scholarly journals Actinomycetes, promising tools to control plant diseases and to promote plant growth

2005 ◽  
Vol 82 (3) ◽  
pp. 85-102 ◽  
Author(s):  
C.L. Doumbou ◽  
M.K. Hamby Salove ◽  
D.L. Crawford ◽  
C. Beaulieu

Actinomycetes represent a high proportion of the soil microbial biomass and have the capacity to produce a wide variety of antibiotics and of extracellular enzymes. Several strains of actinomycetes have been found to protect plants against plant diseases. This review focuses on the potential of actinomycetes as (a) source of agroactive compounds, (b) plant growth promoting organisms, and (c) biocontrol tools of plant diseases. This review also addresses examples of biological control of fungal and bacterial plant pathogens by actinomycetes species which have already reached the market or are likely to be exploited commercially within the next few years.

2021 ◽  
Author(s):  
Mesele Admassie ◽  
Yitbark Wold-Hawariat ◽  
Tesefaye Alemu

Abstract Plant growth promoting rhizo and endophytic bacteria were isolated from different parts of pepper from south eastern Ethiopia. Plant growth promoting bacteria (PGP) are those that may be used to promote plant growth and suppress plant diseases. The objectives of this study were to identify and characterize PGPB indigenous to pepper rhizosphere and endophyte bacteria in Ethiopia, and to determine their capacity to suppress Phytophthora capsici in pepper. From a total of 60 isolates, 20 were selected based on their in vitro antagonism activity of phytopathogens and plant growth promoting traits. From the total 60 strains representing, 38 rhizosphere, and 22 endophytic bacteria were identified based on biochemical assays of semi-automated Vitec 2 compact and ten potential bacteria further identified by molecular methods. Results revealed that only one isolate of rhizosphere and three endophytic bacteria showed more than 50% suppression of test pathogens. The isolates were evaluated for their ability to solubilize phosphate, as well as for ammonia, indole acetic acid, hydrogen cyanide, and biofilm production. The selected isolates produced (0.2–93 µg mL− 1) of indole-3-acetic acid, without supplemented with tryptophan, while supplemented with tryptophan it produces (11.23–159 µg mL− 1). The activities of plant growth-promoting were assessed by measuring their effect on the number of lateral roots, root and shoot length of Arabidopsis plants, and germination percentage of pepper plants. Pepper plants grown from seeds that were treated with these PGPB strains showed significantly higher levels of germination, seedling vigor, and growth, compared to non-treated control plants. Since these PGPB inoculants showed multiple characters useful to the host plants, they may be used as an alternative in the production of new, safe, and effective seed treatments as bio-fungicides. Generally, this work exhibits the potential of bacterial isolates to control Phytophthora infection and promote plant growth.


Author(s):  
Bazilah Marzaini ◽  
Aslizah Mohd-Aris

The agricultural industry worldwide faces challenges in the struggle against plant diseases. In efforts to increase agricultural intensities, the dependency on agrochemicals for crop protection has become significantly high. Moreover, the increasing use of agrochemical-based products has resulted in multidrug-resistant pathogens and environmental pollution. This paper reviews the biocontrol capacity of plant growth-promoting microorganisms (PGPMs) originating from plants towards plant pathogens. The current trend in discovering new compounds has shown antimicrobial activity gaining immense interest due to its vast potential. On a related note, PGPMs are an aspect of that research interest that can be further explored as antimicrobial producers. In this work, we also covered the types of biocontrol mechanisms pertaining to PGPMs as well as their roles in biocontrol activity. A biocontrol approach exploits disease-suppressive microorganisms to improve plant health by controlling related pathogens. The understanding of these microorganisms and mechanisms of pathogen antagonismare primary factors in ensuring improvement for future applications. Inevitably, there is indeed room for rigorous expansion with respect to PGPMs in the future of agriculture.


GIS Business ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. 425-431
Author(s):  
Subin Thomas ◽  
Dr. M. Nandhini

Biofertilizers are fertilizers containing microorganisms that promote plant growth by improving the supply of nutrients to the host plant. The supply of nutrients is improved naturally by nitrogen fixation and solubilizing phosphorus. The living microorganisms in biofertilizers help in building organic matter in the soil and restoring the natural nutrient cycle. Biofertilizers can be grouped into Nitrogen-fixing biofertilizers, Phosphorous-solubilizing biofertilizers, Phosphorous-mobilizing biofertilizers, Biofertilizers for micro nutrients and Plant growth promoting rhizobacteria. This study conducted in Kottayam district was intended to identify the awareness and acceptance of biofertilizers among the farmers of the area. Data have been collected from 120 farmers by direct interviews with structured questionnaire.


Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1071
Author(s):  
Minchong Shen ◽  
Jiangang Li ◽  
Yuanhua Dong ◽  
Hong Liu ◽  
Junwei Peng ◽  
...  

Microbial treatment has recently been attracting attention as a sustainable agricultural strategy addressing the current problems caused by unreasonable agricultural practices. However, the mechanism through which microbial inoculants promote plant growth is not well understood. In this study, two phosphate-solubilizing bacteria (PSB) were screened, and their growth-promoting abilities were explored. At day 7 (D7), the lengths of the root and sprout with three microbial treatments, M16, M44, and the combination of M16 and M44 (Com), were significantly greater than those with the non-microbial control, with mean values of 9.08 and 4.73, 7.15 and 4.83, and 13.98 and 5.68 cm, respectively. At day 14 (D14), M16, M44, and Com significantly increased not only the length of the root and sprout but also the underground and aboveground biomass. Differential metabolites were identified, and various amino acids, amino acid derivatives, and other plant growth-regulating molecules were significantly enhanced by the three microbial treatments. The profiling of key metabolites associated with plant growth in different microbial treatments showed consistent results with their performances in the germination experiment, which revealed the metabolic mechanism of plant growth-promoting processes mediated by screened PSB. This study provides a theoretical basis for the application of PSB in sustainable agriculture.


Author(s):  
Cun Yu ◽  
Ying Yao

Endophytic fungi were isolated from Phoebe bournei and their diversity and antimicrobial and plant growth-promoting activities were investigated. Of the 389 isolated endophytic fungi, 88.90% belonged to phylum Ascomycota and 11.10% to phylum Basidiomycota. The isolates were grouped into four taxonomic classes, 11 orders, 30 genera, and 45 species based on internal transcribed spacer sequencing and morphologic analysis. The host showed a strong affinity for the genera Diaporthe and Phyllosticta. The diversity of the fungi was highest in autumn, followed by spring and summer, and was lowest in winter. The fungi exhibited notable tissue specificity in P. bournei, and the species richness and diversity were highest in the root across all seasons. Five isolates showed antimicrobial activity against eight plant pathogens, and reduced the incidence of leaf spot disease in P. bournei. Additionally, 9 biocontrol isolates showed plant growth-promoting activity, with five significantly promoting P. bournei seedling growth. This is the first report on the endophytic fungi of P. bournei and their potential applicability to plant disease control and growth promotion.


2021 ◽  
Vol 12 (2) ◽  
pp. 1143-1150
Author(s):  
Lavanya J ◽  
Chanthosh S ◽  
Reshma Shrii ◽  
Viknesh V ◽  
Deepika S ◽  
...  

The study was aimed to find an alternate approach for chemicals used in agriculture to avoid microbial infections. Fungal pathogens cause different types of plant diseases and affect a majority of edible crops by destroying the tissues of the plant in a direct or indirect mechanism. So, an alternative approach led to the development of biocontrol agents using endophytic  bacteria. A total of 8 endophytic bacteria were isolated from the root, stem, and leaves of radish (Raphanus sativus). The antagonistic activity of these bacteria against the 2 isolated plant pathogenic fungi was determined in vitro. Two out of eight bacteria showed more than 50% inhibitory activity against one fungus, were further characterized using the 16s rRNA sequencing method. On the basis of the phylogenetic tree of the 16s rRNA method, the endophytic bacterial samples were identified as Tonsilliphilus suis  and Exiguobacterium aurantiacum against plant pathogenic Aspergillus flavus  isolated from Raphanus sativus, which makes them highly suitable as an alternative for chemical fertilizers to provide resistance to plant pathogenic fungi. The cell wall degrading activities such as protease activity, amylase activity, and plant growth-promoting properties such as Hydrogen cyanide (HCN), Indole acetic acid (IAA), ammonia production of these endophytic bacteria were evaluated. The results show that T. suis  is the most effective strain for radish growth development.


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