scholarly journals Endophytic Microorganisms as an Alternative for the Biocontrol of Phytophthora spp.

2021 ◽  
Author(s):  
Hernando José Bolivar-Anillo ◽  
Victoria E. González-Rodríguez ◽  
Giovanna Reyes Almeida ◽  
Inmaculada Izquierdo-Bueno ◽  
Javier Moraga ◽  
...  
Keyword(s):  
Host Plants ◽  
Plant Pathogens ◽  
Antagonistic Activity ◽  
Economic Losses ◽  
Natural Ecosystems ◽  
Phytophthora Spp ◽  
Endophytic Microorganisms ◽  
Wide Range ◽  
Fungicide Activity ◽  
Bacteria And Fungi

The genus Phytophthora with more than 100 described species and 58 officially recognized, phylogenetically distributed in ten clades, are important pathogenic oomycete chromists that cause important diseases in agricultural crops, trees and forests worldwide. This genus is known as \"The Plant Destroyer” which causes great economic losses with costs between 2 and 7 billion dollars per year in agricultural systems and unquantifiable losses in natural ecosystems. The host plants of the genus Phytophthora can vary from a wide range in some species to only one host, however, the host plants of the new species are still being determined and therefore the range continues to expand, that makes control exceedingly difficult. Plant damage can range from alterations in roots, fruits, trunks, stems, foliage and crown to invasive processes in highly susceptible species. Considering the wide range of hosts and organs that can be affected by Phytophthora, the use of endophytic microorganisms for the biocontrol of this phytopathogen can be an alternative to avoid losses of both crops and forests worldwide. Endophytes are microorganisms that live inside plant tissues without causing disease under any circumstances. The fact that endophytic microorganisms are able to colonize an ecological niche similar to that of some plant pathogens qualifies them as potential biocontrol agents. This chapter describes the endophytic bacteria and fungi isolated from different plant species that have shown antagonistic activity against different species of Phytophthora, as well as the metabolites isolated from these microorganisms that have shown fungicide activity and other biocontrol strategies (enzyme production, siderophores, substrate competition, among others) against Phytophthora.

scholarly journals Exploration of the Quorum-Quenching Mechanism in Pseudomonas nitroreducens W-7 and Its Potential to Attenuate the Virulence of Dickeya zeae EC1

2021 ◽  
Vol 12 ◽  
Author(s):  
Wenping Zhang ◽  
Xinghui Fan ◽  
Jiayi Li ◽  
Tian Ye ◽  
Sandhya Mishra ◽  
...  
Keyword(s):  
Host Plants ◽  
Pathogenic Bacteria ◽  
Bacterial Pathogens ◽  
Disease Incidence ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Economic Losses ◽  
Highly Efficient ◽  
Pseudomonas Nitroreducens ◽  
Wide Range

Quorum quenching (QQ) is a novel, promising strategy that opens up a new perspective for controlling quorum-sensing (QS)-mediated bacterial pathogens. QQ is performed by interfering with population-sensing systems, such as by the inhibition of signal synthesis, catalysis of degrading enzymes, and modification of signals. In many Gram-negative pathogenic bacteria, a class of chemically conserved signaling molecules named N-acyl homoserine lactones (AHLs) have been widely studied. AHLs are involved in the modulation of virulence factors in various bacterial pathogens including Dickeya zeae. Dickeya zeae is the causal agent of plant-rot disease of bananas, rice, maize, potatoes, etc., causing enormous economic losses of crops. In this study, a highly efficient AHL-degrading bacterial strain W-7 was isolated from activated-sludge samples and identified as Pseudomonas nitroreducens. Strain W-7 revealed a superior ability to degrade N-(3-oxododecanoyl)-l-homoserine lactone (OdDHL) and completely degraded 0.2 mmol/L of OdDHL within 48 h. Gas chromatography-mass spectrometry (GC-MS) identified N-cyclohexyl-propanamide as the main intermediate metabolite during AHL biodegradation. A metabolic pathway for AHL in strain W-7 was proposed based on the chemical structure of AHL and intermediate products. In addition to the degradation of OdDHL, this strain was also found to be capable of degrading a wide range of AHLs including N-(3-oxohexanoyl)-l-homoserine lactone (OHHL), N-(3-oxooctanoyl)-l-homoserine lactone (OOHL), and N-hexanoyl-l-homoserine lactone (HHL). Moreover, the application of strain W-7 as a biocontrol agent could substantially attenuate the soft rot caused by D. zeae EC1 to suppress tissue maceration in various host plants. Similarly, the application of crude enzymes of strain W-7 significantly reduced the disease incidence and severity in host plants. These original findings unveil the biochemical aspects of a highly efficient AHL-degrading bacterial isolate and provide useful agents that exhibit great potential for the control of infectious diseases caused by AHL-dependent bacterial pathogens.

