Potential of Plant Growth-Promoting and Biocontrol Microorganisms in Controlling Plant Diseases

A special issue of Pathogens (ISSN 2076-0817).

Deadline for manuscript submissions: closed (30 September 2022) | Viewed by 25420

Special Issue Editors

Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P. R. China
Interests: biocontrol of plant diseases; biocontrol agents; plant growth-promoting and biocontrol microorganisms; bacillus biocontrol agents; biocontrol mechanisms; antimicrobial mechanisms of active substances; pseudomonas biocontrol agents; trichoderma biocontrol agents; yeast biocontrol agents; ribosomal and nonribosomal peptide antibiotics; production of phytohormones; volatile organic compounds; induced systemic resistance

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Guest Editor
Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P. R. China
Interests: plant growth-promoting rhizobacteria (PGPR); Regulation and synthesis mechanisms of active substances; antimicrobial mechanisms of active substances; interaction mechanisms between plants and PGPR; biocontrol plants diseases

Special Issue Information

Dear Colleagues,

To ensure the supply of an appropriate quantity and quality of food for human beings, we need enough land to grow plants or crops. But the cultivation of plants or crops is facing numerous challenges due to plant pathogens, such as oomycetes, fungi, bacteria, viruses, and nematodes. To enhance plant biomass production and reduce economic loss, chemical pesticides are widely used. Over the past decades, due to the overuse of chemical pesticides and their subsequent deleterious environmental consequences, the exploration of natural biological techniques for the management of crop diseases, reduction of the use of chemical plant protection products, and reduction of pollution are emerging fields. Among several biocontrol techniques, microorganisms that are beneficial for plant growth and health are applied as biopesticides, biofertilizer, and bio-stimulants to control plant diseases and improve plant yield. These microbial products are environmentally friendly and have attracted significant attention. Many of these beneficial microorganisms have been widely studied and applied in biocontrol of plant diseases, such as fungal species like Trichoderma sp., yeast, bacterial species belonging to genera Bacillus, Pseudomonas, Burkholderia, Streptomyces, etc. These microorganisms are already prevailing in the soil biota. After the colonization of the rhizosphere, root surface, or within radicular tissues, these microbes can promote plant growth by production of phytohormones, and facilitate the nutrient uptake. Biocontrol agents control plant diseases by producing a wide spectrum of bioactive metabolites, such as ribosomal and nonribosomal peptide antibiotics, siderophores, volatiles, and also induce systemic resistance in plants (ISR). However, further studies are required to elucidate the mechanisms of interaction between beneficial microorganisms, plants as well as the phytopathogens. Novel active substances produced by beneficial microorganisms need to be identified. The antimicrobial mechanism underlying the active substance must also be studied. These findings will help to advance the understanding of beneficial microorganisms and contribute to the future development of highly efficient microbe-derived products to control plant diseases.

This Special Issue of Pathogens welcomes submissions on all aspects related to plant growth-promoting and biocontrol microorganisms in controlling plant diseases. We invite you to submit high-quality research or review articles. We look forward to your contribution.

Dr. Huijun Wu
Prof. Dr. Xuewen Gao
Guest Editors

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Keywords

  • Biocontrol of plant diseases 
  • Plant growth-promoting microorganisms 
  • Biocontrol microorganisms Active substances
  • Biocontrol mechanisms
  • Aintimicrobial mechanism of active substance
  • Induced-systemic resistance
  • Ribosomal and nonribosomal peptide antibiotics
  • Volatile organic compounds

Published Papers (9 papers)

