Relative Humidity and the Survival of Epiphytic Bacteria with Buds and Leaves of Cucumber Plants

Leben, Curt

doi:10.1094/phyto-78-179

Cited by 78 publications

(41 citation statements)

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“…This was further shown by the distinct microcolonies and the large aggregates that Salmonella serovar Thompson formed primarily in the vein regions of cilantro leaves 3 and 9 days after inoculation, respectively, as observed by CLSM. The common presence of epiphytic bacteria on the veins of leaves has been reported previously (10). Indeed, both Salmonella serovar Thompson and P. agglomerans, a common epiphyte, were found to be parts of large heterogeneous aggregates on the leaf veins when they were coinoculated onto cilantro.…”

Section: Discussionsupporting

confidence: 68%

“…This may be explained by the high hydrophobicity of the waxy and trichomefree leaf surface of cilantro and the tendency of surface water to accumulate in the depressions of the leaf veins. Leben (10) demonstrated that areas above the veins of cucumber leaves had enhanced wettability and harbored a high proportion of the bacterial flora of the leaves. The presence of water may increase the leaching of nutrients onto the plant surface (24), as well as the solubility of substrates.…”

Section: Discussionmentioning

confidence: 99%

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Fitness of Salmonella enterica serovar Thompson in the Cilantro Phyllosphere

Brandl

Mandrell

2002

Appl Environ Microbiol

234

158

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The epiphytic fitness of Salmonella enterica was assessed on cilantro plants by using a strain of S. enterica serovar Thompson that was linked to an outbreak resulting from cilantro. Salmonella serovar Thompson had the ability to colonize the surface of cilantro leaves, where it was detected by confocal laser scanning microscopy (CLSM) at high densities on the veins and in natural lesions. The population sizes of two common colonizers of plant surfaces, Pantoea agglomerans and Pseudomonas chlororaphis, were 10-fold higher than that of the human pathogen on cilantro incubated at 22°C. However, Salmonella serovar Thompson achieved significantly higher population levels and accounted for a higher proportion of the total culturable bacterial flora on cilantro leaves when the plants were incubated at warm temperatures, such as 30°C, after inoculation, indicating that the higher growth rates exhibited by Salmonella serovar Thompson at warm temperatures may increase the competitiveness of this organism in the phyllosphere. The tolerance of Salmonella serovar Thompson to dry conditions on plants at 60% relative humidity was at least equal to that of P. agglomerans and P. chlororaphis. Moreover, after exposure to low humidity on cilantro, Salmonella serovar Thompson recovered under high humidity to achieve its maximum population size in the cilantro phyllosphere. Visualization by CLSM of green fluorescent protein-tagged Salmonella serovar Thompson and dsRed-tagged P. agglomerans inoculated onto cilantro revealed that the human pathogen and the bacterial epiphyte formed large heterogeneous aggregates on the leaf surface. Our studies support the hypothesis that preharvest contamination of crops by S. enterica plays a role in outbreaks linked to fresh fruits and vegetables.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Fitness of Salmonella enterica serovar Thompson in the Cilantro Phyllosphere

Brandl

Mandrell

2002

Appl Environ Microbiol

234

158

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“…The patchy recovery of bacteria from leaves in leaf imprint studies suggests that bacteria do not occur in a uniform pattern across leaf surfaces but tend to be localized in particular sites (27). The nature of these sites has been qualitatively studied using scanning electron microscopy, and the most-common sites of bacterial colonization reported were at the base of trichomes, at stomates, and in epidermal cell grooves along veins (31,33,43,46).…”