scholarly journals Endophytic microorganisms of tropical tuber crops: Potential and perspectives

2017 ◽  
Vol 9 (2) ◽  
pp. 860-865 ◽  
Author(s):  
Shubhransu Nayak ◽  
Archana Mukherjee ◽  
Soma Samanta
Keyword(s):  
Nitrogen Fixation ◽  
Plant Pathogens ◽  
Thermal Protection ◽  
Beneficial Effects ◽  
Current Review ◽  
Endophytic Microorganisms ◽  
Anti Cancer ◽  
Elephant Foot Yam ◽  
Bacteria And Fungi ◽  
Tuber Crops

Endophytic microorganisms which include both bacteria and fungi colonise almost every plant species. In order to colonize the plant and compete with other microorganisms, they produce a plethora of secondary metabolites, including toxins, enzymes, antibiotics, anti-cancer, anti-inflammatory and antifungal compounds. Endophytic fungi can have profound impacts on plant communities which include abiotic and biotic stress tolerance, increase of biomass, decrease of water consumption and alteration of resource allocation, nitrogen fixation, increased drought resistance, thermal protection, survival under osmotic stress and degradation of pollutants. Though tuber crops are the second most important group of crop plants providing food energy to humans after cereals, less attention has been paid to the these traditional crops in general. Investigations regarding the association of endophytes with the tuber crops have been sparsely studied though in some tuber crops like cassava, sweet potato and yams, presence of endophytes have been reported. Hence from the scarcely available literature, in the current review an attempt was made to put light on the various beneficial activities of endophytes on tuber crops. These reports glorified many symbiotically associated endophytes to have antagonistic properties against many plant pathogens like Rhizoctoniasolani, Pythiumaphanidermatumand Sclerotiumrolfsii. Species like Rahnellawas resilient to cold shock, UV irradiation and antibiotics. Many diazotropihic and non-diazotropihicendophytic bacteria were involved in nitrogen fixation. Actinomycetesendophytes were novel sources of industrially important thermostableamylolytic enzymes. However, inspite of all these profound beneficial effects endophytic associations are still to be studied in many tuber crops like taro, elephant foot yam, greater yam etc. So this review put forward the urge to carry out comprehensive research on these important microbes on such important crops.

scholarly journals Plant thionins: structure, biological functions and potential use in biotechnology

2018 ◽  
Vol 22 (6) ◽  
pp. 667-675 ◽  
Author(s):  
T. I. Odintsova ◽  
M. P. Slezina ◽  
E. A. Istomina
Keyword(s):  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Biological Activities ◽  
Three Dimensional ◽  
Amino Acid Sequences ◽  
Lipid Transfer ◽  
Human Pathogens ◽  
Candida Spp ◽  
Wide Range ◽  
Bacteria And Fungi

