Increasing evidence for the important role of Labyrinthulomycetes in marine ecosystems

Raghukumar, Seshagiri; Damare, Varada S.

doi:10.1515/bot.2011.008

Cited by 85 publications

(72 citation statements)

References 59 publications

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“…We hypothesize that wasting disease has 2 important effects on eelgrass beds: (1) to lower overall plant fitness, potentially contributing to population declines; and (2) to increase the decay rate of senescing leaves, remineralizing nutrients for availability in the food web (Raghukumar 2002, Raghukumar & Damare 2011. During warm seasons, leaves are turned over rapidly in eelgrass shoots, and it is likely that the sampled leaves were weeks away from senescing (Olesen & SandJensen 1994b).…”

Section: Discussionmentioning

confidence: 99%

Plant characteristics associated with widespread variation in eelgrass wasting disease

Groner¹,

Burge²,

Kim³

et al. 2016

Dis. Aquat. Org.

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Seagrasses are ecosystem engineers of essential marine habitat. Their populations are rapidly declining worldwide. One potential cause of seagrass population declines is wasting disease, which is caused by opportunistic pathogens in the genus Labyrinthula. While infection with these pathogens is common in seagrasses, theory suggests that disease only occurs when environmental stressors cause immunosuppression of the host. Recent evidence suggests that host factors may also contribute to disease caused by opportunistic pathogens. In order to quantify patterns of disease, identify risk factors, and investigate responses to infection, we surveyed shoot density, shoot length, epiphyte load, production of plant defenses (phenols), and wasting disease prevalence in eelgrass Zostera marina across 11 sites in the central Salish Sea (Washington state, USA), a region where both wasting disease and eelgrass declines have been documented. Wasting disease was diagnosed by the presence of necrotic lesions, and Labyrinthula cells were identified with histology. Disease prevalence among sites varied from 6 to 79%. The probability of a shoot being diseased was higher in longer shoots, in patches of higher shoot density, and in shoots with higher levels of biofouling from epiphytes. Phenolic concentration was higher in diseased leaves. We hypothesize that this results from the induction of phenols during infection. Additional research is needed to evaluate whether phenols are an adaptive defense against Labyrinthula infection. The high site-level variation in disease prevalence emphasizes the potential for wasting disease to be causing some of the observed decline in eelgrass beds.

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Section: Discussionmentioning

confidence: 99%

Plant characteristics associated with widespread variation in eelgrass wasting disease

Groner¹,

Burge²,

Kim³

et al. 2016

Dis. Aquat. Org.

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“…In contrast, culture-independent studies of environmental 18S rDNA sequences imply that several, and likely many, species of Labyrinthula are typically present in marine ecosystems (e.g., Collado-Mercado et al 2010). Functional roles for most types are incompletely known, but range from strict saprobes and endophytic parasites (Raghukumar and Damare 2011), to the lesser-known as inhabitants of coral mucus (Ben-Dov et al 2009) and endosymbionts of an amoebae associated with fish gills (Dyková et al 2008).…”

Section: Communicated By Kenneth Duntonmentioning

confidence: 99%

Functional, Phylogenetic and Host-Geographic Signatures of Labyrinthula spp. Provide for Putative Species Delimitation and a Global-Scale View of Seagrass Wasting Disease

Martín

Chiari

Boone

et al. 2016

Estuaries and Coasts

102

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Seagrass meadows form ecologically and economically valuable coastal habitat on every continental margin except the Antarctic, but their areal extent is declining by approximately 2-5 % per year. Seagrass wasting disease is a contributing factor in these declines, with the protist Labyrinthula identified as the etiologic agent. To help elucidate the role of Labyrinthula spp. in global seagrass declines, we surveyed roughly one fourth of all seagrass species to identify Labyrinthula diversity at the strain and/or species level, combining results from culturing methods and two common nuclear DNA markers: the ITS and 18S regions of the ribosomal RNA gene complex. After assaying a subset of the resulting isolates (of which 170 were newly sequenced), we produced a cladogenic context for putative seagrasspathogenic versus non-pathogenic Labyrinthula while also defining host and geographic ranges. Assays also suggest that pathogenicity is consistently high (when present; and, even when comparing susceptibility of US East-versus West Coast Zostera marina hosts) while virulence is variable, that some isolate-host combinations have the potential for host cross-infection, and that several modes of transmission can be effective. Taken together, these data provide additional means for delimiting putative species of Labyrinthula, suggesting at least five seagrass-pathogenic and perhaps ten or more non-pathogenic marine Bspecies^, yielding a working definition for ecologists and epidemiologists attempting to reconcile the sundry data related to seagrass wasting disease.

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“…Labylinthulids (labyrinthulomycetes), another heterotrophic stramenopile group, have no fl agella in the trophic stage. However, they are probably important decomposers in marine ecosystems (Raghukumar and Damare 2011 ;Nakai and Naganuma, Chap. 13 ).…”

Section: Stramenopilesmentioning

confidence: 99%

Biology, Diversity and Ecology of Free-Living Heterotrophic Flagellates

Nakayama

2015

Marine Protists

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The free-living heterotrophic fl agellates are phylogenetically very diverse, and their phylogenetic diversity is nearly equal to that of all eukaryotes. They constitute the microbial loop together with bacteria and other protists, and play an indispensable and important role in aquatic ecosystems. However, their diversity has not been fully understood. In addition, recent environmental DNA studies suggest that there are many unidentifi ed heterotrophic fl agellate lineages in nature. This chapter describes the current knowledge on the diversity, biology and ecology of various groups of free-living heterotrophic fl agellates.

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Increasing evidence for the important role of Labyrinthulomycetes in marine ecosystems

Cited by 85 publications

References 59 publications

Plant characteristics associated with widespread variation in eelgrass wasting disease

Plant characteristics associated with widespread variation in eelgrass wasting disease

Functional, Phylogenetic and Host-Geographic Signatures of Labyrinthula spp. Provide for Putative Species Delimitation and a Global-Scale View of Seagrass Wasting Disease

Biology, Diversity and Ecology of Free-Living Heterotrophic Flagellates

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