scholarly journals Plant Growth-Promoting Bacteria as an Emerging Tool to Manage Bacterial Rice Pathogens

2021 ◽  
Vol 9 (4) ◽  
pp. 682
Author(s):  
Mohamad Syazwan Ngalimat ◽  
Erneeza Mohd Hata ◽  
Dzarifah Zulperi ◽  
Siti Izera Ismail ◽  
Mohd Razi Ismail ◽  
...  

As a major food crop, rice (Oryza sativa) is produced and consumed by nearly 90% of the population in Asia with less than 9% produced outside Asia. Hence, reports on large scale grain losses were alarming and resulted in a heightened awareness on the importance of rice plants’ health and increased interest against phytopathogens in rice. To serve this interest, this review will provide a summary on bacterial rice pathogens, which can potentially be controlled by plant growth-promoting bacteria (PGPB). Additionally, this review highlights PGPB-mediated functional traits, including biocontrol of bacterial rice pathogens and enhancement of rice plant’s growth. Currently, a plethora of recent studies address the use of PGPB to combat bacterial rice pathogens in an attempt to replace existing methods of chemical fertilizers and pesticides that often lead to environmental pollutions. As a tool to combat bacterial rice pathogens, PGPB presented itself as a promising alternative in improving rice plants’ health and simultaneously controlling bacterial rice pathogens in vitro and in the field/greenhouse studies. PGPB, such as Bacillus, Pseudomonas, Enterobacter, Streptomyces, are now very well-known. Applications of PGPB as bioformulations are found to be effective in improving rice productivity and provide an eco-friendly alternative to agroecosystems.

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Mariana S. Santos ◽  
Artur B. L. Rondina ◽  
Marco A. Nogueira ◽  
Mariangela Hungria

Seed treatment with chemical pesticides is commonly used as an initial plant protection procedure against pests and diseases. However, the use of such chemicals may impair the survival and performance of beneficial microorganisms introduced via inoculants, such as the plant growth-promoting bacterium Azospirillum brasilense. We assessed the compatibility between the most common pesticide used in Brazil for the treatment of maize seeds, composed of two fungicides, and one insecticide, with the commercial strains Ab-V5 and Ab-V6 of A. brasilense, and evaluated the impacts on initial plant development. The toxicity of the pesticide to A. brasilense was confirmed, with an increase in cell mortality after only 24 hours of exposure in vitro. Seed germination and seedling growth were not affected neither by the A. brasilense nor by the pesticide. However, under greenhouse conditions, the pesticide affected root volume and dry weight and root-hair incidence, but the toxicity was alleviated by the inoculation with A. brasilense for the root volume and root-hair incidence parameters. In maize seeds inoculated with A. brasilense, the pesticide negatively affected the number of branches, root-hair incidence, and root-hair length. Therefore, new inoculant formulations with cell protectors and the development of compatible pesticides should be searched to guarantee the benefits of inoculation with plant growth-promoting bacteria.


2021 ◽  
pp. 100209
Author(s):  
Mariluza Silva Leite ◽  
Tainara Eler Furtado Pinto ◽  
Agda Rabelo Centofante ◽  
Aurélio Rubio Neto ◽  
Fabiano Guimarães Silva ◽  
...  

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248274
Author(s):  
Iliana Julieta Cortese ◽  
María Lorena Castrillo ◽  
Andrea Liliana Onetto ◽  
Gustavo Ángel Bich ◽  
Pedro Darío Zapata ◽  
...  

Plant growth-promoting bacteria (PGPB) are a heterogeneous group of bacteria that can exert beneficial effects on plant growth directly or indirectly by different mechanisms. PGPB-based inoculant formulation has been used to replace chemical fertilizers and pesticides. In our previous studies, two endophytic endospore-forming bacteria identified as Bacillus altitudinis were isolated from roots of Ilex paraguariensis St. Hil. seedlings and selected for their plant growth-promoting (PGP) properties shown in vitro and in vivo. The purposes of this work were to assemble the genomes of B. altitudinis 19RS3 and T5S-T4, using different assemblers available for Windows and Linux and to select the best assembly for each strain. Both genomes were also automatically annotated to detect PGP genes and compare sequences with other genomes reported. Library construction and draft genome sequencing were performed by Macrogen services. Raw reads were filtered using the Trimmomatic tool. Genomes were assembled using SPAdes, ABySS, Velvet, and SOAPdenovo2 assemblers for Linux, and Geneious and CLC Genomics Workbench assemblers for Windows. Assembly evaluation was done by the QUAST tool. The parameters evaluated were the number of contigs ≥ 500 bp and ≥ 1000 bp, the length of the longest contig, and the N50 value. For genome annotation PROKKA, RAST, and KAAS tools were used. The best assembly for both genomes was obtained using Velvet. The B. altitudinis 19RS3 genome was assembled into 15 contigs with an N50 value of 1,943,801 bp. The B. altitudinis T5S-T4 genome was assembled into 24 contigs with an N50 of 344,151 bp. Both genomes comprise several genes related to PGP mechanisms, such as those for nitrogen fixation, iron metabolism, phosphate metabolism, and auxin biosynthesis. The results obtained offer the basis for a better understanding of B. altitudinis 19RS3 and T5S-T4 and make them promissory for bioinoculant development.


