Impact of the wasting disease pathogen, Labyrinthula zosterae, on the photobiology of eelgrass Zostera marina

Ralph, Peter J.; Short, Frederick T.

doi:10.3354/meps226265

Cited by 83 publications

(52 citation statements)

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“…The appropriate sampling of leaf tissues is critical, as preliminary experiments demonstrated that Labyrinthula sp.-induced phenolic accumulations occur only in certain tissues within leaves. For example, our preliminary experiments indicated that the response varies with proximity to the infection site, and even varies depending on whether the tissue is located above or below the infection site (also see Ralph & Short 2002). We observed that the analysis of whole leaves often fails to detect the induced accumulation of phenolics.…”

Section: Methodsmentioning

confidence: 84%

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Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions

Steele¹,

Caldwell²,

Boettcher³

et al. 2005

Mar. Ecol. Prog. Ser.

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Marine protists of the genus Labyrinthula cause the seagrass wasting disease, which is associated with regional die-offs of eelgrass Zostera marina and also infects turtlegrass Thalassia testudinum. The ability of seagrasses to resist pathogen attack is determined by multiple factors, which are poorly understood. One factor hypothesized to influence seagrass disease resistance is the presence of (poly)phenolic natural products such as caffeic acid, which inhibits the growth of L. zosterae in in vitro laboratory bioassays. This hypothesis has been supported by reports of pathogen-induced phenolic accumulations in eelgrass Z. marina. To test the response of T. testudinum to inoculation with Labyrinthula sp., we conducted a series of culture experiments wherein plants were inoculated with Labyrinthula sp. isolated from turtlegrass beds in Perdido Bay, Florida (USA). Concentrations of phenolic acids and condensed tannins were quantified in diseased leaves as well as those treated with 5 mM salicylic acid, a signaling molecule associated with pathogen-induced responses in plants.In infection experiments, increases in the concentrations of several phenolic acids, but not condensed tannins, were observed in tissues above, but not below, microbial lesions. Salicylic acid (SA) treatments did not induce any phenolic compound, either when applied alone or in concert with the pathogen. The induction of phenolic acids above, but not below, infection sites suggests that T. testudinum leaves did not respond to the pathogen specifically. Instead, the pattern is consistent with the predictions of the sink/source model of plant defense, which predicts increased phenolic contents in cases where wounds disrupt plant resource allocation and cause a local overabundance of carbonbased resources. Thus, we suggest that the emergence of Labyrinthula sp. lesions on turtlegrass blades causes a 'pseudo-induction' of specific phenolics as carbon resources over-accumulate in tissues located above wound sites.

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Section: Methodsmentioning

confidence: 84%

“…• Ralph & Short (2002), who reported that, in eelgrass blades, the photosynthetic quantum yield of infected eelgrass shoots was significantly lower than control tissue above, but not below, necrotic lesions. These observations are not consistent with the view that Thalassia testudinum responds to Labyrinthula sp.…”

Section: Discussionmentioning

confidence: 99%

Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions

Steele¹,

Caldwell²,

Boettcher³

et al. 2005

Mar. Ecol. Prog. Ser.

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“…Preliminary histological evaluation of these multi-focal purple lesions re vealed the presence of a stramenophile (ovoid parasites distributed within a mucus net; Petes et al 2003) similar in appearance to the quahog parasite unknown (QPX) parasite of clams (Ragone Calvo et al 1998, Ragan et al 2000 and Labyrinthula zosterae that infects marine grasses (Durako & Kuss 1994, Ralph & Short 2002. Laby rin thulomycetes (Labyrinthulomycota) produce a very distinctive, basophilic-staining ectoplasmic network matrix with continuity from the network matrix to the cell cytoplasm (Porter 1990).…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

“…Laby rin thulomycetes (Labyrinthulomycota) produce a very distinctive, basophilic-staining ectoplasmic network matrix with continuity from the network matrix to the cell cytoplasm (Porter 1990). Although Laby rinthulomycetes are common in estuarine and marine habitats, only a few of the identified Labyrinthulomycetes appear pathogenic and have been reported to be the primary infectious agent implicated in damaging epizootics, especially in the sea grasses Zostera marina and Thalassia testudinum (Muehlstein et al 1991, Durako & Kuss 1994, Ralph & Short 2002, octopus (Polglase 1980), nudibranch (McLean & Porter 1982), abalone (Bower 1987), and the quahog clam Mercenaria mercenaria (Ragone Calvo et al 1998, Ragan et al 2000, Lyons et al 2007). …”

mentioning

confidence: 99%

Friend or foe: the association of Labyrinthulomycetes with the Caribbean sea fan Gorgonia ventalina

Burge¹,

Douglas²,

Conti-Jerpe³

et al. 2012

Dis. Aquat. Org.

