Probiotics: A Mainstream Therapy for the Disease Suppression

Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml–1 or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml–1 significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml–1. In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml–1 with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml–1 2 weeks before planting yielded activity of 20.08 μmol glucose equivalents per gram of soil water (GE g–1 aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 μmol GE g–1 aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.

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The contributions of biotic lines of defence to improving plant disease suppression in soils: A review

Rhizosphere ◽

10.1016/j.rhisph.2021.100372 ◽

2021 ◽

pp. 100372

Author(s):

Nwabunwanne Lilian Nwokolo ◽

Matthew Chekwube Enebe ◽

Chinyere Blessing Chigor ◽

Vincent Nnamdigadi Chigor ◽

Oyeyemi Adigun Dada

Keyword(s):

Plant Disease ◽

Disease Suppression

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Role of Nanoscale Hydroxyapatite in Disease Suppression of Fusarium-Infected Tomato

Environmental Science & Technology ◽

10.1021/acs.est.1c00901 ◽

2021 ◽

Author(s):

Chuanxin Ma ◽

Qingqing Li ◽

Weili Jia ◽

Heping Shang ◽

Jian Zhao ◽

...

Keyword(s):

Disease Suppression ◽

Infected Tomato

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White root rot disease suppression in rubber plant with microbial co-inoculants and silicon addition

Rhizosphere ◽

10.1016/j.rhisph.2020.100221 ◽

2020 ◽

Vol 15 ◽

pp. 100221

Author(s):

Imran Shabbir ◽

Mohd Yusoff Abd Samad ◽

Radziah Othman ◽

Mui-Yun Wong ◽

Zulkefly Sulaiman ◽

...

Keyword(s):

Root Rot ◽

Disease Suppression ◽

White Root Rot ◽

Root Rot Disease ◽

Rubber Plant ◽

Silicon Addition ◽

Rot Disease

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Growth Promotion and Disease Suppression Ability of a Streptomyces sp. CB-75 from Banana Rhizosphere Soil

Frontiers in Microbiology ◽

10.3389/fmicb.2017.02704 ◽

2018 ◽

Vol 8 ◽

Cited By ~ 26

Author(s):

Yufeng Chen ◽

Dengbo Zhou ◽

Dengfeng Qi ◽

Zhufen Gao ◽

Jianghui Xie ◽

...

Keyword(s):

Rhizosphere Soil ◽

Growth Promotion ◽

Disease Suppression ◽

Streptomyces Sp

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Induction of Soil Suppressiveness Against Rhizoctonia solani by Incorporation of Dried Plant Residues into Soil

Phytopathology ◽

10.1094/phyto-96-1372 ◽

2006 ◽

Vol 96 (12) ◽

pp. 1372-1379 ◽

Cited By ~ 19

Author(s):

Masahiro Kasuya ◽

Andriantsoa R. Olivier ◽

Yoko Ota ◽

Motoaki Tojo ◽

Hitoshi Honjo ◽

...

Keyword(s):

Rhizoctonia Solani ◽

Mycelial Growth ◽

Inhibitory Effect ◽

Volatile Substance ◽

Disease Suppression ◽

Plant Residues ◽

Infested Soil ◽

Antagonistic Bacteria ◽

Damping Off ◽

Soil Suppressiveness

Suppressive effects of soil amendment with residues of 12 cultivars of Brassica rapa on damping-off of sugar beet were evaluated in soils infested with Rhizoctonia solani. Residues of clover and peanut were tested as noncruciferous controls. The incidence of damping-off was significantly and consistently suppressed in the soils amended with residues of clover, peanut, and B. rapa subsp. rapifera ‘Saori’, but only the volatile substance produced from water-imbibed residue of cv. Saori exhibited a distinct inhibitory effect on mycelial growth of R. solani. Nonetheless, disease suppression in such residue-amended soils was diminished or nullified when antibacterial antibiotics were applied to the soils, suggesting that proliferation of antagonistic bacteria resident to the soils were responsible for disease suppression. When the seed (pericarps) colonized by R. solani in the infested soil without residues were replanted into the soils amended with such residues, damping-off was suppressed in all cases. In contrast, when seed that had been colonized by microorganisms in the soils containing the residues were replanted into the infested soil, damping-off was not suppressed. The evidence indicates that the laimosphere, but not the spermosphere, is the site for the antagonistic microbial interaction, which is the chief principle of soil suppressiveness against Rhizoctonia damping-off.

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Differences in Microbial Activity and Microbial Populations of Peat Associated with Suppression of Damping-Off Disease Caused by Pythium sylvaticum

Applied and Environmental Microbiology ◽

10.1128/aem.00313-06 ◽

2006 ◽

Vol 72 (10) ◽

pp. 6452-6460 ◽

Cited By ~ 43

Author(s):

Paul J. Hunter ◽

Geoff M. Petch ◽

Leo A. Calvo-Bado ◽

Tim R. Pettitt ◽

Nick R. Parsons ◽

...