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Research

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13 pages, 1115 KiB  
Article
Evaluation of the Biocontrol Efficiency of Bacillus subtilis Wettable Powder on Pepper Root Rot Caused by Fusarium solani
by Junqing Qiao, Rongsheng Zhang, Yongfeng Liu and Youzhou Liu
Pathogens 2023, 12(2), 225; https://doi.org/10.3390/pathogens12020225 - 31 Jan 2023
Cited by 3 | Viewed by 1671
Abstract
The plant-growth-promoting rhizobacteria (PGPR) B. subtilis PTS-394 has been utilized as a biocontrol agent (in a wettable powder form) due to its excellent ability to suppress tomato soil-borne diseases caused by Fusarium oxysporum and Ralstonia solanacearum. In this study, we evaluated the [...] Read more.
The plant-growth-promoting rhizobacteria (PGPR) B. subtilis PTS-394 has been utilized as a biocontrol agent (in a wettable powder form) due to its excellent ability to suppress tomato soil-borne diseases caused by Fusarium oxysporum and Ralstonia solanacearum. In this study, we evaluated the biocontrol efficiency of Bacillus subtilis PTS-394 wettable powder on pepper root rot in pot experiments and field trials. B. subtilis PTS-394 and its lipopeptide crude extract possessed excellent inhibition activity against Fusarium solani, causing pepper root rot; in an antifungal activity test B. subtilis PTS-394 wettable powder exhibited a good ability to promote pepper seed germination and plant height. The experiments in pots and the field indicated that B. subtilis PTS-394 wettable powder had an excellent control effect at 100-fold dilution, and its biocontrol efficacy reached 69.63% and 74.43%, respectively. In this study, the biocontrol properties of B. subtilis PTS-394 wettable powder on pepper root rot were evaluated and its application method was established. It was concluded that B. subtilis PTS-394 wettable powder is a potential biocontrol agent with an excellent efficiency against pepper root rot. Full article
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16 pages, 2862 KiB  
Article
Bacillus spp.-Mediated Growth Promotion of Rice Seedlings and Suppression of Bacterial Blight Disease under Greenhouse Conditions
by Faheem Uddin Rajer, Muhammad Kaleem Samma, Qurban Ali, Waleed Ahmed Rajar, Huijun Wu, Waseem Raza, Yongli Xie, Hafiz Abdul Samad Tahir and Xuewen Gao
Pathogens 2022, 11(11), 1251; https://doi.org/10.3390/pathogens11111251 - 28 Oct 2022
Cited by 13 | Viewed by 2311
Abstract
Rice (Oryza sativa L.) is a major cereal and staple food crop worldwide, and its growth and production are affected by several fungal and bacterial phytopathogens. Bacterial blight (BB) is one of the world’s most devastating rice diseases, caused by Xanthomonas oryzae [...] Read more.
Rice (Oryza sativa L.) is a major cereal and staple food crop worldwide, and its growth and production are affected by several fungal and bacterial phytopathogens. Bacterial blight (BB) is one of the world’s most devastating rice diseases, caused by Xanthomonas oryzae pv. oryzae (Xoo). In the current study, Bacillus atrophaeus FA12 and B. cabrialesii FA26 were isolated from the rice rhizosphere and characterized as having broad-range antifungal and antibacterial activities against various phytopathogens, including Xoo. In addition, the selected strains were further evaluated for their potent rice growth promotion and suppression efficacy against BB under greenhouse conditions. The result shows that FA12 and FA26, applied as seed inoculants, significantly enhanced the vigor index of rice seedlings by 78.89% and 108.70%, respectively. Suppression efficacy against BB disease by FA12 and FA26 reached up to 59.74% and 54.70%, respectively, in pot experiments. Furthermore, MALDI-TOF MS analysis of selected strains revealed the masses ranged from m/z 1040 to 1540, representing that iturins and fengycin are the major antimicrobial compounds in the crude extracts, which might have beneficial roles in rice defence responses against BB. In conclusion, FA12 and FA26 possess broad-range antagonistic activity and have the capability to promote plant growth traits. More importantly, applying these strains has a high potential for implementing eco-friendly, cost-effective, and sustainable management practices for BB disease. Full article
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15 pages, 2872 KiB  
Article
Biocontrol of Wheat Crown Rot Using Bacillus halotolerans QTH8
by Shen Li, Jianqiang Xu, Liming Fu, Guohui Xu, Xiaomin Lin, Junqing Qiao and Yanfei Xia
Pathogens 2022, 11(5), 595; https://doi.org/10.3390/pathogens11050595 - 18 May 2022
Cited by 19 | Viewed by 2814
Abstract
Fusarium pseudograminearum causes crown rot in wheat. This study aimed to assess the effects of the bacterial strain QTH8 isolated from Cotinus coggygria rhizosphere soil against F. pseudograminearum. Bacterial strain QTH8 was identified as Bacillus halotolerans in accordance with the phenotypic traits [...] Read more.
Fusarium pseudograminearum causes crown rot in wheat. This study aimed to assess the effects of the bacterial strain QTH8 isolated from Cotinus coggygria rhizosphere soil against F. pseudograminearum. Bacterial strain QTH8 was identified as Bacillus halotolerans in accordance with the phenotypic traits and the phylogenetic analysis of 16S rDNA and gyrB gene sequence. Culture filtrates of bacterial strain QTH8 inhibited the mycelial growth of F. pseudograminearum and resulted in mycelial malformation such as tumor formation, protoplast condensation, and mycelial fracture. In addition, bacterial strain QTH8 also inhibited the mycelial growth of Hainesia lythri, Pestalotiopsis sp., Botrytis cinerea, Curvularia lunata, Phyllosticta theaefolia, Fusarium graminearum, Phytophthora nicotianae, and Sclerotinia sclerotiorum. The active compounds produced by bacterial strain QTH8 were resistant to pH, ultraviolet irradiation, and low temperature, and were relatively sensitive to high temperature. After 4 h exposure, culture filtrates of bacterial strain QTH8—when applied at 5%, 10%, 15%, 20%, 25%, and 30%—significantly reduced conidial germination of F. pseudograminearum. The coleoptile infection assay proved that bacterial strain QTH8 reduced the disease index of wheat crown rot. In vivo application of QTH8 to wheat seedlings decreased the disease index of wheat crown rot and increased root length, plant height, and fresh weight. Iturin, surfactin, and fengycin were detected in the culture extract of bacterial strain QTH8 by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Bacterial strain QTH8 was identified for the presence of the ituC, bacA, bmyB, spaS, srfAB, fend, and srfAA genes using the specific polymerase chain reaction primers. B. halotolerans QTH8 has a vital potential for the sustainable biocontrol of wheat crown rot. Full article
