Figure - available from: Scientific Reports
This content is subject to copyright. Terms and conditions apply.
Mantles of Cistanthe longiscapa during preflowering (A) and full-flowering (B) stages at the 2017 flowering desert event in the Atacama Desert.
Source publication
Tomato (Solanum lycopersicum L.) is an important vegetable cultivated around the world. Under field conditions, tomato can be negatively affected by water scarcity in arid and semiarid regions. The application of native plant growth-promoting rhizobacteria (PGPR) isolated from arid environments has been proposed as an inoculant to mitigate abiotic...
Similar publications
Plant growth promoting rhizobacteria (PGPR) can attenuate the adverse effects of water deficit on plant growth. Since drought stress tolerance of bacteria has earlier been associated to biofilm formation, we aimed to investigate the role of bacterial biofilm formation in their PGPR activity upon drought stress. To this end, a biofilm-forming bacter...
Citations
... Specifically, microbial consortia with ACCD, IAA and biofilm producing traits are often highlighted as good options for alleviating plant drought stress (Chieb and Gachomo, 2023;Poudel et al., 2021;Etesami and Maheshwari, 2018). This has been demonstrated in several studies (Bouremani et al., 2023;Rashid et al., 2022;Astorga-Eló et al., 2021;Khan and Singh, 2021;Danish et al., 2020;Zhang et al., 2020). Nevertheless, in some cases, consortia can have a worsening effect than individual test strains, especially under abiotic stress (Finkel et al., 2018). ...
Multi-trait efficiency and interactivity of bacterial consortia used to enhance plant performance under water stress conditions
Keywords:
ACC-deaminase; Indole-3-acetic acid; Rhizobacteria; Biofilm Water-stress
A B S T R A C T
Water stress is a major limiting factor for agricultural production under current and projected climate change scenarios. As a sustainable strategy, plant growth-promoting bacterial consortia have been used to reduce plant water stress. However, few studies have examined the effects of stress on multi-trait efficiency and interactivity of bacterial species. In this study, we used several in-vitro experiments, plant assays and greenhouse trials to investigate the effects of stress and bacterial consortia on 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) activities, indole-3-acetic acid (IAA) production and plant growth-promoting traits (Phosphate-solubilization, starch hydrolysis, siderophores and ammonium production). We further assessed biofilm formation and the chemotactic behaviour in response to ACC. A total of fifteen ACCD rhizobacteria with multiple growthpromoting traits from the dominant plant species from the hyperseasonal Aripo Savannas were screened in this study. Five of the isolates were further analyzed based on their ACCD activities and were tested in single and dual consortium to assess their abilities in promoting growth under simulated drought stress (- 0.35 MPa) and chemically induced ACC conditions (0.03 mM). Our findings showed that bacteria which produce high concentrations of IAA affected the isolates’ ability to promote growth under stress, irrespective of microbial combination
with ACCD activity above the minimal threshold of 20 nmol α-ketobutyrate mg-1 h-1. Biofilm production with co-culture interaction varied greatly across treatments, however, the general trend showed an increase in biofilm under stress induce conditions. The best performing co-culture, UWIGT-83 and UWIGT-120 (Burkholderia sp.) showed enhanced growth in germination assays and in greenhouse trials with Capsicum chinense (Moruga red hot peppers) under drought stress, when compared to non-inoculated treatments. The findings highlight the importance of testing interactivity of bacterial species with multiple growth promoting traits under stress conditions; and proposed the use of ACC growth media as a novel biofilm screening method for selecting potential stress plant growth-promoting bacteria. Better screening strategies for appropriate plant growthpromoting bacteria may narrow the inconsistency observed between laboratory and field trials.
... However, there are increasing attempts to develop tailored bacterial consortia to harness synergetic beneficial effects not obtained by using single species only 16 , although the mechanisms leading to such synergetic PGP effects remain vastly elusive. For instance, several studies have demonstrated that two-or three-member consortia enable beneficial plant physiological and biochemical responses to abiotic stress 14,15,17,18 . In another study, Sun et al. 19 described synergistic activities between Bacillus velezensis SQR9 and an endophytic Pseudomonas stutzeri strain leading to increased plant growth and salt stress tolerance of cucumber plant seedlings. ...