Antimicrobial peptides (AMPs) are important components of defense system in both plants and animals. They represent an ancient mechanism of innate immunity providing rapid first line of defense against pathogens. Plant AMPs are classified into several families: thionins, defensins, nonspecific lipid-transfer proteins, hevein- and knottin-type peptides, hairpinins and macrocyclic peptides (cyclotides). The review focuses on the thionin family. Thionins comprise a plant-specific AMP family that consists of short (~5 kDA) cysteine-rich peptides containing 6 or 8 cysteine residues with antimicrobial and toxic properties. Based on similarity in amino acid sequences and the arrangement of disulphide bonds, five structural classes of thionins are discriminated. The three-dimensional structures of a number of thionins were determined. The amphipathic thionin molecule resembles the Greek letter Г, in which the long arm is formed by two antiparallel α-helices, while the short one, by two parallel β-strands. The residues responsible for the antimicrobial activity of thionins were identified. Thionins are synthesized as precursor proteins consisting of a signal peptide, the mature peptide region and the C-terminal prodomain. Thionins protect plants from pathogenic bacteria and fungi acting directly on the membranes of microorganisms at micromolar concentrations, although their precise mode of action remains unclear. In addition to plant pathogens, thionins inhibit growth of a number of human pathogens and opportunistic microorganisms, such as Candida spp., Saccharomyces cerevisiae, Fusarium solani, Staphylococcus aureus and Escherichia coli. Thionins are toxic to different types of cells including mammalian cancer cell lines. Transgenic plants expressing thionin genes display enhanced resistance to pathogens. A wide range of biological activities makes thionins promising candidates for practical application in agriculture and medicine.

A new real-time PCR assay for detecting fungi in genus Ceratocystis

Plant Disease ◽  
2021 ◽  
Author(s):  
Karthikeyan Dharmaraj ◽  
Alice Merrall ◽  
Julie A. Pattemore ◽  
Joanne Mackie ◽  
Brett J.R Alexander ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Plant Pathogens ◽  
Molecular Diagnostic ◽  
Diagnostic Tools ◽  
Stem Tissue ◽  
Natural Ecosystems ◽  
Pcr Assay ◽  
Practical Applications ◽  
Wide Range

The genus Ceratocystis contains several significant plant pathogens, causing wilt and canker disease on a wide range of plants species. Currently, there are over 40 known species of Ceratocystis, some of which are becoming increasingly important in agricultural or natural ecosystems. The diagnostics for most Ceratocystis species currently relies on time consuming and labour-intensive culturing approaches. To provide more time efficient and sensitive molecular diagnostic tools for Ceratocystis, a generic Taq-Man real-time PCR assay was developed using the ITS gene. This novel two-probe Taq-man assay amplified DNA from all tested Ceratocystis species. Some non-specific amplification of a few species from closely related genera was observed under certain conditions; however, these false positive detections could be ruled out using the additional PCR primers developed for further sequence based identification of the detected species. The assay was highly sensitive as it detected 0.2 pg/µl of Ceratocystis DNA in water as well as in host DNA matrix. Further validation with artificially inoculated fig stem tissue demonstrated that the assay was also able to effectively detect the pathogen in infected asymptomatic stem tissue. This newly developed real-time PCR assay has practical applications in biosecurity, conservation, and agriculture, enabling to detect Ceratocystis species directly from plant material, to facilitate more sensitive screening of imported plant germplasm, and allow rapid tracking of pathogens in case of disease outbreaks.

scholarly journals Research Advances of Beneficial Microbiota Associated with Crop Plants

2020 ◽  
Vol 21 (5) ◽  
pp. 1792 ◽  
Author(s):  
Lei Tian ◽  
Xiaolong Lin ◽  
Jun Tian ◽  
Li Ji ◽  
Yalin Chen ◽  
...  
Keyword(s):  
Plant Growth ◽  
Stress Resistance ◽  
Growth And Development ◽  
Host Plants ◽  
Crop Plant ◽  
Plant Growth And Development ◽  
Beneficial Bacteria ◽  
Wide Range ◽  
Microbe Interactions ◽  
Bacteria And Fungi

