Transmission of the Invasive Pathogen Phytophthora ramorum from Symptomatic to Healthy Host Plants During a Five-Year Period in California

2021 ◽  
Author(s):  
Wolfgang Schweigkofler ◽  
Tomas Pastalka ◽  
Nilwala Abeysekara ◽  
Vernon Huffman ◽  
Karen Suslow
Keyword(s):  
Host Plants ◽  
Plant Pathogens ◽  
Management Strategies ◽  
Phytophthora Ramorum ◽  
Symptom Development ◽  
Epidemiological Models ◽  
Total Rainfall ◽  
Forest Pathogen ◽  
Umbellularia Californica ◽  
Leaf Symptoms

Reliable data on the transmission of airborne plant pathogens are crucial for the development of epidemiological models and implementation of management strategies. The short-distance vertical transmission of the forest pathogen Phytophthora ramorum from a symptomatic California bay laurel (Umbellularia californica) to healthy containerized rhododendrons (Rhododendron caucasicum × R. ponticum var. album) was monitored for five winters (2016/17 to 2020/21) in a field experiment in Northern California. Transmission events were observed during four winters at a frequency of 1 to 17 per season, but not during the extremely dry winter of 2020/21, and were positively correlated to total rainfall rates. The first leaf symptoms were detected around mid-December and reached the highest numbers in January of most years. Only limited symptom development was observed in the spring, with the last detections in May. The exposure time (the time between the first rainfall after placing a bait plant under the bay laurel and development of symptoms) varied between 3 and over 150 days, with an average between 14 and 21 days. P. ramorum was detected from water samples collected from the canopy of the symptomatic California bay laurel. No horizontal pathogen spread was detected from symptomatic to healthy rhododendrons placed at a distance of 2 to 6 m.

scholarly journals High-Quality Genome Resource of the Pathogen of Diaporthe (Phomopsis) phragmitis Causing Kiwifruit Soft Rot

2020 ◽  
Author(s):  
Pu Liu ◽  
Wang Xiaojie ◽  
Dong Hongjie ◽  
Jianbin Lan ◽  
Kuan Liang ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Management Strategies ◽  
Soft Rot ◽  
Fruit Rot ◽  
Economic Plant ◽  
High Quality ◽  
Total Size ◽  
Genome Wide ◽  
Solid Foundation ◽  
High Quality Genome

Diaporthe spp. are critical plant pathogens that cause wood cankers, wilt, dieback, and fruit rot in a wide variety of economic plant hosts and are regarded as one of the most acute threats faced by kiwifruit industry worldwide. Diaporthe phragmitis strain NJD1 is a highly pathogenic isolate of soft rot of kiwifruit. Here, we present a high-quality genome-wide sequence of D. phragmitis NJD1 that was assembled into 28 contigs containing a total size of 58.33 Mb and N50 length of 3.55 Mb. These results lay a solid foundation for understanding host–pathogen interaction and improving disease management strategies.

Species composition and host range of fruit-infesting flies (Diptera: Tephritidae) in northern Ghana

2015 ◽  
Vol 35 (03) ◽  
pp. 137-151 ◽  
Author(s):  
K.B. Badii ◽  
M.K. Billah ◽  
K. Afreh-Nuamah ◽  
D. Obeng-Ofori
Keyword(s):  
Host Range ◽  
Plant Species ◽  
Host Plants ◽  
Management Strategies ◽  
Fruit Fly ◽  
Fruit Flies ◽  
Northern Ghana ◽  
Accurate Information ◽  
Wild Host ◽  
Fruit Samples

