Biological Sciences
Plant Fungus
Plant fungus refers to any type of fungus that specifically affects plants. These fungi can cause diseases in plants, leading to reduced crop yields and economic losses in agriculture. They can infect various parts of the plant, including the roots, stems, leaves, and fruits, and are a significant concern for plant health and food production.
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9 Key excerpts on "Plant Fungus"
- Ahamad, Shahid(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
Most plant diseases are caused by fungi belonging to about 50 genera. Potential pathogens have gained considerable attention and appearing to be promising as a biological control ( Table 22.1 ). Especially, using fungal antagonists against fungal plant viable supplement or alternative to chemical control (Papavizas, 1981, 1985). In the broad sense of biological control (Cook and Baker, 1983), crop resistance to disease is the ideal means of controlling diseases. However, many crops have little or no resistance to certain plant pathogens, so that biological control using microorganisms against plant pathogens is an attractive method for disease control. Considerable research has gone into the study of biological control of plant diseases over the past 60 years. In order to establish biocontrol efficacy there are many inherent obstacles to overcome. These include basic aspects of strain selection, efficient production of biomass, formulation, storage ability, and methods of application. Also, a better understanding of mechanisms of action, nutrition and ecology of biological control agents is needed. Further, the potential for genetic manipulation of fungi to create genetically superior strains or hybrids that can perform better than wild types empirically selected from the environment needs to be examined (Elzein and Kroschel, 2003). Mycorrhizas as Biocontrol Agents This ebook is exclusively for this university only. Cannot be resold/distributed. Over the last 30 years there has been an increasing interest in the potential role that both arbuscular mycorrhizal and ectomycorrhizal fungi can play in the control of plant diseases and various aspects of this concept have been reviewed (Borowicz, 2001; Graham, 2001; Sylvia and Chellemi, 2001; Barea et al., 2002). More than 80 disease biocontrol agents are on the market worldwide (Whipps, 2004), but none of these contain mycorrhizal fungi.
eBook - PDFPlant Disease: An Advanced Treatise
How Pathogens Induce Disease
- James G. Horsfall(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
All rights of reproduction in any form reserved ISBN-0-12-356404-2 164 PAUL H. WILLIAMS I I . C O N C E P T U A L I Z A T I O N O F F U N G A L P A T H O G E N E S I S Disease in plants is the injurious alteration of one or more ordered processes of energy utilization caused by a continued irritation by a primary causal factor or factors (see Volume III, Chapter 3 ) . Although there are many causal factors, both animate and inanimate, that are capable of inducing disease in plants this chapter will be concerned with how fungi induce disease. Bateman (see Volume III, Chapter 3) has suggested that the relationships between symbionts, and in particular those involving pathogens and their suscepts, are sufficiently complex that none of the existing theories of parsitism are adequate to provide a sound conceptual basis for meaningful experimentation. Thus, he has proposed a multicomponent hypothesis, which relies on a complete understanding of the environments produced by and surrounding the symbionts in order to determine whether a relationship is mutualistic, commensalistic, neutral, or antagonistic. In the case of disease in plants, an unfavorable environment created by the pathogen confronts a fav-orable environment in the host, whereas, in resistance, an unfavorable environment produced by the host confronts the pathogen. Bateman has purposely defined the basis on which symbioses occur as broadly as possible, providing room for wide-ranging theoretical and experi-mental exploration. It is within the context of the multicomponent hypothesis, therefore, that I would like to consider fungal pathogenesis. The development of fungal diseases in plants is extremely complex and in many ways resembles the intricacies of a Shakespearean tragedy or a Thomas Hardy novel. In the play or novel, the protagonists are placed on stage or in a particular setting in some relationship with one another, and the story is set in motion with a communication of some sort.