Endophytes isolated from extremophile plants are interesting microbes for improving the stress tolerance of agricultural plants. Here, we isolated and characterized endophytic bacteria showing plant growth-promoting (PGP) traits from plants in two extreme Chilean biomes (Atacama Desert and Chilean Patagonia). Forty-two isolates were characterized as both halotolerant auxin producers (2–51 mg L⁻¹) and 1-aminocyclopropane-1-carboxylate (ACC)-degrading bacteria (15–28 µmol αKB mg protein⁻¹ h⁻¹). The most efficient isolates were tested as single strains, in dual and triple consortia, or in combination with previously reported PGP rhizobacteria (Klebsiella sp. 27IJA and 8LJA) for their impact on the germination of salt-exposed (0.15 M and 0.25 M NaCl) wheat seeds. Interestingly, strain P1R9, identified as Variovorax sp., enhanced wheat germination under salt stress conditions when applied individually or as part of bacterial consortia. Under salt stress, plants inoculated with dual consortia containing the strain Variovorax sp. P1R9 showed higher biomass (41%) and reduced lipid peroxidation (33–56%) than uninoculated plants. Although the underlying mechanisms remain elusive, our data suggest that the application of Variovorax sp. P1R9, alone or as a member of PGP consortia, may improve the salt stress tolerance of wheat plants.
... The growth of endophytic strains on DF medium supplemented with ACC was considered positive for ACC − deaminase activity. The putative ability to fix atmospheric N (N 2 ) among isolated endophytic strains was screened on NFb (nitrogen-free broth) semisolid culture medium, as previously used by Astorga-Eló et al. 74 . Bacterial growth as a 'veil-like' pellicle under the medium surface was considered a putative N 2 fixing strain. ...
... Bacterial growth as a 'veil-like' pellicle under the medium surface was considered a putative N 2 fixing strain. Finally, the production of tryptophan-induced auxins, which is related to plant root growth, was determined by using the Salkowski colorimetric method according to the protocol described by Astorga-Eló et al. 74 . Aliquots (10 µL) of fresh cultures of each isolate were transferred to LB broth supplemented with 5 mM tryptophan (Sigma-Aldrich). ...
Chile is a prominent seed exporter globally, but the seed microbiome of vegetables (46% of seeds) and its role in the early stages of plant growth have remained largely unexplored. Here, we employed DNA metabarcoding analysis to investigate the composition and putative functions of endophytic bacterial communities in ungerminated and germinated seeds of the commercial vegetables Apiaceae (parsley and carrot), Asteraceae (lettuce), Brassicaceae (cabbage and broccoli), and Solanaceae (tomato). Bacterial quantification showed 10⁴ to 10⁸ copies of the 16S rRNA gene per gram of ungerminated and germinated seeds. Alpha diversity analysis (e.g., Chao1, Shannon, and Simpson indices) did not indicate significant differences (Kruskal–Wallis test) between ungerminated and germinated seeds, except for Solanaceae. However, beta diversity (PCoA) analysis showed distinctions (Adonis test) between ungerminated and germinated seeds, except Apiaceae. Pseudomonadota and Bacillota were identified as the dominant and specialist taxa in both ungerminated and germinated seed samples. Chemoheterotrophy and fermentation were predicted as the main microbial functional groups in the endophytic bacterial community. Notably, a considerable number of the 143 isolated endophytic strains displayed plant growth-promoting traits (10 to 64%) and biocontrol activity (74% to 82%) against plant pathogens (Xanthomonas and Pseudomonas). This study revealed the high variability in the abundance, diversity, composition, and functionality of endophytic bacteria between ungerminated and germinated seeds in globally commercialized vegetables. Furthermore, potential beneficial endophytic bacteria contained in their seed microbiomes that may contribute to the microbiome of the early stages, development, growth and progeny of vegetables were found.
... The microorganisms in the substrate regulate physicochemical properties, directly or indirectly affecting the growth of seedlings. Rhizosphere microbes, which resist diseases and relieve the pressures of water shortage, play an essential role in the growth and development of seedlings (Kwak et al., 2018;Astorga-Elo et al., 2021;Meng et al., 2022). Microorganisms not only improve the dissolution of nutrients, secrete various bioactive substances, and resist pathogens simultaneously (Zhalnina et al., 2018), but also play a vital role in biological activities such as the circulation of nutrients and the degradation of pollutants. ...
