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Louise-Marie Dandurand

Bio: Louise-Marie Dandurand is an academic researcher from University of Idaho. The author has contributed to research in topics: Globodera pallida & Potato cyst nematode. The author has an hindex of 11, co-authored 44 publications receiving 520 citations.

Papers
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Journal ArticleDOI
TL;DR: In the laboratory, Trichoderma harzianum strain ThzID1, formulated as mycelial fragments in alginate pellets with or without wheat bran incorporated, colonized sclerotia of Sclerotinia sclerOTiorum in raw or steamed soil.
Abstract: In the laboratory, Trichoderma harzianum strain ThzID1, formulated as mycelial fragments in alginate pellets with or without wheat bran incorporated, colonized sclerotia of Sclerotinia sclerotiorum in raw or steamed soil. Incidence of colonization was higher in steamed soil than in raw soil, higher at 25 C than at 15 C, and higher at −500 kPa than at −50 kPa but was not affected by bran in pellets. Some sclerotia were colonized by indigenous Trichoderma spp. Pellets containing T. harzianum were added to soil in a pea (Pisum sativum) field or field microplots at densities of 4 × 10 2 − 2 × 10 4 pellets per square meter, along with sclerotia of S. sclerotiorum (.)

77 citations

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TL;DR: Geostatistical analysis was used to compare rhizoplane colonization patterns of an antibiotic-producing biological control bacterium versus a non-antibiotic-producing mutant strain, indicating that the lack of phenazine production did not influence spatial patterns on the rhizplane.
Abstract: Geostatistical analysis was used to compare rhizoplane colonization patterns of an antibiotic-producing biological control bacterium versus a non-antibiotic-producing mutant strain Pea seeds were inoculated with Pseudomonas fluorescens 2-79RN(inf10) or P fluorescens 2-79-B46 (a phenazine-deficient Tn5 mutant of P fluorescens 2-79RN(inf10)) (10(sup8) CFU/pea), planted in sterile sand, and incubated at 20(deg)C After 3 days, seedlings were prepared for scanning electron microscopy Photomicrographs (x1,000) of the root surface were taken at the seed-root junction and at 05-cm intervals to the root tip Bacterial counts on the root surface were made in 5- by 5-(mu)m sample units over an area which was 105 by 80 (mu)m Coordinates and number of bacteria were recorded for each sample unit Spatial statistics were calculated by covariance for the following directions: omnidirectional, 0, 45, 90, and 135(deg) The ranges of spatial influence and nugget (estimator of spatially dependent variation) were determined For both P fluorescens 2-79RN(inf10) and P fluorescens 2-79-B46, spatial structure was evident along the entire root, particularly in the 0(deg) direction (along the root length) (eg, range = 24 (mu)m, nugget = 052) The degree of spatial dependence observed indicated aggregation of bacterial cells No differences were detected in the spatial patterns of colonies of P fluorescens 2-79RN(inf10) and P fluorescens 2-79-B46, indicating that the lack of phenazine production did not influence spatial patterns on the rhizoplane

65 citations

Journal ArticleDOI
TL;DR: PEG treatment may improve the efficacy of these biocontrol agents by promoting rapid hyphal growth of T. harzianum in soil or rapid sporulation of B. bassiana on foliage, respectively.
Abstract: The biocontrol fungi Trichoderma harzianum, used to control soilborne plant pathogens, and Beauveria bassiana, used to control insect pests, were formulated as mycelial biomass in alginate pellets with wheat bran added. After drying for 0, 4, or 16 h, pellets were placed in water or in aqueous solutions of polyethylene glycol (PEG) 8000 for 4 to 24 h and then allowed to continue drying. PEG-treated pellets containing T. harzianum showed significantly greater proliferation of hyphae in soil than untreated pellets or pellets treated with water. Production of conidia of T. harzianum from PEG-treated pellets was lower than production from untreated pellets after 4 days, although rates were equivalent after 7 days. In contrast, production of conidia of B. bassiana was significantly more rapid from PEG-treated pellets than from untreated pellets. Biocontrol of soilborne plant pathogens or insect pests may be enhanced by rapid hyphal growth of T. harzianum in soil or rapid sporulation of B. bassiana on foliage, respectively. Therefore, PEG treatment may improve the efficacy of these biocontrol agents.

