Microbial signaling and plant growth promotion

2014 ◽  
Vol 94 (6) ◽  
pp. 1051-1063 ◽  
Author(s):  
Fazli Mabood ◽  
Xiaomin Zhou ◽  
Donald L. Smith
Keyword(s):  
Plant Growth ◽  
Recent Work ◽  
Plant Growth Promotion ◽  
Environmental Conditions ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Disease Suppression ◽  
Plant Microbe Interaction ◽  
Plant Growth Promoting ◽  
Soil Microbial Population

Mabood, F., Zhou, X. and Smith, D. L. 2014. Microbial signaling and plant growth promotion. Can. J. Plant Sci. 94: 1051–1063. The rhizosphere offers a complex microhabitat where root exudates provide a diverse mixture of organic compounds that are used as nutrients or signals by the soil microbial population. On the other hand, these soil microorganisms produce compounds that directly or indirectly assist in plant growth promotion. The widely recognized mechanisms of plant growth promotion are biofertilization, production of phytohormones, suppression of diseases through biocontrol, induction of disease resistance and production of volatile signal compounds. During the past few decades our understanding of the interaction between rhizobacteria and plants has expanded enormously and this has resulted in application of microbial products used as crop inoculants (as biofertilizers), for increased crop biomass and disease suppression. However, this plant–microbe interaction is affected by adverse environmental conditions, and recent work has suggested that inoculants carrying plant-to-bacteria or bacteria-to-plant signals can overcome this and promote plant productivity under stressful environmental conditions. Very recent work has also shown that some plant growth-promoting rhizobacteria secrete novel signaling molecules that also promote plant growth. The use of rhizobacterial signaling in promoting plant growth offers a new window of opportunity, especially when we are looking at plants to provide biofuels and novel bioproducts. Developing technologies that can enhance plant growth and productivity is imperative.

scholarly journals Mixtures of Plant-Growth-Promoting Rhizobacteria Enhance Biological Control of Multiple Plant Diseases and Plant-Growth Promotion in the Presence of Pathogens

Plant Disease ◽  
2018 ◽  
Vol 102 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Ke Liu ◽  
John A. McInroy ◽  
Chia-Hui Hu ◽  
Joseph W. Kloepper
Keyword(s):  
Biological Control ◽  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Pythium Ultimum ◽  
Plant Diseases ◽  
Disease Suppression ◽  
Plant Growth Promoting ◽  
Growth Promoting

Several studies have shown that mixtures of plant-growth-promoting rhizobacteria (PGPR) could enhance biological control activity for multiple plant diseases through the mechanisms of induced systemic resistance or antagonism. Prior experiments showed that four individual PGPR strains—AP69 (Bacillus altitudinis), AP197 (B. velezensis), AP199 (B. velezensis), and AP298 (B. velezensis)—had broad-spectrum biocontrol activity via antagonism in growth chambers against two foliar bacterial pathogens (Xanthomonas axonopodis pv. vesicatoria and Pseudomonas syringae pv. tomato) and one of two tested soilborne fungal pathogens (Rhizoctonia solani and Pythium ultimum). Based on these findings, the overall hypothesis of this study was that a mixture of two individual PGPR strains would exhibit better overall biocontrol and plant-growth promotion than the individual PGPR strains. Two separate greenhouse experiments were conducted. In each experiment, two individual PGPR strains and their mixtures were tested for biological control of three different diseases and for plant-growth promotion in the presence of the pathogens. The results demonstrated that the two individual PGPR strains and their mixtures exhibited both biological control of multiple plant diseases and plant-growth promotion. Overall, the levels of disease suppression and growth promotion were greater with mixtures than with individual PGPR strains.

scholarly journals Characterization of Selected Plant Growth-Promoting Rhizobacteria and Their Non-Host Growth Promotion Effects

2021 ◽  
Author(s):  
Di Fan ◽  
Donald L. Smith
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Content Type ◽  
Host Growth ◽  
Plant Growth Promoting ◽  
Growth Promoting

