Papers by Alexandra zum Felde
It is taken for granted that plants grow in a very complex soil environment harboring diverse mic... more It is taken for granted that plants grow in a very complex soil environment harboring diverse microorganisms and are constantly exposed to numerous complex biological interactions that either positively or negatively affect root health and growth. Some scientists believe the soil environment is not complex, and that biological interactions are rare and seldom affect plant growth significantly. Plant pathologists frequently adhere to the low complexity school of thought and therefore often target their research work to a single pest/disease interaction. Similarly biologists studying microbial-based biological control also tend to study one antagonist and one pest, a concept that has been reasonably successful, for example, in biological enhancement of banana planting material with endophytic microorganisms. Good control has been attained regardless of the antagonist involved: mutualistic endophytic fungi or bacteria, arbuscular mycorrhizal fungi, plant health-promoting rhizobacteria ...
Genetic Resources and Crop Evolution, 2015
ABSTRACT
International Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods, 2009
The burrowing nematode of banana, Radopholus similis, is difficult, if not impossible, to control... more The burrowing nematode of banana, Radopholus similis, is difficult, if not impossible, to control effectively. The lack of resistance in commercially acceptable cultivars and the perennial nature of the crop limit management options. Multiplecycle treatment with systemic nematocides is presently the only effective tool available for reducing damage and sustaining yield. Most of these compounds are not toxic to the burrowing nematode, but only inhibit nematode activity for short periods of time. The repetitive application of non-fumigant nematocides has led to an increase in the rapidity of their biodegradation. From environmental, toxicological and consumer viewpoints, this type of pest management is unacceptable. Many attempts have been made to improve the situation with little or no impact to date. Many nematocides have been or are being removed from the market, and new replacement compounds have not been developed. Resistance has never been detected in commercial banana cultivars, and genetically modified cultivars are still unacceptable to a large number of banana consumers. Microbialbased strategies are considered to be a promising alternative approach to nematode management in banana. Progress can only be made if research and crop production systems are streamlined to support new management concepts. The following are discussed: 1) biological enhancement of planting material with fungal endophytes; 2) treatments with multiple nematode antagonists with diverse modes of action; 3) importance of induced systemic resistance in biological control systems; and 4) use of molecular tools to detect effective antagonists.
About one-third of the global banana production comes from sub-Saharan Africa, especially the Gre... more About one-third of the global banana production comes from sub-Saharan Africa, especially the Great Lakes region of East Africa, where millions of subsistence farmers and consumers depend on the crop as a staple food. Dessert banana production is a multi-million dollar industry in Latin America, which produces over 70% of global banana exports. The world over, banana is traditionally propagated by means of field-obtained suckers or side-shoots, which are often contaminated with soil-borne diseases and pests, such as nematodes (Radopholus similis, Pratylenchus goodeyi, P. coffeae, Helicotylenchus multicinctus. Meloidogyne spp.) and banana weevils (Cosmopolites sordidus). With the exception of fastidious bacteria and viruses, normally eliminated at the stock nurseries, tissue cultured (TC) plants provide a source of pest-and disease-free planting material. TC plants also have the benefits of uniformity, enabling better planning for markets and more rapid recovery from broad-scale dama...
What are endophytes? Endophytes are microorganisms that live in plant tissue for part or all of t... more What are endophytes? Endophytes are microorganisms that live in plant tissue for part or all of their lifecycle (Sikora et al. 2007), and can be classified as beneficial, neutral, or detrimental, depending on the nature of their interaction with their host plant. Though not initially identified or recognized as such, many well-known and studied organisms are in fact endophytes: arbuscular mycorrhizal fungi and rhizobia, for example, are beneficial endophytes, whereas the Fusarium spp. causing wilt are examples of detrimental endophytes. Microbial and fungal endophytes have been isolated from a broad range of plants, including grasses, herbs, and trees, and from various plant tissues (Backman & Sikora, 2008). Mutualistc endophytes have been defined as beneficial microorganisms that protect plants from pests and diseases and can enhance plant growth. They are especially interesting for IPM as innovative biological control agents (BCAs). How do mutualistic endophytes work? A lot of res...
