Ultraviolet Radiation (UVR) Sensitivity Analysis and UVR Survival Strategies of a Bacterial Community from the Phyllosphere of Field-Grown Peanut ( Arachis hypogeae L.)

Sundin, George W.; Jacobs, James J.

doi:10.1007/s002489900152

Cited by 120 publications

(97 citation statements)

References 36 publications

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“…Reflective of marked differences in the physicochemical environments of above-ground versus subterranean plant surfaces, the leaf bacterial flora differs substantially from that of roots. For example, pigmented bacteria, which are rarely found in the rhizosphere, dominate leaf surfaces (28,103,104), presumably because solar radiation influences the ecology of the phyllosphere (45,112). The differential composition of leaf and root bacterial communities is further evidenced by the failure of common root colonizers such as Rhizobium (89) and Azospirillum (51) to become established on leaves.…”

Section: Microbial Communities On Leavesmentioning

confidence: 99%

“…Indeed, a striking feature of epiphytic bacteria is the large proportion that are pigmented (28,103); such pigmentation has been presumed to confer protection against UV radiation. A recent detailed examination of the epiphytic bacteria present on peanut plants exposed to high fluxes of UV revealed that most tolerated relatively large UV fluctuations (112). Interestingly, the relative proportion of UV-tolerant strains in the bacterial community in- creased during those parts of the day when leaves were exposed to UV, and the most tolerant strains were those that produced pink or orange pigments (112).…”

Section: The Leaf Surface As a Microbial Habitatmentioning

confidence: 99%

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Microbiology of the Phyllosphere

Lindow

Brandl

2003

Appl Environ Microbiol

1,818

1,418

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2The above-ground parts of plants are normally colonized by a variety of bacteria, yeasts, and fungi. While a few microbial species can be isolated from within plant tissues, many more are recovered from the surfaces of healthy plants. The aerial habitat colonized by these microbes is termed the phyllosphere, and the inhabitants are called epiphytes. While there has been some investigation of the colonists of buds and flowers (1, 48), most work on phyllosphere microbiology has focused on leaves, a more dominant aerial plant structure. Bacteria are by far the most numerous colonists of leaves, often being found in numbers averaging 10 6 to 10 7 cells/cm 2 (up to 10 8 cells/g) of leaf (1,7,41). Because of their numerical dominance on leaves, and because more information is available on the process of bacterial colonization of leaves, we focus on this group of microbes in this review.Compared to most other bacterial habitats, there has been relatively little examination of phyllosphere microbiology. This is somewhat surprising given the abundance of plants in the world and the roles of various phyllosphere bacteria in the important processes discussed below. Leaves constitute a very large microbial habitat. It is estimated that the terrestrial leaf surface area that might be colonized by microbes is about 6.4 ϫ 10 8 km 2 (83). Given the large number of bacteria on leaves in temperate regions of the world and that populations in tropical regions are probably even larger, the planetary phyllosphere bacterial population may be as large as 10 26 cells (83). Clearly, in aggregate, these bacteria are sufficiently numerous to contribute in many processes of importance to global processes, as well as to the behavior of the individual plants on which they live.In the following sections we review available information on the identities and properties of the bacterial colonists of plant surfaces as well as describe the nature of the leaf surface habitat that these bacteria colonize. We emphasize the results of studies using new molecular and microscopic tools that have provided new insights into both the identity and the behavior of epiphytes, as well as into the nature of the plant surfaces that they inhabit. Also, we review recent studies of the interactions of various epiphytic bacteria with plants, which suggest that there is much more interaction between them than in a strict commensalistic relationship, in which they have been traditionally considered to coexist. The interactions that occur between bacteria on leaves have also received considerable attention. We attempt to illustrate how new approaches to defining the nature of leaf surface habitats have helped us to understand the behavior and interactions of epiphytic bacteria as well as why leaves are a particularly suitable habitat for exploring processes in microbial ecology. More comprehensive reviews of phyllosphere microbiology also address other important features of this interesting association (1,7,8,41,47,55,73). MICROBIAL COMMUNITIES ON LEAVESThe microbial ...