57 citations

Journal ArticleDOI
TL;DR: In this paper, spontaneous mutants of Rhizobium leguminosarum biovar viciae strain C1204b were selected for their ability to tolerate 0.2 M NaCl, a growth-inhibiting level of salt for the parental strain.
Abstract: Spontaneous mutants of Rhizobium leguminosarum biovar viciae strain C1204b were selected for their ability to tolerate 0.2 M NaCl, a growth-inhibiting level of salt for the parental strain. Transposon-mediated salt-sensitive mutants of strain C1204b were screened for their inability to grow in 0.08 M NaCl. Quantitation of the free-amino acid pools in the mutants grown in NaCl revealed a dramatic increase in glutamine, serine, glutamate and proline, and to a lesser extent alanine and glycine in the salt-tolerant mutants in comparison with the parental strain exposed to NaCl; but only glutamate and proline increased in the salt-sensitive mutants under NaCl stress. Extracellular polysaccharide levels were quantitated for the salt-tolerant mutants and determined to be approximately two-fold higher than for the parental strain. Although the mutations that occurred in the NaCl-tolerant and NaCl-sensitive strains did not interfere with nodule formation, no nitrogenase activity could be observed in the NaCl tolerant mutants as evaluated by acetylene reduction.

38 citations

Journal ArticleDOI
TL;DR: Results suggest that S. sisymbriifolium has potential to significantly reduce G. pallida populations, and also that the cropping system (i.e. the sequence of non-host and host plants) may play a significant role in the efficacy of fungal biological control agents.
Abstract: The potato cyst nematode, Globodera pallida, is one of the most important pests of potato worldwide. Owing to regulatory considerations and potential environmental impact, control options for this nematode are becoming increasingly limited. Solanum sisymbriifolium and biological control agents offer viable alternative options for controlling G. pallida. Therefore, experiments were conducted to determine the effect of the nematode trap crop S. sisymbriifolium, alone or in combination with the biocontrol agents Trichoderma harzianum or Plectosphaerella cucumerina, on population decline of G. pallida. Experiments were conducted for three different ‘cropping systems’: potato (Solanum tuberosum), S. sisymbriifolium, or soil only (fallow), each followed by a potato crop. Soil was amended with P. cucumerina, T. harzianum or left unamended, and then infested with nematodes at a rate of five eggs g−1 of soil. After 16 weeks in the greenhouse, plants were removed and the soil containing cysts was refrigerated at 4°C for 8 weeks, and then planted to potato. Cysts of G. pallida were counted after an additional 16-week period. The Pf/Pi of G. pallida was significantly reduced by 99% in potato following S. sisymbriifolium compared to both the potato-following-fallow and the potato-following-potato treatments. Amendment of soil with T. harzianum significantly reduced Pf/Pi of G. pallida by 42–47% in the potato-following-potato but not in either the potato-after-fallow nor in the potato-after-S. sisymbriifolium cycles which supports evidence that the plant species may play a role in the biocontrol activity of this fungus. Addition of the fungus P. cucumerina resulted in a 64% decrease in Pf/Pi in the potato-following-fallow in one experiment, and an 88% decrease in Pf/Pi in potato-following-potato but the decrease in Pf/Pi was not consistent over all experiments. However, both biocontrol fungi resulted in lower numbers of progeny cysts after an initial 16-week incubation with potato. To look at the effect of varied population density of the nematode on efficacy of S. sisymbriifolium to reduce G. pallida populations, potato, S. sisymbriifolium, or barley were planted into soil infested with G. pallida at rates of 5, 20 or 40 eggs g−1 soil applied as cysts (20, 80 or 160 cysts pot−1). After 16 weeks, numbers of cysts produced in each treatment were determined for each infestation rate. No new cysts were recovered from either S. sisymbriifolium or barley treatments, confirming that neither plant is a host for G. pallida. High numbers of cysts were recovered with potato. Soil from each treatment (containing original cysts and newly-formed cysts when present) were then planted with potato. After an additional 16 weeks, few cysts were found in the potato-after- S. sisymbriifolium treatments regardless of initial infestation rate. When potato followed barley, numbers of cysts were similar to those found after a single cycle of potato, indicating that the barley crop had no effect on the survival of initial inoculum. Overall, these results suggest that S. sisymbriifolium has potential to significantly reduce G. pallida populations, and also that the cropping system (i.e. the sequence of non-host and host plants) may play a significant role in the efficacy of fungal biological control agents.