- Chandra, Ram(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
Still, much remains to be learned about the microbial ecology of both plant pathogens and their microbial antagonists in different agricultural systems. Fundamental This ebook is exclusively for this university only. Cannot be resold/distributed. work remains to be done on characterizing the different mechanisms by which organic amendments reduce plant disease including those caused by fungal pathogens. More studies on the practical aspects of mass production and formulation need to be undertaken to make new biocontrol products stable, effective, safer and more cost-effective. Fungal pathogens are among the most important factors that cause serious damages and losses to plants. Harmful impacts of the chemical pesticides on the environment and non-target organisms have clearly been documented. The need for the development of non-chemical alternative strategies to protect plants against plant diseases including fungal pathogens is therefore clear. Biological control using fungal and bacterial antagonists to manage plant diseases seems to be a promising alternative strategy and have successfully been applied to control some diseases on different plants and crops. Biocontrol strategies may also be used to manage other plant diseases including foliar ones. Some of the important factors that affect the efficacy of microbial biocontrol agents in controlling plant diseases which should carefully be considered include method of application, formulation of biocontrol microorganisms and timing of application. Various composts and organic amendments as other means of biological control have also been tested on some plants and proven to be promising. There are many products composed of living organisms, primarily bacteria and fungi, being sold that claim they will increase plant health. However, for any material to be considered a biological fungicide the Environmental Protection Agencies and Organizations must register it (Bloom et al ., 2003).
eBook - PDF- Moselio Schaechter(Author)
- 2011(Publication Date)
- Academic Press(Publisher)
Academic Press: New York, Vol. 3. Volk, T. J. (2001b). Tom Volk’s fungi. http://botit.botany.wisc.edu; Department of Biology, University of Wisconsin-LaCrosse. Webster, J., & Weber, R. W. S. (2007). Introduction to fungi (3rd ed.). The University Press: Cambridge. Chapter 9 Fungal and Protist Plant Pathogens 125 This page intentionally left blank Chapter 10 Entomogenous Fungi R.A. Humber USDA-ARS Biological Integrated Pest Management Research Unit, Ithaca, NY, USA Chapter Outline Abbreviations 127 Defining Statement 127 Introduction 127 Infection Processes and Pathobiology 128 Practical Uses of Entomogenous Fungi 134 A Look Forward for Entomogenous Fungi 137 Recent Developments 139 Further Reading 140 ABBREVIATIONS CER Cellular reaction NCR Noncellular reaction DEFINING STATEMENT The biology of the phylogenetically diverse fungi affecting insects and other invertebrates, mainly as pathogens, is summarized with emphasis on the interactions of these di-verse fungi and their hosts, and on their uses for biological control and as sources of biologically active compounds. INTRODUCTION The term ‘entomogenous fungus’ has been used historically to refer to almost any type of association between a fungus and an insect. Despite the prefix’s reference to insects, the term is also generally understood to include fungi asso-ciated with mites, spiders, and other arthropods; even more broadly, ‘entomogenous fungi’ can also be extended to all fungi associated with (usually as pathogens or parasites of) virtually any free-living microinvertebrates including ar-thropods, nematodes, tardigrades, rotifers, and protozoans of all sorts. Most studies of these fungi do, however, focus on those associated directly with insects. The emphasis in this treatment is the traditional one, on the fungi affecting arthropods, without further treatment of the many taxonom-ically diverse fungi from nematodes, tardigrades, rotifers, protozoans, or other nonarthropodous invertebrates.