2020 ◽  
Vol 96 (9) ◽  
Author(s):  
Camila Cristina Vieira Velloso ◽  
Christiane Abreu de Oliveira ◽  
Eliane Aparecida Gomes ◽  
Ubiraci Gomes de Paula Lana ◽  
Chainheny Gomes de Carvalho ◽  
...  

ABSTRACT Plant growth promoting bacteria (PGPB) are an efficient and sustainable alternative to mitigate biotic and abiotic stresses in maize. This work aimed to sequence the genome of two Bacillus strains (B116 and B119) and to evaluate their plant growth-promoting (PGP) potential in vitro and their capacity to trigger specific responses in different maize genotypes. Analysis of the genomic sequences revealed the presence of genes related to PGP activities. Both strains were able to produce biofilm and exopolysaccharides, and solubilize phosphate. The strain B119 produced higher amounts of IAA-like molecules and phytase, whereas B116 was capable to produce more acid phosphatase. Maize seedlings inoculated with either strains were submitted to polyethylene glycol-induced osmotic stress and showed an increase of thicker roots, which resulted in a higher root dry weight. The inoculation also increased the total dry weight and modified the root morphology of 16 out of 21 maize genotypes, indicating that the bacteria triggered specific responses depending on plant genotype background. Maize root remodeling was related to growth promotion mechanisms found in genomic prediction and confirmed by in vitro analysis. Overall, the genomic and phenotypic characterization brought new insights to the mechanisms of PGP in tropical Bacillus.


2021 ◽  
Author(s):  
Komal A. Chandarana ◽  
Rinka S. Pramanik ◽  
Natarajan Amaresan

Abstract Plant growth and productivity depend on the complex and dynamic interaction between the plant roots and soil microflora. At present, the research on rhizosphere associated microbes’ is largely focused on bacteria and fungi; whereas the interaction of soil protists with plants and other microbes remain unexplored. The present study aimed to investigate the impact of a ciliate (Kreyellidae sp. C5) and two plant growth-promoting bacteria (PGPB) i.e., Pseudomonas sp. (Ps) and Enterobacter sp. (Ec), on the growth of rice plants. It was observed that the protist-PGPB interaction significantly modified the root structure leading to an enhanced outgrowth of lateral roots (272.08% − 380.41%) and seminal roots (190.40% -250.45%), in addition to an increase in the primary root length (Turkey’s HSD, p < 0.05). The Phospholipid Fatty Acid (PLFA) analysis indicated a striking shift in the overall soil microbial communities due to the presence of a predator. The combined treatments (with C5Ps and C5Ec) further increased the Microbial Carbon Biomass (MBC) to 223.59% and 310.57% as compared to control and PGPB treatments respectively. A similar enhancement of dehydrogenase enzyme activity was observed in soil samples of rice plants on combined treatments. In contrast, the alkaline phosphatase and fluorescein diacetate enzyme activities were recorded to be more in soil samples treated with PGPB. The combined treatment of rice plants also enhanced the uptake of N and P moderately, as compared to PGPB treated plants. However, this enhancement was significant compared to control plants. The colony-forming unit (CFU) and most probable number (MPN) was found to be more in C5Ec (131.0 ± 3.70×1011 and 5.12 ± 0.06) and C5Ps (24.10 ± 2.19×1010 and 10.52 ± 0.39), as compared to control and PGPB treated soil samples. In conclusion, this is the first study that demonstrates significant modification of root structure and increased nutrient uptake by rice plants through interaction between Kreyellidae sp. and PGPB. In addition, we also report improved respiration and diverse microbial population in soil samples on combined treatment of rice plants.


2019 ◽  
Author(s):  
Adel Hadj Brahim ◽  
Mouna Jlidi ◽  
Lobna Daoud ◽  
Manel Ben-Ali ◽  
Asmahen Akremi ◽  
...  

