IAA-producing bacteria and bacterial-feeding nematodes promote Arabidopsis thaliana root growth in natural soil

Jiang, Ying; Wu, Yue; Xu, Wensi; Cheng, Yongqiang; Chen, Jiandong; Xu, Li; Hu, Feng; Li, Huixin

doi:10.1016/j.ejsobi.2012.05.003

Cited by 33 publications

(24 citation statements)

References 41 publications

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“…This compound is also known to be directly involved in ISR in plants (Weller et al, 2012). Bacterivorous nematodes can also stimulate PGPR effects on plant growth (Jiang et al, 2012). Addition of bacterivorous nematodes together with Burkholderia or Pseudomonas to plants growing in natural soil increased microbial biomass (Jiang et al, 2012), indicating a stimulation of bacterial abundance by grazing.…”

Section: Interactions Between Pseudomonas and Bacterivores And Decompmentioning

confidence: 99%

Getting the ecology into interactions between plants and the plant growth-promoting bacterium Pseudomonas fluorescens

Hol¹,

Bezemer²,

Biere³

2013

Front. Plant Sci.

119

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Plant growth-promoting rhizobacteria (PGPR) are increasingly appreciated for their contributions to primary productivity through promotion of growth and triggering of induced systemic resistance in plants. Here we focus on the beneficial effects of one particular species of PGPR (Pseudomonas fluorescens) on plants through induced plant defense. This model organism has provided much understanding of the underlying molecular mechanisms of PGPR-induced plant defense. However, this knowledge can only be appreciated at full value once we know to what extent these mechanisms also occur under more realistic, species-diverse conditions as are occurring in the plant rhizosphere. To provide the necessary ecological context, we review the literature to compare the effect of P. fluorescens on induced plant defense when it is present as a single species or in combination with other soil dwelling species. Specifically, we discuss combinations with other plant mutualists (bacterial or fungal), plant pathogens (bacterial or fungal), bacterivores (nematode or protozoa), and decomposers. Synergistic interactions between P. fluorescens and other plant mutualists are much more commonly reported than antagonistic interactions. Recent developments have enabled screenings of P. fluorescens genomes for defense traits and this could help with selection of strains with likely positive interactions on biocontrol. However, studies that examine the effects of multiple herbivores, pathogens, or herbivores and pathogens together on the effectiveness of PGPR to induce plant defenses are underrepresented and we are not aware of any study that has examined interactions between P. fluorescens and bacterivores or decomposers. As co-occurring soil organisms can enhance but also reduce the effectiveness of PGPR, a better understanding of the biotic factors modulating P. fluorescens–plant interactions will improve the effectiveness of introducing P. fluorescens to enhance plant production and defense.

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Section: Interactions Between Pseudomonas and Bacterivores And Decompmentioning

confidence: 99%

Getting the ecology into interactions between plants and the plant growth-promoting bacterium Pseudomonas fluorescens

Hol¹,

Bezemer²,

Biere³

2013

Front. Plant Sci.

119

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“…or Xanthomonas sp. have been shown to produce the phytohormone indole acetic acid (IAA) to promote plant root growth and/or the enzyme ACC-deaminase (1-aminocyclopropane-1-carboxylate deaminase), which delays root senescence by reducing ethylene levels under stress conditions [14][15][16][17]. These PGPMs have also been shown to synthesize various antifungal metabolites (e.g.…”

Section: Introductionmentioning

confidence: 99%

Densely rooted rhizosphere hotspots induced around subsurface NH4 +-fertilizer depots: a home for soil PGPMs?

Nkebiwe

Neumann

Müller

2017

Chem. Biol. Technol. Agric.

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Background: Populations of plant growth-promoting microorganisms (PGPMs) inoculated in natural soil typically decline over time due unfavourable biotic and/or abiotic factor(s). Improving subsurface root density may enhance PGPM establishment due to high concentrations of organic nutrients released as root exudates. Placing subsurface root-attracting NH 4 + -fertilizer depots may form such zones of dense localized rooting ("rhizosphere hotspots") that can enhance PGPM survival. Nevertheless, required soil conditions that favour formation of rhizosphere hotspots are unknown. This study aimed to investigate: (1) background soil N min effect on NH 4 + -depot-zone root growth; (2) PGPM tolerance to high NH 4 + concentrations (± nitrification inhibitor, DMPP); (3) ability to solubilize sparingly soluble inorganic phosphates; (4) and establishment in a subsurface NH 4 + -depot. Methods:We conducted a greenhouse rhizobox experiment using spring wheat (Triticum aestivum L.) to investigate the effect of background N min (0, 5, 20 and 60 mg N kg Conclusion:These results show the first promising effects of combining fertilizer placement and application of P-solubilizing PGPMs on plant growth.