- Hazem Shawky Fouda(Author)
- 2019(Publication Date)
- Delve Publishing(Publisher)
Biological Control with Fungi and Bacteria 3 CONTENTS 3.1 Introduction ....................................................................................... 60 3.2 Identification ..................................................................................... 74 3.3 Mechanism ........................................................................................ 84 3.4 Bacterial Bcas .................................................................................... 85 3.5 Mechanisms ...................................................................................... 88 Biological Control of Insects, Pests and Diseases 60 3.1 INTRODUCTION The silivicultural plantations and agricultural crops along with some of the horticultural crops can be influenced by diverse stresses present in the ecosystems. The loss incurred for any crop can be based on the disease potential of the pest, their nature and favorable conditions which can affect the pest positively in causing diseases. If we consider the biotic stresses, it is evident that the microbes can be pathogens which have a crucial role to play in destroying crops. Because of this, there will be a huge loss of crop yield in the qualitative and quantitative terms. Several studies done in this area to establish some relations between the microbial pathogens and the pathogenic potential. There is an obvious demand for the short term and the long term strategies to combat the problems posed on the agricultural systems. It is proved that the biocontrol agents or the BCAs have a vital role in reducing the pathogenic intensity on the crop plants. When we talk about these BCAs, there are two groups which were named as abiotic agents and biotic agents. The fungal members can be considered as an important group which can serve as BCAs. Their presence is felt in plant tissues, air, and soil. These fungal species canbe isolated successfully and stored safely. These species must be stored prior to the identification.
- Katti, Gururaj(Authors)
- 2018(Publication Date)
- Daya Publishing House(Publisher)
There are atleast 300,000 respective hosts in the world flora and around 230 species of AM fungi (Bagyaraj, 2011). AM fungi belong to the phylum Glomeromycota, which has a single class Glomeromycetes with four orders Glomerales, Diversisporales, Paraglomerales and Archaeosporales. There are 11 families, 17 genera and This ebook is exclusively for this university only. Cannot be resold/distributed. 228 species. The commonly occurring genera of AM fungi are Glomus, Gigaspora, Acaulospora, Entrophospora and Scutellospora. The AM endophytes are not host specific, although evidence is growing that certain endophytes may form preferential association with certain host plants. These fungi are obligate biotrophs. Increased plant growth because of AM colonization is attributed to enhanced uptake of diffusion limited nutrients, hormone production, biological nitrogen fixation, drought resistance and suppression of root pathogens. Biological control can be defined as the directed, accurate management of common components of ecosystems to protect plants against pathogens. Biological control of plant pathogens is currently accepted as a key practice in sustainable agriculture because it is based on the management of a natural resource, i.e., certain rhizosphere organisms. Thus, biological control preserves environmental quality by reduction in chemical inputs and is characteristic of sustainable management practices (Barea and Jeffries, 1995). Several workers have reported that AM fungi can act as biocontrol agents for alleviating the severity of disease caused by root pathogenic fungi, bacteria and nematodes. It is evident that an increased capacity for nutrient acquisition resulting from mycorrhizal association could help the resulting stronger plants to resist stress.
eBook - PDF- Marshal Mace(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
Work in this important field is expanding the scope of plant pathologists beyond their traditional concern with parasites that penetrate the host and produce disease. Their studies must now also in-clude microorganisms (nonparasitic pathogens or exopathogens) in the rhizospores that decrease plant growth but rarely or never penetrate the root (Woltz, 1978). Since there is a positive relationship between effectiveness and in-oculum density of the antagonist introduced on seeds, seedlings, and plant propagules, pelleting to increase the biotic load has been used (Merriman et al., 1975). ΙΠ. RELEVANT FEATURES OF PATHOGENIC FUNGI Antagonists must affect either the pathogen or the host if biological control is to be effective. Once wilt pathogens are within the host, they largely escape the effects of antagonists, and biocontrol (with the ex-ception of host resistance) therefore generally has been targeted on the preinfection phase of the pathogen. However, recent studies with avirulent isolates of the pathogen, and studies on the nature of resistance have enlarged this viewpoint. A. Host Resistance Although some may question whether host resistance is a form of biological control, the two fields often are found on close study to be so 14. BIOLOGICAL CONTROL 533 inextricably interwoven that there is no benefit from trying to separate them (see Section II). Disease interactions always involve at least two organisms (the host and the parasite), and frequently also an avirulent strain or a saprophytic microorganism. Resistant varieties may starve a pathogen by the absence of a favorable nutrient base quite as much as does an antagonist or crop rotation. The literature on host resistance is voluminous and specialized and is discussed here only in the interac-tion aspect; Chapters 9-13 deal with host resistance in detail.
