Alfred Souleimanov - Academia.edu (original) (raw)
Papers by Alfred Souleimanov
Frontiers in Plant Science, 2016
Plants, being sessile organisms, are exposed to widely varying environmental conditions throughou... more Plants, being sessile organisms, are exposed to widely varying environmental conditions throughout their life cycle. Compatible plant-microbe interactions favor plant growth and development, and help plants deal with these environmental challenges. Microorganisms produce a diverse range of elicitor molecules to establish symbiotic relationships with the plants they associate with, in a given ecological niche. Lipo-chitooligosaccharide (LCO) and Thuricin 17 (Th17) are two such compounds shown to positively influence plant growth of both legumes and non-legumes. Arabidopsis thaliana responded positively to treatment with the bacterial signal compounds LCO and Th17 in the presence of salt stress (up to 250 mM NaCl). Shotgun proteomics of unstressed and 250 mM NaCl stressed A. thaliana rosettes (7 days post stress) in combination with the LCO and Th17 revealed many known, putative, hypothetical, and unknown proteins. Overall, carbon and energy metabolic pathways were affected under both unstressed and salt stressed conditions when treated with these signals. PEP carboxylase, Rubisco-oxygenase large subunit, pyruvate kinase, and proteins of photosystems I and II were some of the noteworthy proteins enhanced by the signals, along with other stress related proteins. These findings suggest that the proteome of A. thaliana rosettes is altered by the bacterial signals tested, and more so under salt stress, thereby imparting a positive effect on plant growth under high salt stress. The roles of the identified proteins are discussed here in relation to salt stress adaptation, which, when translated to field grown crops can be a crucial component and of significant importance in agriculture and global food production. The mass spectrometry proteomics data have been deposited to the ProteomeXchange with identifier PXD004742.
Plant signaling & behavior, Jan 23, 2016
The objective of this experiment was to assess whether or not the application of lipo-chitooligos... more The objective of this experiment was to assess whether or not the application of lipo-chitooligosaccharide (Nod Bj V [C18:1, MeFuc]) (LCO) would increase yield factors under conditions that would inhibit canola (Brassica napus L.) productivity. The seed application reduced the percentage of plants that were unproductive by 15.10% compared to plants grown from untreated seeds. Based on the 95% confidence interval for the difference, untreated plants would produce 38 to 3% fewer seeds than plants grown from LCO treated seeds. The experimental conditions were artificial, but further experimentation, with agricultural cultivars grown in greenhouses where natural conditions were simulated, confirmed that LCO treatment can contribute to canola yield.
PLOS ONE, 2016
Salt stress is an important abiotic stressor affecting crop growth and productivity. Of the 20 pe... more Salt stress is an important abiotic stressor affecting crop growth and productivity. Of the 20 percent of the terrestrial earth's surface available as agricultural land, 50 percent is estimated by the United Nations Environment Program to be salinized to the level that crops growing on it will be salt-stressed. Increased soil salinity has profound effects on seed germination and germinating seedlings as they are frequently confronted with much higher salinities than vigorously growing plants, because germination usually occurs in surface soils, the site of greatest soluble salt accumulation. The growth of soybean exposed to 40 mM NaCl is negatively affected, while an exposure to 80 mM NaCl is often lethal. When treated with the bacterial signal compounds lipo-chitooligosaccharide (LCO) and thuricin 17 (Th17), soybean seeds (variety Absolute RR) responded positively at salt stress of up to 150 mM NaCl. Shotgun proteomics of unstressed and 100 mM NaCl stressed seeds (48 h) in combination with the LCO and Th17 revealed many known, predicted, hypothetical and unknown proteins. In all, carbon, nitrogen and energy metabolic pathways were affected under both unstressed and salt stressed conditions when treated with signals. PEP carboxylase, Rubisco oxygenase large subunit, pyruvate kinase, and isocitrate lyase were some of the noteworthy proteins enhanced by the signals, along with antioxidant glutathione-S-transferase and other stress related proteins. These findings suggest that the germinating seeds alter their proteome based on bacterial signals and on stress, the specificity of this response plays a crucial role in organ maturation and transition from one stage to another in the plants' life cycle; understanding this response is of fundamental importance in agriculture and, as a result, global food security. The mass spectrometry proteomics data have been deposited to the ProteomeXchange with identifier PXD004106.
Plant Physiology and Biochemistry Ppb Societe Francaise De Physiologie Vegetale, Nov 1, 2006
Jasmonates are signaling molecules involved in induced systemic resistance, wounding and stress r... more Jasmonates are signaling molecules involved in induced systemic resistance, wounding and stress responses of plants. We have previously demonstrated that jasmonates can induce nod genes of Bradyrhizobium japonicum when measured by β-galactosidase activity. In order to test whether jasmonates can effectively induce the production and secretion of Nod factors (lipo-chitooligosaccharides, LCOs) from B. japonicum, we induced two B. japonicum strains, 532C and USDA3, with jasmonic acid (JA), methyl jasmonate (MeJA) and genistein (Ge). As genistein is well characterized as an inducer of nod genes it was used a positive control. The high-performance liquid chromatography (HPLC) profile of LCOs isolated following treatment with jasmonates or genistein showed that both JA and MeJA effectively induced nod genes and caused production of LCOs from bacterial cultures. JA and MeJA are more efficacious inducers of LCO production than genistein. Genistein plus JA or MeJA resulted in greater LCO production than either alone. A soybean root hair deformation assay showed that jasmonate induced LCOs were as effective as those induced by genistein. This is the first report that jasmonates induce Nod factor production by B. japonicum. This report establishes the role of jasmonates as a new class of signaling molecules in the Bradyrhizobium-soybean symbiosis.