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15 pages, 2469 KiB  
Article
Pyoluteorin Produced by the Biocontrol Agent Pseudomonas protegens Is Involved in the Inhibition of Heterobasidion Species Present in Europe
by Martina Pellicciaro, Elio Padoan, Guglielmo Lione, Luisella Celi and Paolo Gonthier
Pathogens 2022, 11(4), 391; https://doi.org/10.3390/pathogens11040391 - 23 Mar 2022
Cited by 2 | Viewed by 2045
Abstract
Pseudomonas protegens (strain DSMZ 13134) is a biocontrol agent with promising antagonistic activity hinging on antibiosis against the fungal forest pathogens Heterobasidion spp. Here, by using High-Performance Liquid Chromatography coupled to Mass Spectrometry (HPLC-MS), we assessed whether monocultures of P. protegens (strain DSMZ [...] Read more.
Pseudomonas protegens (strain DSMZ 13134) is a biocontrol agent with promising antagonistic activity hinging on antibiosis against the fungal forest pathogens Heterobasidion spp. Here, by using High-Performance Liquid Chromatography coupled to Mass Spectrometry (HPLC-MS), we assessed whether monocultures of P. protegens (strain DSMZ 13134) produce the three major determinants of biocontrol activity known for the genus Pseudomonas: 2,4-diacetylphloroglucinol (2,4-DAPG), pyoluteorin (PLT), and pyrrolnitrin (PRN). At the tested culture conditions, we observed the production of PLT at concentrations ranging from 0.01 to 10.21 mg/L and 2,4-DAPG at a concentration not exceeding 0.5 mg/L. Variations of culture conditions involving culture medium, incubation temperature, and incubation period had no consistent influence on PLT production by the bacterium. Assays using culture medium amended with PLT at the same concentration of that present in cell-free filtrate of the bacterium, i.e., 3.77 mg/L, previously documented as effective against Heterobasidion spp., showed a remarkable activity of PLT against genotypes of all the four Heterobasidion species present in Europe, including the non-native invasive H. irregulare. However, such antifungal activity decreased over time, and this may be a constraint for using this molecule as a pesticide against Heterobasidion spp. When the bacterium was co-cultured in liquid medium with genotypes of the different Heterobasidion species, an increased production of PLT was observed at 4 °C, suggesting the bacterium may perform better as a PLT producer in field applications under similar environmental conditions, i.e., at low temperatures. Our results demonstrated the role of PLT in the inhibition of Heterobasidion spp., although all lines of evidence suggest that antibiosis does not rely on a single constitutively produced metabolite, but rather on a plethora of secondary metabolites. Findings presented in this study will help to optimize treatments based on Pseudomonas protegens (strain DSMZ 13134) against Heterobasidion spp. Full article
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16 pages, 2455 KiB  
Article
Bacillus amyloliquefaciens SN16-1-Induced Resistance System of the Tomato against Rhizoctonia solani
by Huihui Zhao, Xiaobing Wang and Wei Wang
Pathogens 2022, 11(1), 35; https://doi.org/10.3390/pathogens11010035 - 29 Dec 2021
Cited by 2 | Viewed by 1784
Abstract
Tomato (Solanum lycopersicum), as an important economical vegetable, is often infected with Rhizoctonia solani, which results in a substantial reduction in production. Therefore, the molecular mechanism of biocontrol microorganisms assisting tomato to resist pathogens is worth exploring. Here, we use [...] Read more.
Tomato (Solanum lycopersicum), as an important economical vegetable, is often infected with Rhizoctonia solani, which results in a substantial reduction in production. Therefore, the molecular mechanism of biocontrol microorganisms assisting tomato to resist pathogens is worth exploring. Here, we use Bacillus amyloliquefaciens SN16-1 as biocontrol bacteria, and employed RNA-Seq technology to study tomato gene and defense-signaling pathways expression. Gene Ontology (GO) analyses showed that an oxidation-reduction process, peptidase regulator activity, and oxidoreductase activity were predominant. Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that phenylpropanoid biosynthesis, biosynthesis of unsaturated fatty acids, aldosterone synthesis and secretion, and phototransduction were significantly enriched. SN16-1 activated defenses in the tomato via systemic-acquired resistance (which depends on the salicylic acid signaling pathway), rather than classic induction of systemic resistance. The genes induced by SN16-1 included transcription factors, plant hormones (ethylene, auxin, abscisic acid, and gibberellin), receptor-like kinases, heat shock proteins, and defense proteins. SN16-1 rarely activated pathogenesis-related proteins, but most pathogenesis-related proteins were induced in the presence of the pathogens. In addition, the molecular mechanisms of the response of tomatoes to SN16-1 and R. solani RS520 were significantly different. Full article
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15 pages, 2260 KiB  
Article
Antagonistic Strain Bacillus amyloliquefaciens XZ34-1 for Controlling Bipolaris sorokiniana and Promoting Growth in Wheat
by Yanjie Yi, Youtian Shan, Shifei Liu, Yanhui Yang, Yang Liu, Yanan Yin, Zhipeng Hou, Pengyu Luan and Ruifang Li
