31% of the phenotypic variability explained by two peaks. QTL analysis of resistance to black stem showed seven QTLs on linkage groups 3, 6, 8, 9, 11, 15 and 17. The detected QTLs together explain 92% of the phenotypic variation of the trait. Crosses between RILs contrasted for their resistance to downy mildew and black stem, and exhibiting molecular polymorphism in detected QTLs, will be made in order to focus more-precisely on the genomic region of interest.
Theoretical and Applied Genetics, 2004
One hundred and fifty F 2 -F 3 families from a cross between two inbred sunflower lines FU and PA... more One hundred and fifty F 2 -F 3 families from a cross between two inbred sunflower lines FU and PAZ2 were used to map quantitative trait loci (QTL) for resistance to white rot (Sclerotinia sclerotiorum) attacks of terminal buds and capitula, and black stem (Phoma macdonaldii). A genetic linkage map of 18 linkage groups with 216 molecular markers spanning 1,937 cM was constructed. Disease resistances were measured in field experiments for S. sclerotiorum and under controlled conditions for P. macdonaldii. For resistance to S. sclerotiorum terminal bud attack, seven QTL were identified, each explaining less than 10% of phenotypic variance. For capitulum attack by this parasite, there were four QTL (each explaining up to 20% of variation) and for P. macdonaldii resistance, four QTL were identified, each having effects of up to 16%. The S. sclerotiorum capitulum resistance QTL were compared with those reported previously and it was concluded that resistance to this disease is governed by a considerable number of QTL, located on almost all the sunflower linkage groups.
European Journal of Biochemistry, 1995
Treatment of bean cell walls with a pure endopolygalacturonase of the bean pathogen Colletotrichu... more Treatment of bean cell walls with a pure endopolygalacturonase of the bean pathogen Colletotrichum lindemuthianum race beta released oligogalacturonides and pectic fragments which were separated according to their charge and size. Among galacturonic-acid-containing components, elicitors and suppressors of the plant cell wall hydroxyproline-rich glycoprotein (HRGP) were recovered. Two active small oligogalacturonides with degrees of polymerization of 2 and 3 were characterized by high-performance anion-exchange-chromatography pulsed amperometric detection and fast-atom-bombardment mass spectrometry; they elicited 40-70% hydroxyproline increase within 48 hours at 450 nmol/bean cutting. In contrast, pectic fragments of higher molecular mass, predominantly composed of galacturonic acid and containing sugars typical of the rhamnogalacturonan II domain of pectic polysaccharides, had the ability to substantially suppress hydroxyproline deposition. Maximum suppressor activity, 30-40% below the activity of the control, occurred in 48 hours. In view of the low one-cycle turnover of these proteins in the cell wall and of their structural role, these changes might significantly affect cell wall properties. Elicitation and/or suppression of hydroxyproline were correlated to modifications of HRGP-extensin gene expression. Northern-blot analysis of RNA showed that changes in the transcript intensity became clearly visible within the first 12 hours after the start of either treatment. The results show that pectic components of the plant extracellular matrix have the potential to regulate wall matrix biogenesis. Implications of this finding in plant defense and development are discussed.
