Exogenous plant growth regulators/plant growth promoting bacteria roles in mitigating water-deficit stress on chicory (Cichorium pumilum Jacq.) at a physiological level

7-Methyl-7,8-dihydro-4a,7-methano-4aH-benzocycloheptene-2,6(9H,5H-dione (6) was prepared and reduced to a 3 : 7 mixture of the trans- and cis-decalin derived ketones (8) and (15). Each compound was further elaborated to the plant-growth-promoting acids (13), (14), (16) and (17). Dienone (5) was also reduced (NaBH4, hydrogenation) to a 7 : 3 mixture of the cis- and trans-decalin derivatives (11) and (9). The stereochemistry of (11), and by inference (12), was determined by correlation with the known ketone (7).

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Phenotypic and genotypic characterization of inhabitant PGPR strains of Pseudomonas from apple orchards

Journal of Applied and Natural Science ◽

10.31018/jans.v7i2.703 ◽

2015 ◽

Vol 7 (2) ◽

pp. 893-902

Author(s):

Kumari Manorma ◽

Shweta Sharma ◽

Mohinder Kaur

Keyword(s):

Antifungal Activity ◽

Plant Growth ◽

Plant Growth Regulators ◽

Growth Regulators ◽

Siderophore Production ◽

Pseudomonas Sp ◽

Genotypic Analysis ◽

Plant Growth Promoting ◽

Growth Promoting

Aim of present research was to isolate and characterize the Pseudomonas strains phenotypically and genotypically from the rhizospheric soil of apple orchard at Maggota (Shimla district) Himachal Pradesh. Phenotypic identification of the test isolates was based on morphological, physiological and biochemical characterization of the bacteria followed by genotypic analysis using rRNA gene sequencing and RAPD-PCR analysis. The fourteen Pseudomonas sp. isolates were screened out for various plant growth promoting activities such as siderophore production, antifungal activity, phosphate solubilisation, HCN and ammonia production, production of plant growth regulators and lytic enzymes. Isolates showed production of plant growth regulators (auxins, gibberellins and cytokinins) in the range of 19.67-83.33μg/ml, 21.00-58.67 μg/ml and 12.33-43.33 μg/ml respectively. Pseudomonas strains showed phosphate solubilising activity in the range of 12.33-63.33 Pi μg/ml, 53.66-93.44 % SU siderophore production and 11.33-96.33mm (diameter) protease activity in plate assay. Five Pseudomonas isolates i.e. An-16-kul, An-1-mag, An-2-mag, An-3-mag and An-6-mag showed maximum antifungal activity against plant pathogenic fungi. Therefore, the aim of present investigation was to study multifarious plant growth promoting qualities of Pseudomonas sp. and to select more efficient PGPR strain of fluorescent Pseudomonas sp. which can be further used as biofertilizer.

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Biofilm Producing Rhizobacteria With Multiple Plant Growth-Promoting Traits Promote Growth of Tomato Under Water-Deficit Stress

Frontiers in Microbiology ◽

10.3389/fmicb.2020.542053 ◽

2020 ◽

Vol 11 ◽

Author(s):

Md. Manjurul Haque ◽

Md Khaled Mosharaf ◽

Moriom Khatun ◽

Md. Amdadul Haque ◽

Md. Sanaullah Biswas ◽

...

Keyword(s):

Plant Growth ◽

Water Deficit ◽

Xanthomonas Campestris ◽

Plant Pathogens ◽

Water Deficit Stress ◽

Rrna Gene ◽

Growth Promoters ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Plant Growth Promoting Traits

Plant growth-promoting rhizobacteria (PGPR) not only enhance plant growth but also control phytopathogens and mitigate abiotic stresses, including water-deficit stress. In this study, 21 (26.9%) rhizobacterial strains isolated from drought-prone ecosystems of Bangladesh were able to form air–liquid (AL) biofilms in the glass test tubes containing salt-optimized broth plus glycerol (SOBG) medium. Based on 16S rRNA gene sequencing, Pseudomonas chlororaphis (ESR3 and ESR15), P. azotoformans ESR4, P. poae ESR6, P. fluorescens (ESR7 and ESR25), P. gessardii ESR9, P. cedrina (ESR12, ESR16, and ESR23), P. veronii (ESR13 and ESR21), P. parafulva ESB18, Stenotrophomonas maltophilia ESR20, Bacillus cereus (ESD3, ESD21, and ESB22), B. horikoshii ESD16, B. aryabhattai ESB6, B. megaterium ESB9, and Staphylococcus saprophyticus ESD8 were identified. Fourier transform infrared spectroscopy studies showed that the biofilm matrices contain proteins, polysaccharides, nucleic acids, and lipids. Congo red binding results indicated that these bacteria produced curli fimbriae and nanocellulose-rich polysaccharides. Expression of nanocellulose was also confirmed by Calcofluor binding assays and scanning electron microscopy. In vitro studies revealed that all these rhizobacterial strains expressed multiple plant growth-promoting traits including N2 fixation, production of indole-3-acetic acid, solubilization of nutrients (P, K, and Zn), and production of ammonia, siderophores, ACC deaminase, catalases, lipases, cellulases, and proteases. Several bacteria were also tolerant to multifarious stresses such as drought, high temperature, extreme pH, and salinity. Among these rhizobacteria, P. cedrina ESR12, P. chlororaphis ESR15, and B. cereus ESD3 impeded the growth of Xanthomonas campestris pv. campestris ATCC 33913, while P. chlororaphis ESR15 and B. cereus ESD21 prevented the progression of Ralstonia solanacearum ATCC® 11696TM. In a pot experiment, tomato plants inoculated with P. azotoformans ESR4, P. poae ESR6, P. gessardii ESR9, P. cedrina ESR12, P. chlororaphis ESR15, S. maltophilia ESR20, P. veronii ESR21, and B. aryabhattai ESB6 exhibited an increased plant growth compared to the non-inoculated plants under water deficit-stressed conditions. Accordingly, the bacterial-treated plants showed a higher antioxidant defense system and a fewer tissue damages than non-inoculated plants under water-limiting conditions. Therefore, biofilm-producing PGPR can be utilized as plant growth promoters, suppressors of plant pathogens, and alleviators of water-deficit stress.

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