Plants are associated with hundreds of thousands of microbes that are present outside on the surfaces or colonizing inside plant organs, such as leaves and roots. Plant-associated microbiota plays a vital role in regulating various biological processes and affects a wide range of traits involved in plant growth and development, as well as plant responses to adverse environmental conditions. An increasing number of studies have illustrated the important role of microbiota in crop plant growth and environmental stress resistance, which overall assists agricultural sustainability. Beneficial bacteria and fungi have been isolated and applied, which show potential applications in the improvement of agricultural technologies, as well as plant growth promotion and stress resistance, which all lead to enhanced crop yields. The symbioses of arbuscular mycorrhizal fungi, rhizobia and Frankia species with their host plants have been intensively studied to provide mechanistic insights into the mutual beneficial relationship of plant–microbe interactions. With the advances in second generation sequencing and omic technologies, a number of important mechanisms underlying plant–microbe interactions have been unraveled. However, the associations of microbes with their host plants are more complicated than expected, and many questions remain without proper answers. These include the influence of microbiota on the allelochemical effect caused by one plant upon another via the production of chemical compounds, or how the monoculture of crops influences their rhizosphere microbial community and diversity, which in turn affects the crop growth and responses to environmental stresses. In this review, first, we systematically illustrate the impacts of beneficial microbiota, particularly beneficial bacteria and fungi on crop plant growth and development and, then, discuss the correlations between the beneficial microbiota and their host plants. Finally, we provide some perspectives for future studies on plant–microbe interactions.

scholarly journals Leafhopper Viral Pathogens: Ultrastructure of salivary gland infection of Taastrup-like virus inPsammotettix alienusDahlbom; and a novel Rhabdovirus inHomalodisca vitripennis(Germar) Hemiptera: Cicadellidae

2018 ◽  
Author(s):  
Thorben Lundsgaard ◽  
Wayne B. Hunter ◽  
Scott Adkins
Keyword(s):  
Next Generation Sequencing ◽  
Plant Pathogens ◽  
Insect Pests ◽  
Economic Losses ◽  
Type I ◽  
Next Generation ◽  
Viral Pathogen ◽  
Thin Sections ◽  
Wide Range ◽  
Generation Sequencing

AbstractViruses that are pathogenic to insect pests can be exploited as biological control agents. Viruses that are pathogenic to beneficial insects and other arthropods, as in honey bees, silk worms, and shrimp, cause millions of dollars of losses to those industries. Current advances in next generation sequencing technologies along with molecular and cellular biology have produced a wealth of information about insect viruses and their potential applications. Leafhoppers cause economic losses as vectors of plant pathogens which significantly reduce the worlds’ food crops. Each year more viruses are discovered primarily through the use of next generation sequencing of the leafhopper hosts. The diversity of viruses from leafhoppers demonstrates a wide range of taxonomic members that includes genomes of DNA or RNA from families like: Reoviridae, Iridoviridae, Dicistroviridae, Iflaviridae, and others yet to be classified. Discussed is a recent viral pathogen isolated from the leafhopperPsammotettix alienus, name Taastrup Virus. Taastrup virus (TV) is a novel virus with a RNA genome, a Filovirus-like morphology, being tentatively placed within theMononegavirales. AdultPsammotettix alienusinfected with TV, showed the highest concentration of virions in salivary glands, consisting of a principal gland (type I-VI-cells) and an accessory gland. Examination of thin sections revealed enveloped particles, about 1300 nm long and 62 nm in diameter, located singly or in paracrystalline arrays in canaliculi of type III- and IV-cells. In gland cells with TV particles in canaliculi, granular masses up to 15 μm in diameter were present in the cytoplasm. These masses are believed to be viroplasms, the sites for viral replication. TV particles were observed at the connection between a canaliculus and the salivary duct system. A TV-like virus with strongly similar morphology was discovered in the ornamental plant,Liriope, near Fort Pierce, Florida, USA. When the virus was inoculated to a leafhopper cell culture, HvWH, made from the glassy-winged sharpshooter,Homalodisca vitripennis(Germar), the cells rapidly degraded with 100% mortality in 48 hours. These two instances are the only reported cases of this newly discovered viral pathogen of leafhoppers.