An important aspect of fruit fly management is accurate information on the species and their host spectrum. Studies were conducted between October 2011 and September 2013 to determine the host range and species diversity of pest fruit flies in the northern savannah ecology of Ghana. Fruit samples from 80 potential host plants (wild and cultivated) were collected and incubated for fly emergence; 65 (81.5%) of the plant species were positive to fruit flies. From records in Africa, 11 plant species were reported to be new hosts to the African invader fly,Bactrocera invadens(Drew, Tsuruta and White, 2005). This study documented the first records ofDacus ciliatus(Loew) andTrirhithrum nigerrimum(Bezzi) in northern Ghana although both species have been previously reported in other parts of the country. Infestation byB. invadenswas higher in the cultivated fruits;Ceratitis cosyradominated in most wild fruits. Cucurbitaceae were mainly infested by three species ofDacusandBactroceracucurbitae, a specialized cucurbit feeder. Among the commercial fruit species, the highest infestations were observed in mango, tomato, sweet pepper and watermelon, whereas marula plum, soursop, tropical almond, sycamore fig, African peach, shea nut, persimmon, icacina and albarillo dominated the wild host flora. The widespread availability of host plants and the incidence of diverse fly species in the ecology call for particular attention to their impact on commercial fruits and the development of sustainable management strategies against these economically important pests in Ghana.

scholarly journals Bioactive Secondary Metabolites of the Genus Diaporthe and Anamorph Phomopsis from Terrestrial and Marine Habitats and Endophytes: 2010–2019

2021 ◽  
Vol 9 (2) ◽  
pp. 217
Author(s):  
Tang-Chang Xu ◽  
Yi-Han Lu ◽  
Jun-Fei Wang ◽  
Zhi-Qiang Song ◽  
Ya-Ge Hou ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Small Molecules ◽  
Host Plants ◽  
Plant Pathogens ◽  
Bioactive Metabolites ◽  
Drug Candidates ◽  
The Past ◽  
Marine Habitats ◽  
Bioactive Secondary Metabolites ◽  
Unidentified Species

The genus Diaporthe and its anamorph Phomopsis are distributed worldwide in many ecosystems. They are regarded as potential sources for producing diverse bioactive metabolites. Most species are attributed to plant pathogens, non-pathogenic endophytes, or saprobes in terrestrial host plants. They colonize in the early parasitic tissue of plants, provide a variety of nutrients in the cycle of parasitism and saprophytism, and participate in the basic metabolic process of plants. In the past ten years, many studies have been focused on the discovery of new species and biological secondary metabolites from this genus. In this review, we summarize a total of 335 bioactive secondary metabolites isolated from 26 known species and various unidentified species of Diaporthe and Phomopsis during 2010–2019. Overall, there are 106 bioactive compounds derived from Diaporthe and 246 from Phomopsis, while 17 compounds are found in both of them. They are classified into polyketides, terpenoids, steroids, macrolides, ten-membered lactones, alkaloids, flavonoids, and fatty acids. Polyketides constitute the main chemical population, accounting for 64%. Meanwhile, their bioactivities mainly involve cytotoxic, antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory, anti-algae, phytotoxic, and enzyme inhibitory activities. Diaporthe and Phomopsis exhibit their potent talents in the discovery of small molecules for drug candidates.

scholarly journals Management Strategies for Conservation of Tanoak in California Forests Threatened by Sudden Oak Death: A Disease-Community Feedback Modelling Approach

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1103
Author(s):  
João A. N. Filipe ◽  
Richard C. Cobb ◽  
Maëlle Salmon ◽  
Christopher A. Gilligan
Keyword(s):  
Disease Management ◽  
Community Dynamics ◽  
Management Strategies ◽  
Phytophthora Ramorum ◽  
Ecological Impacts ◽  
Control Measures ◽  
Forest Community ◽  
Forest Composition ◽  
Cumulative Impact ◽  
Modelling Approach