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Section: Microbial Communities On Leavesmentioning

confidence: 99%

Section: The Leaf Surface As a Microbial Habitatmentioning

confidence: 99%

Microbiology of the Phyllosphere

Lindow

Brandl

2003

Appl Environ Microbiol

1,818

1,418

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“…3). Indeed, the abundance of chromogenic species common to the phyllosphere (e.g., Erwinia herbicola [renamed Pantoea agglomerans; however, we will refer to the bacterium by the more familiar name E. herbicola], xanthomonads, fluorescent pseudomonads, and pink-pigmented facultative methylotrophs) has led to the yet unresolved speculation that pigment production may confer a selective advantage to bacteria that colonize a habitat which is exposed to solar radiation daily (58,182,251,272). At present there is some effort under way to determine if UV radiation affects the survival or fitness of bacteria in the phyllosphere (273).…”

Section: The Playersmentioning

confidence: 99%

Bacteria in the Leaf Ecosystem with Emphasis onPseudomonas syringae—a Pathogen, Ice Nucleus, and Epiphyte

Hirano

Upper

2000

Microbiol Mol Biol Rev

834

610

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SUMMARY The extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. This review focuses on the bacterial component of leaf microbial communities, with emphasis on Pseudomonas syringae—a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. Among the diversity of bacteria that colonize leaves, none has received wider attention than P. syringae, as it gained notoriety for being the first recombinant organism (Ice− P. syringae) to be deliberately introduced into the environment. We focus on P. syringae to illustrate the attractiveness and somewhat unique opportunities provided by leaf ecosystems for addressing fundamental questions of microbial population dynamics and mechanisms of plant-bacterium interactions. Leaf ecosystems are dynamic and ephemeral. The physical environment surrounding phyllosphere microbes changes continuously with daily cycles in temperature, radiation, relative humidity, wind velocity, and leaf wetness. Slightly longer-term changes occur as weather systems pass. Seasonal climatic changes impose still a longer cycle. The physical and physiological characteristics of leaves change as they expand, mature, and senesce and as host phenology changes. Many of these factors influence the development of populations of P. syringae upon populations of leaves. P. syringae was first studied for its ability to cause disease on plants. However, disease causation is but one aspect of its life strategy. The bacterium can be found in association with healthy leaves, growing and surviving for many generations on the surfaces of leaves as an epiphyte. A number of genes and traits have been identified that contribute to the fitness of P. syringae in the phyllosphere. While still in their infancy, such research efforts demonstrate that the P. syringae-leaf ecosystem is a particularly attractive system with which to bridge the gap between what is known about the molecular biology of genes linked to pathogenicity and the ecology and epidemiology of associated diseases as they occur in natural settings, the field.

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“…On arrival, new immigrants are challenged with the harsh conditions of the leaf environment (11,12), including highly fluctuating water availability, exposure to UV radiation from sunlight, and limited access to nutrient resources. To cope with these conditions and to survive the leaf environment, microorganisms have adopted different strategies (13) such as the production of pigments to protect against the effects of UV radiation (14) or the secretion of polysaccharides to prevent desiccation when water becomes scarce (15,16).…”

mentioning

confidence: 99%

Appetite of an epiphyte: Quantitative monitoring of bacterial sugar consumption in the phyllosphere

Leveau

Lindow

2001

Proc. Natl. Acad. Sci. U.S.A.

311

289

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We report here the construction, characterization, and application of a bacterial bioreporter for fructose and sucrose that was designed to monitor the availability of these sugars to microbial colonizers of the phyllosphere. Plasmid pPfruB-gfp[AAV] carries the Escherichia coli fruB promoter upstream from the gfp[AAV] allele that codes for an unstable variant of green fluorescent protein (GFP). In Erwinia herbicola, this plasmid brings about the accumulation of GFP fluorescence in response to both fructose and sucrose. Cells of E. herbicola (pP fruB-gfp[AAV]) were sprayed onto bean plants, recovered from leaves at various time intervals after inoculation, and analyzed individually for GFP content by quantitative analysis of digital microscope images. We observed a positive correlation between single-cell GFP accumulation and ribosomal content as determined by fluorescence in situ hybridization, indicating that foliar growth of E. herbicola occurred at the expense of fructose and͞or sucrose. One hour after inoculation, nearly all bioreporter cells appeared to be actively engaged in fructose consumption. This fraction dropped to approximately 11% after 7 h and to Ϸ1% a day after inoculation. This pattern suggests a highly heterogeneous availability of fructose to individual E. herbicola cells as they colonize the phyllosphere. We estimated that individual cells were exposed to local initial fructose abundances ranging from less than 0.15 pg fructose to more than 4.6 pg.

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Ultraviolet Radiation (UVR) Sensitivity Analysis and UVR Survival Strategies of a Bacterial Community from the Phyllosphere of Field-Grown Peanut ( Arachis hypogeae L.)

Cited by 120 publications

References 36 publications

Microbiology of the Phyllosphere

Microbiology of the Phyllosphere

Bacteria in the Leaf Ecosystem with Emphasis onPseudomonas syringae—a Pathogen, Ice Nucleus, and Epiphyte

Appetite of an epiphyte: Quantitative monitoring of bacterial sugar consumption in the phyllosphere

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