Plant root-bacterial interactions in biological control of soilborne diseases and potential extension to systemic and foliar diseases

1999 ◽  
Vol 28 (1) ◽  
pp. 21 ◽  
Author(s):  
J.W. Kloepper ◽  
R. Rodríguez-Kábana ◽  
G.W. Zehnder ◽  
J.F. Murphy ◽  
E. Sikora ◽  
...  
Keyword(s):  
Biological Control ◽  
Plant Root ◽  
Soilborne Diseases ◽  
Foliar Diseases ◽  
Bacterial Interactions

scholarly journals OPTIMALISASI PRODUKSI ENZIM KITINASE PADA ISOLAT JAMUR KITINOLITIK DARI SAMPEL TANAH RIZOSFER

2018 ◽  
Vol 3 (01) ◽  
pp. 62-69
Author(s):  
Eka Corneliyawati ◽  
Massora Massora ◽  
Khikmah Khikmah ◽  
As’ad Syamsul Arifin
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Rhizosphere Soil ◽  
Plant Root ◽  
Optimal Growth ◽  
Chitinase Activity ◽  
Fungal Species ◽  
Plant Roots ◽  
Chitinase Production

The rhizosphere is the zone of soil surrounding a plant root where plant roots, soil and the soil biota interact with each other. Chitinolytic fungi has been effectively used in biological control agens. The chitinase activity causes lysis of the fungi cell wall pathogen. The aim of the research was to find optimization of activity chitinase enzyme from rhizosphere soil was conducted in vitro. Optimal growth chitinase production for TKR3 fungi isolate were concentration of chitin 0,2% (b/v), pH 5,5, temperature 30ºC, agitation 150 rpm and incubation time at four days. The optimum yield of chitinase production is influenced by fungal species and environmental conditions.

scholarly journals The Biocontrol Agent and Insect Pathogen Photorhabdus luminescens Interacts with Plant Roots

2020 ◽  
Vol 86 (17) ◽  
Author(s):  
Alice Regaiolo ◽  
Nazzareno Dominelli ◽  
Karsten Andresen ◽  
Ralf Heermann
Keyword(s):  
Biological Control ◽  
Pest Management ◽  
Root Exudates ◽  
Biological Control Agent ◽  
Plant Root ◽  
Specific Interaction ◽  
Plant Roots ◽  
Photorhabdus Luminescens ◽  
Content Type ◽  
Root Interactions

ABSTRACT The number of sustainable agriculture techniques to improve pest management and environmental safety is rising, as biological control agents are used to enhance disease resistance and abiotic stress tolerance in crops. Here, we investigated the capacity of the Photorhabdus luminescens secondary variant to react to plant root exudates and their behavior toward microorganisms in the rhizosphere. P. luminescens is known to live in symbiosis with entomopathogenic nematodes (EPNs) and to be highly pathogenic toward insects. The P. luminescens-EPN relationship has been widely studied, and this combination has been used as a biological control agent; however, not much attention has been paid to the putative lifestyle of P. luminescens in the rhizosphere. We performed transcriptome analysis to show how P. luminescens responds to plant root exudates. The analysis highlighted genes involved in chitin degradation, biofilm regulation, formation of flagella, and type VI secretion system. Furthermore, we provide evidence that P. luminescens can inhibit growth of phytopathogenic fungi. Finally, we demonstrated a specific interaction of P. luminescens with plant roots. Understanding the role and the function of this bacterium in the rhizosphere might accelerate the progress in biocontrol manipulation and elucidate the peculiar mechanisms adopted by plant growth-promoting rhizobacteria in plant root interactions. IMPORTANCE Insect-pathogenic Photorhabdus luminescens bacteria are widely used in biocontrol strategies against pests. Very little is known about the life of these bacteria in the rhizosphere. Here, we show that P. luminescens can specifically react to and interact with plant roots. Understanding the adaptation of P. luminescens in the rhizosphere is highly important for the biotechnological application of entomopathogenic bacteria and could improve future sustainable pest management in agriculture.

scholarly journals Biological and Application-Oriented Factors Influencing Plant Disease Suppression by Biological Control: A Meta-Analytical Review

2006 ◽  
Vol 96 (11) ◽  
pp. 1168-1174 ◽  
Author(s):  
P. S. Ojiambo ◽  
H. Scherm
Keyword(s):  
Biological Control ◽  
Effect Size ◽  
Untreated Control ◽  
Plant Disease ◽  
Biocontrol Agent ◽  
Disease Suppression ◽  
Effect Sizes ◽  
Biological Control Agents ◽  
Control Effect ◽  
Soilborne Diseases

