Endophytes for Managing Biotic and Abiotic Stress in Plants

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Plant Microbe Interactions".

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 37304

Special Issue Editors


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Guest Editor
Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
Interests: plant microbe interactions; soil and plant microbiome; microbial diversity; biological control; biofertilizers; biofungicides; plant nutrition; medicinal plant
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Guest Editor
Babasaheb Bhimrao Ambedkar University, Lukhnow, UP, India
Interests: plant microbe interactions; PGPR; rhizosphere

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Guest Editor
State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
Interests: microbiology in extreme environments; environmental microbiology; microbial ecology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Endophytes are microorganisms that symbiotically reside in plant tissues either inter- or intra-cellularly, maintaining a mutualistic association. These unique microorganisms influence several vital activities of host plants by playing key roles as proficient plant-growth promoters, inducing systemic resistance against pathogen attack, and helping to counteract abiotic stresses such as salinity, drought, extreme temperatures, and metal toxicity. Molecular mechanisms governing endophyte-mediated stress responses include the modification of host genetic machinery through cascades of actions or directly by the secretion of metabolites. This is carried out through the elicitation of stress-related genes or inducing the synthesis of biomolecules which in turn trigger plant defense pathways resulting in tolerance to environmental stresses. Endophytes could represent an eco-friendly approach to improving the growth and yield of crops in a sustainable manner. They could also be used for climate-resilient cropping systems, which are needed in the era of climate change. Endophytes are now also known to be a source of novel metabolites, and can be exploited in areas like bioremediation, biodegradation, pharmaceuticals, and more. However, studies of plant–endophyte interactions are still in their nascent stage, and there are several untapped mechanisms which need to be explored and unleashed. With the amalgamation of prominent biotechnological approaches, future insights in this area could open numerous paths towards multifaceted arrays of finely evolved plant–microbe interactions. This Special Issue invites research articles and reviews in the abovementioned areas, which should be largely focused on unraveling the plant–endophyte interactions, the mechanisms involved, and the role of these exceptional microorganisms in mitigating the biotic and abiotic stresses faced by plants.

Dr. Egamberdieva Dilfuza
Prof. Dr. Naveen Kumar Arora
Prof. Dr. Wen Jun Li
Guest Editors

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Keywords

  • endophytes
  • biotic stress
  • abiotic stress
  • salinity
  • drought
  • phytopathogens

Published Papers (12 papers)

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Research

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14 pages, 1549 KiB  
Article
In Vitro and In Planta Antagonistic Effect of Endophytic Bacteria on Blight Causing Xanthomonas axonopodis pv. punicae: A Destructive Pathogen of Pomegranate
by Nripendra Vikram Singh, Jyotsana Sharma, Manjushri Dinkar Dongare, Ramakant Gharate, Shivkumar Chinchure, Manjunatha Nanjundappa, Shilpa Parashuram, Prakash Goudappa Patil, Karuppannan Dhinesh Babu, Dhananjay Morteppa Mundewadikar, Unnati Salutgi, Muskan Tatiya, Aundy Kumar and Rajiv Arvind Marathe
Microorganisms 2023, 11(1), 5; https://doi.org/10.3390/microorganisms11010005 - 20 Dec 2022
Cited by 1 | Viewed by 1827
Abstract
Pomegranate bacterial blight caused by Xanthomonas axonopodis pv. punicae (Xap) is a highly destructive disease. In the absence of host resistance to the disease, we aimed to evaluate the biocontrol potential of endophytic bacteria against Xap. Thus, in this study, [...] Read more.