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“…For treatment of turf, the producer recommended rate is 10 g Proradix suspended in 200-400 l water and applied on an area of 1000 m 2 . This rate is commensurate with 4.4 × 10 6 CFUs kg −1 soil DM, assuming a soil bulk density of 1.5 g cm −3 and a treated soil depth of 10 cm. The producer also refers to higher application rates for different plant species: 1 × 10 10 CFUs kg −1 soil for substrate-inoculation in pot-grown tomato or barley [40,41] and 8 × 10 10 CFUs kg −1 seed for seed-inoculation in pot-and field-grown barley [41].…”

Section: Pot Experimentsmentioning

confidence: 98%

“…After a few minutes, color change along the root surface could be observed, yellow for acidification below pH 5.2 and purple for alkalinization above pH 6.8. In order to read pH changes, color standards were prepared by mixing 50 µl pH buffer solutions (4,5,6,7,8,9, and 10) with 450 µl bromocresol-purple-agar solution in small transparent glass-vial caps and allowed to solidify.…”

Section: Rhizobox Experimentsmentioning

confidence: 99%

“…PGPMs have been shown to fix N [3], mineralize organic soil N [4], stimulate plant root growth [5][6][7] and mycorrhization [8][9][10], which enhances spatial nutrient acquisition from large soil volumes, and induce tolerance or resistance to biotic [11] and abiotic stresses [12,13]. Nevertheless, plant growth-promoting effects of PGPMs realized in labs and greenhouses tend to be weak or even disappear when PGPMs are tested under field conditions.…”

Section: Introductionmentioning

confidence: 99%

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Improving fertilizer-depot exploitation and maize growth by inoculation with plant growth-promoting bacteria: from lab to field

Nkebiwe

Weinmann

Müller

2016

Chem. Biol. Technol. Agric.

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Background: Among other responses, plants tend to increase root growth to scavenge nutrients from more soil when soil nutrient concentrations are low. Placement of fertilizers near seeds or roots facilitates nutrient acquisition by target crop plants. Nevertheless, nutrient uptake from soil-placed fertilizer-depots depends on increased uptake rates and efficient spatial exploitation of the depot by roots. The aim of our study was to optimize exploitation of subsurface fertilizer-depots by inoculating the depot zone with promising plant growth-promoting microorganisms (PGPMs) as bio-effectors. If included in depots, root-attracting NH 4 + or HPO 4 2− /H 2 PO 4 − ions may also enhance rooting within the depot, which in turn improves survival and root colonization by inoculated PGPMs; a consequence of high levels of microbial nutrients exuded in densely rooted soil. Methods:We tested maize (Zea mays L.) in two greenhouse (pot and rhizobox) and two field experiments (2014 and 2015). A core treatment was NH 4 + -fertilizer placed as a subsurface depot (Depot). In the field, there was also NH 4 + -fertilizer broadcasted and incorporated in soil (Broad). Depot and Broad were each with PGPM as bio-effector (BE) or without (NoBE). Bio-effectors included: Pseudomonas sp. DSMZ 13134 (BE1) and Bacillus amyloliquefaciens FZB42 (BE2, only in field trials). Results and discussion:In pots, Depot with BE1 led to 59 % higher shoot dry matter, 50 % higher shoot N content, and 64 % higher shoot P content than without PGPM. In rhizoboxes, higher root length density (RLD), lower rhizosphere pH, and higher BE1-colonization rate were measured in the fertilizer depot compared to the corresponding zone for controls with homogenous NO 3 − supply. Depot led to higher shoot N and P concentrations (+26.6 % N; +20.6 % P) and contents (+11.1 % N; +17.6 % P) than control. BE1 led to higher shoot N concentration (+13.5 %) than NoBE. In the field, fertilizer-depot soil had higher RLD than corresponding non-depot soil. BE1 led to doubled fertilizer-depot RLD in comparison to without (2014). In 2014, Depot led to 7.4 % higher grain yield than Broad (not statistically significant), whereas BE broadcast had no effect. In 2015, Depot led to 5.8 % higher fresh shoot biomass than Broad, below-seed placement of BE1 led to higher fresh (+7.1 %) and dry (+8.0 %) shoot biomass than NoBE. Conclusion: Results show promising growth-effects of Pseudomonas sp. DSMZ 13134 on field-grown maize.

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IAA-producing bacteria and bacterial-feeding nematodes promote Arabidopsis thaliana root growth in natural soil

Cited by 33 publications

References 41 publications

Getting the ecology into interactions between plants and the plant growth-promoting bacterium Pseudomonas fluorescens

Getting the ecology into interactions between plants and the plant growth-promoting bacterium Pseudomonas fluorescens

Densely rooted rhizosphere hotspots induced around subsurface NH4 +-fertilizer depots: a home for soil PGPMs?

Improving fertilizer-depot exploitation and maize growth by inoculation with plant growth-promoting bacteria: from lab to field

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