scholarly journals Improvement of Cadmium Detoxification Potential and Plant Growth Promotion by Bacterial Endophytes

Author(s):  
Ihsan Ullah

Cadmium (Cd) is a heavy metal that suppresses plant growth; however, application of endophytic bacteria can increase resistance of plants against Cd, as well as improve plant growth. Two bacterial endophytic strains were isolated from Solanum nigrum and were identified as Serratia sp. AI001 and Enterobacter sp. AI002 by 16S DNA sequencing. Strains AI001 and AI002, tolerated up to 25 mg/mL Cd in broth culture and showed phosphate solubilization potential in Pikovskaya agar medium. AI001 and AI002 produced indole-3-acetic acid, which was confirmed by gas spectrometry-mass chromatography. Brassica plants stressed with 0, 5, 15, and 25 mg/L Cd showed significant decrease in plant growth, chlorophyll content and biomass, and significant increase in Cd dose-dependent electrolyte leakage. Inoculation of strain AI001 or AI002 significantly enhanced the plant growth attributes of shoot length, root length, chlorophyll content, and biomass as compared to those in uninoculated plants. Reduced glutathione contents in plants stressed with different concentrations of Cd also increased with inoculation of AI001 and AI002. The reason of Cd resistance enhancement in plants by inocula could be due to their greater plant growth promoting activities as well as their antioxidative response.

Author(s):  
Cun Yu ◽  
Ying Yao

Endophytic fungi were isolated from Phoebe bournei and their diversity and antimicrobial and plant growth-promoting activities were investigated. Of the 389 isolated endophytic fungi, 88.90% belonged to phylum Ascomycota and 11.10% to phylum Basidiomycota. The isolates were grouped into four taxonomic classes, 11 orders, 30 genera, and 45 species based on internal transcribed spacer sequencing and morphologic analysis. The host showed a strong affinity for the genera Diaporthe and Phyllosticta. The diversity of the fungi was highest in autumn, followed by spring and summer, and was lowest in winter. The fungi exhibited notable tissue specificity in P. bournei, and the species richness and diversity were highest in the root across all seasons. Five isolates showed antimicrobial activity against eight plant pathogens, and reduced the incidence of leaf spot disease in P. bournei. Additionally, 9 biocontrol isolates showed plant growth-promoting activity, with five significantly promoting P. bournei seedling growth. This is the first report on the endophytic fungi of P. bournei and their potential applicability to plant disease control and growth promotion.


1996 ◽  
Vol 42 (3) ◽  
pp. 279-283 ◽  
Author(s):  
T. C. Noel ◽  
C. Sheng ◽  
C. K. Yost ◽  
R. P. Pharis ◽  
M. F. Hynes

Early seedling root growth of the nonlegumes canola (Brassica campestris cv. Tobin, Brassica napus cv. Westar) and lettuce (Lactuca saliva cv. Grand Rapids) was significantly promoted by inoculation of seeds with certain strains of Rhizobium leguminosarum, including nitrogen- and nonnitrogen-fixing derivatives under gnotobiotic conditions. The growfh-promotive effect appears to be direct, with possible involvement of the plant growth regulators indole-3-acetic acid and cytokinin. Auxotrophic Rhizobium mutants requiring tryptophan or adenosine (precursors for indole-3-acetic acid and cytokinin synthesis, respectively) did not promote growth to the extent of the parent strain. The findings of this study demonstrate a new facet of the Rhizobium–plant relationship and that Rhizobium leguminosarum can be considered a plant growth-promoting rhizobacterium (PGPR).Key words: Rhizobium, plant growth-promoting rhizobacteria, PGPR, indole-3-acetic acid, cytokinin, roots, auxotrophic mutants.


2013 ◽  
Vol 26 (5) ◽  
pp. 546-553 ◽  
Author(s):  
Ana Zúñiga ◽  
María Josefina Poupin ◽  
Raúl Donoso ◽  
Thomas Ledger ◽  
Nicolás Guiliani ◽  
...  