Pomegranate bacterial blight caused by Xanthomonas axonopodis pv. punicae (Xap) is a highly destructive disease. In the absence of host resistance to the disease, we aimed to evaluate the biocontrol potential of endophytic bacteria against Xap. Thus, in this study, we isolated endophytes from pomegranate plants, identified them on the basis of 16S rDNA sequencing, tested them against Xap, and estimated the endophyte-mediated host defense response. The population of isolated endophytes ranged from 3 × 106 to 8 × 107 CFU/g tissue. Furthermore, 26 isolates were evaluated for their biocontrol activity against Xap, and all the tested isolates significantly reduced the in vitro growth of Xap (15.65% ± 1.25% to 56.35% ± 2.66%) as compared to control. These isolates could reduce fuscan, an uncharacterized factor of Xap involved in its aggressiveness. Lower blight incidence (11.6%) and severity (6.1%) were recorded in plants sprayed with endophytes 8 days ahead of Xap spray (Set-III) as compared to control plants which were not exposed to endophytes (77.33 and 50%, respectively%) during in vivo evaluation. Moreover, significantly high phenolic and chlorophyll contents were estimated in endophyte-treated plants as compared to control. The promising isolates mostly belonged to the genera Bacillus, Burkholderia, and Lysinibacillus, and they were deposited to the National Agriculturally Important Microbial Culture Collection, India. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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15 pages, 1127 KiB  
Article
Maize Apoplastic Fluid Bacteria Alter Feeding Characteristics of Herbivore (Spodoptera frugiperda) in Maize
by Sellappan Ranjith, Thangavel Kalaiselvi, Muruganagounder Muthusami and Uthandi Sivakumar
Microorganisms 2022, 10(9), 1850; https://doi.org/10.3390/microorganisms10091850 - 16 Sep 2022
Cited by 4 | Viewed by 1593
Abstract
Maize is an important cereal crop which is severely affected by Spodoptera frugiperda. The study aims to identify endophytic bacteria of maize root and leaf apoplastic fluid with bioprotective traits against S. frugiperda and plant growth promoting properties. Among 15 bacterial endophytic [...] Read more.
Maize is an important cereal crop which is severely affected by Spodoptera frugiperda. The study aims to identify endophytic bacteria of maize root and leaf apoplastic fluid with bioprotective traits against S. frugiperda and plant growth promoting properties. Among 15 bacterial endophytic isolates, two strains—namely, RAF5 and LAF5—were selected and identified as Alcaligenes sp. MZ895490 and Bacillus amyloliquefaciens MZ895491, respectively. The bioprotective potential of B. amyloliquefaciens was evaluated through bioassays. In a no-choice bioassay, second instar larvae of S. frugiperda fed on B. amyloliquefaciens treated leaves (B+) recorded comparatively lesser growth (1.10 ± 0.19 mg mg−1 day−1) and consumptive (7.16 ± 3.48 mg mg−1 day−1) rates. In larval dip and choice bioassay, the same trend was observed. In detached leaf experiment, leaf feeding deterrence of S. frugiperda was found to be greater due to inoculation with B. amyloliquefaciens than Alcaligenes sp. The phenolics content of B. amyloliquefaciens inoculated plant was also found to be greater (3.06 ± 0.09 mg gallic acid g−1). However, plant biomass production was more in Alcaligenes sp inoculated treatment. The study thus demonstrates the potential utility of Alcaligenes sp. and B. amyloliquefaciens for improving growth and biotic (S. frugiperda) stress tolerance in maize. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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14 pages, 4390 KiB  
Article
Genotype-Specific Plastic Responses to Seed Bacteria under Drought Stress in Lactuca serriola
by Seorin Jeong, Tae-Min Kim, Byungwook Choi, Yousuk Kim, Hwan Kim and Eunsuk Kim
Microorganisms 2022, 10(8), 1604; https://doi.org/10.3390/microorganisms10081604 - 09 Aug 2022
Cited by 1 | Viewed by 1492
Abstract
Recent studies have demonstrated that seed-borne bacteria can enhance the performance of invasive plants in novel introduced habitats with environmental stresses. The effect of this plant-bacteria interaction may vary with plant species or even genotype; however, the genotype-dependent effects of seed bacteria have [...] Read more.