Agronomy For Sustainable Development, Sep 15, 2014
Climate change is forecasted to induce more drought stress events. Water scarcity is already the ... more Climate change is forecasted to induce more drought stress events. Water scarcity is already the most limiting abiotic stress for crop production. With higher food demand, there is a need for sustainable solutions to cope with the loss of productivity due to water stress. It is known that plant growth-promoting rhizobacteria (PGPR) can colonize plant roots and increase plant growth. However, there is actually no sustainable method to decrease the impact of water stress. Therefore, we hypothesized that an application of thuricin-17, a molecule produced by the PGPR Bacillus thuringiensis, could enhance soybean tolerance to water stress. We grew soybean plants for 1 month in growth chambers in order to evaluate their response to thuricin-17 root application under drought, in association with the inoculation of N 2 -fixing Bradyrhizobium japonicum. We measured traits reflecting root architecture: number of tips, root diameter, root length, number of nodules; water fluxes: water potential, stomatal conductance; carbon nutrition: leaf area, photosynthetic rate, biomass and carbon partitioning; nitrogen nutrition: nitrogen partitioning and hormone signalling: abscisic acid concentration during the vegetative growth period. Our results show that thuricin-17 application under water stress increased plant biomass by 17 %, thus masking drought impact. This effect is due to modifications of below-ground structures, with 37 % increase of root and 55 % increase of nodule biomass, and to slight increases of leaf area and photosynthetic rate. We also observed that application of thuricin-17 induced a 30 % increase of root abscisic acid, an increase of root length and of leaf water potential. Finally, thuricin-17 induced an activation of nodule formation by 40 %, a partial restoration of nodule-specific activity, nodule growth and consequently, an increase by 17 % of the total nitrogen amount in the plant. Overall, our findings reveal a new method to decrease the negative impact of water stress. Results also demonstrate that the plant restored an adequate water and N balance by changing its root structure.
Plant Growth Regulation, 2015
The present invention relates to agriculture. More particularly, the invention relates to a metho... more The present invention relates to agriculture. More particularly, the invention relates to a method of increasing photosynthesis of a plant and more particularly of crop plants. In addition, the invention relates to a method of increasing photosynthesis and/or yield in crop plants, comprising an exposure thereof to lipo-chitooligosaccharides, and compositions therefor. Further, the invention relates to an agricultural composition for enhancing a plant crop photosynthetic rate and/or growth thereof comprising a photosynthetic rate-promoting amount of at least one lipo-chitooligosaccharide (LCO) together with an agriculturally suitable carrier and methods using same.
The soil bacterium Sinorhizobium meliloti forms a symbiotic relationship with alfalfa (Medicago s... more The soil bacterium Sinorhizobium meliloti forms a symbiotic relationship with alfalfa (Medicago sativa) roots, which results in the formation of intracellular root nodules. This symbiosis increases nitrogen (N) in the soil; however, to establish such a synergistic relationship, a complex communication system is required between the bacterium and its legume host. Rhizobacteria are known to respond to plant root exudates and produce signal molecules known as “Nod” factors. Research suggests that the brown seaweed (Ascophyllum nodosum) extract (ANE) stimulates both root nodulation and growth of alfalfa (Khan et al. 2011 ). To elucidate the mechanism of action, the effects of ANE on the early stages of root–rhizobia interactions were examined. A. nodosum extract (ANE) and its organic fractions were prepared and alfalfa roots were treated. After 2 days, the treated roots were inoculated with S. meliloti. The roots from treated plants were excised and observed for colony-forming units. To...
Crop Science
ABSTRACT,and nonlegumes under laboratory, greenhouse, and field conditions (Souleimanov et al., 2... more ABSTRACT,and nonlegumes under laboratory, greenhouse, and field conditions (Souleimanov et al., 2002; Prithiviraj et al., Nod factors, also known as lipo-chitooligosaccharides (LCOs), are 2003). signal molecules produced by rhizobia during rhizobia-legume sym- biosis. These Nod factors often must be purified, sterilized, and stored Enzymatic degradation of LCOs has been studied. before use in research experiments. Therefore, we evalufore, the present experiments were conducted to evalu- ate whether purification, sterilization, and storage pro- cedures,affect the quantity and the biological activity S
![Research paper thumbnail of Supplementation with solutions of lipo-chitooligosacharide Nod Bj V (C18:1, MeFuc) and thuricin 17 regulates leaf arrangement, biomass, and root development of canola (Brassica napus [L.])](https://attachments.academia-assets.com/53826904/thumbnails/1.jpg)
](Plant Growth Regulation, 2015
Recent work has shown that plant-to-microbe signals can enhance the growth of a wide range of cro... more Recent work has shown that plant-to-microbe signals can enhance the growth of a wide range of crops. Nevertheless, canola (Brassica napus L.), which forms neither arbuscular mycorrhizal nor nitrogen-fixing symbioses, has not been rigorously evaluated for its capacity to perceive and respond to microbe-to-plant signals. It was shown previously that the Bradyrhizobium japonicum lipo-chitooligosaccharide (LCO) and Bacillus thuringiensis bacteriocin thuricin 17 enhance the germination and growth of other crop species. To evaluate canola's response, B. napus plants were grown in controlled environment chambers, in either peat pellets or large plant culture vessels. In the peat pellet system, plants that were irrigated with 10 -6 M LCO, and grown at 30°C, produced one more leaf than water-or signal-treated plants that were grown at 25/20°C. The numbers of cotyledons (seed leaves) produced by thuricin 17-treated plants was greater than LCO treated plants and the control treatment. Among the plants grown in vessels, those grown with 0.2 M NaCl and 10 -9 M thuricin 17 were taller than either treated or untreated plants that were grown with 10 -5 M NaCl. Under 10/4°C and 4 9 10 -5 M NaCl conditions, only seeds treated with thuricin 17 produced roots. Among the plants grown in vessels at 30/30°C, those treated with 10 -11 M thuricin 17 resulted in approximately one more leaf per plant than nM. Root lengths were shortened with 10 -5 M NaCl and 10 -9 M thuricin 17, compared to lower salinities. At 30/30°C, plants grown with 10 -5 M NaCl and 10 -9 M thuricin 17 were heavier than plants grown in nonsaline media without thuricin 17. Where LCO supplementation may stimulate a competitive form, thuricin 17 supplementation triggers a reduction in the plant's surface area, which may reduce the plant's vulnerability to prohibitive salinity levels.