Plant Science, 2007
Phoma macdonaldii infects different tissues of sunflower and causes reduction in yield and oil co... more Phoma macdonaldii infects different tissues of sunflower and causes reduction in yield and oil content. The aim of present research was to identify genomic regions involved in partial resistance of sunflower to four Phoma macdonaldii basal stem and root necrosis isolates using our improved map constructed with 191 SSR and 304 AFLP markers. The experiment was conducted using F9 recombinant
Plant Pathology, 1996
ABSTRACT Genetic variability of partial resistance to bacterial leaf streak was investigated in h... more ABSTRACT Genetic variability of partial resistance to bacterial leaf streak was investigated in hexaploid winter wheat (Triticum aestivum.), using 16 parental genotypes and 48 pure lines (F10) derived from a composite cross programme. Two experiments were undertaken in a controlled growth chamber. Seeds of all genotypes were grown under controlled conditions using a randomized block design with three replications. Each replication consisted of a row of 20 seedlings of each parent and pure line. An Iranian strain of bacterial leaf streak was used for the inoculation of 12-day-old seedlings. In a third experiment, eight genotypes from parents and F10 pure lines representing a large variability for partial resistance were inoculated with four other Iranian strains of bacterial leaf streak. A large genetic variability was observed amongst the 64 genotypes for partial resistance to the disease. Partial resistance heritability estimates were rather high (70%), indicating that the resistance factors may be transmitted by crossing. Amongst all genotypes investigated, ‘DC2-30-N2’ and ‘IBPT-66’ displayed the highest partial resistance to the disease. Significant correlations between strains in the third experiment show that a genotype resistant or susceptible to one strain will have similar reactions with other strains. No significant genetic gain was observed for partial resistance in the best pure line of the 48 lines studied, when compared with the best parental line. Increasing the number of pure lines is likely to result in the identification of genotypes that might prove to be more resistant.
Plant Pathology, 2007
Two experiments were undertaken to determine the partial resistance of sunflower genotypes to sev... more Two experiments were undertaken to determine the partial resistance of sunflower genotypes to seven isolates of Phoma macdonaldii . In the first experiment, 28 genotypes, including recombinant inbred lines and their parents, M6 mutant lines developed by gamma irradiation, and some genotypes from different geographical origins, were used. The experiment consisted of a split-plot design with three replications, each with 12 seedlings per genotype per isolate, in controlled conditions. Seven days after inoculation, plantlets were scored on a 1-9 scale for percentage necrotic area. Highly significant differences were observed among genotypes, isolates and their interactions. The presence of a differential interaction between genotypes and P. macdonaldii isolates was confirmed in a second experiment using 12 genotypes representing large variability for partial resistance to P. macdonaldii isolates, as identified in the first experiment. Inbred lines B454/03, ENSAT-B5 and LC1064C were the most susceptible sunflower genotypes, whereas two American lines SDR19 and SDR18 presented high partial resistance to all P. macdonaldii isolates studied. The least and most aggressive isolates were MA6 and MP3, respectively. Isolates interacted differentially with sunflower genotypes. This study identified two genotypes (AS613 and PAC2) presenting specific resistance to isolate MP8. The results also showed a wide range of isolate-nonspecific partial resistances among the lines tested. The information presented here could assist sunflower breeders to choose parents of crosses for breeding of durable resistance to phoma black stem disease.
Plant Pathology, 2000
Two programmes to investigate the inheritance of resistance to black stem in sunflowers were unde... more Two programmes to investigate the inheritance of resistance to black stem in sunflowers were undertaken in a controlled-environment growth chamber. In the first, an experiment was performed using a randomized complete block design with 24 lines, six male-sterile (A lines), six maintainers (B lines), six restorers (R lines) and their six F 1 hybrids in six replications. Each treatment consisted of 12 seedlings. Twelve-day-old seedlings were inoculated with a suspension of pycniospores, and 7 days later the two cotyledon petioles of each seedling were scored on a 1±9 scale for the percentage of necrotic area. Some alloplasmic lines (which have the same nucleus and different cytoplasms) gave a significant cytoplasmic effect for improved partial resistance to the disease. Deviation of F 1 hybrids from the mean of the parent values was significant for partial resistance to Phoma macdonaldii in three of the six F 1 hybrids. Two further experiments with eight lines (resistant and susceptible) at the fifth leaf-pair and flowering stages were carried out under the same conditions. At both growth stages the previous classification of lines at the seedling stage was confirmed. In the second programme, five male-sterile sunflower lines were crossed with five fertility-restorers in a factorial mating design. The 10 inbred lines and their 25 F 1 hybrids were studied in two successive experiments under the same conditions and with the same experimental design and isolate of Phoma as in the seedling-stage experiment in the first programme. Analysis of variance showed that male-sterile and restorer lines possessed general combining abilities, and also that specific combining abilities of F 1 hybrids were significant. The estimates of general combining ability for partial resistance were significant in AS617A, AS618A and AS614R inbred lines. These lines are available for developing F 1 hybrids with improved resistance to Phoma in sunflower-breeding programmes.