Recent studies have demonstrated that seed-borne bacteria can enhance the performance of invasive plants in novel introduced habitats with environmental stresses. The effect of this plant-bacteria interaction may vary with plant species or even genotype; however, the genotype-dependent effects of seed bacteria have rarely been assessed. In this study, we examined the effects of bacterial strains isolated from seeds on the genotypes of an invasive xerophytic plant, Lactuca serriola. Plant genotypes were grown under drought conditions, and their plastic responses to bacterial infections were evaluated. Some genotypes produced more biomass, whereas others produced less biomass in response to infection with the same bacterial strain. Notably, the quantity of root-adhering soil depended on the bacterial treatment and plant genotypes and was positively correlated with the plastic responses of plant performance. Because tested bacteria could colonize the plant rhizosphere, bacterial infection appears to induce the differential formation of soil rhizosheaths among plant genotypes, consequently affecting the maintenance of soil water content under drought conditions. Given that drought tolerance is a critical attribute for the invasive success of L. serriola, these results imply that bacterial symbionts can facilitate the establishment of alien plant species, but their effects are likely genotype-specific. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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21 pages, 1490 KiB  
Article
Biopriming of Durum Wheat Seeds with Endophytic Diazotrophic Bacteria Enhances Tolerance to Fusarium Head Blight and Salinity
by Adel Hadj Brahim, Manel Ben Ali, Lobna Daoud, Mouna Jlidi, Ismahen Akremi, Houda Hmani, Naser Aliye Feto and Mamdouh Ben Ali
Microorganisms 2022, 10(5), 970; https://doi.org/10.3390/microorganisms10050970 - 05 May 2022
Cited by 7 | Viewed by 2323
Abstract
There is growing interest in the use of bio inoculants based on plant growth-promoting bacteria (PGPB) to promote plant growth under biotic and abiotic stresses. Here, we provided a detailed account of the effectiveness of a number of endophytic PGPB strains, isolated from [...] Read more.
There is growing interest in the use of bio inoculants based on plant growth-promoting bacteria (PGPB) to promote plant growth under biotic and abiotic stresses. Here, we provided a detailed account of the effectiveness of a number of endophytic PGPB strains, isolated from the roots of the halophyte Salicornia brachiata in promoting durum wheat growth and enhancing its tolerance to salinity and fusarium head blight (FHB) disease. Bacillus spp. strains MA9, MA14, MA17, and MA19 were found to have PGPB characteristics as they produced indole-3-acetic acid, siderophores, and lytic enzymes, fixed free atmospheric nitrogen, and solubilized inorganic phosphate in vitro. Additionally, the in vivo study that involved in planta inoculation assays under control and stress conditions indicated that all PGPB strains significantly (p < 0.05) increased the total plant length, dry weight, root area, seed weight, and nitrogen, protein, and mineral contents. Particularly, the MA17 strain showed a superior performance since it was the most efficient in reducing disease incidence in wheat explants by 64.5%, in addition to having the strongest plant growth promotion activity under salt stress. Both in vitro and in vivo assays showed that MA9, MA14, MA17, and MA19 strains were able to play significant PGPB roles. However, biopriming with Bacillus subtilis MA17 offered the highest plant growth promotion and salinity tolerance, and bioprotection against FHB. Hence, it would be worth testing the MA17 strain under field conditions as a step towards its commercial production. Moreover, the strain could be further assessed for its plausible role in bioprotection and growth promotion in other crop plants. Thus, it was believed that the strain has the potential to significantly contribute to wheat production in arid and semi-arid regions, especially the salt-affected Middle Eastern Region, in addition to its potential role in improving wheat production under biotic and abiotic stresses in other parts of the world. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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21 pages, 1467 KiB  
Article
Synergistic Plant-Microbe Interactions between Endophytic Actinobacteria and Their Role in Plant Growth Promotion and Biological Control of Cotton under Salt Stress
by Osama Abdalla Abdelshafy Mohamad, Yong-Hong Liu, Li Li, Jin-Biao Ma, Yin Huang, Lei Gao, Bao-Zhu Fang, Shuang Wang, Ashraf F. El-Baz, Hong-Chen Jiang and Wen-Jun Li
Microorganisms 2022, 10(5), 867; https://doi.org/10.3390/microorganisms10050867 - 21 Apr 2022
Cited by 3 | Viewed by 2821
Abstract
Bacterial endophytes are well-acknowledged inoculants to promote plant growth and enhance their resistance toward various pathogens and environmental stresses. In the present study, 71 endophytic strains associated with the medicinal plant Thymus roseus were screened for their plant growth promotion (PGP), and the [...] Read more.