![Research paper thumbnail of The Plant Growth Regulator Lipo-chitooligosaccharide (LCO) Enhances the Germination of Canola (Brassica napus [L.])](https://attachments.academia-assets.com/53826888/thumbnails/1.jpg)
](Journal of Plant Growth Regulation, 2014
In agricultural environments where canola (Brassica napus) is grown, slow germination can increas... more In agricultural environments where canola (Brassica napus) is grown, slow germination can increase the susceptibility of seedlings to pathogens, delay maturity, and decrease yield. Bacterial products that enhance germination have been identified for a variety of plants. Three signal molecules were investigated: Bradyrhizobium japonicum 532C product lipochitooligosaccharide (LCO), Bacillus thuringiensis NEB17 product thuricin 17, and chitopentaose, which is the undecorated chitin backbone of LCO. Gompertz functions were estimated and used for inferences regarding the signal, cultivar-by-temperature, and signalby-temperature effects on 6 cultivars (02C3, 02C6, 04C111, 04C204, Polo, and Topas). LCO (10 -6 M) was found to increase Polo germination by 75.0 %, during the 5-15 growing degree day period. Such early B. napus germination can, under field conditions, increase canopy coverage and yield. Further experimentation with the other experimental cultivars discerned an improvement in the germination of Topas, following treatment with LCO, under ideal (24 h 25°C) and abiotic stress (24 h 10°C) growing conditions, as compared to Polo and 04C204. The response to LCO was discernable for Polo under AOSA (J Seed Technol 16:112, 1993) standard temperature conditions and for Topas when considered across temperature conditions in comparison to Polo and 04C204.
Agronomy for Sustainable Development, 2014
Climate change is forecasted to induce more drought stress events. Water scarcity is already the ... more Climate change is forecasted to induce more drought stress events. Water scarcity is already the most limiting abiotic stress for crop production. With higher food demand, there is a need for sustainable solutions to cope with the loss of productivity due to water stress. It is known that plant growth-promoting rhizobacteria (PGPR) can colonize plant roots and increase plant growth. However, there is actually no sustainable method to decrease the impact of water stress. Therefore, we hypothesized that an application of thuricin-17, a molecule produced by the PGPR Bacillus thuringiensis, could enhance soybean tolerance to water stress. We grew soybean plants for 1 month in growth chambers in order to evaluate their response to thuricin-17 root application under drought, in association with the inoculation of N 2 -fixing Bradyrhizobium japonicum. We measured traits reflecting root architecture: number of tips, root diameter, root length, number of nodules; water fluxes: water potential, stomatal conductance; carbon nutrition: leaf area, photosynthetic rate, biomass and carbon partitioning; nitrogen nutrition: nitrogen partitioning and hormone signalling: abscisic acid concentration during the vegetative growth period. Our results show that thuricin-17 application under water stress increased plant biomass by 17 %, thus masking drought impact. This effect is due to modifications of below-ground structures, with 37 % increase of root and 55 % increase of nodule biomass, and to slight increases of leaf area and photosynthetic rate. We also observed that application of thuricin-17 induced a 30 % increase of root abscisic acid, an increase of root length and of leaf water potential. Finally, thuricin-17 induced an activation of nodule formation by 40 %, a partial restoration of nodule-specific activity, nodule growth and consequently, an increase by 17 % of the total nitrogen amount in the plant. Overall, our findings reveal a new method to decrease the negative impact of water stress. Results also demonstrate that the plant restored an adequate water and N balance by changing its root structure.
Planta, 2003
Lipo-chitooligosaccharides (LCOs), or Nod factors, are host-specific bacteria-to-plant signal mol... more Lipo-chitooligosaccharides (LCOs), or Nod factors, are host-specific bacteria-to-plant signal molecules essential for the establishment of a successful N(2)-fixing legume-rhizobia symbiosis. At submicromolar concentrations Nod factors induce physiological changes in host and non-host plants. Here we show that the Nod factor Nod Bj V(C18:1,MeFuc) of Bradyrhizobium japonicum 532C enhances germination of a variety of economically important plants belonging to diverse botanical families: Zea mays, Oryza sativa (Poaceae), Beta vulgaris (Chenopodaceae), Glycine max, Phaseolus vulgaris (Fabaceae), and Gossypium hirsutum (Malvaceae), under laboratory, greenhouse and field conditions. Similar increases in germination were observed for filtrates of genistein-induced cultures of B. japonicum 532C, while non-induced B. japonicum, induced Bj 168 (a nodC mutant of B. japonicum deficient in Nod factor synthesis) or the pentamer of chitin did not invoke such responses, demonstrating the role of Nod...