Plant Pathology, 2007
Basal stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the most important dis... more Basal stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the most important diseases of sunflower. Quantitative trait loci (QTL) implicated in partial resistance to two isolates of S. sclerotiorum (SSU107 and SSKH41) were investigated using F 9 recombinant inbred lines (RILs) from the cross between sunflower parental lines PAC2 and RHA266. Experiments were conducted in completely randomized design with 3-6 replications under controlled conditions. The reaction of genotypes to basal stem rot disease was evaluated by measuring the percentage of necrosis area three days after inoculation. Combined analysis of experiments showed significant interactions between sunflower genotypes and S. sclerotiorum isolates suggesting that partial resistance to S. sclerotiorum should be isolate-specific in sunflower. QTLs were mapped using an updated high-density SSR and SNP linkage map. The map consisted of 210 SSRs and 11 genederived markers placed in 17 linkage groups (LGs). The total map length was 1,653.1 cM with a mean density of 1 marker per 7.44 cM. A total of 14 QTLs were detected for partial resistance to two isolates. The phenotypic variance explained by QTLs (R 2 ) ranged from 0.10 to 9.85. The sign of additive gene effects showed that favorable alleles for partial resistance to isolates came from both parents. Six QTLs were common between two isolates on LGs 1, 8 and 17, whereas the others were specific for each isolate. Colocalized QTLs on LG 1 were linked to the glutathione S-transferase gene (GST). The colocalized QTLs for partial resistance to basal stem rot isolates could be good candidates for marker assisted selection (MAS).
Plant Pathology, 1996
Six wheat genotypes with wide genetic variability for resistance to bacterial leaf streak were cr... more Six wheat genotypes with wide genetic variability for resistance to bacterial leaf streak were crossed in diallel fashion to determine the inheritance of resistance to this disease. Parental genotypes and their F1 hybrids were inoculated at the second leaf stage with an Iranian isolate of Xanthomonas campestris pv. cerealis. Two experiments were undertaken in a controlled environment chamber. Results showed that the genotypes IBPT66, IBPT84 and IBPT34 had a high level of partial resistance to the disease. General and specific combining abilities presented several significant positive or negative values, showing the importance of both additive and dominant genetic control for partial resistance to this bacterial disease. The resistant line IBPT66 could be a good donor of partial resistance to bacterial leaf streak in wheat.
Plant Pathology, 2000
ABSTRACT Growth of 17 isolates of Phoma macdonaldii, the causal agent of sunflower black stem, wa... more ABSTRACT Growth of 17 isolates of Phoma macdonaldii, the causal agent of sunflower black stem, was investigated for response to pH and temperature, and for morphology and asexual morphogenesis (pycnidiogenesis and pycnidium size). For all isolates, the optimum pH for growth was between 4 and 5, and the optimum temperature varied between 20 and 30°C and radial growth was slowest at 5 and 35°C. Significant differences in the number and size of pycnidia were observed between isolates. Pycniospore germination was investigated under various conditions in five isolates chosen for their geographical origins, pigmentation, optimum growth temperature and pycnidiogenesis. Increasing the concentration from 106 to 107 pycniospores per mL decreased the germination rate. The optimum temperature for pycniospore germination varied between 15 and 30°C, depending on the isolate, and the optimum and maximum pH values were 5 and 7, respectively. The optimum and minimum relative humidities allowing pycniospore germination were 100 and 95%, respectively. Pycniospore germination was photo-independent. An artificial inoculation method was developed and the aggressiveness of the pathogen was assessed on a susceptible sunflower cultivar, using a 1–9 scale that integrated the percentage of necrotic area on the cotyledon petiole at the stage when the first pair of leaves was fully developed. Significant differences in aggressiveness were observed among the 17 isolates. The parameters investigated clearly suggest the occurrence of a wide phenotypic variability in Phoma macdonaldii.