Abstract Background There is growing interest in the use of bioinoculants based on plant growth promoting bacteria (PGPB) to promote plant growth under biotic and abiotic stresses. To our knowledge much work has not been, thus far, done on seedbiopriming of durum wheat for tolerance to biotic and abiotic stresses. In the present work, we report detailed account of the effectiveness a potent bacterial strain with proven plant growth-promoting ability and antimicrobial activity. The isolate was selected following screening of several bacterial strains isolated from halophytes that grow in a coastal saline soil in Tunisia for their role in enhancing durum wheat tolerance to both salinity stress and head blight disease. Results Accordingly, Bacillus 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. The in vivo study that involved in planta inoculation assays under control (25 mM NaCl) and stress (125 mM NaCl) conditions indicated that all PGPB strains significantly (P < 0.05) increased the total plant length, dry weight, root area, seed weight, nitrogen, protein and total mineral content. On the other hand, strain MA17 reduced Fusarium Head Blight (FHB) disease incidence in wheat explants by 64.5%, showing that the strain has antifungal activity as was also displayed by in vitro inhibition study. Conclusions Both in vitro and in vivo studies showed that MA9, MA14 MA9, MA14, MA17 and MA19 strains were able to play the PGPB role. Yet, biopriming with Bacillus strain MA17 offered the highest bioprotection against FHB, plant growth promotion, and salinity tolerance. Hence, the MA17 strain should further be evaluated under field condition and formulated for commercial production. Besides, the strain could further be evaluated for its potential role in bioprotection and growth promotion of other crop plants. We believe, the strain has potential to significantly contribute to wheat production in the arid and semi-arid region, especially the salt affected Middle Eastern Region, besides its potential role in improving wheat production under biotic and abiotic stresses in other parts of the world.


Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2436
Author(s):  
Marika Pellegrini ◽  
Claudia Ercole ◽  
Carmelo Gianchino ◽  
Matteo Bernardi ◽  
Loretta Pace ◽  
...  

Industrial hemp (Cannabis sativa L.) is a multipurpose plant used in several fields. Several phytopathogens attack hemp crops. Fusarium oxysporum is a common fungal pathogen that causes wilt disease in nurseries and in field cultivation and causes high losses. In the present study, a pathogenic strain belonging to F. oxysporum f. sp. cannabis was isolated from a plant showing Fusarium wilt. After isolation, identification was conducted based on morphological and molecular characterizations and pathogenicity tests. Selected plant growth-promoting bacteria with interesting biocontrol properties—Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae and Burkholderia ambifaria—were tested against this pathogen. In vitro antagonistic activity was determined by the dual culture method. Effective strains (in vitro inhibition > of 50%) G. diazotrophicus, H. seropedicae and B. ambifaria were combined in a consortium and screened for in planta antagonistic activity in pre-emergence (before germination) and post-emergence (after germination). The consortium counteracted Fusarium infection both in pre-emergence and post-emergence. Our preliminary results show that the selected consortium could be further investigated as an effective biocontrol agent for the management of this pathogen.


Bragantia ◽  
2016 ◽  
Vol 75 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Leandro Teodoski Spolaor ◽  
Leandro Simões Azeredo Gonçalves ◽  
Odair José Andrade Pais dos Santos ◽  
André Luiz Martinez de Oliveira ◽  
Carlos Alberto Scapim ◽  
...  

ABSTRACT The use of plant growth-promoting bacteria is a promising alternative with low environmental impact to increase the efficiency of use of chemical fertilizers, ensuring high yield with better cost-effective ratio. In maize crops, several studies have demonstrated an increased yield when Azospirillum-based inoculants are used. In the case of popcorn, there are no available studies related to use of inoculation and its response on yield parameters. Thus, the aim of this study was to evaluate the field performance of popcorn when inoculated with the commercial product Masterfix L (A. brasilense Ab-V5 and A. brasilense Ab-V6) and the non-commercial inoculant UEL (A. brasilense Ab-V5 + Rhizobium sp. 53GRM1) associated with nitrogen fertilization. The trials were conducted in Londrina and Maringá, Paraná State, Brazil, in a randomized block design with four replications, in a split plot design with the inoculation treatments located in the plots (uninoculated, Masterfix L, and UEL) and the different N rates located in the subplots where ammonium sulphate was applied in the topdressing at the V6 stage (0, 50, 100, and 150 kg∙ha–1). The variance analysis showed significant effects (p < 0.05) of inoculation (Londrina environment) and N rates (both environments) only for grain yield. There was no inoculation effect in the grain yield when inoculants were applied together with N-fertilization at topdressing. In the absence of N-fertilization at topdressing, the inoculants Masterfix L. and UEL promoted higher grain yield as compared to the uninoculated plants, with resulting increases of 13.21 and 26.61% in yield, respectively.


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