The utilization of organic solid waste (OSW) for preparing standardized seedling substrates is a main challenge due to its temporal and spatial variability. This study aims to form models based on data from the literature and validate them through experiments to explore a standardized seedling substrate. The typical OSW in Hainan Province, including municipal sewage sludge (MSS), coconut bran (CB), seaweed mud (SM), and municipal sewage sludge biochar (MSSB), was used as raw material. A series of six mixing ratios was tested, namely: T1 (0% MSS: 90% CB), T2 (10% MSS: 80% CB), T3 (30% MSS: 60% CB), T4 (50% MSS: 40% CB), T5 (70% MSS: 20% CB), and T6 (90% MSS: 0% CB). SM and MSSB were added as amendment materials at 5% (w/w) for each treatment. The physicochemical properties of substrates, agronomic traits of rice seedlings and microbial diversity were analyzed. The results showed that the four kinds of OSW played an active role in providing rich sources of nutrients. The dry weight of the above-ground part was 2.98 times greater in T3 than that of the commercial substrate. Furthermore, the microbial analysis showed a higher abundance of Actinobacteria in T3, representing the stability of the composted products. Finally, the successful fitting of the results with the linear regression models could establish relationship equations between the physicochemical properties of the substrate and the growth characteristics of seedlings. The relevant parameters suitable for the growth of rice seedlings were as follows: pH (6.46–7.01), EC (less than 2.12 mS cm−1), DD (0.13–0.16 g cm−3), and TPS (65.68–82.73%). This study proposed relevant parameters and models for standardization of seedling substrate, which would contribute to ensuring the quality of seedlings and OSW resource utilization.
... Thermophilic bacteria from the genus Bacillus isolated from agricultural soils were found to improve wheat growth (Santana et al. 2013;Santana et al. 2020). Tomatoes inoculated with a consortium of thermophilic Bacillus species derived from a native desert flower have also shown improved growth when grown at different levels of water limitation (Astorga-Eló et al. 2021). Similarly, a consortium of thermophilic Bacillus species from hot springs enhanced the field production of mung bean when cultivated under drought condition (Verma et al. 2018). ...
Malaysia is home to a number of hot springs that are rich in microbial diversity including the photosynthetic cyanobacteria. Although this microbial community has been characterised based on metagenomics approach, the culturable thermophilic isolates have not been isolated and characterised extensively. Compared to the mesophiles, information on plant growth promoting (PGP) properties of these thermophiles remain largely untapped. As the amount of arable land for microbial bioprospecting is decreasing due to extensive human activities, the search for alternative source for microbial strains with PGP properties is important for the development of potential biofertilizers. This study sought to isolate and characterise culturable cyanobacteria strains from two local hot springs – Sungai Klah (SK) and Lubuk Timah (LT) located in Perak using morphological and molecular methods. The IAA production from the axenic cultures were measured. The PGP properties were also measured by priming the rice seeds with cyanobacterial water extracts. A total of six strains were isolated from both hot springs. Strains LTM and LTW from LT were identified as Leptolyngbya sp. whereas strains SEM, SEH, STH and STM were identified as Thermosynechococcus elongatus. All six strains produced IAA ranged from 670.10 pg/ ?L to 2010 pg/?L. The water extracts were found to increase the seed amylase activity of the rice seeds from 5th day of germination (DAG) to 10th DAG. In general, the IAA production and increased seed amylase activity might have contributed in enhancing the longest root length, shoot length and root-to-shoot (RS) ratio. To conclude, the thermophilic cyanobacteria from hot springs can be further exploited as a novel source of PGP microbes for the development of biofertilisers.
... These results are in line with numerous other studies that show the potential of PGPR belonging to Bacillus, Brevibacillus, and Pseudomonas genera as biofertilisers [24,28,29,[43][44][45][46][47][48][49][50][51][52]. Bacillus spp. ...
... Similarly, Wang et al. [52] reported that B. laterosporus AMCC100017 promoted the growth of apple rootstock Malus robusta plants by synthesising IAA, increasing photosynthetic efficiency and affecting the plant through multiple metabolic pathways. Astorga-Eló et al. [45] reported that B. laterosporus DSM 25 exhibited ACC deaminase activity in vitro. Also, several studies reported that P. azotoformans strains possess various growth promotion mechanisms, including N fixation, P and K solubilisation, the production of IAA, ammonium, and siderophores, and the exhibition of ACC deaminase activity [24,[26][27][28][29]43,47,59]. ...