Molecular Biotechnology, 2012
To find out the genetic diversity of Indian Foc isolates of banana, a total of 107 isolates of Fu... more To find out the genetic diversity of Indian Foc isolates of banana, a total of 107 isolates of Fusarium which includes 98 Foc isolates obtained from different banana growing regions of India and seven Foc isolates belong to all known VCGs obtained from Australia and two non-pathogenic Fusarium oxysporum (npFo) isolates were subjected to ISSR analysis. In the initial screening of ISSR primers, out of 34, 10 primers which generated more polymorphic bands were selected for further analysis. The Phylogenetic analysis carried out based on the fingerprints obtained through ISSR analysis indicated the presence of wide genetic diversity among the Foc isolates of India and also its polyphyletic nature. Totally, seven different clusters were obtained and these clusters differentiated the Foc isolates of India based on the races/VCGs. Besides, the cluster analysis clearly distinguished the freshly emerged Foc strain obtained from cv. Grand Naine (Cavendish-AAA) and Poovan (Mysore-AAB) from the other Foc isolates. The non-pathogenic F. oxysporum isolates which have been included for comparison purpose also clustered separately. All these above said findings indicates for the first time the discriminatory power of ISSR to clearly distinguish and separate the Foc isolates according to its race/VCGs and also its virulence. This study would be useful not only to design and develop effective management strategies but also useful for quarantine purposes.
hss.ulb.uni-bonn.de
... April 2008 von Alexandra zum Felde aus München, Deutschland Page 2. Diese Dissertation ist au... more ... April 2008 von Alexandra zum Felde aus München, Deutschland Page 2. Diese Dissertation ist auf dem Hochschulschriftenserver der ULB Bonn http://hss.ulb.uni-bonn.de/diss_online elektronisch publiziert (2008). Referent: Prof. Dr. RA Sikora Korreferent: Prof. Dr. M. Becker ...
Banana Root System: …, 2005
Research has demonstrated that plants lose up to 33% of their assimilates to the soil. Why does a... more Research has demonstrated that plants lose up to 33% of their assimilates to the soil. Why does a plant, in this case banana, exert large amounts of energy to produce nutrients that land unused in the soil? We believe that: (1) roots are damaged by pests and diseases and the plant cannot utilize the nutrients produced in the shoot; and/or (2) the plant has evolved a health support system made up of "rhizosphere specific microbial communities" (RSMC) that live on these nutrients in symbiotic and/or mutualistic associations. These RSMC are not enhanced by standard banana production systems even though they are important for root health and growth. Research has shown that the interactions between banana and certain endophytic fungi are important for root health and growth. This interaction has been studied in detail and these forms of microbial communities have evolved concomitantly with the plant over evolutionary time. We have shown that specific fungi, and probably even bacteria, that have plant health promoting abilities are important for root health. When an ecological state is reached in which RSMC are well established and are functioning properly, we believe this leads to a disease or pest suppressive agro-ecosystem. Such a system was studied in Guatemala. The research indicated that: 1) pest nematodes are suppressed in certain areas of the Motagua Valley, Guatemala; 2) endophytic fungi play a major role in this suppressive system, and 3) endophytic Fusarium oxysporum and Trichoderma atroviride suppress Radopholus similis in banana roots.
Research has demonstrated that plants lose up to 33% of their assimilates to the soil. Why does a... more Research has demonstrated that plants lose up to 33% of their assimilates to the soil. Why does a plant, in this case banana, exert large amounts of energy to produce nutrients that land unused in the soil? We believe that: (1) roots are damaged by pests and diseases and the plant cannot utilize the nutrients produced in the shoot; and/or (2) the plant has evolved a health support system made up of "rhizosphere specific microbial communities" (RSMC) that live on these nutrients in symbiotic and/or mutualistic associations. These RSMC are not enhanced by standard banana production systems even though they are important for root health and growth. Research has shown that the interactions between banana and certain endophytic fungi are important for root health and growth. This interaction has been studied in detail and these forms of microbial communities have evolved concomitantly with the plant over evolutionary time. We have shown that specific fungi, and probably even bacteria, that have plant health promoting abilities are important for root health. When an ecological state is reached in which RSMC are well established and are functioning properly, we believe this leads to a disease or pest suppressive agro-ecosystem. Such a system was studied in Guatemala. The research indicated that: 1) pest nematodes are suppressed in certain areas of the Motagua Valley, Guatemala; 2) endophytic fungi play a major role in this suppressive system, and 3) endophytic Fusarium oxysporum and Trichoderma atroviride suppress Radopholus similis in banana roots.