Pathogens 2021, 10(11), 1526; https://doi.org/10.3390/pathogens10111526 - 22 Nov 2021
Cited by 16 | Viewed by 3112
Abstract
Common root rot, caused by Bipolaris sorokiniana, is one of the most prevalent diseases of wheat and has led to major declines in wheat yield and quality worldwide. Here, strain XZ34-1 was isolated from soil and identified as Bacillus amyloliquefaciens based on [...] Read more.
Common root rot, caused by Bipolaris sorokiniana, is one of the most prevalent diseases of wheat and has led to major declines in wheat yield and quality worldwide. Here, strain XZ34-1 was isolated from soil and identified as Bacillus amyloliquefaciens based on the morphological, physiological, biochemical characteristics and 16S rDNA sequence. Culture filtrate (CF) of strain XZ34-1 showed a high inhibition rate against B.sorokiniana and had a broad antifungal spectrum. It also remarkably inhibited the mycelial growth and spore germination of B. sorokiniana. In pot control experiments, the incidence and disease index of common root rot in wheat seedlings were decreased after treatment with CF, and the biological control efficacy was significant, up to 78.24%. Further studies showed XZ34-1 could produce antifungal bioactive substances and had the potential of promoting plant growth. Lipopeptide genes detection with PCR indicated that strain XZ34-1 may produce lipopeptides. Furthermore, activities of defense-related enzymes were enhanced in wheat seedlings after inoculation with B.sorokiniana and treatment with CF, which showed induced resistance could be produced in wheat to resist pathogens. These results reveal that strain XZ34-1 is a promising candidate for application as a biological control agent against B.sorokiniana. Full article
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22 pages, 2811 KiB  
Article
Fusaricidins, Polymyxins and Volatiles Produced by Paenibacillus polymyxa Strains DSM 32871 and M1
by Pascal Mülner, Elisa Schwarz, Kristin Dietel, Stefanie Herfort, Jennifer Jähne, Peter Lasch, Tomislav Cernava, Gabriele Berg and Joachim Vater
Pathogens 2021, 10(11), 1485; https://doi.org/10.3390/pathogens10111485 - 15 Nov 2021
Cited by 15 | Viewed by 3217
Abstract
Paenibacilli are efficient producers of potent agents against bacterial and fungal pathogens, which are of great interest both for therapeutic applications in medicine as well as in agrobiotechnology. Lipopeptides produced by such organisms play a major role in their potential to inactivate pathogens. [...] Read more.
Paenibacilli are efficient producers of potent agents against bacterial and fungal pathogens, which are of great interest both for therapeutic applications in medicine as well as in agrobiotechnology. Lipopeptides produced by such organisms play a major role in their potential to inactivate pathogens. In this work we investigated two lipopeptide complexes, the fusaricidins and the polymyxins, produced by Paenibacillus polymyxa strains DSM 32871 and M1 by MALDI-TOF mass spectrometry. The fusaricidins show potent antifungal activities and are distinguished by an unusual variability. For strain DSM 32871 we identified numerous yet unknown variants mass spectrometrically. DSM 32871 produces polymyxins of type E (colistins), while M1 forms polymyxins P. For both strains, novel but not yet completely characterized polymyxin species were detected, which possibly are glycosylated. These compounds may be of interest therapeutically, because polymyxins have gained increasing attention as last-resort antibiotics against multiresistant pathogenic Gram-negative bacteria. In addition, the volatilomes of DSM 32781 and M1 were investigated with a GC–MS approach using different cultivation media. Production of volatile organic compounds (VOCs) was strain and medium dependent. In particular, strain M1 manifested as an efficient VOC-producer that exhibited formation of 25 volatiles in total. A characteristic feature of Paenibacilli is the formation of volatile pyrazine derivatives. Full article
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11 pages, 1992 KiB  
Article
Biological Control of Take-All and Growth Promotion in Wheat by Pseudomonas chlororaphis YB-10
by Wen Xu, Lingling Xu, Xiaoxu Deng, Paul H. Goodwin, Mingcong Xia, Jie Zhang, Qi Wang, Runhong Sun, Yamei Pan, Chao Wu and Lirong Yang
Pathogens 2021, 10(7), 903; https://doi.org/10.3390/pathogens10070903 - 17 Jul 2021
Cited by 14 | Viewed by 2963
Abstract
Wheat is a worldwide staple food crop, and take-all caused by Gaeumannomyces graminis var. tritici can lead to a tremendous decrease in wheat yield and quality. In this study, strain YB-10 was isolated from wheat rhizospheric soil and identified as Pseudomonas chlororaphis by [...] Read more.
Wheat is a worldwide staple food crop, and take-all caused by Gaeumannomyces graminis var. tritici can lead to a tremendous decrease in wheat yield and quality. In this study, strain YB-10 was isolated from wheat rhizospheric soil and identified as Pseudomonas chlororaphis by morphology and 16S rRNA gene sequencing. Pseudomonas chlororaphis YB-10 had extracellular protease and cellulase activities and strongly inhibited the mycelium growth of Gaeumannomyces graminis var. tritici in dual cultures. Up to 87% efficacy of Pseudomonas chlororaphis YB-10 in controlling the take-all of seedlings was observed in pot experiments when wheat seed was coated with the bacterium. Pseudomonas chlororaphis YB-10 was also positive for indole acetic acid (IAA) and siderophore production, and coating wheat seed with the bacterium significantly promoted the growth of seedlings at 107 and 108 CFU/mL. Furthermore, treatment with Pseudomonas chlororaphis YB-10 increased activities of the wheat defense-related enzymes POD, SOD, CAT, PAL and PPO in seedlings, indicating induced resistance against pathogens. Overall, Pseudomonas chlororaphis YB-10 is a promising new seed-coating agent to both promote wheat growth and suppress take-all. Full article
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Review