scholarly journals Species Diversity in Colletotrichum Causing Anthracnose of Aromatic and Ornamental Lamiaceae in Italy

Agronomy ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 613 ◽  
Author(s):  
Guarnaccia ◽  
Gilardi ◽  
Martino ◽  
Garibaldi ◽  
Gullino
Keyword(s):  
Host Plants ◽  
Plant Pathogens ◽  
Ornamental Plants ◽  
Management Program ◽  
Origanum Vulgare ◽  
Colletotrichum Species ◽  
Species Complexes ◽  
Major Species ◽  
Wide Range ◽  
Colletotrichum Spp

Species of Colletotrichum are considered important plant pathogens, saprobes, and endophytes on a wide range of host plants. In Italy, several Colletotrichum species have been reported in glasshouse environments. In this study, we have explored the occurrence, diversity, and pathogenicity of Colletotrichum spp. associated with aromatic and ornamental plants belonging to the Lamiaceae family. Surveys were carried out during the 2011–2018 period in Liguria and Piedmont, Italy. A total of 19 Colletotrichum isolates were collected from symptomatic leaves and seeds of Ocimum basilicum (basil), Origanum vulgare (oregano) and different Salvia spp. A multi-locus phylogeny was established based on the basis of four genomic loci (ITS, GAPDH, ACT and TUB2). The aggressiveness of selected, representative isolates were tested. Colletotrichum isolates were identified as being members of three major species complexes: C. acutatum, C. destructivum, and C. gloeosporioides. Colletotrichum fioriniae, C. bryonicola, and C. fructicola were found in association with leaf lesions on Salvia leucantha, S. nemorosa, and S. greggii, respectively. Colletotrichum nigrum was isolated from twig lesions of S. greggii. Moreover, C. fioriniae and C. ocimi were found to be responsible for causing leaf anthracnose of oregano and basil, respectively. All the tested isolates were pathogenic and reproduced identical symptoms to those observed in commercial glasshouses. The present study improves our understanding of Colletotrichum species associated with several hosts belonging to the Lamiaceae family, which are cultivated extensively throughout Italy for different purpose, and provides information that may be useful for an effective disease management program.

scholarly journals The Endophytic Microbiome as a Hotspot of Synergistic Interactions, with Prospects of Plant Growth Promotion

Biology ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 101
Author(s):  
Udaya Kumar Vandana ◽  
Jina Rajkumari ◽  
L. Paikhomba Singha ◽  
Lakkakula Satish ◽  
Hemasundar Alavilli ◽  
...  
Keyword(s):  
Plant Growth ◽  
Microbial Communities ◽  
Plant Growth Promotion ◽  
Endophytic Bacteria ◽  
Host Plants ◽  
Plant Pathogens ◽  
Growth Promotion ◽  
Plant Root ◽  
Endophytic Microorganisms ◽  
Microbe Interactions

The plant root is the primary site of interaction between plants and associated microorganisms and constitutes the main components of plant microbiomes that impact crop production. The endophytic bacteria in the root zone have an important role in plant growth promotion. Diverse microbial communities inhabit plant root tissues, and they directly or indirectly promote plant growth by inhibiting the growth of plant pathogens, producing various secondary metabolites. Mechanisms of plant growth promotion and response of root endophytic microorganisms for their survival and colonization in the host plants are the result of complex plant-microbe interactions. Endophytic microorganisms also assist the host to sustain different biotic and abiotic stresses. Better insights are emerging for the endophyte, such as host plant interactions due to advancements in ‘omic’ technologies, which facilitate the exploration of genes that are responsible for plant tissue colonization. Consequently, this is informative to envisage putative functions and metabolic processes crucial for endophytic adaptations. Detection of cell signaling molecules between host plants and identification of compounds synthesized by root endophytes are effective means for their utilization in the agriculture sector as biofertilizers. In addition, it is interesting that the endophytic microorganism colonization impacts the relative abundance of indigenous microbial communities and suppresses the deleterious microorganisms in plant tissues. Natural products released by endophytes act as biocontrol agents and inhibit pathogen growth. The symbiosis of endophytic bacteria and arbuscular mycorrhizal fungi (AMF) affects plant symbiotic signaling pathways and root colonization patterns and phytohormone synthesis. In this review, the potential of the root endophytic community, colonization, and role in the improvement of plant growth has been explained in the light of intricate plant-microbe interactions.