Journal of microbiology and biotechnology, 2011
The objective of this work was to investigate the ability of the plant growth-promoting rhizobact... more The objective of this work was to investigate the ability of the plant growth-promoting rhizobacterium Pseudomonas aureofaciens 63-28 to induce plant defense systems, including defense-related enzyme levels and expression of defense-related isoenzymes, and isoflavone production, leading to improved resistance to the phytopathogen Rhizoctonia solani AG-4 in soybean seedlings. Seven-dayold soybean seedlings were inoculated with P. aureofaciens 63-28, R. solani AG-4, or P. aureofaciens 63-28 plus R. solani AG-4 (P+R), or not inoculated (control). After 7 days of incubation, roots treated with R. solani AG-4 had obvious damping-off symptoms, but P+R-treated soybean plants had less disease development, indicating suppression of R. solani AG-4 in soybean seedlings. Superoxide dismutase (SOD) and catalase (CAT) activities of R. solani AG-4-treated roots increased by 24.6% and 54.0%, respectively, compared with control roots. Ascorbate peroxidase (APX) and phenylalanine ammonia lyase (PAL) ...
Plant Growth Regulation, 2010
are bacteriato-plant signals required for the establishment of rhizobialegume nitrogen fixing sym... more are bacteriato-plant signals required for the establishment of rhizobialegume nitrogen fixing symbioses. The ability of LCO [Nod Bj V (C 18:1 , MeFuc)] isolated from B. japonicum (strain 532C), and of oligomers of chitosan (tetramer, pentamer) and chitin (pentamer) to affect the developmental morphology of roots in Arabidopsis thaliana (L.) Heynh ecotype Columbia (Col-0) was assessed using an interactive scannerbased image analysis system. LCOs have been shown to play a role in plant organogenesis at nanomolar concentrations. LCO and the chitin pentamer promoted root growth and development in Arabidopsis at concentrations of 10 nM and 100 lM, respectively. The LCO treated Arabidopsis plants had about 35% longer roots than untreated control plants. Similarly, treatment with 100 lM chitin pentamer (CHIT5) resulted in 26% longer roots than the untreated plants; however, chitosan oligomer (CH4 or CH5) treated plants did not differ from the control plants at either concentration (100 or 1 lM). Both LCOs and the chitin pentamer at higher concentrations increased root surface area, mean root diameter and number of root tips. However, leaf area increase was observed only in plants treated with LCO at 10 nM.
Soil Biology and Biochemistry, 2002
Lipo-chitooligosaccharides (LCOs), also known as nod factors, are the bacteria-to-plant signal mo... more Lipo-chitooligosaccharides (LCOs), also known as nod factors, are the bacteria-to-plant signal molecules synthesized in response to the plant-to-bacteria signals, usually flavonoids. In Canada, low soil temperature is potentially a major factor limiting soybean growth and ...
Planta, 2009
The mechanisms by which many plant growth promoting rhizobacteria (PGPR) affect plants are unknow... more The mechanisms by which many plant growth promoting rhizobacteria (PGPR) affect plants are unknown. We recently isolated a rhizosphere bacterium (Bacillus thuringiensis NEB17), that promotes soybean growth and screened the liquid growth medium in which it grew for plant growth stimulating materials. We have also shown that it produces a bacteriocin (named by us as thuricin-17 and a member of the recently described class IId bacteriocins). Here we show that application of this bacteriocin to leaves (spray) or roots (drench) directly stimulates the growth of both a C(3) dicot (soybean) and a C(4) monocot (corn). This growth stimulation is similar in nature to that previously seen when plants are treated with Nod factors. Strain NEB17 contains three copies of the gene for thuricin 17 that code for identical amino acid sequences. These two lines of evidence suggest that the dual functions of these proteins may have constrained their evolution. This is the first report of direct plant growth enhancement by a bacteriocin.
Plant Physiology and Biochemistry, 2005
Plants possess highly sensitive perception systems by which microbial signal molecules are recogn... more Plants possess highly sensitive perception systems by which microbial signal molecules are recognized. In the Bradyrhizobium-soybean (Glycine max (L.) Merr.) symbiosis, recognition is initiated through exchange of signal molecules, generally flavonoids from soybean and lipo-chitooligosaccharides (Nod factors) from the microsymbiont. Application of the Nod factor Nod Bj-V (C 18:1 , MeFuc) induced soybean resistance to powdery mildew caused by Microsphaera diffusa. Addition of Nod factor (concentrations ranging from 10 −6 to 10 −10 M) to soybean root systems led to reductions in disease incidence. The lowest disease incidence was caused by Nod factor treatment at 10 −6 M. The effect of Nod factor application on fungal growth and development was measured at 4, 12, 48, and 96 h after inoculation. Colony diameter and number of germ tubes per conidium were decreased by 10 −6 M Nod factor. Phenylalanine ammonia lyase (PAL, EC.4.3.1.1.) is the first enzyme of the phenyl propanoid pathway, and is commonly activated as part of plant responses to disease. Treatment of soybean seedlings with Nod factor, through stem wounds, induced PAL activity; the most rapid increase followed treatment with 10 −6 M Nod factor. These data show that soybean plants are able to detect root applied LCO and respond by increased disease resistance.