There are pressing needs to reduce the use of agrochemicals, and PGPR are receiving increasing interest in plant growth promotion and disease protection. This study follows up our previous report that the four newly isolated rhizobacteria promote the growth of Arabidopsis thaliana .

scholarly journals Burkholderia sp. from rhizosphere of Rhododendron arboretum: Isolation, identification and plant growth promotory (PGP) activities

2014 ◽  
Vol 6 (2) ◽  
pp. 473-479 ◽  
Author(s):  
Shweta Nailwal ◽  
Md. Shahbaz Anwar ◽  
Kamal Kant Budhani ◽  
Amit Verma ◽  
Tapan Kumar Nailwal
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Research Work ◽  
Growth Index ◽  
Wheat Plant ◽  
Plant Growth Promoting Rhizobacteria ◽  
Remarkable Change ◽  
Enhanced Production ◽  
Plant Growth Promoting

Plant growth promoting rhizobacteria (PGPR) is beneficial bacteria that colonize plant roots and enhance plant growth by wide variety of mechanism like phosphate solubilisation, etc. Use of PGPR has steadily increased in agriculture and offers an attractive way to replace chemical fertilizers, pesticides and supplements. The present research work was designed to isolate and characterize the PGP activity of Burkholderia sp. For this purpose rhizospheric soil from Rhododendron arboreum of Kumaun Himalaya was collected and efficient bacterial strain was screened on the basis of phosphate solubilization. Further, assessment of various parameters of plant growth promotion activity was done and enhanced production of IAA (16.4 μgml-1) and (20.8 μgml-1) was observed in the presence of 250μgml-1 and 500 μg ml-1 of tryptophan, respectively. Correspondingly, in respect of 7.8 μg ml-1 IAA without tryptophan, and their confirmation was executed by TLC. A remarkable change in color from green to reddish-brown zone on CAS plates, suggests the positive result for siderophore production, and finally the seed germination and pot trial experiment depicted the growth index of wheat plant. Therefore, the present study suggests that Burkholderia sp. is beneficial for plant growth promotion.

scholarly journals A Framework for the Selection of Plant Growth-Promoting Rhizobacteria Based on Bacterial Competence Mechanisms

2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Carol V. Amaya-Gómez ◽  
Mario Porcel ◽  
Leyanis Mesa-Garriga ◽  
Martha I. Gómez-Álvarez
Keyword(s):  
Hydrogen Peroxide ◽  
Plant Growth ◽  
Decision Analysis ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Screening Strategy ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Selection Of

ABSTRACT The use of plant growth-promoting rhizobacteria (PGPR) is increasingly meaningful for the development of more environmentally friendly agricultural practices. However, often the PGPR strains selected in the laboratory fail to confer the expected beneficial effects when evaluated in plant experiments. Insufficient rhizosphere colonization is pointed out as one of the causes. With the aim of minimizing this inconsistency, we propose that besides studying plant growth promotion traits (PGP), the screening strategy should include evaluation of the microbial phenotypes required for colonization and persistence. As a model, we carried out this strategy in three Rhizobium sp. strains that showed phosphorus solubilization ability and production of siderophores. All strains displayed colonization phenotypes like surface spreading, resistance to hydrogen peroxide, and formed biofilms. Regarding their ability to persist, biofilm formation was observed to be influenced by pH and the phosphorus nutrient provided in the growth media. Differences in the competence of the strains to use several carbon substrates were also detected. As part of our framework, we compared the phenotypic characteristics of the strains in a quantitative manner. The data analysis was integrated using a multicriteria decision analysis (MCDA). All our results were scored, weighted, and grouped as relevant for PGP, colonization, or persistence. MCDA demonstrated that, when the phenotypes related to PGP and colonization are weighted over those for persistence, strain B02 performs better than the other two Rhizobium sp. strains. The use of our framework could assist the selection of more competent strains to be tested in greenhouse and field trials. IMPORTANCE Numerous plant growth-promoting rhizobacteria (PGPR) have been inoculated into the soil with the aim of improving the supply of nutrients to crop plants and decreasing the requirement of chemical fertilizers. However, sometimes these microbes fail to competitively colonize the plant roots and rhizosphere. Hence, the plant growth promotion effect is not observed. Here, we describe a new screening strategy aiming at the selection of more competent PGPR. We evaluated bacterial phenotypes related to plant growth promotion, colonization, and persistence. Our results demonstrated that despite the fact that our Rhizobium sp. strains successfully solubilized phosphorus and produced siderophores, their abilities to spread over surfaces, resist hydrogen peroxide, and form biofilms varied. Additionally, a multicriteria decision analysis was used to analyze the data that originated from bacterial physiological characterizations. This analysis allowed us to innovatively evaluate each strain as a whole and compare the performances of the strains under hypothetical scenarios of bacterial-trait requirements.