Rhizosphere bacteria can provide multiple benefits to plants, including increased nutrient supply, pathogen/disease control, and abiotic stress tolerance, but results from pot trials do not always translate to field conditions. This study tested whether rhizosphere biocontrol bacteria can also provide plant growth promotion and how benefits can be provided at a commercial farm. Commercial lettuce seeds and plants were treated with rhizosphere biocontrol bacteria Bacillus velezensis UQ9000N, B. amyloliquefaciens 33YE, Brevibacillus laterosporus 4YE, and Pseudomonas azotoformans UQ4510An. 33YE increased the head diameter, plant height, and fresh weight of the Green Moon cultivar, while 33YE, UQ4510An, and UQ9000N increased the fresh and dry weight of Liston, a more heat-tolerant cultivar, via a single seed treatment or repeat root treatments under nursery and field conditions across different inoculation schedules and growth stages. Significant growth promotion was also demonstrated when inoculating field plants after transplanting (in particular for 33YE). Applications of these microbial biostimulants to lettuce seeds or plantlets potentially enable earlier transplanting and earlier harvests. Repeat inoculations using irrigation water and long-lasting formulations may further advance the benefits of these biostimulants as microbial biofertilisers for plant growth promotions in the field.
... These results are in line with numerous other studies that show the potential of PGPR belonging to Bacillus, Brevibacillus, and Pseudomonas genera as biofertilisers [24,28,29,[43][44][45][46][47][48][49][50][51][52]. Bacillus spp. ...
... Similarly, Wang et al. [52] reported that B. laterosporus AMCC100017 promoted the growth of apple rootstock Malus robusta plants by synthesising IAA, increasing photosynthetic efficiency and affecting the plant through multiple metabolic pathways. Astorga-Eló et al. [45] reported that B. laterosporus DSM 25 exhibited ACC deaminase activity in vitro. Also, several studies reported that P. azotoformans strains possess various growth promotion mechanisms, including N fixation, P and K solubilisation, the production of IAA, ammonium, and siderophores, and the exhibition of ACC deaminase activity [24,[26][27][28][29]43,47,59]. ...
Citation: Shao, Z.; Arkhipov, A.; Batool, M.; Muirhead, S.R.; Harry, M.S.; Ji, X.; Mirzaee, H.; Carvalhais, L.C.; Schenk, P.M. Rhizosphere Bacteria Biofertiliser Formulations Improve Lettuce Growth and Yield under Nursery and Field Conditions. Agriculture 2023, 13, 1911. https://doi. Abstract: Rhizosphere bacteria can provide multiple benefits to plants, including increased nutrient supply, pathogen/disease control, and abiotic stress tolerance, but results from pot trials do not always translate to field conditions. This study tested whether rhizosphere biocontrol bacteria can also provide plant growth promotion and how benefits can be provided at a commercial farm. Commercial lettuce seeds and plants were treated with rhizosphere biocontrol bacteria Bacillus velezensis UQ9000N, B. amyloliquefaciens 33YE, Brevibacillus laterosporus 4YE, and Pseudomonas azotoformans UQ4510An. 33YE increased the head diameter, plant height, and fresh weight of the Green Moon cultivar, while 33YE, UQ4510An, and UQ9000N increased the fresh and dry weight of Liston, a more heat-tolerant cultivar, via a single seed treatment or repeat root treatments under nursery and field conditions across different inoculation schedules and growth stages. Significant growth promotion was also demonstrated when inoculating field plants after transplanting (in particular for 33YE). Applications of these microbial biostimulants to lettuce seeds or plantlets potentially enable earlier transplanting and earlier harvests. Repeat inoculations using irrigation water and long-lasting formulations may further advance the benefits of these biostimulants as microbial biofertilisers for plant growth promotions in the field.
... Frontiers in Plant Science frontiersin.org Tiwari et al., 2018;Moreno-Galvań et al., 2020;Astorga-Elóet al., 2021). The increase in abundance of Candidatus Nitrosocosmicus (Archaea, Thaumarchaeota phylum) was evidenced in all soils after G10, but especially in tolerant plants to water deficit from R+F soils. ...