Studies to evaluate the effectiveness of biological control in suppressing plant disease often report inconsistent results, highlighting the need to identify general factors that influence the success or failure of biological control in plant pathology. We conducted a quantitative synthesis of previously published research by applying meta-analysis to determine the overall effectiveness of biocontrol in relation to biological and application-oriented factors. For each of 149 entries (antagonist-disease combinations) from 53 reports published in Biological & Cultural Tests between 2000 and 2005, an effect size was calculated as the difference in disease intensity expressed in standard deviation units between the biocontrol treatment and its corresponding untreated control. Effect sizes ranged from -1.15 (i.e., disease strongly enhanced by application of the biocontrol agent) to 4.83 (strong disease suppression by the antagonist) with an overall weighted mean of 0.62, indicating moderate effectiveness on average. There were no significant (P >0.05) differences in effect sizes between entries from studies carried out in the greenhouse versus the field, between those involving soilborne versus aerial diseases, or among those carried out in conditions of low, medium, or high disease pressure (expressed relative to the disease intensity in the untreated control). However, effect sizes were greater on annual than on perennial crops, regardless of whether the analysis was carried out for all entries (P = 0.0268) or for those involving only soilborne diseases (P = 0.0343). Effect sizes were not significantly different for entries utilizing fungal versus bacterial biocontrol agents or for those targeting fungal versus bacterial pathogens. However, entries that used r-selected biological control agents (i.e., those having short generation times and producing large numbers of short-lived offspring) were more effective than those that applied antagonists that were not r-selected (P = 0.0312). Interestingly, effect sizes for entries that used Bacillus spp. as biological control agents were lower than for those that applied other antagonists (P = 0.0046 for all entries and P = 0.0114 for soilborne diseases). When only aerial diseases were considered, mean effect size was greater for entries that received one or two sprays than for those that received more than eight sprays of the biocontrol agent (P = 0.0002). This counterintuitive result may indicate that investigators often attempt unsuccessfully to compensate for anticipated poor performance in antagonist-disease combinations by making more applications.

scholarly journals Strategies to Improve Biological Control of Soilborne Plant Diseases

2021 ◽  
Vol 9 (1) ◽  
pp. 1-3
Keyword(s):  
Biological Control ◽  
Systemic Acquired Resistance ◽  
Cultural Practices ◽  
Acquired Resistance ◽  
Complete Removal ◽  
Plant Diseases ◽  
Attractive Alternative ◽  
Control Methods ◽  
Complete Control ◽  
Soilborne Diseases

Biological control of plant soilborne diseases has appeared as an attractive alternative to other control methods. For the biological control of plant soilborne diseases, microorganisms mainly bacteria and fungi are used, which suppress growth and virulence traits or even kill pathogens and induce plant systemic acquired resistance. In recent years, the demand for organic food increased the use of biological control agents; however, complete control of plant diseases has not been achieved yet. The beneficial microbes used for biological control of plant diseases perform admirably under controlled greenhouse conditions but are not always successful under field conditions, which highly discourages the biological control methods. Hence, complete removal of chemicals from agricultural systems may not be impossible but a logical reduction in their application is feasible. Therefore, systematic integrated methods including both chemical and biological control and other control methods like cultural practices, resistant varieties and crop rotation are highly recommended.

scholarly journals Ex VivoApplication of Secreted Metabolites Produced by Soil-Inhabiting Bacillus spp. Efficiently Controls Foliar Diseases Caused by Alternaria spp.

2015 ◽  
Vol 82 (2) ◽  
pp. 478-490 ◽  
Author(s):  
Gul Shad Ali ◽  
Ashraf S. A. El-Sayed ◽  
Jaimin S. Patel ◽  
Kari B. Green ◽  
Mohammad Ali ◽  
...  
Keyword(s):  
Biological Control ◽  
Plant Pathogens ◽  
Foliar Application ◽  
Control Plant ◽  
Complex Mixture ◽  
Biological Control Agents ◽  
In Planta ◽  
Content Type ◽  
Foliar Diseases ◽  
Culture Filtrates

ABSTRACTBacterial biological control agents (BCAs) are largely used as live products to control plant pathogens. However, due to variable environmental and ecological factors, live BCAs usually fail to produce desirable results against foliar pathogens. In this study, we investigated the potential of cell-free culture filtrates of 12 different bacterial BCAs isolated from flower beds for controlling foliar diseases caused byAlternariaspp.In vitrostudies showed that culture filtrates from two isolates belonging toBacillus subtilisandBacillus amyloliquefaciensdisplayed strong efficacy and potencies againstAlternariaspp. The antimicrobial activity of the culture filtrate of these two biological control agents was effective over a wider range of pH (3.0 to 9.0) and was not affected by autoclaving or proteolysis. Comparative liquid chromatography-mass spectrometry (LC-MS) analyses showed that a complex mixture of cyclic lipopeptides, primarily of the fengycin A and fengycin B families, was significantly higher in these two BCAs than inactiveBacillusspp. Interaction studies with mixtures of culture filtrates of these two species revealed additive activity, suggesting that they produce similar products, which was confirmed by LC-tandem MS analyses. Inin plantapre- and postinoculation trials, foliar application of culture filtrates ofB. subtilisreduced lesion sizes and lesion frequencies caused byAlternaria alternataby 68 to 81%. Taken together, our studies suggest that instead of live bacteria, culture filtrates ofB. subtilisandB. amyloliquefacienscan be applied either individually or in combination for controlling foliar diseases caused byAlternariaspecies.

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