Although not fully understood, molecular communication in the rhizosphere plays an important role regulating traits involved in plant–bacteria association. Burkholderia phytofirmans PsJN is a well-known plant-growth-promoting bacterium, which establishes rhizospheric and endophytic colonization in different plants. A competent colonization is essential for plant-growth-promoting effects produced by bacteria. Using appropriate mutant strains of B. phytofirmans, we obtained evidence for the importance of N-acyl homoserine lactone-mediated (quorum sensing) cell-to-cell communication in efficient colonization of Arabidopsis thaliana plants and the establishment of a beneficial interaction. We also observed that bacterial degradation of the auxin indole-3-acetic acid (IAA) plays a key role in plant-growth-promoting traits and is necessary for efficient rhizosphere colonization. Wildtype B. phytofirmans but not the iacC mutant in IAA mineralization is able to restore promotion effects in roots of A. thaliana in the presence of exogenously added IAA, indicating the importance of this trait for promoting primary root length. Using a transgenic A. thaliana line with suppressed auxin signaling (miR393) and analyzing the expression of auxin receptors in wild-type inoculated plants, we provide evidence that auxin signaling in plants is necessary for the growth promotion effects produced by B. phytofirmans. The interplay between ethylene and auxin signaling was also confirmed by the response of the plant to a 1-aminocyclopropane-1-carboxylate deaminase bacterial mutant strain.


2015 ◽  
Vol 3 (5) ◽  
Author(s):  
Arvind Gulati ◽  
Mohit Kumar Swarnkar ◽  
Pratibha Vyas ◽  
Praveen Rahi ◽  
Rishu Thakur ◽  
...  

The complete genome sequence of 6.45 Mb is reported here for Pseudomonas trivialis strain IHBB745 (MTCC 5336), which is an efficient, stress-tolerant, and broad-spectrum plant growth-promoting rhizobacterium. The gene-coding clusters predicted the genes for phosphate solubilization, siderophore production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, indole-3-acetic acid (IAA) production, and stress response.


2020 ◽  
Vol 25 (2) ◽  
pp. 22
Author(s):  
Rethinasamy Velazhahan ◽  
Shima Nasser Hamed Al-Mamari ◽  
Abdullah Mohammed Al-Sadi ◽  
Issa Hashil Al-Mahmooli ◽  
S. P. Sathish Babu

Spent mushroom substrate (SMS) is widely used as fertilizer and to control plant diseases. The microorganisms surviving in SMS play a crucial role in plant growth promotion and biocontrol properties of SMS. In this study, an effort was made to isolate and characterize the bacterial species present in the SMS of Agaricus bisporus and to study their antagonistic potential, plant growth-promoting ability and indole-3-acetic acid (IAA) producing trait. Six different bacterial isolates exhibiting morphological variabilities were obtained from the SMS by serial dilution technique. On the basis of 16S rRNA gene sequences, these isolates were identified as Staphylococcus epidermidis (Sh1 and Sh3), S. aureus (Sh2), Bacillus albus (Sh4), Delftia lacustris (Sh6) and Comamonas aquatica (Sh7). These bacterial strains were assayed for their antagonism against Pythium aphanidermatum, a phytopathogenic oomycete. The results of in vitro dual culture assay revealed that all the 6 bacterial isolates showed low levels of suppression of P. aphanidermatum and recorded less than 5 mm inhibition zone. Among the bacterial isolates, S. epidermidis Sh3 recorded the maximum inhibition zone of 4.2 mm. Plant growth promotion test using roll paper towel method revealed that C. aquatica Sh7, B. albus Sh4, D. lacustris Sh6 and S. epidermidis Sh3 caused a significant increase in seedling vigour of cucumber compared to control. The seeds treated with the bacterial isolate C. aquatica Sh7 showed the maximum seedling vigor. Assessment of in vitro production of IAA by the bacterial isolates revealed that the bacterial isolates highly varied (ranging from 0.28 to 9.25 mg L-1) in their potential for production of IAA. The maximum amount of IAA was produced by C. aquatica Sh7 (9.25 mg L-1), while the minimum was produced by S. epidermidis Sh1 (0.28 mg L-1).