We use a new modelling approach to predict the cumulative impact of Phytophthora ramorum on the dynamic distribution of tanoak (Notholithocarpus densiflorus) and other tree species in coastal-Californian forest-communities. We explore the effectiveness of disease-management strategies for the conservation of tanoak at stand level. Forest resources are increasingly threatened by emerging pathogens such as P. ramorum, a generalist that kills hosts and has altered ecosystems in the USA and Europe. In coastal California, P. ramorum has the greatest impact on tanoak through leaf sporulation and lethal bole infections, but also sporulates on the common overstory-tree bay laurel (Umbellularia californica) without significant health impact. Such epidemiological differences impede host-species coexistence and challenge pathogen management. For most disease-impacted natural systems, however, empirical evidence is still insufficient to identify effective and affordable pathogen-control measures for retaining at-risk host populations. Yet, landscape-scale tree mortality requires swift actions to mitigate ecological impacts and loss of biodiversity. We apply a mathematical model of the feedback between disease and forest-community dynamics to assess the impacts of P. ramorum invasion on tanoak under stand-scale disease-management strategies by landowners aiming to retain tanoak and slow disease progression: (1) removal of inoculum through reduction of bay laurel abundance; (2) prevention of tanoak infection through chemical protection (acting epidemiologically like a vaccine); and (3) a combination strategy. The model results indicate that: (1) both bay laurel removal and tanoak protection are required to help maintain tanoak populations; (2) treatment effectiveness depends on forest composition and on threshold criteria; (3) sustainable tanoak conservation would require long-term follow-up of preventive treatments; (4) arresting basal sprouting upon tree removal may help to reduce inoculum. These findings suggest potential treatments for specific forest conditions that could be tested and implemented to reduce P. ramorum inoculum and disease and to conserve tanoak at stand level.

scholarly journals Drivers of Foliar Fungal Endophytic Communities of Kudzu (Pueraria montana var. lobata) in the Southeast United States

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 185
Author(s):  
Maryam Shahrtash ◽  
Shawn P. Brown
Keyword(s):  
United States ◽  
Plant Pathogens ◽  
Invasive Plant ◽  
Fungal Endophytes ◽  
Management Strategies ◽  
Environmental Parameters ◽  
Plant Management ◽  
Host Genotype ◽  
Southeast United States ◽  
Pueraria Montana

Fungal endophytes play important roles in plant fitness and plant–microbe interactions. Kudzu (Pueraria montana var. lobata) is a dominant, abundant, and highly aggressive invasive plant in the Southeast United States. Kudzu serves as a pathogen reservoir that impacts economically important leguminous crops. We conducted the first investigations on kudzu fungal endophytes (Illumina MiSeq—ITS2) to elucidate drivers of endophytic communities across the heart of the invasive range in the Southeast United States (TN, MS, AL, GA). We tested the impacts of multiple environmental parameters (Chlorophyll, NO3−, K+, soil pH, leaf area, host genotype, traffic intensity, and geographic location) on foliar endophyte communities. Endophytic communities were diverse and structured by many factors in our PerMANOVA analyses, but location, genotype, and traffic (proxy for pollution) were the strongest drivers of community composition (R2 = 0.152, p < 0.001, R2 = 0.129, p < 0.001, and R2 = 0.126, p < 0.001, respectively). Further, we examined the putative ecological interactions between endophytic fungi and plant pathogens. We identify numerous OTUs that are positively and strongly associated with pathogen occurrence, largely within the families Montagnulaceae and Tremellales incertae sedis. Taken together, these data suggest location, host genetics and local pollution play instrumental roles in structuring communities, and integrative plant management must consider these factors when developing management strategies.

scholarly journals Comparative Genomic and Proteomic Analyses of Three Widespread Phytophthora Species: Phytophthora chlamydospora, Phytophthora gonapodyides and Phytophthora pseudosyringae

2020 ◽  
Vol 8 (5) ◽  
pp. 653 ◽  
Author(s):  
Jamie McGowan ◽  
Richard O’Hanlon ◽  
Rebecca A. Owens ◽  
David A. Fitzpatrick
Keyword(s):  
Mass Spectrometry ◽  
Plant Pathogens ◽  
Genome Structure ◽  
Draft Genome ◽  
Phytophthora Species ◽  
Comparative Genomic ◽  
Tandem Gene Duplication ◽  
Widespread Species ◽  
Forest Pathogen ◽  
Extracellular Proteome

