scholarly journals A metabolomics characterisation of natural variation in the resistance of cassava to whitefly

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Laura Perez-Fons ◽  
Adriana Bohorquez-Chaux ◽  
Maria L. Irigoyen ◽  
Danielle C. Garceau ◽  
Kris Morreel ◽  
...  
Keyword(s):  
Time Course ◽  
Management Strategies ◽  
Resistance Mechanism ◽  
Central Africa ◽  
Susceptible Variety ◽  
Induced Response ◽  
Genotypic Differences ◽  
Germplasm Collections ◽  
Resistant Varieties ◽  
Quantitative Changes

Abstract Background Cassava whitefly outbreaks were initially reported in East and Central Africa cassava (Manihot esculenta Crantz) growing regions in the 1990’s and have now spread to other geographical locations, becoming a global pest severely affecting farmers and smallholder income. Whiteflies impact plant yield via feeding and vectoring cassava mosaic and brown streak viruses, making roots unsuitable for food or trading. Deployment of virus resistant varieties has had little impact on whitefly populations and therefore development of whitefly resistant varieties is also necessary as part of integrated pest management strategies. Suitable sources of whitefly resistance exist in germplasm collections that require further characterization to facilitate and assist breeding programs. Results In the present work, a hierarchical metabolomics approach has been employed to investigate the underlying biochemical mechanisms associated with whitefly resistance by comparing two naturally occurring accessions of cassava, one susceptible and one resistant to whitefly. Quantitative differences between genotypes detected at pre-infestation stages were consistently observed at each time point throughout the course of the whitefly infestation. This prevalent differential feature suggests that inherent genotypic differences override the response induced by the presence of whitefly and that they are directly linked with the phenotype observed. The most significant quantitative changes relating to whitefly susceptibility were linked to the phenylpropanoid super-pathway and its linked sub-pathways: monolignol, flavonoid and lignan biosynthesis. These findings suggest that the lignification process in the susceptible variety is less active, as the susceptible accession deposits less lignin and accumulates monolignol intermediates and derivatives thereof, differences that are maintained during the time-course of the infestation. Conclusions Resistance mechanism associated to the cassava whitefly-resistant accession ECU72 is an antixenosis strategy based on reinforcement of cell walls. Both resistant and susceptible accessions respond differently to whitefly attack at biochemical level, but the inherent metabolic differences are directly linked to the resistance phenotype rather than an induced response in the plant.

scholarly journals Environmentally Induced Variability in the Host Reaction of Barley to Net Blotch

1969 ◽  
Vol 22 (5) ◽  
pp. 1237 ◽  
Author(s):  
TN Khan ◽  
WJR Boyd
Keyword(s):  
Environmental Conditions ◽  
Susceptible Variety ◽  
Post Inoculation ◽  
Net Blotch ◽  
Host Reaction ◽  
Drechslera Teres ◽  
Resistant Varieties

The host reaction of two Ethiopian and four Manchurian resistant varieties, and one susceptible variety of barley to isolate 177 of Drechslera teres was studied under a range of environmental conditions. The effects were specific to the variety(ies) used, with the exception of the factor of post-inoculation temperature. High post-inoculation temperatures brought about the breakdown of resistance in all the varieties.

scholarly journals Three decades of cotton disease surveys in NSW, Australia

2013 ◽  
Vol 64 (8) ◽  
pp. 774 ◽  
Author(s):  
K. A. Kirkby ◽  
P. A. Lonergan ◽  
S. J. Allen
Keyword(s):  
Bacterial Blight ◽  
Cultural Practices ◽  
Management Strategies ◽  
Cotton Production ◽  
South Wales ◽  
Resistant Varieties ◽  
Dramatic Decline ◽  
Disease Surveys ◽  
Production Areas ◽  
The Impact

Three decades of disease survey data have shown Verticillium wilt was one of the first major diseases of cotton recorded in the 1984–85 season. Survey reports the mean incidence was 4.1% in the 1984–85 season and rose to 16.6% in the 1989–90 season. Prior to 1984 all commercial varieties of cotton available in Australia were susceptible to bacterial blight and the disease was common. The adoption of the resistant varieties contributed to a dramatic decline in the incidence of bacterial blight and the removal of bacterial blight as a significant pathogen to Australian cotton crops by 1992. Survey results showed the incidence of black root rot increased on farms with a long history of growing cotton during the 1990s. Fusarium wilt of cotton was first reported in New South Wales (NSW) in 1994. The disease is now widespread, being confirmed on 86 NSW farms in six of the eight cotton production areas in NSW. These four significant plant disease ‘problems’ have challenged the cotton industry in NSW. Data provided by the surveys have indicated the relative importance of each of the diseases present and the impact of cultural practices and the adoption of new varieties on disease distribution, incidence and severity. The results have therefore been used to support and justify requests for research funding and have contributed to the development of Integrated Disease Management strategies. The NSW Department of Primary Industries continues to monitor the distribution of disease and the incidence and severity present in commercial cotton crops in all production areas of NSW. The aim of this paper is to highlight four significant cotton diseases in Australia and show relationships between cultural practices and declining and increasing incidence of disease.