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A new syndrome in sea fans Gorgonia ventalina consisting of multifocal purple spots (MFPS) has been observed in the Caribbean Sea. Surveys of MFPS on sea fans were conducted from 2006 to 2010 at a shallow and deep site in La Parguera, Puerto Rico (PR). At the shallow site, MFPS increased between 2006 and 2010 (site average ranged from 8 to 23%), with differences found at depths over time using an analysis of covariance (ANCOVA, p < 0.0001). As a potential causative agent we examined a Labyrinthulomycota-like ovoid parasite that was observed to be abundant in MFPS lesions in light micrographs. Labyrinhylomycetes were successfully isolated, cultured and characterized in sea fans from Florida and PR. Sequence information obtained from the small subunit (SSU) rRNA gene indicated that Labyrinthulomycetes in most sea fans (healthy and MFPS sea fans from Florida; MFPS from PR) and the cultured microorganism are in the genus Aplanochytrium, although some healthy sea fans from PR contained members of the genus Thraustochytrium. Both genera fall within the family Thraustochytriidae. Histology confirmed ob servations of thraustochytrids within apparently healthy and MFPS sea fans from PR, and specific staining indicated a host melanization response only in colonies containing Labyrinthulomycetes or fungal infections. Growth trials indicate that the temperature-growth optima for the cultured microorganism is ~30°C. In inoculation experiments, the cultured Aplanochytrium did not induce purple spots, and histology revealed that many of the apparently healthy recipients contained Labyrinthulomycetes prior to inoculation. Taken together, these results indicate that the Labyrinthulomycetes associated with sea fans is likely an opportunistic pathogen. Further studies are needed to understand the pathogenesis of this microorganism in sea fans and its relationship with MFPS.KEY WORDS: Labyrinthulomycota · Caribbean sea fan · Gorgonia ventalina · Multi-focal purple spots · MFPS Resale or republication not permitted without written consent of the publisherDis Aquat Org 101: [1][2][3][4][5][6][7][8][9][10][11][12] 2012 increase in the number of purple sclerites and is a generalized response to invading pathogens or other biotic agents (Petes et al. 2003, Alker et al. 2004, Smith & Weil 2004. Necrotic lesions, surrounded by purple halos in G. ventalina, have been described as aspergillosis (Smith et al. 1996, Nagelkerken et al. 1997, Kim & Harvell 2001. The terrestrial fungus Aspergillus sy dowii was isolated from fans with these signs and Koch's postulates fulfilled in controlled laboratory experiments (Smith et al. 1996, Geiser et al. 1998). More recently, culture-dependent sampling showed that fungal species other than A. sydowii can be associated with lesions (ToledoHernández et al. 2008). During field surveys in Mexico, Florida, and Puerto Rico, a new type of lesion was identified (Weil & Hooten 2009, Weil & Rogers 2011 our Fig. 1) that is characterized by small (1 to 3 mm in diameter), circular to oblong multi-focal...

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“…Des travaux ont montré que ce parasite présent de manière assez générale dans les feuilles à l'état cryptique pouvait présenter des phases de développement rapide, diminuant les possibilités de photosynthèse de la plante de 50%. Les rhizomes, privés d'apports nutritifs finissent par mourir (Ralph & Short, 2002).…”

Section: • Dégradations Indirectesunclassified

Drivers of change in the relative abundance of dugongs in New Caledonia

et al. 2017

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Context Sound understanding of temporal changes in the abundance of wildlife species is required for assessing their status and for effective conservation and management. In New Caledonia, a single baseline aerial survey of dugongs in 2003 estimated a population of 2026 (± 553 s.e.) individuals. A second, similar survey in 2008 produced a lower estimate of 606 (± 200 s.e.) individuals, leading to concerns that the dugong population was experiencing a decline. Aims This study used data collected from additional aerial surveys with the aim of updating information on the current size of the dugong population in New Caledonia and investigating the drivers of change in the estimates. Methods Four additional surveys were conducted: one in each of the cool (June) and warm (November) seasons of 2011 and 2012 around the main Island of New Caledonia. Dugong relative abundance and density were calculated and compared among survey years and survey regions. Drivers of change in the dugong population size were then investigated. Key results The abundance estimates obtained from our four surveys ranged from 649 (± 195 s.e.) to 1227 (± 296 s.e.) dugongs. These new results were not significantly different to the 2008 estimate but were significantly lower than the 2003 estimate. There was no significant variation in the proportion of calves throughout the entire time series of surveys. Conclusions The dugong population of New Caledonia was relatively stable between 2008 and 2012. We could not find sufficient evidence to show whether the discrepancy between 2003 and the remainder of the time series is due to a real decline in the population or the result of the confounding effects of variation in environmental conditions, animal behaviour and sampling biases. Implications The stability of the dugong population between 2008 and 2012 is a positive outcome for local conservation and management of dugongs. This study also highlights the advisability of replicating baseline surveys to enable robust interpretation of temporal variation in population size estimates, and in turn, to improve the management of wildlife species.

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Impact of the wasting disease pathogen, Labyrinthula zosterae, on the photobiology of eelgrass Zostera marina

Cited by 83 publications

References 19 publications

Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions

Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions

Friend or foe: the association of Labyrinthulomycetes with the Caribbean sea fan Gorgonia ventalina

Drivers of change in the relative abundance of dugongs in New Caledonia

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Impact of the wasting disease pathogen, Labyrinthula zosterae, on the photobiology of eelgrass Zostera marina

Cited by 83 publications

References 19 publications

Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions

Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions

Friend or foe: the association of Labyrinthulomycetes with the Caribbean sea fan Gorgonia ventalina

Drivers of change in the relative abundance of dugongs in New Caledonia

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Product

Resources

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Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions

Seagrasspathogen interactions: pseudo-induction of turtlegrass phenolics near wasting disease lesions