scholarly journals Biopesticide Activity from Drimanic Compounds to Control Tomato Pathogens

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 2053 ◽  
Author(s):  
Iván Montenegro ◽  
Alejandro Madrid ◽  
Mauricio Cuellar ◽  
Michael Seeger ◽  
Juan Alfaro ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Economic Losses ◽  
Clavibacter Michiganensis ◽  
Synthetic Compound ◽  
Tomato Production ◽  
Minimal Inhibitory Concentrations ◽  
Phytophthora Spp ◽  
Fungal Plant Pathogens

Tomato crops can be affected by several infectious diseases produced by bacteria, fungi, and oomycetes. Four phytopathogens are of special concern because of the major economic losses they generate worldwide in tomato production; Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato, causative agents behind two highly destructive diseases, bacterial canker and bacterial speck, respectively; fungus Fusarium oxysporum f. sp. lycopersici that causes Fusarium Wilt, which strongly affects tomato crops; and finally, Phytophthora spp., which affect both potato and tomato crops. Polygodial (1), drimenol (2), isonordrimenone (3), and nordrimenone (4) were studied against these four phytopathogenic microorganisms. Among them, compound 1, obtained from Drimys winteri Forst, and synthetic compound 4 are shown here to have potent activity. Most promisingly, the results showed that compounds 1 and 4 affect Clavibacter michiganensis growth at minimal inhibitory concentrations (MIC) values of 16 and 32 µg/mL, respectively, and high antimycotic activity against Fusarium oxysporum and Phytophthora spp. with MIC of 64 µg/mL. The results of the present study suggest novel treatment alternatives with drimane compounds against bacterial and fungal plant pathogens.

scholarly journals New Phytophthoras in Western Australia’s natural ecosystems

2012 ◽  
Vol 33 (1) ◽  
pp. 31
Author(s):  
Michael JC Stukely
Keyword(s):  
Dna Sequencing ◽  
New Taxa ◽  
Western Australia ◽  
Phylogenetic Relationships ◽  
Plant Pathogens ◽  
New Records ◽  
Natural Vegetation ◽  
Natural Ecosystems ◽  
Phytophthora Spp ◽  
Diverse Species

Phytophthora spp. are recognised as important plant pathogens. Ten new and genetically diverse species, not previously reported from elsewhere, have recently been described from natural ecosystems in Western Australia (WA): Phytophthora multivora1; P. elongata; P. thermophila, P. gregata, P. gibbosa, P. litoralis; P. arenaria, P. constricta; P. fluvialis; and P. amnicola. They were identified by DNA sequencing of recent and historical isolates from the WA Department of Environment and Conservation (DEC). Several additional new taxa await description. New records for WA of at least eight other Phytophthora taxa that are known overseas, some of them as yet undescribed, have also been confirmed: P. inundata; P. taxon niederhauserii, P. taxon asparagi, P. taxon PgChlamydo, P. taxon personii; P. taxon salixsoil; P. palmivora and P. rosacearum. Furthermore, numerous Phytophthora hybrids have been identified in natural vegetation and waterways in WA. The phylogenetic relationships of the new WA Phytophthora taxa, with their nearest relatives, are shown in Figure 1.

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