Frontiers in Plant Science, 2016
Plants, being sessile organisms, are exposed to widely varying environmental conditions throughou... more Plants, being sessile organisms, are exposed to widely varying environmental conditions throughout their life cycle. Compatible plant-microbe interactions favor plant growth and development, and help plants deal with these environmental challenges. Microorganisms produce a diverse range of elicitor molecules to establish symbiotic relationships with the plants they associate with, in a given ecological niche. Lipo-chitooligosaccharide (LCO) and Thuricin 17 (Th17) are two such compounds shown to positively influence plant growth of both legumes and non-legumes. Arabidopsis thaliana responded positively to treatment with the bacterial signal compounds LCO and Th17 in the presence of salt stress (up to 250 mM NaCl). Shotgun proteomics of unstressed and 250 mM NaCl stressed A. thaliana rosettes (7 days post stress) in combination with the LCO and Th17 revealed many known, putative, hypothetical, and unknown proteins. Overall, carbon and energy metabolic pathways were affected under both unstressed and salt stressed conditions when treated with these signals. PEP carboxylase, Rubisco-oxygenase large subunit, pyruvate kinase, and proteins of photosystems I and II were some of the noteworthy proteins enhanced by the signals, along with other stress related proteins. These findings suggest that the proteome of A. thaliana rosettes is altered by the bacterial signals tested, and more so under salt stress, thereby imparting a positive effect on plant growth under high salt stress. The roles of the identified proteins are discussed here in relation to salt stress adaptation, which, when translated to field grown crops can be a crucial component and of significant importance in agriculture and global food production. The mass spectrometry proteomics data have been deposited to the ProteomeXchange with identifier PXD004742.
Plant signaling & behavior, Jan 23, 2016
The objective of this experiment was to assess whether or not the application of lipo-chitooligos... more The objective of this experiment was to assess whether or not the application of lipo-chitooligosaccharide (Nod Bj V [C18:1, MeFuc]) (LCO) would increase yield factors under conditions that would inhibit canola (Brassica napus L.) productivity. The seed application reduced the percentage of plants that were unproductive by 15.10% compared to plants grown from untreated seeds. Based on the 95% confidence interval for the difference, untreated plants would produce 38 to 3% fewer seeds than plants grown from LCO treated seeds. The experimental conditions were artificial, but further experimentation, with agricultural cultivars grown in greenhouses where natural conditions were simulated, confirmed that LCO treatment can contribute to canola yield.
PLOS ONE, 2016
Salt stress is an important abiotic stressor affecting crop growth and productivity. Of the 20 pe... more Salt stress is an important abiotic stressor affecting crop growth and productivity. Of the 20 percent of the terrestrial earth's surface available as agricultural land, 50 percent is estimated by the United Nations Environment Program to be salinized to the level that crops growing on it will be salt-stressed. Increased soil salinity has profound effects on seed germination and germinating seedlings as they are frequently confronted with much higher salinities than vigorously growing plants, because germination usually occurs in surface soils, the site of greatest soluble salt accumulation. The growth of soybean exposed to 40 mM NaCl is negatively affected, while an exposure to 80 mM NaCl is often lethal. When treated with the bacterial signal compounds lipo-chitooligosaccharide (LCO) and thuricin 17 (Th17), soybean seeds (variety Absolute RR) responded positively at salt stress of up to 150 mM NaCl. Shotgun proteomics of unstressed and 100 mM NaCl stressed seeds (48 h) in combination with the LCO and Th17 revealed many known, predicted, hypothetical and unknown proteins. In all, carbon, nitrogen and energy metabolic pathways were affected under both unstressed and salt stressed conditions when treated with signals. PEP carboxylase, Rubisco oxygenase large subunit, pyruvate kinase, and isocitrate lyase were some of the noteworthy proteins enhanced by the signals, along with antioxidant glutathione-S-transferase and other stress related proteins. These findings suggest that the germinating seeds alter their proteome based on bacterial signals and on stress, the specificity of this response plays a crucial role in organ maturation and transition from one stage to another in the plants' life cycle; understanding this response is of fundamental importance in agriculture and, as a result, global food security. The mass spectrometry proteomics data have been deposited to the ProteomeXchange with identifier PXD004106.
Plant Physiology and Biochemistry Ppb Societe Francaise De Physiologie Vegetale, Nov 1, 2006
Jasmonates are signaling molecules involved in induced systemic resistance, wounding and stress r... more Jasmonates are signaling molecules involved in induced systemic resistance, wounding and stress responses of plants. We have previously demonstrated that jasmonates can induce nod genes of Bradyrhizobium japonicum when measured by β-galactosidase activity. In order to test whether jasmonates can effectively induce the production and secretion of Nod factors (lipo-chitooligosaccharides, LCOs) from B. japonicum, we induced two B. japonicum strains, 532C and USDA3, with jasmonic acid (JA), methyl jasmonate (MeJA) and genistein (Ge). As genistein is well characterized as an inducer of nod genes it was used a positive control. The high-performance liquid chromatography (HPLC) profile of LCOs isolated following treatment with jasmonates or genistein showed that both JA and MeJA effectively induced nod genes and caused production of LCOs from bacterial cultures. JA and MeJA are more efficacious inducers of LCO production than genistein. Genistein plus JA or MeJA resulted in greater LCO production than either alone. A soybean root hair deformation assay showed that jasmonate induced LCOs were as effective as those induced by genistein. This is the first report that jasmonates induce Nod factor production by B. japonicum. This report establishes the role of jasmonates as a new class of signaling molecules in the Bradyrhizobium-soybean symbiosis.
