scholarly journals Biocontrol of Soil-Borne Pathogens of Solanum lycopersicum L. and Daucus carota L. by Plant Growth-Promoting Actinomycetes: In Vitro and In Planta Antagonistic Activity

Pathogens ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1305
Author(s):  
Rihab Djebaili ◽  
Marika Pellegrini ◽  
Claudia Ercole ◽  
Beatrice Farda ◽  
Mahmoud Kitouni ◽  
...  

Biotic stress caused by pathogenic microorganisms leads to damage in crops. Tomato and carrot are among the most important vegetables cultivated worldwide. These plants are attacked by several pathogens, affecting their growth and productivity. Fourteen plant growth-promoting actinomycetes (PGPA) were screened for their in vitro biocontrol activity against Solanum lycopersicum and Daucus carota microbial phytopathogens. Their antifungal activity was evaluated against Fusarium oxysporum f. sp. radicis-lycopersici (FORL) and Rhizoctonia solani (RHS). Antibacterial activity was evaluated against Pseudomonas syringae, Pseudomonas corrugata, Pseudomonas syringae pv. actinidiae, and Pectobacterium carotovorum subsp. carotovorum. Strains that showed good in vitro results were further investigated in vitro (cell-free supernatants activity, scanning electron microscope observations of fungal inhibition). The consortium of the most active PGPA was then utilized as biocontrol agents in planta experiments on S. lycopersicum and D. carota. The Streptomyces albidoflavus H12 and Nocardiopsis aegyptica H14 strains showed the best in vitro biocontrol activities. The diffusible and volatile compounds and cell-free supernatants of these strains showed both antifungal (in vitro inhibition up to 85%, hyphal desegregation and fungicidal properties) and antibacterial activity (in vitro inhibition >25 mm and bactericidal properties). Their consortium was also able to counteract the infection symptoms of microbial phytopathogens during in planta experiments, improving plant status. The results obtained highlight the efficacy of the selected actinomycetes strains as biocontrol agents of S. lycopersicum and D. carota.

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1109
Author(s):  
Nandni Sharma ◽  
Kanika Khanna ◽  
Rajesh Kumari Manhas ◽  
Renu Bhardwaj ◽  
Puja Ohri ◽  
...  

Root-knot nematodes (RKN), Meloidogyne sp. hinders functioning of crops and causes global losses in terms of productivity and yield. Meloidogyne sp. are microscopic, obligatory endoparasites with ubiquitous distribution in different parts of the world. Taking into consideration these aspects, the present study was conducted to explore nematicidal activity of the Streptomyces hydrogenans strain DH-16 against M. incognita to regulate its pathogenicity in plants. In-vitro experimentation revealed that pretreated seeds with solvent and culture supernatant lowered root galls in infested plants and promoted growth of Solanum lycopersicum seedlings, revealed through the morphological analysis. Additionally, antioxidative defense responses were induced with microbes. However, oxidative stress markers were considerably reduced after microbial inoculations. Apart from this, secondary metabolites were assessed and modulated in RKN infested plants on microbial supplementations. Confocal studies evaluated glutathione accumulation within root apices and its enhancement was directly proportional to defense responses. Therefore, the current study concluded the role of S. hydrogenans in stimulating antioxidant potential against RKN along with growth promoting aids. Thus, the outcome of the current study endorses that metabolites produced by S. hydrogenans can be used as safe biocontrol agents against M. incognita and also as plant growth promoting agents.


Jurnal Agro ◽  
10.15575/4665 ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 110-122
Author(s):  
Yulmira Yanti ◽  
Imam Rifai ◽  
Yogie Aditya Pratama ◽  
Muhammad Ihsan Harahap