mentioning

confidence: 99%

Frequency, Size, and Localization of Bacterial Aggregates on Bean Leaf Surfaces

Monier

Lindow

2004

Appl Environ Microbiol

233

195

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Using epifluorescence microscopy and image analysis, we have quantitatively described the frequency, size, and spatial distribution of bacterial aggregates on leaf surfaces of greenhouse-grown bean plants inoculated with the plant-pathogenic bacterium Pseudomonas syringae pv. syringae strain B728a. Bacterial cells were not randomly distributed on the leaf surface but occurred in a wide range of cluster sizes, ranging from single cells to over 10 4 cells per aggregate. The average cluster size increased through time, and aggregates were more numerous and larger when plants were maintained under conditions of high relative humidity levels than under dry conditions. The large majority of aggregates observed were small (less than 100 cells), and aggregate sizes exhibited a strong right-hand-skewed frequency distribution. While large aggregates are not frequent on a given leaf, they often accounted for the majority of cells present. We observed that up to 50% of cells present on a leaf were located in aggregates containing 10 3 cells or more. Aggregates were associated with several different anatomical features of the leaf surface but not with stomates. Aggregates were preferentially associated with glandular trichomes and veins. The biological and ecological significance of aggregate formation by epiphytic bacteria is discussed.

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“…bras. 29(6), nov -dez 2004 dimento se aproveitem de vantagens como tolerar as adversidades ambientais ou colonizar os sítios protegidos, uma vez que nestes locais ocorre grande competição entre microrganismos, que procuram um ambiente com maior estabilidade (Schneider & Grogan, 1977;Leben, 1988). Além disso, dois fatores oferecem vantagens na colonização destes sítios: uma maior capacidade de sobrevivência por serem locais menos sujeitos a estresses ambientais (Beattie & Lindow, 1995;Beattie & Lindow, 1999;Wilson et al, 1999) e o acesso a nutrientes pouco disponíveis (Andrews & Hirano, 1991).…”

Section: Resultsunclassified

Métodos de isolamento de bactérias do filoplano de tomateiro visando populações específicas e implicações como agentes de biocontrole

2004

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RESUMOEm um processo de seleção de bactérias do filoplano de tomateiro (Lycopersicon esculentum) com potencial para o controle de doenças da parte aérea da cultura, diferentes métodos de isolamento foram utilizados visando obter isolados da população total, da população da superfície foliar e isolados que habitam locais protegidos do filoplano e/ou que toleram fatores de estresse. Foi testada a capacidade de 300 isolados em controlar in vivo, as doenças causadas por Alternaria solani, Pseudomonas syringae pv. tomato e Phytophthora infestans. Os testes foram repetidos para cada um dos antagonistas selecionados, estudando-se, também, a capacidade de controlar a mancha-bacteriana, causada por Xanthomonas vesicatoria. Os resultados demonstraram haver predomínio de antagonistas provenientes de folíolos do terço superior da planta de população total ou da superfície. Entretanto, o único antagonista selecionado, isolado de folíolos do terço inferior, foi obtido de locais protegidos do filoplano e/ou capaz de tolerar fatores de estresse.Palavras-chave adicionais: Lycopersicon esculentum, controle biológico, residentes do filoplano. ABSTRACT Isolation methods of tomato phylloplane bacteria aiming specific populations and implications as biocontrol agentsIn a process of selecting tomato (Lycopersicon esculentum) phylloplane bacteria with potential for controlling aerial diseases of this crop, different isolation methods were used to obtain the isolates from total leaf surface and also from protected sites of the phylloplane. Three hundred isolates were tested in vivo for their ability to control diseases caused by Alternaria solani, Pseudomonas syringae pv. tomato and Phytophthora infestans. The results demonstrated a predominance of antagonists in the total population originating on the surface of the leaflets harvested from the upper leaves of the plants. Only one selected antagonistic isolate obtained from the lower leaves was recovered from the protected sites of the phylloplane and/or was stress tolerant.

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Relative Humidity and the Survival of Epiphytic Bacteria with Buds and Leaves of Cucumber Plants

Cited by 78 publications

References 0 publications

Fitness of Salmonella enterica serovar Thompson in the Cilantro Phyllosphere

Fitness of Salmonella enterica serovar Thompson in the Cilantro Phyllosphere

Frequency, Size, and Localization of Bacterial Aggregates on Bean Leaf Surfaces

Métodos de isolamento de bactérias do filoplano de tomateiro visando populações específicas e implicações como agentes de biocontrole

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