Agronomy For Sustainable Development, Sep 15, 2014
Climate change is forecasted to induce more drought stress events. Water scarcity is already the ... more Climate change is forecasted to induce more drought stress events. Water scarcity is already the most limiting abiotic stress for crop production. With higher food demand, there is a need for sustainable solutions to cope with the loss of productivity due to water stress. It is known that plant growth-promoting rhizobacteria (PGPR) can colonize plant roots and increase plant growth. However, there is actually no sustainable method to decrease the impact of water stress. Therefore, we hypothesized that an application of thuricin-17, a molecule produced by the PGPR Bacillus thuringiensis, could enhance soybean tolerance to water stress. We grew soybean plants for 1 month in growth chambers in order to evaluate their response to thuricin-17 root application under drought, in association with the inoculation of N 2 -fixing Bradyrhizobium japonicum. We measured traits reflecting root architecture: number of tips, root diameter, root length, number of nodules; water fluxes: water potential, stomatal conductance; carbon nutrition: leaf area, photosynthetic rate, biomass and carbon partitioning; nitrogen nutrition: nitrogen partitioning and hormone signalling: abscisic acid concentration during the vegetative growth period. Our results show that thuricin-17 application under water stress increased plant biomass by 17 %, thus masking drought impact. This effect is due to modifications of below-ground structures, with 37 % increase of root and 55 % increase of nodule biomass, and to slight increases of leaf area and photosynthetic rate. We also observed that application of thuricin-17 induced a 30 % increase of root abscisic acid, an increase of root length and of leaf water potential. Finally, thuricin-17 induced an activation of nodule formation by 40 %, a partial restoration of nodule-specific activity, nodule growth and consequently, an increase by 17 % of the total nitrogen amount in the plant. Overall, our findings reveal a new method to decrease the negative impact of water stress. Results also demonstrate that the plant restored an adequate water and N balance by changing its root structure.
Plant Growth Regulation, 2015
The present invention relates to agriculture. More particularly, the invention relates to a metho... more The present invention relates to agriculture. More particularly, the invention relates to a method of increasing photosynthesis of a plant and more particularly of crop plants. In addition, the invention relates to a method of increasing photosynthesis and/or yield in crop plants, comprising an exposure thereof to lipo-chitooligosaccharides, and compositions therefor. Further, the invention relates to an agricultural composition for enhancing a plant crop photosynthetic rate and/or growth thereof comprising a photosynthetic rate-promoting amount of at least one lipo-chitooligosaccharide (LCO) together with an agriculturally suitable carrier and methods using same.
The soil bacterium Sinorhizobium meliloti forms a symbiotic relationship with alfalfa (Medicago s... more The soil bacterium Sinorhizobium meliloti forms a symbiotic relationship with alfalfa (Medicago sativa) roots, which results in the formation of intracellular root nodules. This symbiosis increases nitrogen (N) in the soil; however, to establish such a synergistic relationship, a complex communication system is required between the bacterium and its legume host. Rhizobacteria are known to respond to plant root exudates and produce signal molecules known as “Nod” factors. Research suggests that the brown seaweed (Ascophyllum nodosum) extract (ANE) stimulates both root nodulation and growth of alfalfa (Khan et al. 2011 ). To elucidate the mechanism of action, the effects of ANE on the early stages of root–rhizobia interactions were examined. A. nodosum extract (ANE) and its organic fractions were prepared and alfalfa roots were treated. After 2 days, the treated roots were inoculated with S. meliloti. The roots from treated plants were excised and observed for colony-forming units. To...
Crop Science
ABSTRACT,and nonlegumes under laboratory, greenhouse, and field conditions (Souleimanov et al., 2... more ABSTRACT,and nonlegumes under laboratory, greenhouse, and field conditions (Souleimanov et al., 2002; Prithiviraj et al., Nod factors, also known as lipo-chitooligosaccharides (LCOs), are 2003). signal molecules produced by rhizobia during rhizobia-legume sym- biosis. These Nod factors often must be purified, sterilized, and stored Enzymatic degradation of LCOs has been studied. before use in research experiments. Therefore, we evalufore, the present experiments were conducted to evalu- ate whether purification, sterilization, and storage pro- cedures,affect the quantity and the biological activity S
Plant Growth Regulation, 2015
Recent work has shown that plant-to-microbe signals can enhance the growth of a wide range of cro... more Recent work has shown that plant-to-microbe signals can enhance the growth of a wide range of crops. Nevertheless, canola (Brassica napus L.), which forms neither arbuscular mycorrhizal nor nitrogen-fixing symbioses, has not been rigorously evaluated for its capacity to perceive and respond to microbe-to-plant signals. It was shown previously that the Bradyrhizobium japonicum lipo-chitooligosaccharide (LCO) and Bacillus thuringiensis bacteriocin thuricin 17 enhance the germination and growth of other crop species. To evaluate canola's response, B. napus plants were grown in controlled environment chambers, in either peat pellets or large plant culture vessels. In the peat pellet system, plants that were irrigated with 10 -6 M LCO, and grown at 30°C, produced one more leaf than water-or signal-treated plants that were grown at 25/20°C. The numbers of cotyledons (seed leaves) produced by thuricin 17-treated plants was greater than LCO treated plants and the control treatment. Among the plants grown in vessels, those grown with 0.2 M NaCl and 10 -9 M thuricin 17 were taller than either treated or untreated plants that were grown with 10 -5 M NaCl. Under 10/4°C and 4 9 10 -5 M NaCl conditions, only seeds treated with thuricin 17 produced roots. Among the plants grown in vessels at 30/30°C, those treated with 10 -11 M thuricin 17 resulted in approximately one more leaf per plant than nM. Root lengths were shortened with 10 -5 M NaCl and 10 -9 M thuricin 17, compared to lower salinities. At 30/30°C, plants grown with 10 -5 M NaCl and 10 -9 M thuricin 17 were heavier than plants grown in nonsaline media without thuricin 17. Where LCO supplementation may stimulate a competitive form, thuricin 17 supplementation triggers a reduction in the plant's surface area, which may reduce the plant's vulnerability to prohibitive salinity levels.
