Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

Five bacteria (Pseudomonas fluorescens, P. fluorescens subgroup G strain 2, P. marginalis, P. putida subgroup B strain 1 and P. syringae strain 1) and three fungi (Penicillium brevicompactum, P. solitum strain 1 and Trichoderma atroviride) were evaluated to determine their promoting effect on the growth of mature healthy tomato plants grown under hydroponic conditions. P. putida and T. atroviride were shown to improve fruit yields in rockwool and in organic medium. The production or degradation of indole acetic acid (IAA) by the two microorganisms was investigated as possible mechanisms for plant growth stimulation. Both P. putida and T. atroviride were shown to produce IAA. The production of IAA by the two microorganisms was stimulated in vitro by the addition of l -tryptophan, tryptamine and tryptophol (200 μg ml−1) in the culture medium. P. putida and T. atroviride also increased the fresh weight of both the shoot and the roots of tomato seedlings grown in the presence of increasing concentrations of l -tryptophan (up to 0.75 mM). Both microorganisms showed partial degradation of IAA in vitro when grown in a minimal medium with or without sucrose. In addition, the capacity of these microorganisms to reduce the deleterious effect of exogenous IAA was investigated using tomato seedlings. The results showed that the roots of tomato seedlings grown in the presence of increasing concentrations of IAA (0–10 μg ml−1) were significantly longer when seeds were previously treated with P. putida or T. atroviride. The reduction in the detrimental effect of IAA on root elongation could be associated with a reduced ethylene production resulting from a decrease of its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) by microbial degradation of IAA in the rhizosphere and/or by ACC deaminase activity present in both microorganisms.

Growth stimulation and fruit yield improvement of greenhouse tomato plants by inoculation with pseudomonas putida or Trichoderma atroviride: Possible role of indole acetic acid (IAA)

Production of exopolysaccharides (EPS) can be used as a criteria for the isolation of stress tolerant microorganisms. In the present study, EPS-producing fluorescent pseudomonads were isolated from alfisols, vertisols, inseptisols, oxisols, and aridisols of different semiarid millet growing regions of India and were screened in vitro for drought tolerance in trypticase soy broth supplemented with different concentrations of polyethylene glycol (PEG6000). Out of the total 81 isolates, 26 could tolerate maximum level of stress (−0.73 MPa) and were monitored for the amount of EPS produced under maximum level of water stress. The strain GAP-P45, isolated from alfisol of sunflower rhizosphere, showed the highest level of EPS production under water stress conditions, was identified as Pseudomonas putida on the basis of 16S rDNA sequence analysis, and was used as seed treatment to study its effect in alleviating drought stress effects in sunflower seedlings. Inoculation of Pseudomonas sp. strain GAP-P45 increased the survival, plant biomass, and root adhering soil/root tissue ratio of sunflower seedlings subjected to drought stress. The inoculated bacteria could efficiently colonize the root adhering soil and rhizoplane and increase the percentage of stable soil aggregates. Scanning electron microscope studies showed the formation of biofilm of inoculated bacteria on the root surface and this, along with a better soil structure, might have protected the plants from the water stress.

Alleviation of drought stress effects in sunflower seedlings by the exopolysaccharides producing Pseudomonas putida strain GAP-P45

Minor components of pulses and their potential impact on human health

This study was conducted with sugar beet in greenhouse and field at two soil type with different organic matter (containing 2.4 and 15.9% OM, referred as the low- and high-OM soil) conditions in order to investigate seed inoculation of sugar beet, with five N2-fixing and two phosphate solubilizing bacteria in comparison to control and mineral fertilizers (N and P) application. Three bacterial strains dissolved P; all bacterial strains fixed N2 and significantly increased growth of sugar beet. In the greenhouse, inoculations with PGPR increased sugar beet root weight by 2.8–46.7% depending on the species. Leaf, root and sugar yield were increased by the bacterial inoculation by 15.5–20.8, 12.3–16.1, and 9.8–14.7%, respectively, in the experiment of low- and high-OM soil. Plant growth responses were variable and dependent on the inoculants strain, soil organic matter content, growing stage, harvest date and growth parameter evaluated. The effect of PGPR was greater at early growth stages than at the later. Effective Bacillus species, such as OSU-142, RC07 and M-13, Paenibacillus polymyxa RC05, Pseudomonas putida RC06 and Rhodobacter capsulatus RC04 may be used in organic and sustainable agriculture.