eBook - PDFNatural Enemies
An Introduction to Biological Control
- Ann E. Hajek, Jørgen Eilenberg(Authors)
- 2018(Publication Date)
- Cambridge University Press(Publisher)
This group includes many species that can look like molds. The sexual spores of the Ascomycota are usually produced in groups of eight within small sacs, or asci. A complete fungal life cycle usually includes both sexual and asexual stages, but the formal taxonomy of fungi is historically based on the sexual stages. As explained in Chapter 12, in the past many of these fungal species had two names (one for the sexual stage and one for asexual) but mycologists are deciding which only one name will remain in use, under the “one fungus – one name” rule. The most common fungal genus used as a biological control agent is probably the green-colored mold Trichoderma. Trichoderma antagonists are particularly effective because they are fast growing and aggressive, and because they are versatile because of their employment of multiple modes of action (see Box 17.2, p. 316). Aside from Trichoderma, another group of fungi commonly studied as antagonists include the nematode-trapping fungi, discussed in Sections 16.5.2 and 17.5. Finally, some fungi used as antagonists actually belong to the same genera as fungal pathogens, but they do not cause plant diseases. An example of this is a nonpathogenic strain of Aspergillus 312 17 Microbial Antagonists Combating Plant Pathogens and Plant Parasitic Nematodes flavus, which occupies the same niche as pathogenic strains of A. flavus and can there- fore compete with this devastating cereal pathogen. Although many of the fungal species used for biological control belong to the Ascomycota, antagonists from other groups of fungi are also important. A fungus grow- ing as single cells, the yeast Candida oleophila, is used to control pathogens attack- ing fruits and vegetables after they have been harvested. The fungus applied to stumps of conifers, Phlebiopsis gigantea (see Box 16.2), belongs to the group of fungi that includes mushrooms, the Basidiomycota.
eBook - PDFFungi
Biology and Applications
- Kevin Kavanagh(Author)
- 2005(Publication Date)
- Wiley(Publisher)
Biotrophic plant pathogens have evolved specialized appressoria, which are highly organized enlarged ends of hyphae (Figure 9.3). Once the hypha senses an appropriate site, it enlarges and adheres to the leaf surface. This adher- ence is necessary to support the amount of mechanical force used to penetrate into the plant via a hypha called a penetration peg. 9.6.2 Pathogen metabolite-mediated parasitism Enzymes Fungi produce a range of enzymes that facilitate host plant infection and colo- nization by degrading the cellular and intercellular constituents of plants (certain fungal pathogens also produce non-enzymatic proteins that inhibit the activity of plant enzymes involved in the host defence response). The cuticle forms a continuous layer over aerial plant parts and is an important barrier against pathogens and other stresses. Cutin is the major structural component of the cuticle barrier and some fungi secrete cutinases that hydrolyse ester linkages between cutin molecules. In doing so, they, release monomers as well as oligomers, thus breaking the integrity of the cuticle barrier and facilitating plant parasitism. The plant cell wall presents a complex and important physical barrier against invading fungi. Pectinaceous substrates form part of the cell wall and are usually a major constituent of the middle lamella that adheres to adjacent plant cells. They are polysaccharides, consisting mostly of galacturonan molecules inter- spersed with rhamnose molecules and side-chains of galacturonan and other sugars. There are many pectin-degrading enzymes that attack different parts of the polysaccharide, including pectin esterases, polygalgacturonases and pectate lyases, resulting in a general disintegration of the host tissue. Cellulose, the most abundant natural polymer and a component of plant cell walls, consists of repeating units of glucose molecules, and these chains cross- link to form fibrils embedded in a matrix of other polymers such as pectin and lignin.
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