Bacterial endophytes are well-acknowledged inoculants to promote plant growth and enhance their resistance toward various pathogens and environmental stresses. In the present study, 71 endophytic strains associated with the medicinal plant Thymus roseus were screened for their plant growth promotion (PGP), and the applicability of potent strains as bioinoculant has been evaluated. Regarding PGP traits, the percentage of strains were positive for the siderophore production (84%), auxin synthesis (69%), diazotrophs (76%), phosphate solubilization (79%), and production of lytic enzymes (i.e., cellulase (64%), lipase (62%), protease (61%), chitinase (34%), and displayed antagonistic activity against Verticillium dahliae (74%) in vitro. The inoculation of strain XIEG05 and XIEG12 enhanced plant tolerance to salt stress significantly (p < 0.05) through the promotion of shoot, root development, and reduced the activities of antioxidant enzymes (SOD, POD, and CAT), compared with uninoculated controls in vivo. Furthermore, inoculation of strain XIEG57 was capable of reducing cotton disease incidence (DI) symptoms caused by V. dahliae at all tested salt concentrations. The GC-MS analysis showed that many compounds are known to have antimicrobial and antifungal activity. Our findings provide valuable information for applying strains XIEG05 and XIEG12 as bioinoculant fertilizers and biological control agent of cotton under saline soil conditions. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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17 pages, 1793 KiB  
Article
Biocontrol Ability and Production of Volatile Organic Compounds as a Potential Mechanism of Action of Olive Endophytes against Colletotrichum acutatum
by Yosra Sdiri, Teresa Lopes, Nuno Rodrigues, Kevin Silva, Isabel Rodrigues, José Alberto Pereira and Paula Baptista
Microorganisms 2022, 10(3), 571; https://doi.org/10.3390/microorganisms10030571 - 06 Mar 2022
Cited by 9 | Viewed by 2520
Abstract
Olive anthracnose, mainly caused by Colletotrichum acutatum, is considered a key biotic constraint of the olive crop worldwide. This work aimed to evaluate the ability of the endophytes Aureobasidium pullulans and Sarocladium summerbellii isolated from olive trees to reduce C. acutatum growth [...] Read more.
Olive anthracnose, mainly caused by Colletotrichum acutatum, is considered a key biotic constraint of the olive crop worldwide. This work aimed to evaluate the ability of the endophytes Aureobasidium pullulans and Sarocladium summerbellii isolated from olive trees to reduce C. acutatum growth and anthracnose symptoms, and to assess A. pullulans-mediated changes in olive fruit volatile organic compounds (VOCs) and their consequences on anthracnose development. Among the endophytes tested, only A. pullulans significantly reduced the incidence (up to 10-fold) and severity (up to 35-fold) of anthracnose in detached fruits, as well as the growth (up to 1.3-fold), sporulation (up to 5.9-fold) and germination (up to 3.5-fold) of C. acutatum in dual culture assays. Gas chromatography–mass spectrometry analysis of olives inoculated with A. pullulans + C. acutatum and controls (olives inoculated with C. acutatum, A. pullulans or Tween) led to the identification of 37 VOCs, with alcohols being the most diversified and abundant class. The volatile profile of A. pullulans + C. acutatum revealed qualitative and quantitative differences from the controls and varied over the time course of microbial interactions. The most significant differences among treatments were observed at a maximal reduction in anthracnose development. At this stage, a set of VOCs, particularly Z-3-hexen-1-ol, benzyl alcohol and nonanal, were highly positively correlated with the A. pullulans + C. acutatum treatment, suggesting they play a critical role in anthracnose reduction. 6-Methyl-5-hepten-2-one and 2-nonanone were positively associated with the C. acutatum treatment and thus likely have a role in pathogen infection. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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16 pages, 2490 KiB  
Article
Diversity and Biocontrol Potential of Cultivable Endophytic Bacteria Associated with Halophytes from the West Aral Sea Basin
by Lei Gao, Jinbiao Ma, Yonghong Liu, Yin Huang, Osama Abdalla Abdelshafy Mohamad, Hongchen Jiang, Dilfuza Egamberdieva, Wenjun Li and Li Li
Microorganisms 2021, 9(7), 1448; https://doi.org/10.3390/microorganisms9071448 - 06 Jul 2021
Cited by 16 | Viewed by 3224
Abstract
Endophytes associated with halophytes may contribute to the host’s adaptation to adverse environmental conditions through improving their stress tolerance and protecting them from various soil-borne pathogens. In this study, the diversity and antifungal activity of endophytic bacteria associated with halophytic samples growing on [...] Read more.