Plant Disease, 2010
ABSTRACT Three inoculation methods were evaluated for effectiveness to cause sunflower premature ... more ABSTRACT Three inoculation methods were evaluated for effectiveness to cause sunflower premature ripening (PR). Evaluations were conducted on a sunflower (Helianthus annuus) cultivar susceptible to PR in replicated, multilocation experiments under greenhouse conditions. Plants were inoculated with Phoma macdonaldii. either with mycelium, conidia, or infected residues at the stem base or with buried residues. Disease severity (DS) was measured by percent girdling necrosis at the stern base and percent final PR; the infection spread was assessed using the area under the disease progress curve (AUDPC). Inoculation with mycelia or 1 x 10(6) spores/ml caused significantly more DS and PR than lower spore concentrations or infected residues (P < 0.05). Amending soil with residues induced root necrosis but no PR. P macdonaldii was mainly isolated at the stern base and above but rarely on root systems. Microscopic evaluations showed that hyphae colonized mainly the cortex and vascular stem tissues. The overall results demonstrated a clear role of aerial infection in PR compared with soilborne inoculum, and that inoculation at the stem base with a spore suspension could be used for screening genotypes for resistance to PR.
Phytopathology, 2000
ABSTRACT An ultrastructural investigation of the artificial inoculation of sunflower with Phoma m... more ABSTRACT An ultrastructural investigation of the artificial inoculation of sunflower with Phoma macdonaldii conidia was undertaken using light, scanning, and transmission electron microscopy to elucidate the host-parasite relationship. The behavior of the conidia deposited on the cotyledon petiole was investigated at various time intervals after inoculation. Conidia adhesion and germination were observed first. The cotyledon petiole was invaded by the fungus directly through the cuticle and via stomata. Externally, the spore and germ tube were covered with a mucilaginous polysaccharide sheath of a cotton-like appearance and of variable thickness. At the time of penetration, the host cuticle was perforated mechanically. The cuticle was slightly depressed and no enzymatic alteration could be observed. The fungus did not form appressoria on the surface of the host tissues but developed an infection peg. As soon as the cuticle barrier was crossed, the fungus rapidly colonized the host parietal layer. In a first step, the plasmalemma of the host cell appeared to be stuck against the cell wall. As soon as the fungus passed through the epidermal cell wall to reach the host cytoplasm, the plasmalemma was disrupted, and the subsequent rapid breakdown of cell integrity favored the colonization of the tissues by the pathogen.
Helia, 2002
Phoma macdonaldii, the causal agent of the sunflower black stem disease, is responsible for quali... more Phoma macdonaldii, the causal agent of the sunflower black stem disease, is responsible for qualitative and quantitative damage which can result in up to 60% yield losses in France and worldwide. An early inoculation method has been developed in the laboratory to test sunflower genotype tolerance to Phoma. It was thus important to check whether the method was relevant by assessing the possible incidence of the growth stage of the plant on its reaction to Phoma. Six sunflower genotypes, which were known to be more or less susceptible to Phoma, were inoculated with an aggressive isolate at four different growth stages: cotyledon, unfolded leaves 3-6, budding and early flowering stage. Data analysis showed there is no interaction between the growth stage and the genotype: the test developed discriminates between genotypes early and the grading is representative of what occurs at a more advanced stage as it remains unchanged. Taking into account these data and the large genetic variability of Phoma macdonaldii, the strain-genotype interaction was investigated on isolates originating from France and other countries, in the search for possible pathotypes. For this purpose, ten isolates of Phoma, which were considered to be representative of the fungus variability, with differing aggressiveness, geographical origins and types of symptoms, were tested on ten different sunflower lines. Preliminary results suggest the existence of five pathotypes. Plant breeders could thus use these pathotypes for testing rapidly and reliably the tolerance of their genetic material to Phoma.
European Journal of Plant Pathology, 2007
... partial resistance to Phoma black stem in sunflower has been reported in both the field (Pére... more ... partial resistance to Phoma black stem in sunflower has been reported in both the field (Pére`s, Allard, Deverche`re, & Penaud, 1994) and under controlled conditions (Abou Al Fadil, Dechamp-Guillaume, Poormo-hammad, & Sarrafi, 2004; Bert et al., 2004; Rachid Al-Chaarani ...