Rizobakteri merupakan kelompok bakteri yang aktif mengkolonisasi akar tanaman, meningkatkan pertumbuhan dan mengendalikan patogen tanaman. Penelitian ini bertujuan untuk memperoleh isolat rizobakteri indigenous  terbaik dalam meningkatkan pertumbuhan kelapa sawit dan mengendalikan penyakit busuk pangkal batang di pre-nursery kelapa sawit secara in planta serta karakterisasi kemampuan antagonisnya secara in vitro. Penelitian bersifat eksperimental terdiri atas 3 tahap dengan menggunakan Rancangan Acak Lengkap (RAL): (1) Isolasi dan karakterisasi isolat rizobakteri indigenous  di Kabupaten Pasaman Barat, (2) Pengujian isolat rizobakteri indigenous  (RBI) sebagai plant growth promoting rihzobacteria (PGPR), dan untuk pengendalian G.boninense di pre-nursery kelapa sawit terdiri dari 29 perlakuan (27 isolat RBI, tanpa inokulasi G. boninense sebagai kontrol positif, dan inokulasi G. boninense sebagai kontrol negatif) dengan masing-masing 5 ulangan, serta (3) Pengujian aktivitas antagonisme isolat RBI terhadap G. boninense. Data dianalisis dengan sidik ragam, apabila berbeda nyata dilanjutkan dengan uji Least Significance Different (LSD) pada taraf 5%. Hasil penelitian menunjukkan diperoleh tiga isolat terbaik (R10 2.2, R9 2.1, dan R10 2.3) yang mampu meningkatkan pertumbuhan kelapa sawit dan menekan perkembangan penyakit busuk pangkal batang G.boninense secara in planta dan in vitro.ABSTRACTRhizobacteria is a group of bacteria that actively colonize plant roots, increase growth and control plant pathogen. The objective of the research was to obtain indigenous rhizobacteria isolate (RBI) to increase growth and control basal stem rot on oil palm seedlings in in planta and characterize of antagonistic ability in in vitro. Experimental research consisted of 3 stages by using Completely Randomized Design (CRD): (1) Isolation of indigenous rhizobacteria in West Pasaman region, (2) Indigenous rhizobacteria isolate testing as a plant growth promoting rhizobacteria (PGPR) and to control of G. boninense on pre nursery of oil palm consisted of 29 treatments (27 RBI isolates, without G. boninense inoculation as positive control, and G. boninense inoculation as negative control) with 5 replications each. (3) Testing of RBI isolate antagonism activity towards G. boninense. Data were analyzed by variance, if the result significantly different, it was continued by using Least Significance Different (LSD) at 5% level. The results showed that best three isolates (R10 2.2, R9 2.1 and R10 2.3) were able to increase growth of palm oil and to suppress the development of G.boninense basal stem rot in in planta and in in vitro.


2021 ◽  
Vol 8 ◽  
Author(s):  
Khaled A. El-Tarabily ◽  
Arjun Sham ◽  
Alaa A. Elbadawi ◽  
Amira H. Hassan ◽  
Bashaer K. K. Alhosani ◽  
...  

Gray mangrove (Avicennia marina) is the dominant vegetation distributed along the coast of the United Arab Emirates (UAE). Despite its performance as natural coastal guardians, very little is known about the reforestation projects to increase mangrove cover over the years in the UAE and in the Arabian Gulf. Plant growth-promoting actinobacteria (PGPA) were isolated from the mangrove rhizosphere sediments found in the UAE and were evaluated for their potential to produce plant growth regulators (PGRs) and to enhance mangrove growth under seawater irrigation conditions. In vitro screening identified nine rhizosphere-competent actinobacterial isolates, in a naturally competitive environment, of which Streptomyces coelicoflavus (Sc) showed a high phosphorus solubilizing activity. Moreover, Streptomyces polychromogenes (Sp), Streptomyces bacillaris (Sb), and Streptomyces ferrugineus (Sf) produced auxins, polyamines (PAs), and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, respectively. Although sediment inoculation with single isolates significantly improved the dry biomass of mangrove shoots (43.2–74.0%) and roots (40.8–75.9%), the consortium of isolates (Sc/Sp/Sb/Sf) caused a greater increase in the dry weight of shoots (82.1%) and roots (81.6%) compared with seawater-irrigated plants (control). In our greenhouse experiments, the levels of photosynthetic pigments, in planta auxins, and PAs significantly increased in plant tissues inoculated with Sc/Sp/Sb/Sf; whereas ACC contents were reduced. This was also evident as the maximum velocity of rubisco carboxylation (Vcmax) increased four-fold in plants treated with the mixture of isolates over control. To the best of our knowledge, this is the first study reporting culturable halotolerant, rhizosphere-competent PGPA inhabiting salty and arid ecosystems applied individually or in combination to promote mangrove growth under harsh conditions such as those found in the Arabian coastal areas.


2017 ◽  
Vol 107 (8) ◽  
pp. 928-936 ◽  
Author(s):  
Ke Liu ◽  
Molli Newman ◽  
John A. McInroy ◽  
Chia-Hui Hu ◽  
Joseph W. Kloepper

A study was designed to screen individual strains of plant growth-promoting rhizobacteria (PGPR) for broad-spectrum disease suppression in vitro and in planta. In a preliminary screen, 28 of 196 strains inhibited eight different tested pathogens in vitro. In a secondary screen, these 28 strains showed broad spectrum antagonistic activity to six different genera of pathogens, and 24 of the 28 strains produced five traits reported to be related to plant growth promotion, including nitrogen fixation, phosphate solubilization, indole-3-acetic acid production, siderophore production, and biofilm formation. In advanced screens, the 28 PGPR strains selected in vitro were tested in planta for biological control of multiple plant diseases including bacterial spot of tomato caused by Xanthomonas axonopodis pv. vesicatoria, bacterial speck of tomato caused by Pseudomonas syringae pv. tomato, damping-off of pepper caused by Rhizoctonia solani, and damping-off of cucumber caused by Pythium ultimum. In all, 5 of the 28 tested strains significantly reduced three of the four tested diseases, and another 19 strains showed biological control to two tested diseases. To understand the observed broad-spectrum biocontrol capacity, antiSMASH was used to predict secondary metabolite clusters of selected strains. Multiple gene clusters encoding for secondary metabolites, e.g., bacillibactin, bacilysin, and microcin, were detected in each strain. In conclusion, selected individual PGPR strains showed broad-spectrum biocontrol activity to multiple plant diseases.