Endophytes associated with halophytes may contribute to the host’s adaptation to adverse environmental conditions through improving their stress tolerance and protecting them from various soil-borne pathogens. In this study, the diversity and antifungal activity of endophytic bacteria associated with halophytic samples growing on the shore of the western Aral Sea in Uzbekistan were investigated. The endophytic bacteria were isolated from the nine halophytic samples by using the culture-dependent method and identified according to their 16S rRNA gene sequences. The screening of endophytic bacterial isolates with the ability to inhibit pathogenic fungi was completed by the plate confrontation method. A total of 289 endophytic bacterial isolates were isolated from the nine halophytes, and they belong to Firmicutes, Actinobacteria, and Proteobacteria. The predominant genera of the isolated endophytic bacteria were Bacillus, Staphylococcus, and Streptomyces, accounting for 38.5%, 24.7%, and 12.5% of the total number of isolates, respectively. The comparative analysis indicated that the isolation effect was better for the sample S8, with the highest diversity and richness indices. The diversity index of the sample S7 was the lowest, while the richness index of samples S5 and S6 was the lowest. By comparing the isolation effect of 12 different media, it was found that the M7 medium had the best performance for isolating endophytic bacteria associated with halophytes in the western Aral Sea Basin. In addition, the results showed that only a few isolates have the ability to produce ex-enzymes, and eight and four endophytic bacterial isolates exhibited significant inhibition to the growth of Valsa mali and Verticillium dahlia, respectively. The results of this study indicated that halophytes are an important source for the selection of microbes that may protect plant from soil-borne pathogens. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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16 pages, 2724 KiB  
Article
Gluconacetobacter diazotrophicus Pal5 Enhances Plant Robustness Status under the Combination of Moderate Drought and Low Nitrogen Stress in Zea mays L.
by Muhammad Aammar Tufail, María Touceda-González, Ilaria Pertot and Ralf-Udo Ehlers
Microorganisms 2021, 9(4), 870; https://doi.org/10.3390/microorganisms9040870 - 17 Apr 2021
Cited by 10 | Viewed by 4460
Abstract
Plant growth promoting endophytic bacteria, which can fix nitrogen, plays a vital role in plant growth promotion. Previous authors have evaluated the effect of Gluconacetobacter diazotrophicus Pal5 inoculation on plants subjected to different sources of abiotic stress on an individual basis. The present [...] Read more.
