Phyllosphere: Difference between revisions

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Research into the characteristics of microbial life in the phyllosphere is of great commercial importance to the agricultural industry for two reasons. First, understanding the survival of plant disease-causing bacteria and fungi is vital for developing new ways to control their spread. Second, there has been a recent rise in the number of food poisoning cases associated with fruit and vegetables contaminated with bacteria such as Salmonella and E. coli O157:H7. This is particularly true of fresh fruits and salads which are not cooked prior to consumption. Preventing these outbreaks by developing better decontamination strategies is important to protect public health.
Research into the characteristics of microbial life in the phyllosphere is of great commercial importance to the agricultural industry for two reasons. First, understanding the survival of plant disease-causing bacteria and fungi is vital for developing new ways to control their spread. Second, there has been a recent rise in the number of food poisoning cases associated with fruit and vegetables contaminated with bacteria such as Salmonella and E. coli O157:H7. This is particularly true of fresh fruits and salads which are not cooked prior to consumption. Preventing these outbreaks by developing better decontamination strategies is important to protect public health.


==Physical environment==
The leaf surface has long been considered a hostile environment for bacterial colonists. The leaf surface is exposed to rapidly fluctuating temperature and relative humidity, as well as repeated alternation between presence and absence of free moisture due to rain and dew. The leaf also provides limited nutrient resources to bacterial colonists.  Such rapid and extreme fluctuations in the physical conditions of above ground plant surfaces yields a hostile microbe environment.
Describe the physical and chemical characteristics of the environment, using as many sections/subsections as you require. Look at other topics available in MicrobeWiki. Which involve processes similar to yours? Create links where relevant.
Several factors may influence the microhabitat experienced by bacteria on leaves
First, the leaf itself is surrounded by a very thin laminar layer in which moisture emitted through stomata may be sequestered, thereby alleviating the water stress to which epiphytes are exposed. Second, some cells in a leaf bacterial population, particularly in plant-pathogenic populations, may not reside in exposed sites on the leaf surface but instead may at least locally invade the interior of the leaf, avoiding the stresses on the exterior of the leaf by residing in substomatal chambers or other interior locations (78, 118). Thus, while some phytopathogens may have the option of avoiding stresses, most other epiphytes apparently must tolerate them in some way.


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Revision as of 20:54, 11 April 2010

Introduction

Phyllosphere b gross.png


The phyllosphere is a term used in microbiology to refer to leaf surfaces or total above-ground surfaces of a plant as a habitat for microorganisms. All plants are host to numerous and diverse communities of microorganisms including bacteria, fungi, and yeasts. Some are beneficial to the plant, others function as plant pathogens and may damage the host plant or even kill it. However, the majority of bacterial colonists on any given plant have no noticeable effect on plant growth or function.

Research into the characteristics of microbial life in the phyllosphere is of great commercial importance to the agricultural industry for two reasons. First, understanding the survival of plant disease-causing bacteria and fungi is vital for developing new ways to control their spread. Second, there has been a recent rise in the number of food poisoning cases associated with fruit and vegetables contaminated with bacteria such as Salmonella and E. coli O157:H7. This is particularly true of fresh fruits and salads which are not cooked prior to consumption. Preventing these outbreaks by developing better decontamination strategies is important to protect public health.

The leaf surface has long been considered a hostile environment for bacterial colonists. The leaf surface is exposed to rapidly fluctuating temperature and relative humidity, as well as repeated alternation between presence and absence of free moisture due to rain and dew. The leaf also provides limited nutrient resources to bacterial colonists. Such rapid and extreme fluctuations in the physical conditions of above ground plant surfaces yields a hostile microbe environment. Several factors may influence the microhabitat experienced by bacteria on leaves First, the leaf itself is surrounded by a very thin laminar layer in which moisture emitted through stomata may be sequestered, thereby alleviating the water stress to which epiphytes are exposed. Second, some cells in a leaf bacterial population, particularly in plant-pathogenic populations, may not reside in exposed sites on the leaf surface but instead may at least locally invade the interior of the leaf, avoiding the stresses on the exterior of the leaf by residing in substomatal chambers or other interior locations (78, 118). Thus, while some phytopathogens may have the option of avoiding stresses, most other epiphytes apparently must tolerate them in some way.

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Biological interactions

Are there important biological interactions that are important in this environment? Do these interactions influence microbial populations and their activities? How do these interactions influence other organisms? Describe biological interactions that might take place in this environment, using as many sections/subsections as you require. Look at other topics available in MicrobeWiki. Create links where relevant.

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Microbial processes

What microbial processes define this environment? Describe microbial processes that are important in this habitat, adding sections/subsections as needed. Look at other topics in MicrobeWiki. Are some of these processes already described? Create links where relevant.

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Key Microorganisms

What kind of microbes do we typically find in this environment? Or associated with important processes in this environment? Describe key groups of microbes that we find in this environment, and any special adaptations they may have evolved to survive in this environment. Add sections/subsections as needed. Look at other microbe listings in MicrobeWiki. Are some of the groups of microbes from your environment already described? Create links to those pages. Specific microbial populations will be included in the next section.

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Examples of organisms within the group

List examples of specific microbes that represent key groups or are associated with important processes found in this environment. Link to other MicrobeWiki pages where possible.

Current Research

Enter summaries of recent research here--at least three required

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Angela Kent at the University of Illinois at Urbana-Champaign.