The burrowing nematode of banana, Radopholus similis, is difficult, if not
impossible, to control... more The burrowing nematode of banana, Radopholus similis, is difficult, if not
impossible, to control effectively. The lack of resistance in commercially acceptable cultivars and the perennial nature of the crop limit management options. Multiple- cycle treatment with systemic nematocides is presently the only effective tool available for reducing damage and sustaining yield. Most of these compounds are not toxic to the burrowing nematode, but only inhibit nematode activity for short periods of time. The repetitive application of non-fumigant nematocides has led to an increase in the rapidity of their biodegradation. From environmental, toxicological and consumer viewpoints, this type of pest management is unacceptable. Many attempts have been made to improve the situation with little or no impact to date. Many nematocides have been or are being removed from the market, and new replacement compounds have not been developed. Resistance has never been detected in commercial banana cultivars, and genetically modified cultivars are still unacceptable to a large number of banana consumers. Microbial- based strategies are considered to be a promising alternative approach to nematode management in banana. Progress can only be made if research and crop production systems are streamlined to support new management concepts. The following are discussed: 1) biological enhancement of planting material with fungal endophytes; 2) treatments with multiple nematode antagonists with diverse modes of action; 3) importance of induced systemic resistance in biological control systems; and 4) use of molecular tools to detect effective antagonists.
It is taken for granted that plants grow in a very complex soil environment
harboring diverse mic... more It is taken for granted that plants grow in a very complex soil environment
harboring diverse microorganisms and are constantly exposed to numerous complex biological interactions that either positively or negatively affect root health and growth. Some scientists believe the soil environment is not complex, and that biological interactions are rare and seldom affect plant growth significantly. Plant pathologists frequently adhere to the low complexity school of thought and therefore often target their research work to a single pest/disease interaction. Similarly biologists studying microbial-based biological control also tend to study one antagonist and one pest, a concept that has been reasonably successful, for example, in biological enhancement of banana planting material with endophytic microorganisms. Good control has been attained regardless of the antagonist involved: mutualistic endophytic fungi or bacteria, arbuscular mycorrhizal fungi, plant health-promoting rhizobacteria or entomopathogenic fungi. There are many practical reasons for a single antagonist approach, but in planta suppressiveness in the field is not an industrial-based phenomenon but is based on unique interrelationships between the microbial community and plants, which result in a healthy root system. Success has been achieved with biological enhancement of plant material for the management of plant-parasitic nematodes in Musa. Practical application is no longer a question of if, but a question of when and where. However, a number of questions still confront those working with the biological enhancement concept: 1) can we increase the levels of control presently attained? 2) can we extend the spectrum of target pests affected? and 3) can in planta suppressiveness be established for long term control? Since in planta suppressiveness is clearly related to the activity of microbial communities and not to a single organism, the question that requires answering is – do we need a cocktail?
Biological Control, 2008
This paper reviews the development of the concept of biological enhancement of plants with mutual... more This paper reviews the development of the concept of biological enhancement of plants with mutualistic fungal endophytes for the management of plant parasitic nematodes. The vast majority of the research conducted to date on biological enhancement of plants with fungal endophytes involves the use of nonpathogenic strains of Fusarium oxysporum and, to a lesser extent, species of Trichoderma, for biological control of nematodes. The main crops thus far studied for biological enhancement with endophytes have been banana, tomato and rice. Because the concept of using nonpathogenic fungi that colonize the endorhiza for biological control is still relatively new, information on this subject in the form of published literature is scare, in the form of Ph.D. theses or in unpublished form. Taking this limitation into account, it is nevertheless hoped that this review will be useful to those working or planning to work with mutualistic fungal endophytes for biological enhancement of plants for nematode management.
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Papers by Alexandra zum Felde
impossible, to control effectively. The lack of resistance in commercially acceptable cultivars and the perennial nature of the crop limit management options. Multiple- cycle treatment with systemic nematocides is presently the only effective tool available for reducing damage and sustaining yield. Most of these compounds are not toxic to the burrowing nematode, but only inhibit nematode activity for short periods of time. The repetitive application of non-fumigant nematocides has led to an increase in the rapidity of their biodegradation. From environmental, toxicological and consumer viewpoints, this type of pest management is unacceptable. Many attempts have been made to improve the situation with little or no impact to date. Many nematocides have been or are being removed from the market, and new replacement compounds have not been developed. Resistance has never been detected in commercial banana cultivars, and genetically modified cultivars are still unacceptable to a large number of banana consumers. Microbial- based strategies are considered to be a promising alternative approach to nematode management in banana. Progress can only be made if research and crop production systems are streamlined to support new management concepts. The following are discussed: 1) biological enhancement of planting material with fungal endophytes; 2) treatments with multiple nematode antagonists with diverse modes of action; 3) importance of induced systemic resistance in biological control systems; and 4) use of molecular tools to detect effective antagonists.