The Phytophthora genus includes some of the most devastating plant pathogens. Here we report draft genome sequences for three ubiquitous Phytophthora species—Phytophthora chlamydospora, Phytophthora gonapodyides, and Phytophthora pseudosyringae. Phytophthora pseudosyringae is an important forest pathogen that is abundant in Europe and North America. Phytophthora chlamydospora and Ph. gonapodyides are globally widespread species often associated with aquatic habitats. They are both regarded as opportunistic plant pathogens. The three sequenced genomes range in size from 45 Mb to 61 Mb. Similar to other oomycete species, tandem gene duplication appears to have played an important role in the expansion of effector arsenals. Comparative analysis of carbohydrate-active enzymes (CAZymes) across 44 oomycete genomes indicates that oomycete lifestyles may be linked to CAZyme repertoires. The mitochondrial genome sequence of each species was also determined, and their gene content and genome structure were compared. Using mass spectrometry, we characterised the extracellular proteome of each species and identified large numbers of proteins putatively involved in pathogenicity and osmotrophy. The mycelial proteome of each species was also characterised using mass spectrometry. In total, the expression of approximately 3000 genes per species was validated at the protein level. These genome resources will be valuable for future studies to understand the behaviour of these three widespread Phytophthora species.

scholarly journals The Probing Behavior Component of Disease Transmission in Insect-Transmitted Bacterial Plant Pathogens

Insects ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 212 ◽  
Author(s):  
Timothy A. Ebert
Keyword(s):  
Host Plant ◽  
Plant Resistance ◽  
Host Plant Resistance ◽  
Disease Transmission ◽  
Plant Pathogens ◽  
Management Strategies ◽  
Resistance Mechanism ◽  
Electrical Circuit ◽  
Plant Diseases ◽  
Candidatus Liberibacter

Insects can be effective vectors of plant diseases and this may result in billions of dollars in lost agricultural productivity. New, emerging or introduced diseases will continue to cause extensive damage in afflicted areas. Understanding how the vector acquires the pathogen and inoculates new hosts is critical in developing effective management strategies. Management may be an insecticide applied to kill the vector or a host plant resistance mechanism to make the host plant less suitable for the vector. In either case, the tactic must act before the insect performs the key behavior(s) resulting in either acquisition or transmission. This requires knowledge of the timing of behaviors the insect uses to probe the plant and commence ingestion. These behaviors are visualized using electropenetrography (EPG), wherein the plant and insect become part of an electrical circuit. With the tools to define specific steps in the probing process, we can understand the timing of acquisition and inoculation. With that understanding comes the potential for more relevant testing of management strategies, through insecticides or host plant resistance. The primary example will be Candidatus Liberibacter asiaticus transmitted by Diaphorina citri Kuwayama in the citrus agroecosystem, with additional examples used as appropriate.

scholarly journals Genetic and Ecological Relationships of Anastrepha ludens (Diptera: Tephritidae) Populations in Southern Mexico

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 815
Author(s):  
Lorena Ruiz-Montoya ◽  
Rodrigo Verónica Vallejo ◽  
David Haymer ◽  
Pablo Liedo
Keyword(s):  
Sexual Selection ◽  
Genetic Differentiation ◽  
Host Plants ◽  
Control Strategies ◽  
Mangifera Indica ◽  
Random Mating ◽  
Management Strategies ◽  
Fruit Fly ◽  
Anastrepha Ludens ◽  
Southern Mexico

Knowledge of the influence of evolutionary factors that promote either the differentiation or cohesion of pest insect populations is critical for the improvement of control strategies. Here, we explore the extent to which genetic differentiation occurs between populations of the Mexican fruit fly, Anastrepha ludens, in association with four plant hosts (Citrus sinensis, C. paradisi, Mangifera indica and Casimiroa edulis) in the Soconusco region of Chiapas (Mexico). Using variants from six enzymatic loci, we obtained measures of genetic diversity for three sample arrangements: (1) by sex per locality, (2) by locality and (3) by host. The extent of genetic differentiation in populations was assessed using the Analyses of Molecular Variance (AMOVA) method for each array of samples, and moderate to high levels of genetic variation were observed between the sexes, as well as among localities and host plants. A Bayesian approach was then used to assess any population structure underlying the genetic data we obtained, but this analysis showed no significant structuring due to locality or host plant. We also considered whether the observed genotypic frequencies in male and females matched those expected under a hypothesis of random mating. Here we found significant deviations from expected genotypic frequencies, suggesting that sexual selection is acting on these populations. Overall, our results indicate that sexual selection, along with the presence of some heterogeneity in environments provided by both geographical factors and availability of host plants, has influenced the evolution of pest populations in this region of Mexico. Implications for area-wide pest management strategies are discussed.

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