Climate change challenges modern agriculture to develop alternative and eco-friendly solutions to alleviate abiotic and/or biotic stresses. The use of soil microbiomes from extreme environments opens new avenues to discover novel microorganisms and microbial functions to protect plants. In this study we confirm the ability of a bioinoculant, generated by natural engineering, to promote host development under water stress. Microbiome engineering was mediated through three factors i) Antarctic soil donation, ii) water deficit and iii) multigenerational tomato host selection. We revealed that tomato plants growing in soils supplemented with Antarctic microbiota were tolerant to water deficit stress after 10 generations. A clear increase in tomato seedling tolerance against water deficit stress was observed in all soils over generations of Host Mediated Microbiome Engineering, being Fildes mixture the most representatives, which was evidenced by an increased survival time, plant stress index, biomass accumulation, and decreased leaf proline content. Microbial community analysis using 16s rRNA gene amplicon sequencing data suggested a microbiome restructuring that could be associated with increased tolerance of water deficit. Additionally, the results showed a significant increase in the relative abundance of Candidatus Nitrosocosmicus and Bacillus spp. which could be key taxa associated with the observed tolerance improvement. We proposed that in situ microbiota engineering through the evolution of three factors (long-standing extreme climate adaption and host and stress selection) could represent a promising strategy for novel generation of microbial inoculants.
... Rhizosphere microbiota have an essential role in plant disease resistance and the mitigation of water scarcity stress (Astorga-Elo et al., 2021;Kwak et al., 2018). To further investigate the relationship between rhizobacteria composition with seedling growth, samples were collected from representative tomato substrates at the end of the seedling stage, and rhizobacteria composition was measured using 16 S rRNA high-throughput sequencing technology. ...
High-value utilization of biogas residue is essential to drive the development of the biogas industry. This study investigated the feasibility of total or partial replacement for peat (100%, 75%, 50%, 25% and 0%) by corn straw biogas residue and dairy manure biogas residue in growth media for tomato and pepper seedlings. The experiment was arranged in a completely-randomized design, tomato and pepper seeds were sown into each media and grown under commercial nursery conditions until they reached commercial transplant size. The results showed that growth of tomato and pepper was reduced in media containing corn straw biogas residue. However, tomato and pepper seedlings growing in a media of 50% dairy manure biogas residue were considered to be the most satisfactory. The results of the bacterial community analysis showed that the highest abundance of Anaerolineaceae was found in CS100 that meaning immaturity. Furthermore, for a biogas plant with a daily biogas production of 10,000 m³, biogas energy utilization and biogas residue substitution for peat could reduce 439,437 kg/year of CO2 equivalent emissions and arouse 3300,000￥benefit per year by replacing peat. Thus, partial replacement of peat by dairy manure biogas residue as a growth media could be promoted for its wide environmental and economic benefits.
... Similar results were reported by Fernandes et al. [39], who tested the same biostimulants on common bean and suggested water-stress-mitigating effects of the tested biostimulants on nutritional value parameters such as fat, proteins and ash content. These results could be associated with the improved nutrient status of plants, since previous studies have established the positive role of arbuscular mycorrhizal fungi (AMF), bacteria and seaweed extracts on nutrient uptake [31,35,[46][47][48]. Moreover, the application of biostimulants containing chelated metals improved specific nutritional aspects of tomato fruit under full irrigation, which could be considered as a sustainable tool to improve fruit quality. ...
The aim of the present study was to evaluate the effects of three biostimulant products (Nomoren (N), Twin Antistress (TW), x-Stress (XS) and control treatment (C: no biostimulants added)) on the nutritional value, chemical composition and bioactive properties of greenhouse tomato fruit grown under full (W+: 100% of field capacity) and deficit irrigation (W-: 70% of field capacity) conditions. Fat content was the highest for the fully irrigated plants that received no bi-ostimulants (CW+), while proteins and carbohydrates and energetic value were the highest in the XSW+ treatment. The content of the main detected sugars (fructose, glucose and trehalose) varied depending on the irrigation and biostimulant treatment. The highest amounts of individual and total organic acids and tocopherols were recorded in fully irrigated plants treated with Twin Antis-tress (TW), whereas the lowest overall values were observed under deficit irrigation for plants that received the XS treatment. The most abundant fatty acids were palmitic (27.5-36.0%) and linoleic acid (27.4-35.4%), followed by oleic (9.2-21.2%), linolenic (5.4-13.1%) and stearic acid (5.3-6.8%). Moreover, the highest values of β-carotene and lycopene were recorded for the CW-and NW+ treatments , respectively. The TWW+ showed the highest antioxidant activity for both assays tested (TBARS and OxHLIA). Most of the tested extracts showed lower antibacterial activity against the tested bacteria compared to the positive controls. On the other hand, CW+, XSW+ and XSW-treatments showed higher antifungal activity (MIC values) than positive controls. In conclusion, each biostimulant product had a different effect on the determined characteristics depending on the level of irrigation. Therefore, more research is needed to better identify the mechanisms of action and the physiological processes, after which the tested biostimulants may be used to standardize the application of such products in tomato cultivation.