Plant growth promoting endophytic bacteria, which can fix nitrogen, plays a vital role in plant growth promotion. Previous authors have evaluated the effect of Gluconacetobacter diazotrophicus Pal5 inoculation on plants subjected to different sources of abiotic stress on an individual basis. The present study aimed to appraise the effect of G. diazotrophicus inoculation on the amelioration of the individual and combined effects of drought and nitrogen stress in maize plants (Zea mays L.). A pot experiment was conducted whereby treatments consisted of maize plants cultivated under drought stress, in soil with a low nitrogen concentration and these two stress sources combined, with and without G. diazotrophicus seed inoculation. The inoculated plants showed increased plant biomass, chlorophyll content, plant nitrogen uptake, and water use efficiency. A general increase in copy numbers of G. diazotrophicus, based on 16S rRNA gene quantification, was detected under combined moderate stress, in addition to an increase in the abundance of genes involved in N fixation (nifH). Endophytic colonization of bacteria was negatively affected by severe stress treatments. Overall, G. diazotrophicus Pal5 can be considered as an effective tool to increase maize crop production under drought conditions with low application of nitrogen fertilizer. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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14 pages, 1463 KiB  
Article
Effects of the Fungal Endophyte Epichloë festucae var. lolii on Growth and Physiological Responses of Perennial Ryegrass cv. Fairway to Combined Drought and Pathogen Stresses
by Fang Li, Tingyu Duan and Yanzhong Li
Microorganisms 2020, 8(12), 1917; https://doi.org/10.3390/microorganisms8121917 - 02 Dec 2020
Cited by 22 | Viewed by 2142
Abstract
Perennial ryegrass (Lolium perenne) is widely cultivated around the world for turf and forage. However, the plant is highly susceptible to disease and is sensitive to drought. The present study aims to determine the effect of the fungal endophyte Epichloë festucae [...] Read more.
Perennial ryegrass (Lolium perenne) is widely cultivated around the world for turf and forage. However, the plant is highly susceptible to disease and is sensitive to drought. The present study aims to determine the effect of the fungal endophyte Epichloë festucae var. lolii of perennial ryegrass on the combined stresses of drought and disease caused by Bipolaris sorokiniana in the greenhouse. In the experiment, plants infected (E+) or not infected (E−) with the fungal endophyte were inoculated with Bipolaris sorokiniana and put under different soil water regimes (30%, 50%, and 70%). The control treatment consisted of E+ and E− plants not inoculated with B. sorokiniana. Plant growth, phosphorus (P) uptake, photosynthetic parameters, and other physiological indices were evaluated two weeks after pathogen infection. The fungal endophyte in E+ plants increased P uptake, plant growth, and photosynthetic parameters but decreased the malondialdehyde concentration, proline content, and disease incidence of perennial ryegrass (p < 0.05). E+ plants had the lowest disease incidence at 70% soil water (p < 0.05). The study demonstrates that the fungal endophyte E. festucae var. lolii is beneficial for plant growth and stress tolerance in perennial ryegrass exposed to the combined stresses of drought and B. sorokiniana. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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10 pages, 1247 KiB  
Article
Response of Soybean to Hydrochar-Based Rhizobium Inoculation in Loamy Sandy Soil
by Dilfuza Egamberdieva, Hua Ma, Jakhongir Alimov, Moritz Reckling, Stephan Wirth and Sonoko Dorothea Bellingrath-Kimura
Microorganisms 2020, 8(11), 1674; https://doi.org/10.3390/microorganisms8111674 - 28 Oct 2020
Cited by 11 | Viewed by 2582
Abstract
Hydrochar is rich in nutrients and may provide a favorable habitat or shelter for bacterial proliferation and survival. Therefore, in this study, we investigate the efficiency of a hydrochar-based rhizobial inoculant (Bradyrhizobium japonicum) on the symbiotic performance of soybean under both [...] Read more.