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 Quantifying the Use of Forest Ecosystem Services by Local Populations in Southeastern Cameroon

2020 ◽  
Vol 12 (6) ◽  
pp. 2505 ◽  
Author(s):  
Simon Lhoest ◽  
Cédric Vermeulen ◽  
Adeline Fayolle ◽  
Pierre Jamar ◽  
Samuel Hette ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Rural Communities ◽  
Tropical Forests ◽  
Management Strategies ◽  
Central Africa ◽  
Cultural Services ◽  
Deforestation Rate ◽  
Local Populations ◽  
Forest Ecosystem Services ◽  
Integrated Assessments

In order to improve sustainability and design adequate management strategies in threatened tropical forests, integrated assessments of the use of ecosystem services are needed, combining biophysical, social, and economic approaches. In particular, no integrated ecosystem services (ES) assessment has been conducted in Central Africa, where rural communities deeply depend on forests in a high-poverty context. Here, we aimed to quantify the use of ES provided by tropical forests to local populations in the Dja area (Cameroon), identify its determinants and evaluate its sustainability. We conducted various interviews and field surveys with 133 households in three villages, focusing on three provisioning services (bushmeat, firewood, and timber), and five cultural services (cultural heritage, inspiration, spiritual experience, recreation, and education). Local populations consumed a mean of 56 kg of bushmeat/person/year (hunting zones covering on average 213 km2), 1.17 m3 of firewood/person/year (collection zones covering on average 4 km2), and 0.03 m3 of timber/person/year. Between 25% and 86% of respondents considered cultural services as important. The use of ES was mainly influenced by population size, deforestation rate, and forest allocations, whereas the influence of socio-demographic characteristics of households remained limited to slight differences between Baka and Bantu people. We conclude that the consumption of firewood and timber is sustainable, whereas high hunting pressure has resulted in severe defaunation in the area due to the large decline in the abundance and biomass of forest mammals hunted for bushmeat by local populations.

scholarly journals Development of a single uredinium inoculation method for Puccinia kuehnii, the causal agent of sugarcane orange rust

2018 ◽  
Vol 44 (4) ◽  
pp. 311-316 ◽  
Author(s):  
Lis Natali Rodrigues Porto ◽  
Alfredo Seiiti Urashima
Keyword(s):  
Phenotypic Diversity ◽  
Susceptible Variety ◽  
Resistant Genotype ◽  
Puccinia Kuehnii ◽  
Inoculation Techniques ◽  
Resistant Varieties ◽  
Injured Area ◽  
Significant Difference ◽  
Ideal Method

ABSTRACT The use of resistant varieties is the ideal method to control rusts. Nevertheless, knowing the pathogen’s diversity is fundamental to the success of this measure. Diversity can be analyzed phenotypically and/or genotypically. For phenotypic diversity, the reaction of genotypes is assessed by means of inoculations of the pathogen generally obtained from several uredinia. One handicap of this technique is its impossibility to detect diversity among these uredinia, assuming that they are all homogenous. Therefore, the aim of the present study was to develop a single uredinium technique for Puccinia kuehnii to be used in studies of rust diversity in sugarcane. The comparison between the two inoculation methods was done by employing urediniospores from SP89-1115 on the varieties SP89-1115 (susceptible) and RB975201 (resistant). The adopted design was completely randomized with five and seven replicates, respectively, examining incubation, latency, disease score, and injured area at 14 and 21 days. The two inoculation techniques were significantly equal for the susceptible variety, considering all evaluated parameters. For the resistant genotype, a significant difference was identified in the injured area and such difference did not interfere in the classification of the reaction of the material since values were below 1%. The single uredinium technique developed in this study showed to be reliable since the genotypic profile of the inoculated fungus was similar to that of pathogens from the produced lesions.

scholarly journals Predicting future invaders and future invasions

2019 ◽  
Vol 116 (16) ◽  
pp. 7905-7910 ◽  
Author(s):  
Alice Fournier ◽  
Caterina Penone ◽  
Maria Grazia Pennino ◽  
Franck Courchamp
Keyword(s):  
Papua New Guinea ◽  
Ecosystem Functioning ◽  
Species Distribution Models ◽  
Invasive Alien Species ◽  
Management Strategies ◽  
Central Africa ◽  
Invasive Ants ◽  
Distribution Models ◽  
Proactive Management ◽  
Local Extinctions

Invasive alien species are a great threat to biodiversity and human livelihoods worldwide. The most effective way to limit their impacts and costs is to prevent their introduction into new areas. Identifying invaders and invasions before their occurrence would arguably be the most efficient strategy. Here, we provide a profiling method to predict which species—with which particular ecological characteristics—will invade, and where they could invade. We illustrate our approach with ants, which are among the most detrimental invasive species, as they are responsible for declines of numerous taxa, are involved in local extinctions, disturb ecosystem functioning, and impact multiple human activities. Based on statistical profiling of 1,002 ant species from an extensive trait database, we identify 13 native ant species with an ecological profile that matches that of known invasive ants. Even though they are not currently described as such, these species are likely to become the next global invaders. We couple these predictions with species distribution models to identify the regions most at risk from the invasion of these species: Florida and Central America, Brazil, Central Africa and Madagascar, Southeast Asia, Papua New Guinea Northeast Australia, and many islands worldwide. This framework, applicable to any other taxa, represents a remarkable opportunity to implement timely and specifically shaped proactive management strategies against biological invasions.