European Journal of Agronomy, 2012
ABSTRACT In France, premature ripening (PR) is a widespread damage of a fungal disease of sunflow... more ABSTRACT In France, premature ripening (PR) is a widespread damage of a fungal disease of sunflower caused by Phoma macdonaldii. Previous results indicated that girdling canker at the stem base, caused by P. macdonaldii, was its primary cause. Previous studies have reported the influence of nitrogen and water supply on the incidence and severity of PR but an additional study was required to analyze the effect of plant density on the level of attack for a more comprehensive cultural control of PR.In a 2-year field study (2008 and 2009) in Toulouse (France), a susceptible cultivar (cv. Heliasol) artificially inoculated at star bud stage with P. macdonaldii was grown at three plant densities (4, 6.5 and 9 plants m−2) factorially combined with three N fertilization rates (0, 50/75 and 150 kg N ha−1) and two water regimes (irrigated and rainfed). P. macdonaldii symptoms were scored weekly to calculate the area under disease progress curve (AUDPC) and percentage of PR plants. Microclimatic conditions were monitored using thermo-hygrometers within the crop. The fraction of photosynthetically active radiation intercepted by the canopy (fPARi) and leaf area index (LAI) were measured at anthesis. Plant water status during the disease progression was characterized by crop simulation (SUNFLO) and N status at anthesis was assessed from shoot N content (Nm) analysis and N Nutrition Index (NNI) calculation.Increasing plant density resulted in a greater proportion of PR plants, and this proportion increased further when N was applied at 150 kg ha−1, the highest rate, and the crop was not irrigated. Despite differing canopy development, differences in microclimatic conditions between density levels were too small to explain the PR differences. However plant N concentration and diameter at stem base were closely related to PR incidence. Thin plants (grown at high density) with non-limiting N supply were the most susceptible to premature ripening.This study opens new avenues for the control of PR through crop management and emphasizes the key role of plant morphology in the development of the disease. Stem base diameter is a morphological trait that could be manipulated through crop management (plant density, N fertilization) and probably breeding in the future when developing integrated disease management systems in sunflower.
Acta Agriculturae Scandinavica, Section B - Plant Soil Science, 2009
... Rachid Al-Chaarani, G., Roustaee, A., Gentzbittel, L., Mokrani, L., Barrault, G., Dechamp-Gui... more ... Rachid Al-Chaarani, G., Roustaee, A., Gentzbittel, L., Mokrani, L., Barrault, G., Dechamp-Guillaume, G. and Sarrafi, A. 2002. ... Theoretical and Applied Genetics , 104: 490496. [CrossRef], [PubMed], [Web of Science ®], [CSA] View all references; Abou Al Fadil et al., 20041. Abou ...
New Phytologist, 2006
To identify the genes involved in the partial resistance of sunflower ( Helianthus annuus ) to th... more To identify the genes involved in the partial resistance of sunflower ( Helianthus annuus ) to the necrotrophic fungus Phoma macdonaldii , we developed a 1000element cDNA microarray containing carefully chosen genes putatively involved in primary metabolic pathways, signal transduction and biotic stress responses. • A two-pass general linear model was used to normalize the data and then to detect differentially expressed genes. This method allowed us to identify 38 genes differentially expressed among genotypes, treatments and times, mainly belonging to plant defense, signaling pathways and amino acid metabolism. • Based on a set of genes whose differential expression was highly significant, we propose a model in which negative regulation of a dual-specificity MAPK phosphatase could be implicated in sunflower defense mechanisms against the pathogen. The resulting activation of the MAP kinase cascade could subsequently trigger defense responses (e.g. thaumatin biosynthesis and phenylalanine ammonia lyase activation), under the control of transcription factors belonging to MYB and WRKY families. Concurrently, the activation of protein phosphatase 2A (PP2A), which is implicated in cell death inhibition, could limit pathogen development.
Uploads
Papers by Gregory Dechamp-guillaume