Enhancement of verticillium wilt resistance in tomato transplants by in vitro co-culture of seedlings with a plant growth promoting rhizobacterium (Pseudomonas sp. strain PsJN)

1998 ◽  
Vol 44 (6) ◽  
pp. 528-536 ◽  
Author(s):  
V K Sharma ◽  
J Nowak
Keyword(s):  
Plant Growth ◽  
Verticillium Wilt ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Disease Suppression ◽  
Pseudomonas Sp ◽  
Plant Growth Promoting ◽  
Growth Promoting

The potential utilization of a plant growth promoting rhizobacterium, Pseudomonas sp. strain PsJN, to enhance the resistance of tomato transplants to verticillium wilt was investigated. Plant growth and disease development were tested on the disease-susceptible cultivar Bonny Best after Verticillium dahliae infection of tissue culture plantlets bacterized in vitro (by co-culturing with the bacterium) and seedlings bacterized in vivo (after 3 weeks growth in the greenhouse). Significant differences in both disease suppression and plant growth were obtained between in vitro bacterized and nonbacterized (control) plants. The degree of protection afforded by in vitro bacterization depended on the inoculum density of V. dahliae; the best and worst protection occurred at the lowest (103 conidia ·mL-1) and highest (106 conidia ·mL-1) levels, respectively. In contrast, the in vivo bacterized tomatoes did not show plant growth promotion when compared to the nonbacterized control plants. When challenged with Verticillium, significant growth differences between in vivo bacterized plants (26.8% for shoot height) and nonbacterized controls were only seen at the 3rd week after inoculation. Compared with the in vitro inoculation, there was no delay in the verticillium wilt symptom expression, even at the lowest concentration of V. dahliae, by in vivo PsJN inoculation. These results suggest that endophytic colonization of tomato tissues is required for the Verticillium-resistance responses. Plant growth promotion preceeds the disease-resistance responses and may depend on the colonization thresholds and subsequent sensitization of hosts.Key words: Pseudomonas sp., plant growth promoting rhizobacterium, Verticillium dahliae, tomato, colonization, plant growth promotion, disease suppression.

scholarly journals Long Term Comparison of Talc- and Peat-Based Phytobeneficial Pseudomonas fluorescens and Pseudomonas synxantha Bioformulations for Promoting Plant Growth

2020 ◽  
Vol 4 ◽  
Author(s):  
Amy Novinscak ◽  
Martin Filion
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Quantitative Polymerase Chain Reaction ◽  
Plant Growth Promoting Rhizobacteria ◽  
Promotion Activity ◽  
Plant Growth Promoting ◽  
Commercial Applications ◽  
Micro Organisms

