Involvement ofgacSandrpoSin enhancement of the plant growth-promoting capabilities ofEnterobacter cloacaeCAL2 and UW4

2001 ◽  
Vol 47 (8) ◽  
pp. 698-705 ◽  
Author(s):  
Saleema S Saleh ◽  
Bernard R Glick

The plant growth-promoting bacteria Enterobacter cloacae CAL2 and UW4 were genetically transformed with a multicopy plasmid containing an rpoS or gacS gene from Pseudomonas fluorescens. The transformed strains were compared with the nontransformed strains for growth, indoleacetic acid (IAA) production, antibiotic production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, siderophore production, cell morphology, and the ability to promote canola root elongation. All transformed strains had a longer lag phase, were slower in reaching stationary phase, and attained a higher cell density than the nontransformed strains. Transformation resulted in cells that were significantly shorter than the nontransformed cells. The transformed strains also produced significantly more IAA than the nontransformed strains. Introduction of rpoS or gacS from Pseudomonas fluorescens was associated with a reduction in the production of both antibiotics, 2,4-diacetylphloroglucinol and mono-acetylphloroglucinol, produced by Enterobacter cloacae CAL2. With Enterobacter cloacae CAL2, plasmid-borne rpoS, but not gacS, increased the level of ACC deaminase activity, while introduction of rpoS in Enterobacter cloacae UW4 caused a decrease in ACC deaminase activity. Neither gacS nor rpoS significantly affected the level of siderophores synthesized by either bacterial strain. Overproduction of either GacA or RpoS in Enterobacter cloacae CAL2 resulted in a significant increase in the root lengths of canola seedlings when seeds were treated with the bacteria, and overproduction of RpoS caused an increase in canola shoot as well as root lengths.Key words: plant growth-promoting bacteria, canola, ethylene, ACC deaminase, GacS, RpoS, indoleacetic acid, siderophores, antibiotics.

2005 ◽  
Vol 51 (6) ◽  
pp. 511-514 ◽  
Author(s):  
Qiaosi Li ◽  
Saleema Saleh-Lakha ◽  
Bernard R Glick

Carnation cuttings treated with non-transformed and 1-aminocyclopropane (ACC) deaminase-containing Azospirillum brasilense Cd1843 produced significantly more roots than untreated controls and fewer roots than cuttings treated with 0.1% indolebutyric acid (IBA). The roots produced by cuttings treated with ACC deaminase-containing Azospirillum brasilense Cd1843 were the longest roots resulting from any of the treatments, followed by non-transformed Azospirillum brasilense Cd1843, 0.1% IBA, and treatment with water. The results are interpreted in terms of a previously proposed model of bacterial promotion of plant growth by ACC deaminase and indoleacetic acid, and may have implications for the use of plant growth-promoting bacteria in the flower industry.Key words: ACC deaminase, carnation, cuttings, rooting, Azospirillum brasilense.


2007 ◽  
Vol 53 (12) ◽  
pp. 1291-1299 ◽  
Author(s):  
Youai Hao ◽  
Trevor C. Charles ◽  
Bernard R. Glick

In addition to the well-known roles of indoleacetic acid and cytokinin in crown gall formation, the plant hormone ethylene also plays an important role in this process. Many plant growth-promoting bacteria (PGPB) encode the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which can degrade ACC, the immediate precursor of ethylene in plants, to α-ketobutyrate and ammonia and thereby lower plant ethylene levels. To study the effect of ACC deaminase on crown gall development, an ACC deaminase gene from the PGPB Pseudomonas putida UW4 was introduced into Agrobacterium tumefaciens C58, so that the effect of ACC deaminase activity on tumour formation in tomato and castor bean plants could be assessed. Plants were also coinoculated with A. tumefaciens C58 and P. putida UW4 or P. putida UW4-acdS– (an ACC deaminase minus mutant strain). In both types of experiments, it was observed that the presence of ACC deaminase generally inhibited tumour development on both tomato and castor bean plants.


2001 ◽  
Vol 47 (4) ◽  
pp. 368-372 ◽  
Author(s):  
Donna M Penrose ◽  
Bernard R Glick

It was previously proposed that plant growth-promoting bacteria that possess 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase could utilize ACC that is present in the exudate of germinating canola seeds. The uptake and cleavage of ACC by these bacteria would lower the level of ACC, and thus ethylene within the plant, and reduce the extent of its inhibition on root elongation. To test part of the above mentioned model, ACC levels were monitored in canola seed tissues and exudate during germination. Lower amounts of ACC were present in the exudate and tissues of seeds treated with the plant growth-promoting bacterium Enterobacter cloacae CAL3, than in control seeds treated with MgSO4. The ACC-related compounds, α- and γ-aminobutyric acids, both known to stimulate ethylene production, were also measured in the canola seed exudate and tissues. Approximately the same levels of α-aminobutyric acid were present in the exudates of the bacterium-treated seeds and the control seeds, but the amount of α-aminobutyric acid was lower in the tissues of the bacterium-treated seeds than in the control seeds. Smaller quantities of γ-aminobutyric acid were seen in both the exudate and tissues of the E. cloacae CAL3-treated seeds than in the control seeds.Key words: ACC ethylene, canola, seed extract, seed exudate, plant growth-promoting bacteria.