Keyword(s):

Microbial Activity ◽

Denaturing Gradient Gel Electrophoresis ◽

Small Subunit ◽

Disease Suppression ◽

Rrna Gene ◽

Damping Off ◽

Small Subunit Rrna ◽

Pythium Sylvaticum ◽

Gradient Gel Electrophoresis ◽

Microbial Groups

ABSTRACT The microbiological characteristics associated with disease-suppressive peats are unclear. We used a bioassay for Pythium sylvaticum-induced damping-off of cress seedlings to identify conducive and suppressive peats. Microbial activity in unconditioned peats was negatively correlated with the counts of P. sylvaticum at the end of the bioassay. Denaturing gradient gel electrophoresis (DGGE) profiling and clone library analyses of small-subunit rRNA gene sequences from two suppressive and two conducive peats differed in the bacterial profiles generated and the diversity of sequence populations. There were also significant differences between bacterial sequence populations from suppressive and conducive peats. The frequencies of a number of microbial groups, including the Rhizobium-Agrobacterium group (specifically sequences similar to those for the genera Ochrobactrum and Zoogloea) and the Acidobacteria, increased specifically in the suppressive peats, although no single bacterial group was associated with disease suppression. Fungal DGGE profiles varied little over the course of the bioassay; however, two bands associated specifically with suppressive samples were detected. Sequences from these bands corresponded to Basidiomycete yeast genera. Although the DGGE profiles were similar, fungal sequence diversity also increased during the bioassay. Sequences highly similar to those of Cryptococcus increased in relative abundance during the bioassay, particularly in the suppressive samples. This study highlights the importance of using complementary approaches to molecular profiling of complex populations and provides the first report that basidiomycetous yeasts may be associated with the suppression of Pythium-induced diseases in peats.

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Efficacy of Different Level of Systemic Fungicides on Management of Rice Blast at Baitadi, Nepal

The Geographic Base ◽

10.3126/tgb.v7i0.34267 ◽

2020 ◽

Vol 7 ◽

pp. 33-42

Author(s):

Ashok Acharya ◽

Prabin Ghimire ◽

Dhurba Raj Joshi ◽

Kishor Shrestha ◽

Govinda Sijapati ◽

...

Keyword(s):

Disease Severity ◽

Rice Blast ◽

Fungal Pathogens ◽

Block Design ◽

Rice Variety ◽

Disease Suppression ◽

Systemic Fungicide ◽

Disease Development ◽

Systemic Fungicides ◽

Different Levels

Rice blast (Pyriculariaoryzae Cavara) is one of the most devastating diseases affecting the rice crop in across the world. Systemic fungicides are used for the suppression of blast diseases caused by fungal pathogens. Propiconazole and Carbendazim are commercial chemical control products available in markets for the control of the fungal pathogen. An experiment was conducted to examine the effectiveness of systemic fungicide on suppression of rice blast incidence in farmers' field during wet seasons in 2016. The treatments consisted of the use of different levels of propiconazole and Carbendazim on ‘Rato Basmati’ a landrace rice variety. The experiments were arranged in a randomized complete block design with three replications. The disease was scored according to the standard scale developed by the International Rice Research Institute (IRRI). Disease severity and Area under Disease Progressive curve (AUDPC) was computed based on that scale score. Propiconazole and Carbendazim at different levels reduce disease development than no treatment (control). But its efficacy was not consistent. The magnitude of disease suppression by Propiconazole was high as compared to Carbendazim. The application of propiconazole at the rate of 1.5 ml effectively reduced disease severity and AUDPC at different dates. So propiconazole at the rate of 1.5 ml thrice at weekly intervals is effective to reduce the disease development

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Characterization of Antagonistic Bacillus methylotrophicus Isolated From Rhizosphere and Its Biocontrol Effects on Maize Stalk Rot

Phytopathology ◽

10.1094/phyto-07-18-0220-r ◽

2019 ◽

Vol 109 (4) ◽

pp. 571-581 ◽

Cited By ~ 9

Author(s):

Xingkai Cheng ◽

Xiaoxue Ji ◽

Yanzhen Ge ◽

Jingjing Li ◽

Wenzhe Qi ◽

...

Keyword(s):

Biochemical Characterization ◽

Disease Incidence ◽

Field Trials ◽

Control Measures ◽

Disease Suppression ◽

Effective Control ◽

Stalk Rot ◽

Bacillus Methylotrophicus ◽

Transmission Electron ◽

Potential Biocontrol Agent

Stalk rot is one of the most serious and widespread diseases in maize, and effective control measures are currently lacking. Therefore, this study aimed to develop a new biological agent to manage this disease. An antagonistic bacterial strain, TA-1, was isolated from rhizosphere soil and identified as Bacillus methylotrophicus based on morphological and biochemical characterization and 16S ribosomal RNA and gyrB gene sequence analyses. TA-1 exhibited a strong antifungal effect on the growth of Fusarium graminearum mycelium, with 86.3% inhibition at a concentration of 108 CFU per ml. Transmission electron microscopy showed that TA-1 could disrupt the cellular structure of the fungus, induce necrosis, and degrade the cell wall. Greenhouse and field trials were performed to evaluate the biocontrol efficacy of TA-1 on maize stalk rot, and the results of greenhouse experiment revealed that the bacterium significantly reduced disease incidence and disease index. Seeds treated with a 108 CFU ml−1 cell suspension had the highest disease suppression at 86.8%. Results of field trials show that seed bacterization with TA-1 could not only reduce maize stalk rot incidence but also increase maize height, stem diameter, and grain yield. The lipopeptide antibiotics were isolated from the culture supernatants of TA-1 and identified as surfactins and iturins. Consequently, B. methylotrophicus TA-1 is a potential biocontrol agent against maize stalk rot.

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