Effect of some Pseudomonas strains and Agave americana L. on wheat germination under salt stress

Currently, several efforts focus remedying the problem of agricultural soil salinity using eco-friendly strategies. This study aimed particularly the study of Triticum durum (durum wheat) seeds germination in the presence of Pseudomonas strains and hydro-alcoholic extract of Agave americana L. under saline stress conditions. The preliminary phytochemical screening of A. americana, phylogenetic identification and production of indole-3-acetic acid (IAA) by Pseudomonas strains, in vitro impact of hydro-alcoholic extract and Pseudomonas strains combination on salt stress resistance, preliminary effects of A. americana on Triticum durum germination and phytopathogenic fungi inhibition under salt stress were carried out using corresponding protocols. In in vitro trials, phytochemical screening revealed the richness of A. americana in polyphenols (1014.062±161.017 mM GA equivalent/g FW) and flavonoids (51.065±27.391 mg quercetin equivalent/g FW). The ability of Pseudomonas strains to produce the phytohormone indole-3-acetic acid (IAA) varied from 116.67±8.25 µg/ml to 857.14±80.50 µg/ml. The leaf extract of A. americana is an effective osmoprotectant that improves the resistance of the strain P1 Pseudomonas plecoglissicida to saline stress. In in vivo experiments, the extract of A. americana did not show any effect on the germination of wheat seeds. However, it effectively inhibited the contamination of seeds by phytopathogenic fungi during germination and saline conditions. Findings of the study revealed that Pseudomonas plecoglissicida and A. americana extract are very promising for the inhibition of phytopathogenic fungi and the alleviation of salt stress

Plant Growth Promoting Microbes as Biofertilizers: Promising solutions for sustainable agriculture under climate change associated abiotic stresses

Abiotic stresses are major constraints for plant growth, crop yield and global food security. Plant physiological, biochemical and molecular processes are highly affected under unfavorable environmental conditions, resulting in substantial losses to crop productivity and requiring an immediate response. Abiotic stress resistant plant growth-promoting rhizobacteria (PGPR) are a profitable and sustainable solution because of their efficiency in plant growth regulation, crop yield improvement and abiotic stress alleviation. They help plants to cope with growth inhibitory effects of abiotic stresses through several mechanisms, mainly phytohormones and osmolyte production, improvement of nutrient acquisition, enhancement of antioxidant system. Plant-PGPR interactions are vital for sustainable agriculture and industrial purposes, because they are based on biological processes and replace conventional agricultural practices. PGPR may play a key role as an ecological engineer to solve environmental stress problems. The use of microbes is a feasible and potential technology to help meeting the future global food needs with reduced impact on soil and environmental quality. Present review deals about the abiotic stresses (drought and salinity) affecting plant growth and highlights the impact of PGPR on restoration of plant growth under the stressful conditions with the goal of developing an eco-friendly and cost-effective strategy for agricultural sustainability

Bacterial Inoculation and Extracts of Opuntia Rackets or Marine Algae Trigger Distinct Proline Balances in Tomato Salt Stress Alleviation

High salt levels in soil can severely limit plant development and diminish the positive effect of plant-growth-promoting rhizobacteria (PGPR). However, extracts of organisms adapted to high salinity, such as Opuntia ficus-indica (OFI) and Enteromorpha intestinalis (EI), can restore the growth of PGPR. Therefore, we used OFI or EI extracts and their combination with the PGPR Achromobacter xylosoxidans BOA4 to evaluate salt stress relief in tomato (Solanum lycopersicum). The experimental setup consisted of a plant pot trial under greenhouse conditions with 12 treatments: control, irrigation with OFI extract; EI extract; BOA4-inoculated plus OFI extract and BOA4-inoculated plus EI extract under no salinity or salinity conditions (150 mM NaCl). The percentage of germination, and plant’s fresh and dry weight were registered 30 and 46 days after sowing. At 46 days, the ratio between proline and glutamic acid concentration (PR/GA) was determined, expecting high PR/GA ratios in plants more responsive to salt stress since proline is an osmolyte mainly synthesized from glutamate. The results showed that 52% of the control seeds under salt stress germinated, a figure that was increased to 92% in OFI-treated seeds. Tomato plants were shown to be very sensitive to salt stress since the dry weight was ca. one fourth that of the plants grown without salinity. However, EI or BOA4 plus EI stimulated plant biomass by ca. 3 times compared to the control with salt, restoring plant biomass to values comparable to those of control plants grown without salinity. The joint treatments with BOA4 and EI or OFI caused distinct PR/GA levels in plant tissues. An inverse relationship between the sum of relative shoot proline and glutamic acid contents and shoot biomass accumulation was observed, namely in treatments accumulating more biomass under no salinity and salinity conditions. This indicates that the proline/glutamate pathway represents a carbon sink that is needed to fight stress and is competing with the carbon flow used for growth.info:eu-repo/semantics/publishedVersio

Potential of Pseudomonas stutzeri strains isolated from rhizospheric soil endowed with antifungal activities against phytopathogenic fungus Stemphylium botryosum

Abstract. Mokrani S, Bejaoui B, Belabid L, Nabti E, Mokrani S. 2020. Potential of Pseudomonas stutzeri strains isolated from rhizospheric soil endowed with antifungal activities against phytopathogenic fungus Stemphylium botryosum. Biodiversitas 21: 47-54. In this present study, two Pseudomonas strains P4 and P5 isolated from rhizospheric soil were characterized for PGP (Plant Growth Promoting) traits production like HCN (Hydrogen Cyanid), siderophores and IAA (Indole Acetic Acid). Phylogenic tree based on 16S DNAr identification-related the two strains P4 and P5 to Pseudomonas stutzeri NR 116489 and NR 113652.1. One phytopathogenic fungus St-bt (Stemphylium botryosum) was isolated from Phaseolus vulgaris L. Macroscopic and microscopic identification attributed it to the genus Stemphylium. Antifungal activities of the two Pseudomonas strains P4 and P5 against fungus isolate St-bt had revealed very highly significant inhibition percentages of 38.46± 3.85% and 56.56± 2.22% for each strain, respectively.</jats:p