2004 ◽  
Vol 50 (7) ◽  
pp. 475-481 ◽  
Author(s):  
Chunxia Wang ◽  
Daoben Wang ◽  
Qi Zhou

Pseudomonas fluorescens CS85, which was previously isolated from the rhizosphere of cotton seedlings, acts as both a plant growth-promoting bacterium and a biocontrol agent against cotton pathogens, including Rhizoctonia solani, Colletotrichum gossypii, Fusarium oxysporum f sp. vasinfectum, and Verticillium dahliae. Strain CS85 was labeled separately with luxAB and gusA. The labeled strains were stably maintained and had high levels of expression of the marker genes, luxAB and gusA, after successive transfers on nonselective medium, long-term preservation, and after recovery from soil. The labeled strains displayed similar biocontrol characteristics (e.g., antibiosis, effects of growth -promotion and disease -control) to the original strain. The labeled strains colonized all surfaces of the young plant root zones, such as roots hairs and lateral roots, although the distribution of the labeled strains on the root surfaces was not uniform. Moreover, the population densities of the labeled strains on the root surface were stably maintained at high levels during the first 2 weeks of plant growth in the native soil, so that about 107–108 CFU/g root were detected, then decreased gradually. Nevertheless, approximately 106 CFU/g root of the labeled strains were observed on the root surfaces 35 d after planting.Key words: plant growth-promoting bacteria, luxAB, gusA, root colonization.


2016 ◽  
Vol 4 (3) ◽  
Author(s):  
Rocío M. Gamez ◽  
Fernando Rodríguez ◽  
Sandra Ramírez ◽  
Yolanda Gómez ◽  
Richa Agarwala ◽  
...  

Pseudomonas fluorescens is a well-known plant growth-promoting rhizobacterium (PGPR). We report here the first whole-genome sequence of PGPR P. fluorescens evaluated in Colombian banana plants. The genome sequences contains genes involved in plant growth and defense, including bacteriocins, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, and genes that provide resistance to toxic compounds.


2021 ◽  
Vol 9 (9) ◽  
pp. 1841
Author(s):  
Angelika Fiodor ◽  
Surender Singh ◽  
Kumar Pranaw

Combating the consequences of climate change is extremely important and critical in the context of feeding the world’s population. Crop simulation models have been extensively studied recently to investigate the impact of climate change on agricultural productivity and food security. Drought and salinity are major environmental stresses that cause changes in the physiological, biochemical, and molecular processes in plants, resulting in significant crop productivity losses. Excessive use of chemicals has become a severe threat to human health and the environment. The use of beneficial microorganisms is an environmentally friendly method of increasing crop yield under environmental stress conditions. These microbes enhance plant growth through various mechanisms such as production of hormones, ACC deaminase, VOCs and EPS, and modulate hormone synthesis and other metabolites in plants. This review aims to decipher the effect of plant growth promoting bacteria (PGPB) on plant health under abiotic soil stresses associated with global climate change (viz., drought and salinity). The application of stress-resistant PGPB may not only help in the combating the effects of abiotic stressors, but also lead to mitigation of climate change. More thorough molecular level studies are needed in the future to assess their cumulative influence on plant development.


2001 ◽  
Vol 47 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Donna M Penrose ◽  
Barbara A Moffatt ◽  
Bernard R Glick

Previously, it was proposed that plant growth-promoting bacteria that possess the enzyme, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, can reduce the amount of ethylene produced by a plant and thereby promote root elongation. To test this model, canola seeds were imbibed in the presence of the chemical ethylene inhibitor, 2-aminoethoxyvinyl glycine (AVG), various strains of plant growth-promoting bacteria, and a psychrophilic bacterium containing an ACC deaminase gene on a broad host range plasmid. The extent of root elongation and levels of ACC, the immediate precursor of ethylene, were measured in the canola seedling roots. A modification of the Waters AccQ*Tag Amino Acid Analysis Method(tm) was used to quantify ACC in the root extracts. It was found that, in the presence of the ethylene inhibitor, AVG, or any one of several ACC deaminase-containing strains of bacteria, the growth of canola seedling roots was enhanced and the ACC levels in these roots were lowered.


1998 ◽  
Vol 44 (9) ◽  
pp. 833-843 ◽  
Author(s):  
Salehuzzaman Shah ◽  
Jiping Li ◽  
Barbara A Moffatt ◽  
Bernard R Glick

We have recently proposed that one way that plant growth-promoting rhizobacteria (PGPR) stimulate plant growth is through the activity of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which causes a lowering of plant ethylene levels resulting in longer roots. As part of an effort to understand the role of this enzyme in PGPR, the genes for ACC deaminase from two PGPR, Enterobacter cloacae CAL2 and UW4, have been isolated. These genes are highly homologous to the ACC deaminase genes from Pseudomonas strains 6G5 and F17 and similar to the ACC deaminase gene from Pseudomonas sp. strain ACP. The region downstream (i.e., at the 3'-terminal end) of the strain UW4 ACC deaminase gene has a potential hairpin-like transcription termination site. The regions upstream of the strains UW4 and CAL2 ACC deaminase genes contain putative ribosome-binding sites; however, the promoter sequences have not yet been identified. Southern hybridization experiments suggest that there is a single copy of the ACC deaminase gene in Enterobacter cloacae strains UW4 and CAL2 and that there may be several different types of ACC deaminase genes in different microbes. The cloned ACC deaminase gene can be expressed in Escherichia coli enabling this bacterium to grow on ACC as a sole source of nitrogen and confers upon both Escherichia coli and Pseudomonas spp. strains that are transformed with this gene the ability to promote the elongation of the roots of canola seedlings.Key words: plant growth-promoting rhizobacteria, PGPR, 1-aminocyclopropane-1-carboxylate, ACC, ACC deaminase, ethylene, soil bacteria.


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