Growth promotion of plants by plant growth-promoting rhizobacteria under greenhouse and two different field soil conditions

An efficient protocol was developed for qualitative screening of phosphate-solubilizing bacteria, based upon visual observation. Our results indicate that, by using our formulation containing bromophenol blue, it is possible to quickly screen on a qualitative basis the phosphate-solubilizing bacteria. Qualitative analysis of the phosphate solubilized by various groups correlated well with grouping based upon quantitative analysis of bacteria isolated from soil, effect of carbon, nitrogen, salts, and phosphate solubilization-defective transposon mutants. However, unlike quantitative analysis methods that involve time-consuming biochemical procedures, the time for screening phosphate-solubilizing bacteria is significantly reduced by using our simple protocol. Therefore, it is envisaged that usage of this formulation based upon qualitative analysis will be salutary for the quick screening of phosphate-solubilizing bacteria. Our results indicate that the formulation can also be used as a quality control test for expeditiously screening the commercial bioinoculant preparations, based on phosphate solubilizers.

An efficient method for qualitative screening of phosphate-solubilizing bacteria.

Efficacy of seven strains of Pseudomonas fluorescens (Pfsl-7), plant growth-promoting rhizobacteria (PGPR), were tested under field conditions for their ability to protect Cicer arietinum against Sclerotium rolfsii infection. Best protection was observed in strain Pfs3 where 23% seedling mortality was recorded in comparison to 44% in non-treated control. To correlate the induction of phenolic compounds by the PGPRs with disease resistance, qualitative and quantitative alterations of phenolic compounds in different parts of C. arietinum were estimated following PGPR application as seed treatment. High performance liquid chromatographic (HPLC) analysis of the leaves, collars and roots of the PGPR-treated and non-treated (control) plants showed the presence of gallic, ferulic, chlorogenic and cinnamic acids with varied amounts in the PGPR-treated as well as non-treated (control) plants. Maximum accumulation of cinnamic acid was observed in plants treated with Pfs3 strain (1660 ng g -1 fresh wt.) which was almost 19.5 times higher than untreated control plants and also significantly high when compared to other PGPR treatments. Pfs3 also caused maximum accumulation of total phenolics and gallic acid in all chickpea plant parts as compared to other treatments and untreated control. A direct relationship between the level of total phenolics and seedling survivability was observed. PGPR-mediated induction of phenolic compounds as a biochemical barrier in C. arietinum against S. rolfsii infection is envisaged.

Plant Growth‐Promoting Rhizobacteria‐Elicited Alterations in Phenolic Profile of Chickpea (Cicer arietinum) Infected by Sclerotium rolfsii

Collar rot disease of betelvine (Piper betle L.) caused by Sclerotium rolfsii is difficult to control by conventional means by use of chemicals; therefore, use of biocontrol agents is desirable. In the present study, 186 bacterial strains of different morphological types were screened for their biocontrol activity against S. rolfsii under in vitro conditions. Two strains, Pseudomonas fluorescens NBRI-N6 and P. fluorescens NBRI-N, were selected for further studies because of their ability to inhibit the mycelial growth of the pathogen significantly. Spontaneous rifampicin-resistant (Rifr) derivatives of P. fluorescens NBRI-N6 and P. fluorescens NBRI-N showing growth rate and membrane protein composition comparable to the wild type were selected to facilitate their monitoring in the rhizosphere. Field trials demonstrated that strain P. fluorescens NBRI-N6 was better than P. fluorescens NBRI-N in increasing the yield of betelvine significantly, whereas a consortium of the two strains controlled the disease more than either of the strains. The screening method should prove useful in identifying rhizosphere bacteria with the greatest potential for controlling diseases caused by phytopathogenic fungi. RID=”” ID=”” Correspondence to: C.S. Nautiyal; email: nautiyalnbricyahoo.com

Biocontrol of collar rot disease of betelvine (Piper betle L.) caused by Sclerotium rolfsii by using rhizosphere-competent Pseudomonas fluorescens NBRI-N6 and P. fluorescens NBRI-N.

Effect of long-term fertilizer application on crop yields, nutrient uptake and available soil nutrients under different cropping sequences.

“We can be proud of the achievements of independent India in eradicating a begging-bowl image and in creating self-confidence in our agricultural capability. The tasks now relate to the total eradication of hunger and the promotion of an evergreen revolution rooted in the principles of ecology, social and gender equity and employment generation - M. S. Swaminathan”

Sangeeta Mehta

Papers

An efficient method for qualitative screening of phosphate-solubilizing bacteria.

Plant Growth‐Promoting Rhizobacteria‐Elicited Alterations in Phenolic Profile of Chickpea (Cicer arietinum) Infected by Sclerotium rolfsii

Biocontrol of collar rot disease of betelvine (Piper betle L.) caused by Sclerotium rolfsii by using rhizosphere-competent Pseudomonas fluorescens NBRI-N6 and P. fluorescens NBRI-N.

Effect of long-term fertilizer application on crop yields, nutrient uptake and available soil nutrients under different cropping sequences.

Go-mutra and dung based products as viable alternative for sustainable agriculture for our rural marginal farmers