Journal of Plant Growth Regulation, 2014
In agricultural environments where canola (Brassica napus) is grown, slow germination can increas... more In agricultural environments where canola (Brassica napus) is grown, slow germination can increase the susceptibility of seedlings to pathogens, delay maturity, and decrease yield. Bacterial products that enhance germination have been identified for a variety of plants. Three signal molecules were investigated: Bradyrhizobium japonicum 532C product lipochitooligosaccharide (LCO), Bacillus thuringiensis NEB17 product thuricin 17, and chitopentaose, which is the undecorated chitin backbone of LCO. Gompertz functions were estimated and used for inferences regarding the signal, cultivar-by-temperature, and signalby-temperature effects on 6 cultivars (02C3, 02C6, 04C111, 04C204, Polo, and Topas). LCO (10 -6 M) was found to increase Polo germination by 75.0 %, during the 5-15 growing degree day period. Such early B. napus germination can, under field conditions, increase canopy coverage and yield. Further experimentation with the other experimental cultivars discerned an improvement in the germination of Topas, following treatment with LCO, under ideal (24 h 25°C) and abiotic stress (24 h 10°C) growing conditions, as compared to Polo and 04C204. The response to LCO was discernable for Polo under AOSA (J Seed Technol 16:112, 1993) standard temperature conditions and for Topas when considered across temperature conditions in comparison to Polo and 04C204.
Agronomy for Sustainable Development, 2014
Climate change is forecasted to induce more drought stress events. Water scarcity is already the ... more Climate change is forecasted to induce more drought stress events. Water scarcity is already the most limiting abiotic stress for crop production. With higher food demand, there is a need for sustainable solutions to cope with the loss of productivity due to water stress. It is known that plant growth-promoting rhizobacteria (PGPR) can colonize plant roots and increase plant growth. However, there is actually no sustainable method to decrease the impact of water stress. Therefore, we hypothesized that an application of thuricin-17, a molecule produced by the PGPR Bacillus thuringiensis, could enhance soybean tolerance to water stress. We grew soybean plants for 1 month in growth chambers in order to evaluate their response to thuricin-17 root application under drought, in association with the inoculation of N 2 -fixing Bradyrhizobium japonicum. We measured traits reflecting root architecture: number of tips, root diameter, root length, number of nodules; water fluxes: water potential, stomatal conductance; carbon nutrition: leaf area, photosynthetic rate, biomass and carbon partitioning; nitrogen nutrition: nitrogen partitioning and hormone signalling: abscisic acid concentration during the vegetative growth period. Our results show that thuricin-17 application under water stress increased plant biomass by 17 %, thus masking drought impact. This effect is due to modifications of below-ground structures, with 37 % increase of root and 55 % increase of nodule biomass, and to slight increases of leaf area and photosynthetic rate. We also observed that application of thuricin-17 induced a 30 % increase of root abscisic acid, an increase of root length and of leaf water potential. Finally, thuricin-17 induced an activation of nodule formation by 40 %, a partial restoration of nodule-specific activity, nodule growth and consequently, an increase by 17 % of the total nitrogen amount in the plant. Overall, our findings reveal a new method to decrease the negative impact of water stress. Results also demonstrate that the plant restored an adequate water and N balance by changing its root structure.
Planta, 2003
Lipo-chitooligosaccharides (LCOs), or Nod factors, are host-specific bacteria-to-plant signal mol... more Lipo-chitooligosaccharides (LCOs), or Nod factors, are host-specific bacteria-to-plant signal molecules essential for the establishment of a successful N(2)-fixing legume-rhizobia symbiosis. At submicromolar concentrations Nod factors induce physiological changes in host and non-host plants. Here we show that the Nod factor Nod Bj V(C18:1,MeFuc) of Bradyrhizobium japonicum 532C enhances germination of a variety of economically important plants belonging to diverse botanical families: Zea mays, Oryza sativa (Poaceae), Beta vulgaris (Chenopodaceae), Glycine max, Phaseolus vulgaris (Fabaceae), and Gossypium hirsutum (Malvaceae), under laboratory, greenhouse and field conditions. Similar increases in germination were observed for filtrates of genistein-induced cultures of B. japonicum 532C, while non-induced B. japonicum, induced Bj 168 (a nodC mutant of B. japonicum deficient in Nod factor synthesis) or the pentamer of chitin did not invoke such responses, demonstrating the role of Nod...