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23 pages, 10817 KiB  
Review
Control Strategies to Cope with Late Wilt of Maize
by Ofir Degani
Pathogens 2022, 11(1), 13; https://doi.org/10.3390/pathogens11010013 - 23 Dec 2021
Cited by 8 | Viewed by 4219
Abstract
Control of maize late wilt disease (LWD) has been at the forefront of research efforts since the discovery of the disease in the 1960s. The disease has become a major economic restraint in highly affected areas such as Egypt and Israel, and is [...] Read more.
Control of maize late wilt disease (LWD) has been at the forefront of research efforts since the discovery of the disease in the 1960s. The disease has become a major economic restraint in highly affected areas such as Egypt and Israel, and is of constant concern in other counties. LWD causes dehydration and collapsing at a late stage of maize cultivation, starting from the male flowering phase. The disease causal agent, Magnaporthiopsis maydis, is a seed- and soil-borne phytoparasitic fungus, penetrating the roots at sprouting, colonizing the vascular system without external symptoms, and spreading upwards in the xylem, eventually blocking the water supply to the plant’s upperparts. Nowadays, the disease’s control relies mostly on identifying and developing resistant maize cultivars. Still, host resistance can be limited because M. maydis undergoes pathogenic variations, and virulent strains can eventually overcome the host immunity. This alarming status is driving researchers to continue to seek other control methods. The current review will summarize the various strategies tested over the years to minimize the disease damage. These options include agricultural (crop rotation, cover crop, no-till, flooding the land before sowing, and balanced soil fertility), physical (solar heating), allelochemical, biological, and chemical interventions. Some of these methods have shown promising success, while others have contributed to our understanding of the disease development and the environmental and host-related factors that have shaped its outcome. The most updated global knowledge about LWD control will be presented, and knowledge gaps and future aims will be discussed. Full article
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