harboring diverse microorganisms and are constantly exposed to numerous complex biological interactions that either positively or negatively affect root health and growth. Some scientists believe the soil environment is not complex, and that biological interactions are rare and seldom affect plant growth significantly. Plant pathologists frequently adhere to the low complexity school of thought and therefore often target their research work to a single pest/disease interaction. Similarly biologists studying microbial-based biological control also tend to study one antagonist and one pest, a concept that has been reasonably successful, for example, in biological enhancement of banana planting material with endophytic microorganisms. Good control has been attained regardless of the antagonist involved: mutualistic endophytic fungi or bacteria, arbuscular mycorrhizal fungi, plant health-promoting rhizobacteria or entomopathogenic fungi. There are many practical reasons for a single antagonist approach, but in planta suppressiveness in the field is not an industrial-based phenomenon but is based on unique interrelationships between the microbial community and plants, which result in a healthy root system. Success has been achieved with biological enhancement of plant material for the management of plant-parasitic nematodes in Musa. Practical application is no longer a question of if, but a question of when and where. However, a number of questions still confront those working with the biological enhancement concept: 1) can we increase the levels of control presently attained? 2) can we extend the spectrum of target pests affected? and 3) can in planta suppressiveness be established for long term control? Since in planta suppressiveness is clearly related to the activity of microbial communities and not to a single organism, the question that requires answering is – do we need a cocktail?
impossible, to control effectively. The lack of resistance in commercially acceptable cultivars and the perennial nature of the crop limit management options. Multiple- cycle treatment with systemic nematocides is presently the only effective tool available for reducing damage and sustaining yield. Most of these compounds are not toxic to the burrowing nematode, but only inhibit nematode activity for short periods of time. The repetitive application of non-fumigant nematocides has led to an increase in the rapidity of their biodegradation. From environmental, toxicological and consumer viewpoints, this type of pest management is unacceptable. Many attempts have been made to improve the situation with little or no impact to date. Many nematocides have been or are being removed from the market, and new replacement compounds have not been developed. Resistance has never been detected in commercial banana cultivars, and genetically modified cultivars are still unacceptable to a large number of banana consumers. Microbial- based strategies are considered to be a promising alternative approach to nematode management in banana. Progress can only be made if research and crop production systems are streamlined to support new management concepts. The following are discussed: 1) biological enhancement of planting material with fungal endophytes; 2) treatments with multiple nematode antagonists with diverse modes of action; 3) importance of induced systemic resistance in biological control systems; and 4) use of molecular tools to detect effective antagonists.
harboring diverse microorganisms and are constantly exposed to numerous complex biological interactions that either positively or negatively affect root health and growth. Some scientists believe the soil environment is not complex, and that biological interactions are rare and seldom affect plant growth significantly. Plant pathologists frequently adhere to the low complexity school of thought and therefore often target their research work to a single pest/disease interaction. Similarly biologists studying microbial-based biological control also tend to study one antagonist and one pest, a concept that has been reasonably successful, for example, in biological enhancement of banana planting material with endophytic microorganisms. Good control has been attained regardless of the antagonist involved: mutualistic endophytic fungi or bacteria, arbuscular mycorrhizal fungi, plant health-promoting rhizobacteria or entomopathogenic fungi. There are many practical reasons for a single antagonist approach, but in planta suppressiveness in the field is not an industrial-based phenomenon but is based on unique interrelationships between the microbial community and plants, which result in a healthy root system. Success has been achieved with biological enhancement of plant material for the management of plant-parasitic nematodes in Musa. Practical application is no longer a question of if, but a question of when and where. However, a number of questions still confront those working with the biological enhancement concept: 1) can we increase the levels of control presently attained? 2) can we extend the spectrum of target pests affected? and 3) can in planta suppressiveness be established for long term control? Since in planta suppressiveness is clearly related to the activity of microbial communities and not to a single organism, the question that requires answering is – do we need a cocktail?