The control of bacterial blight in rain-grown cotton. II. Some effects of infection on growth and yield

1965 ◽  
Vol 65 (1) ◽  
pp. 29-40 ◽  
Author(s):  
M. H. Arnold
Keyword(s):  
Bacterial Blight ◽  
Susceptible Variety ◽  
Growth And Yield ◽  
Crop Loss ◽  
Seed Cotton ◽  
The Third ◽  
Seed Dressing ◽  
Resistant Varieties ◽  
Series Of Experiments ◽  
Moderately Resistant

Three series of experiments are described from which minimum estimates of crop loss caused by bacterial blight were obtained. In the first two, the estimates were derived from seed-dressing trials, and in the third, seed dressing was used in conjunction with resistant varieties.Losses amounted to as much as 354 ± 39 lb. seed cotton/acre for a susceptible variety but could be reduced both by seed dressing and by using resistant varieties. The effectiveness of resistance in moderately resistant varieties varied from one season to the next, an effect comparable with the genotype-environment interactions previously described for reactions to inoculation.

scholarly journals Changes in intermediate haemoglobins during autoxidation of haemoglobin

1981 ◽  
Vol 195 (2) ◽  
pp. 485-492 ◽  
Author(s):  
A Tomoda ◽  
Y Yoneyama ◽  
A Tsuji
Keyword(s):  
Isoelectric Focusing ◽  
Phosphate Buffer ◽  
Time Course ◽  
Inositol Hexaphosphate ◽  
Reaction Rate Constants ◽  
The Media ◽  
Beta 2 ◽  
Quantitative Changes ◽  
Ph Range ◽  
Experimental Values

The time course of haemoglobin autoxidation was studied under various conditions at 37 degrees C, and the changes in oxyhaemoglobin, intermediate haemoglobins and methaemoglobin during the reaction were analysed by isoelectric focusing on Ampholine/polyacrylamide-gel plates. Under various conditions (10 mM-phosphate buffer, 10 mM-phosphate buffer with 0.1 M-phosphate buffer, 10 mM-phosphate buffer with 0.1 M-NaCl, and 10 mM-phosphate buffer with 0.5 mM-inositol hexaphosphate; pH range 6.6-7.8 each case), the intermediate haemoglobins were found to be present as (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2 valency hybrids from their characteristic positions on electrophoresis. Oxyhaemoglobin changed consecutively to (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2, which were further oxidized to methaemoglobin, and the amounts of (alpha 3+beta 2+)2 were greater than those of (alpha 2+ beta 3+)2 during the reaction. The modes of the quantitative changes in oxyhaemoglobin, intermediate haemoglobins, and methaemoglobin were very similar in all the media used except for the inositol hexaphosphate addition. In the presence of inositol hexaphosphate, the autoxidation rates were considerably accelerated, and the modes of the changes in the haemoglobin derivatives were also considerably altered; the effects of this organic phosphate were maximal at acidic pH and minimal at alkaline pH. It was concluded that haemoglobin autoxidation proceeds by first-order kinetics through two paths: and (formula: see text). The reaction rate constants (k+1-k+4) best fitting all experimental values obtained by the isoelectric-focusing analysis were evaluated. By using these values, the mechanism of haemoglobin autoxidation is discussed.

Barrier Zone Formation as a Resistance Mechanism of Elms to Dutch Elm Disease

IAWA Journal ◽  
1985 ◽  
Vol 6 (1) ◽  
pp. 71-77 ◽  
Author(s):  
K.J.M. Bonsen ◽  
R.J. Scheffer ◽  
D.M. Elgersma
Keyword(s):  
Time Course ◽  
Resistance Mechanism ◽  
Dutch Elm Disease ◽  
Host Responses ◽  
Moderate Degree ◽  
Zone Formation ◽  
Ophiostoma Ulmi ◽  
Time Course Study ◽  
High Degree ◽  
Barrier Zone

Host responses of elms susceptible and resistant to Dutch elm disease were histologically examined. In a time course study the susceptible elm clone Ulmus × hollandica 'Belgica' and U. × hollandica '390', a clone which shows a high degree of resistance to non-aggressive isolates and a moderate degree of resistance to aggressive isolates of Ophiostoma ulmi, were inoculated in twig or trunk with either an aggressive or a non-aggressive isolate of O. ulmi. For purposes of comparison, the susceptible elm U. americana and the more resistant clones U. × hollandica 'Groeneveld', U. 'Lobel' and U. 'Sapporo Autumn Gold' were included. Depending on clone-isolate compatibility, infected twigs reacted by a walling off process, by barrier zone formation, or failed to resist the infection and died. Trees inoculated into the trunk reacted comparably but in the case of a compatible combination they always formed a barrier zone and the cambium never died in the year of inoculation.

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