Journal of microbiology and biotechnology, 2011
The objective of this work was to investigate the ability of the plant growth-promoting rhizobact... more The objective of this work was to investigate the ability of the plant growth-promoting rhizobacterium Pseudomonas aureofaciens 63-28 to induce plant defense systems, including defense-related enzyme levels and expression of defense-related isoenzymes, and isoflavone production, leading to improved resistance to the phytopathogen Rhizoctonia solani AG-4 in soybean seedlings. Seven-dayold soybean seedlings were inoculated with P. aureofaciens 63-28, R. solani AG-4, or P. aureofaciens 63-28 plus R. solani AG-4 (P+R), or not inoculated (control). After 7 days of incubation, roots treated with R. solani AG-4 had obvious damping-off symptoms, but P+R-treated soybean plants had less disease development, indicating suppression of R. solani AG-4 in soybean seedlings. Superoxide dismutase (SOD) and catalase (CAT) activities of R. solani AG-4-treated roots increased by 24.6% and 54.0%, respectively, compared with control roots. Ascorbate peroxidase (APX) and phenylalanine ammonia lyase (PAL) ...
Plant Growth Regulation, 2010
are bacteriato-plant signals required for the establishment of rhizobialegume nitrogen fixing sym... more are bacteriato-plant signals required for the establishment of rhizobialegume nitrogen fixing symbioses. The ability of LCO [Nod Bj V (C 18:1 , MeFuc)] isolated from B. japonicum (strain 532C), and of oligomers of chitosan (tetramer, pentamer) and chitin (pentamer) to affect the developmental morphology of roots in Arabidopsis thaliana (L.) Heynh ecotype Columbia (Col-0) was assessed using an interactive scannerbased image analysis system. LCOs have been shown to play a role in plant organogenesis at nanomolar concentrations. LCO and the chitin pentamer promoted root growth and development in Arabidopsis at concentrations of 10 nM and 100 lM, respectively. The LCO treated Arabidopsis plants had about 35% longer roots than untreated control plants. Similarly, treatment with 100 lM chitin pentamer (CHIT5) resulted in 26% longer roots than the untreated plants; however, chitosan oligomer (CH4 or CH5) treated plants did not differ from the control plants at either concentration (100 or 1 lM). Both LCOs and the chitin pentamer at higher concentrations increased root surface area, mean root diameter and number of root tips. However, leaf area increase was observed only in plants treated with LCO at 10 nM.
Soil Biology and Biochemistry, 2002
Lipo-chitooligosaccharides (LCOs), also known as nod factors, are the bacteria-to-plant signal mo... more Lipo-chitooligosaccharides (LCOs), also known as nod factors, are the bacteria-to-plant signal molecules synthesized in response to the plant-to-bacteria signals, usually flavonoids. In Canada, low soil temperature is potentially a major factor limiting soybean growth and ...
Planta, 2009
The mechanisms by which many plant growth promoting rhizobacteria (PGPR) affect plants are unknow... more The mechanisms by which many plant growth promoting rhizobacteria (PGPR) affect plants are unknown. We recently isolated a rhizosphere bacterium (Bacillus thuringiensis NEB17), that promotes soybean growth and screened the liquid growth medium in which it grew for plant growth stimulating materials. We have also shown that it produces a bacteriocin (named by us as thuricin-17 and a member of the recently described class IId bacteriocins). Here we show that application of this bacteriocin to leaves (spray) or roots (drench) directly stimulates the growth of both a C(3) dicot (soybean) and a C(4) monocot (corn). This growth stimulation is similar in nature to that previously seen when plants are treated with Nod factors. Strain NEB17 contains three copies of the gene for thuricin 17 that code for identical amino acid sequences. These two lines of evidence suggest that the dual functions of these proteins may have constrained their evolution. This is the first report of direct plant growth enhancement by a bacteriocin.
Plant Physiology and Biochemistry, 2005
Plants possess highly sensitive perception systems by which microbial signal molecules are recogn... more Plants possess highly sensitive perception systems by which microbial signal molecules are recognized. In the Bradyrhizobium-soybean (Glycine max (L.) Merr.) symbiosis, recognition is initiated through exchange of signal molecules, generally flavonoids from soybean and lipo-chitooligosaccharides (Nod factors) from the microsymbiont. Application of the Nod factor Nod Bj-V (C 18:1 , MeFuc) induced soybean resistance to powdery mildew caused by Microsphaera diffusa. Addition of Nod factor (concentrations ranging from 10 −6 to 10 −10 M) to soybean root systems led to reductions in disease incidence. The lowest disease incidence was caused by Nod factor treatment at 10 −6 M. The effect of Nod factor application on fungal growth and development was measured at 4, 12, 48, and 96 h after inoculation. Colony diameter and number of germ tubes per conidium were decreased by 10 −6 M Nod factor. Phenylalanine ammonia lyase (PAL, EC.4.3.1.1.) is the first enzyme of the phenyl propanoid pathway, and is commonly activated as part of plant responses to disease. Treatment of soybean seedlings with Nod factor, through stem wounds, induced PAL activity; the most rapid increase followed treatment with 10 −6 M Nod factor. These data show that soybean plants are able to detect root applied LCO and respond by increased disease resistance.