Author(s):  
Jitendra Mishra ◽  
Malvika Rajnandani ◽  
Naveen Kumar Arora

In India, maize is the third most important food crop after rice and wheat but the productivity is severely affected as the plant is also prone to a number of diseases caused by fungi and bacteria. Ear rot caused by <italic>Fusarium moniliforme</italic> is one of the economically important soil and seed borne disease of maize and not easily controlled by chemical methods. Antagonistic bacteria may constitute an alternative for improving the crop productivity. In this study 13 fluorescent pseudomonads were isolated from rhizosphere of different plants and screened for plant growth promoting activities and biocontrol potential against <italic>F. moniliforme</italic> ITCC No. 2193. Among them a potential isolate, W3Gr-6(b) not only inhibited growth of <italic>F. moniliforme</italic> under in-vitro conditions but was also capable of maize growth promotion in presence of pathogen.


2019 ◽  
Vol 18 (3) ◽  
Author(s):  
Toga Pangihotan Napitupulu ◽  
Atit Kanti ◽  
I Made Sudiana

The objective of the study was to isolate microorganism that can produce growth hormone, fix atmospheric nitrogen, and solubilize inorganic phosphate that may be used for enhancing the growth of banana in marginal land.  A total of 25 bacteria associated with banana that belonged to six genera were isolated from namely Acinetobacter, Enterobacter, Pantoea, Klebsiella, Rhizobium, and Cupriavidus genera. Gammaproteobacteria is the dominant class, followed by Betaproteobacteria and Alphaproteobacteria. All isolates were screened for multiple plant growth promoting traits which may play a role in banana growth, namely fixing nitrogen, solubilizing phosphate, and producing Indole Acetic Acid (IAA). Twenty-two isolates were capable to fix nitrogen, 21 isolates can solubilize insoluble phosphate, and 15 isolates produced IAA dependent of L-Tryptophan presence. Despite most of the bacteria isolates exhibited one plant growth-promoting activities, Enterobacter and Klebsiella genera showed three of plant growth promoting bacteria traits. 


2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Prashant Singh ◽  
Vinod Kumar ◽  
Sanjeev Agrawal

Bacterial inoculants are known to possess plant growth promoting abilities and have potential as liquid biofertilizer application. Four phytase producing bacterial isolates (phytase activity in the range of 0.076–0.174 U/mL), identified asAdvenellaspecies (PB-05, PB-06, and PB-10) andCellulosimicrobiumsp. PB-09, were analyzed for their plant growth promoting activities like siderophore production, IAA production, HCN production, ammonia production, phosphate solubilization, and antifungal activity. All isolates were positive for the above characteristics except for HCN production. The solubilization index for phosphorus on Pikovskaya agar plates was in the range of 2–4. Significant amount of IAA (7.19 to 35.03 μg/mL) production and solubilized phosphate (189.53 to 746.84 μg/mL) was noticed by these isolates at different time intervals. Besides that, a greenhouse study was also conducted with Indian mustard to evaluate the potential of these isolates to promote plant growth. Effect of seed bacterization on various plant growth parameters and P uptake by plant were used as indicators. The plant growth promoting ability of bacterial isolates in pot experiments was correlated to IAA production, phosphate solubilization, and otherin vitrotests. On the basis of present findings, isolate PB-06 was most promising in plant growth promotion with multiple growth promoting characteristics.


2011 ◽  
Vol 19 (4) ◽  
pp. 476-484 ◽  
Author(s):  
Luo Fei ◽  
Wang Ya ◽  
Zeng Qinggui ◽  
Yan Riming ◽  
Zhang Zhibin ◽  
...  

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