Siderophores: Augmentation of Soil Health and Crop Productivity

Shahid

et al. 2020

IJERPH

Excessive use of fungicides in agriculture may result in substantial accumulation of active residues in soil, which affect crop health and yield. We investigated the response of Raphanus sativus (white radish) to fungicides in soil and potential beneficial interactions of radish plants with fungicide-tolerant plant growth-promoting rhizobacteria (PGPR). The PGPR were isolated from cabbage and mustard rhizospheres. Morphological and biochemical characteristics measured using standard methods, together with analysis of partial 16S rRNA gene sequences, revealed that fungicide-tolerant PGPR, isolates PS3 and AZ2, were closely related to Pseudomonas spp. These PGPR survived in the presence of high fungicide concentrations i.e., up to 2400 μg mL−1 carbendazim (CBZM) and 3200 μg mL−1 hexaconazole (HEXA). Bacterial isolates produced plant growth stimulants even under fungicide stress, though fungicides induced surface morphological distortion and alteration in membrane permeability of these bacteria, which was proved by a set of microscopic observations. Fungicides considerably affected the germination efficiency, growth, and physiological development of R. sativus, but these effects were relieved when inoculated with PGPR isolates. For instance, CBZM at 1500 mg kg−1 decreased whole dry biomass by 71%, whole plant length by 54%, total chlorophyll by 50%, protein content by 61%, and carotenoid production by 29%. After applying isolate AZ2 for white radish grown in CBZM (10 mg kg−1)-amended soil, it could improve plant growth and development with increased whole plant dry weight (10%), entire plant length (13%) and total chlorophyll content (18%). Similarly, isolate PS3 enhanced plant survival by relieving plant stress with declined biomarkers, i.e., proline (12%), malondialdehyde (3%), ascorbate peroxidase (6.5%), catalase (18%), and glutathione reductase (4%). Application of isolates AZ2 and PS3 could be effective for remediation of fungicide-contaminated soil and for improving the cultivation of radish plants while minimizing inputs of fungicides.

Section: Resultsmentioning

confidence: 99%

Fungicide-Tolerant Plant Growth-Promoting Rhizobacteria Mitigate Physiological Disruption of White Radish Caused by Fungicides Used in the Field Cultivation

Shahid

et al. 2020

IJERPH

“…As for Fe uptake, plants can release phyto-siderophores. However, these tend to have a lower affinity for iron compared to microbial siderophores [ 86 ]. Therefore, PGPMs can chelate Fe 3+ to make it available to plant roots, absorbing it through the degradation of chelating agents and their consequent release of iron, the direct uptake of siderophore-Fe complexes or through a ligand exchange reaction [ 87 ].…”

Section: Yeasts As Biostimulant and Biofertilizer Agentsmentioning

confidence: 99%

Culturable Yeasts as Biofertilizers and Biopesticides for a Sustainable Agriculture: A Comprehensive Review

Hernández-Fernández

Cordero-Bueso

Ruíz-Muñoz

et al. 2021

Plants

The extensive use of synthetic fertilizers and pesticides has negative consequences in terms of soil microbial biodiversity and environmental contamination. Faced with this growing concern, a proposed alternative agricultural method is the use of microorganisms as biofertilizers. Many works have been focused on bacteria, but the limited literature on yeasts and their potential ability to safely promote plant growth is gaining particular attention in recent years. Thus, the objective of this review is to highlight the application of yeasts as biological agents in different sectors of sustainable agricultural practices through direct or indirect mechanisms of action. Direct mechanisms include the ability of yeasts to provide soluble nutrients to plants, produce organic acids and phytohormones (indole-3-acetic acid). Indirect mechanisms involve the ability for yeasts to act as biocontrol agents through their high antifungal activity and lower insecticidal and herbicidal activity, and as soil bioremediating agents. They also act as protective agents against extreme environmental factors by activating defense mechanisms. It is evident that all the aspects that yeasts offer could be useful in the creation of quality biofertilizers and biopesticides. Hence, extensive research on yeasts could be promising and potentially provide an environmentally friendly solution to the increased crop production that will be required with a growing population.

“…Siderophore showed the ability to dissolve and reduce the level of heavy metal; thus, it could be claimed to exert a beneficial role in soil normalization in ecosystem. 18 The secondary metabolite was produced by microbe elicited by heavy metals. 19…”

Section: Plant Growth Promoting Activities Of Potential Actinobacteriamentioning

confidence: 99%

Characterization of sponge-associated actinobacteria with potential to promote plant growth on tidal swamps

et al. 2019

Tidal swamps have become one of the highlighted topics in agricultural land development. Rice productivity in a tidal swamp is still low due to the high concentration of Fe, Al, and low pH. Siderophore-producing bacteria were known to alleviate the toxicity of heavy metals for plants. However, the potential of sponge-associated actinobacteria has been rarely reported in siderophore production. This work aimed to characterize the sponge-associated actinobacteria based on their tidal swamps characters and their potency to produce plant growth promoter on stressful tidal swamp imposed characters. The in vitro assay showed that, at the presence of Fe and Al, Car21t isolate produced a dry weight of mycelium reaching up to 289 mg and 204 mg in Yeast Malt Extract medium, respectively. Interestingly, all isolates were able to grow in relatively high salinity condition (7%). Indeed, under stress condition, inoculum of five actinobacteria isolates could produce Indole Acetic Acid and siderophore. These experimental results suggested that all potential isolates provided beneficial effects on the host plant, as evidenced by the rise of root length (9.86%), shoot length (9.44%), and root number (13.93%). Subsequently, our experimental data also indicated that these potential isolates belonged to the genus Streptomyces.