34 citations


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Journal ArticleDOI
TL;DR: The Rhizobium-legume (herb or tree) symbiosis is suggested to be the ideal solution to the improvement of soil fertility and the rehabilitation of arid lands and is an important direction for future research.
Abstract: Biological N2 fixation represents the major source of N input in agricultural soils including those in arid regions. The major N2-fixing systems are the symbiotic systems, which can play a significant role in improving the fertility and productivity of low-N soils. The Rhizobium-legume symbioses have received most attention and have been examined extensively. The behavior of some N2-fixing systems under severe environmental conditions such as salt stress, drought stress, acidity, alkalinity, nutrient deficiency, fertilizers, heavy metals, and pesticides is reviewed. These major stress factors suppress the growth and symbiotic characteristics of most rhizobia; however, several strains, distributed among various species of rhizobia, are tolerant to stress effects. Some strains of rhizobia form effective (N2-fixing) symbioses with their host legumes under salt, heat, and acid stresses, and can sometimes do so under the effect of heavy metals. Reclamation and improvement of the fertility of arid lands by application of organic (manure and sewage sludge) and inorganic (synthetic) fertilizers are expensive and can be a source of pollution. The Rhizobium-legume (herb or tree) symbiosis is suggested to be the ideal solution to the improvement of soil fertility and the rehabilitation of arid lands and is an important direction for future research.

1,542 citations

01 Jan 2016
TL;DR: Thank you very much for reading input output analysis foundations and extensions, as many people have search hundreds of times for their chosen readings like this, but end up in infectious downloads.
Abstract: Thank you very much for reading input output analysis foundations and extensions. As you may know, people have search hundreds times for their chosen readings like this input output analysis foundations and extensions, but end up in infectious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they are facing with some malicious virus inside their desktop computer.

1,316 citations

Journal ArticleDOI
TL;DR: Attachment is required for biofilm formation, and bacteria interact with plant tissues through adhesins including polysaccharides and surface proteins, with initial contact often mediated by active motility.
Abstract: Plants support a diverse array of bacteria, including parasites, mutualists, and commensals on and around their roots, in the vasculature, and on aerial tissues These microbes have a profound influence on plant health and productivity Bacteria physically interact with surfaces to form complex multicellular and often multispecies assemblies, including biofilms and smaller aggregates There is growing appreciation that the intensity, duration, and outcome of plant-microbe interactions are significantly influenced by the conformation of adherent microbial populations Biofilms on different tissues have unique properties, reflecting the prevailing conditions at those sites Attachment is required for biofilm formation, and bacteria interact with plant tissues through adhesins including polysaccharides and surface proteins, with initial contact often mediated by active motility Recognition between lectins and their cognate carbohydrates is a common means of specificity Biofilm development and the resulting intimate interactions with plants often require cell-cell communication between colonizing bacteria

725 citations

Journal ArticleDOI
TL;DR: The vast surface of the plant axis, stretching from root tips occasionally buried deeply in anoxic sediment, to apical meristems held far aloft, provides an extraordinarily diverse habitat for microorganisms.
Abstract: ▪ Abstract The vast surface of the plant axis, stretching from root tips occasionally buried deeply in anoxic sediment, to apical meristems held far aloft, provides an extraordinarily diverse habitat for microorganisms. Each zone has to a greater or lesser extent its own cohort of microorganisms, in aggregate comprising representatives from all three primary domains of life—Bacteria, Archaea, and Eucarya. While the plant sets the stage for its microbial inhabitants, they, in turn, have established varied relationships with their large partner. These associations range from relatively inconsequential (transient epiphytic saprophytes) to substantial (epiphytic commensals, mutualistic symbionts, endophytes, or pathogens). Through recent technological breakthroughs, a much better perspective is beginning to emerge on the nature of these relationships, but still relatively little is known about the role of epiphytic microbial associations in the life of the plant.

587 citations

Journal ArticleDOI
TL;DR: This review summarizes the progress and achievements made in the last decade in mass production formulation and application technology of the entomopathogenic fungus Beauveria bassiana and provides technological details about mass production of B. bassiana in China.
Abstract: This review summarizes the progress and achievements made in the last decade in mass production formulation and application technology of the entomopathogenic fungus Beauveria bassiana. Reports published on relevant research from Belgium, Canada, China, Cuba, Czechoslovakia (former), France, Germany, Great Britain, Philippines, Poland, Switzerland, USA and USSR (former) regarding this topic have been covered. Much of the non‐English language literature, particularly that from Eastern European and Chinese sources, has not been translated and is inaccessible to most English or other western language readers. We have done this translation and through this review provide technological details about mass production of B. bassiana in China. Various aspects of B. bassiana growth, substrate use, production of mycelia, conidiospore and blastospores, process technologies associated with separation, drying and milling, formulation, storage and ‘shelf‐life’, and field efficacy are reviewed. Data are presented on: a m...

512 citations