2021 ◽  
Vol 9 (9) ◽  
pp. 1924
Author(s):  
Pierre Joly ◽  
Alexandra Calteau ◽  
Aurélie Wauquier ◽  
Rémi Dumas ◽  
Mylène Beuvin ◽  
...  

Agriculture is in need of alternative products to conventional phytopharmaceutical treatments from chemical industry. One solution is the use of natural microorganisms with beneficial properties to ensure crop yields and plant health. In the present study, we focused our analyses on a bacterium referred as strain B25 and belonging to the species Bacillus velezensis (synonym B. amyloliquefaciens subsp. plantarum or B. methylotrophicus), a promising plant growth promoting rhizobacterium (PGPR) and an inhibitor of pathogenic fungi inducing crops diseases. B25 strain activities were investigated. Its genes are well preserved, with their majority being common with other Bacillus spp. strains and responsible for the biosynthesis of secondary metabolites known to be involved in biocontrol and plant growth-promoting activities. No antibiotic resistance genes were found in the B25 strain plasmid. In vitro and in planta tests were conducted to confirm these PGPR and biocontrol properties, showing its efficiency against 13 different pathogenic fungi through antibiosis mechanism. B25 strain also showed good capacities to quickly colonize its environment, to solubilize phosphorus and to produce siderophores and little amounts of auxin-type phytohormones (around 13,051 µg/mL after 32 h). All these findings combined to the fact that B25 demonstrated good properties for industrialization of the production and an environmental-friendly profile, led to its commercialization under market authorization since 2018 in several biostimulant preparations and opened its potential use as a biocontrol agent.


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.


2020 ◽  
Vol 367 (13) ◽  
Author(s):  
Marika Pellegrini ◽  
Claudia Ercole ◽  
Chiara Di Zio ◽  
Federica Matteucci ◽  
Loretta Pace ◽  
...  

ABSTRACT Potatoes (Solanum tuberosum L.) and tomatoes (Solanum lycopersicum L.), among the main crops belonging to the Solanaceae family, are attacked by several pathogens. Among them Fusarium oxysporum f. sp. radicis-lycopersici and Rhizoctonia solani are very common and cause significant losses. Four plant growth-promoting rhizobacteria, Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae and Burkholderia ambifaria were tested against these pathogens. In vitro antagonistic activities of single strains were assessed through dual culture plates. Strains showing antagonistic activity (G. diazotrophicus, H. seropedicae and B. ambifaria) were combined and, after an in vitro confirmation, the consortium was applied on S. lycopersicum and S. tuberosum in a greenhouse pot experiment. The bioprotection was assessed in pre-emergence (infection before germination) and post-emergence (infection after germination). The consortium was able to successfully counteract the infection of both F. oxysporum and R. solani, allowing a regular development of plants. The biocontrol of the fungal pathogens was highlighted both in pre-emergence and post-emergence conditions. This selected consortium could be a valid alternative to agrochemicals and could be exploited as biocontrol agent to counteract losses due to these pathogenic fungi.


2021 ◽  
pp. 66-72
Author(s):  
Alina Pastoshchuk ◽  
Yuliia Yumyna ◽  
Pavlyna Zelena ◽  
Larysa Skivka

The aim of this work was to isolate endophytic bacteria from wheat grains and to evaluate their plant growth promoting traits (PGPT) as well as an inhibitory effect on P. syringae pv. atrofaciens (McCulloch) growth. Endophytic bacteria were isolated by a culture-dependent protocol from the grains of winter wheat variety of Ukrainian selection Podolyanka with high resistance to syringae. Totally 2.7±0.09 CFU/1 g of dry wheat grain were isolated, ten cultivable bacterial isolates were obtained. Spore-forming bacilli predominated in the wheat grain endophytic community. Gram-negative fermenting and non-fermenting rod-shaped bacteria and Gram-positive cocci were also present. Seven out of ten isolates possessed numerous plant growth promoting traits including phosphate solubilization, oligonitrotrophy, and indolic compound producing. Two isolates possessed antagoniscic activity against syringae in vitro along with plant growth promoting features. According to biochemical profiling and mass-spectrophotometric identification, these two isolates were assigned to Paenibacillus and Brevibacillus genera. These endophytic bacteria can be considered as promising objects for agrobiotechnology. However, more research is needed to confirm their biotechnological potential in planta experiments


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