Hydrochar is rich in nutrients and may provide a favorable habitat or shelter for bacterial proliferation and survival. Therefore, in this study, we investigate the efficiency of a hydrochar-based rhizobial inoculant (Bradyrhizobium japonicum) on the symbiotic performance of soybean under both greenhouse and field conditions. There were positive and significant effects of hydrochar-based inoculation on the root and shoot growth of soybean as compared to uninoculated plants grown under irrigated and drought conditions. The drought stress significantly inhibited the symbiotic performance of rhizobia with soybean. Soybean inoculated with hydrochar-based B. japonicum produced twofold more nodules under drought stress conditions as compared to plants inoculated with a commercial preparation/inoculant carrier B. japonicum (HISTICK). The N concentration of inoculated plants with hydrochar-based B. japonicum was by 31% higher than that of un-inoculated plants grown in pots and by 22% for HISTICK. Furthermore, the soybean treated with hydrochar-based B. japonicum showed higher grain yield of 29% under irrigated conditions and 40% higher under rainfed condition compared to un-inoculated plants. In conclusion, the obtained results proved the potential of hydrochar-based B. japonicum inoculant for soybean in terms of increased symbiotic performance and agronomic traits, especially under rainfed conditions. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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18 pages, 2119 KiB  
Article
Trichoderma Enhances Net Photosynthesis, Water Use Efficiency, and Growth of Wheat (Triticum aestivum L.) under Salt Stress
by Abraham Mulu Oljira, Tabassum Hussain, Tatoba R. Waghmode, Huicheng Zhao, Hongyong Sun, Xiaojing Liu, Xinzhen Wang and Binbin Liu
Microorganisms 2020, 8(10), 1565; https://doi.org/10.3390/microorganisms8101565 - 11 Oct 2020
Cited by 38 | Viewed by 4226
Abstract
Soil salinity is one of the most important abiotic stresses limiting plant growth and productivity. The breeding of salt-tolerant wheat cultivars has substantially relieved the adverse effects of salt stress. Complementing these cultivars with growth-promoting microbes has the potential to stimulate and further [...] Read more.
Soil salinity is one of the most important abiotic stresses limiting plant growth and productivity. The breeding of salt-tolerant wheat cultivars has substantially relieved the adverse effects of salt stress. Complementing these cultivars with growth-promoting microbes has the potential to stimulate and further enhance their salt tolerance. In this study, two fungal isolates, Th4 and Th6, and one bacterial isolate, C7, were isolated. The phylogenetic analyses suggested that these isolates were closely related to Trichoderma yunnanense, Trichoderma afroharzianum, and Bacillus licheniformis, respectively. These isolates produced indole-3-acetic acid (IAA) under salt stress (200 mM). The abilities of these isolates to enhance salt tolerance were investigated by seed coatings on salt-sensitive and salt-tolerant wheat cultivars. Salt stress (S), cultivar (C), and microbial treatment (M) significantly affected water use efficiency. The interaction effect of M x S significantly correlated with all photosynthetic parameters investigated. Treatments with Trichoderma isolates enhanced net photosynthesis, water use efficiency and biomass production. Principal component analysis revealed that the influences of microbial isolates on the photosynthetic parameters of the different wheat cultivars differed substantially. This study illustrated that Trichoderma isolates enhance the growth of wheat under salt stress and demonstrated the potential of using these isolates as plant biostimulants. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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Review

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20 pages, 996 KiB  
Review
Microorganisms in Plant Growth and Development: Roles in Abiotic Stress Tolerance and Secondary Metabolites Secretion
by Ntombikhona Appear Koza, Afeez Adesina Adedayo, Olubukola Oluranti Babalola and Abidemi Paul Kappo
Microorganisms 2022, 10(8), 1528; https://doi.org/10.3390/microorganisms10081528 - 28 Jul 2022
Cited by 66 | Viewed by 5502
Abstract
Crops aimed at feeding an exponentially growing population are often exposed to a variety of harsh environmental factors. Although plants have evolved ways of adjusting their metabolism and some have also been engineered to tolerate stressful environments, there is still a shortage of [...] Read more.
Crops aimed at feeding an exponentially growing population are often exposed to a variety of harsh environmental factors. Although plants have evolved ways of adjusting their metabolism and some have also been engineered to tolerate stressful environments, there is still a shortage of food supply. An alternative approach is to explore the possibility of using rhizosphere microorganisms in the mitigation of abiotic stress and hopefully improve food production. Several studies have shown that rhizobacteria and mycorrhizae organisms can help improve stress tolerance by enhancing plant growth; stimulating the production of phytohormones, siderophores, and solubilizing phosphates; lowering ethylene levels; and upregulating the expression of dehydration response and antioxidant genes. This article shows the secretion of secondary metabolites as an additional mechanism employed by microorganisms against abiotic stress. The understanding of these mechanisms will help improve the efficacy of plant-growth-promoting microorganisms. Full article
(This article belongs to the Special Issue Endophytes for Managing Biotic and Abiotic Stress in Plants)
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