Use of plant growth promoting rhizobacteria (PGPR) is an important strategy in sustainable agriculture. Among PGPR, many Pseudomonas strains are of great interest due to their abilities to colonize and thrive in the rhizosphere, in addition to displaying mechanisms in plant growth promotion and biocontrol activities. However, as Pseudomonas strains are non-spore forming micro-organisms, their development into stable bioformulations for commercial applications can be difficult. This study examined over a long term period the effect of two different carriers, peat and talc, to prepare bioformulations using phytobeneficial Pseudomonas strains belonging to two taxonomical groups of interest: P. fluorescens and P. synxantha. Each strain has previously demonstrated plant growth promotion activity when inoculated in the rhizosphere. Each bioformulation was stored at ambient temperature and their viability was measured up to 180 days. In parallel, every 30 days (up to 180 days) each bioformulation was also applied in the rhizosphere of plantlets to validate their plant growth promotion activity, and their establishment in the rhizosphere was quantified by using strain-specific quantitative polymerase chain reaction assays. The viability of both Pseudomonas strains in the bioformulations was found to decrease after the first 15 days and remained relatively stable for up to 180 days. When applying the bioformulations to Buglossoides arvensis plantlets, the expected plant growth promotion was observed when using up to 180 day-old formulations of P. fluorescens and up to 120 day-old formulations of P. synxantha, with similar results for both carriers. Establishment of both Pseudomonas strains in the rhizosphere inoculated with the peat-based carrier bioformulations stored for up to 180 days was found to be stable. While a lower establishment of P. fluorecens in the rhizosphere was observed when talc-based bioformulations were stored for 90 days or more, rhizosphere colonization by P. synxantha talc-based bioformulations remained stable for up to 180 days. In conclusion, both peat and talc appear to be suitable carriers for Pseudomonas bioformulations, however strain-specific variability exists and therefore the viability of each Pseudomonas strain and its capacity to maintain its plant growth promotion activity should be validated in different substrates before determining which formulation to use.

scholarly journals Effects of two rhizobacteria inoculants on maize growth performance at different concentrations of glyphosate

2020 ◽  
Vol 37 (1) ◽  
pp. 21-37
Author(s):  
P.O. Akintokun ◽  
E. Ezaka ◽  
A.K. Akintokun ◽  
O.A. Oyedele
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Field Studies ◽  
Significant Difference ◽  
Plant Growth Promoting ◽  
Number Of Leaves ◽  
Growth Promoting ◽  
Screen House

The use of Rhizobacteria as biofertilizer is on the increase due to the ability of some of the bacteria to solubilize some insoluble essential nutrients in the soil and produce phytohormones necessary for plant growth. The effectiveness of two plant growth promoting rhizobacteria (Bacillus cereus and Pseudomonas aeruginosa) in plant growth promotion at different concentrations of glyphosate were evaluated. Some agronomic parameters such as plant height, size of girth, number of leaves on the screen house and field were measured and recorded. The results of the effects of P. aeruginosa on the height of maize at different concentrations showed that the plants inoculated with the isolates and planted on the soil without glyphosate (control) recorded the highest height on the 2nd (34.9 cm), 4th (52.45 cm), 6th (61.17 cm) and 8th (66.25 cm) weeks after planting, when compared to those planted on the soil spiked with different concentrations of glyphosate. The effects of the isolates on the size of girth of maize on the soil spiked with different concentrations of glyphosate showed the highest girth size on the soil inoculated with P. aeruginosa eight weeks after planting (8 WAP) with a girth size of 2.0cm and least at 14.4 mg/ml of glyphosate with a girth size of 1.2 cm at 8 weeks after planting. Similar trend was observed on the soil inoculated with B. cereus (without glyphosate) with the highest girth in the 2nd and 4th WAP (1.02 and 1.42 cm, respectively). The results of our field studies showed no significant difference (P≤0.05) in the height and number of leaves of the maize at different treatments and time (weeks after planting). Similar trend was observed i n the yield of maize. This study has shown that these isolates can be useful as biofertilizers especially in the absence or at low concentration of glyphosate. Keywords: Rhizobacteria, maize, Inoculants, Plant-growth-promotion.

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