O12 Motoaki

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O12 Motoaki

  1. 1. Advances in the morphological and molecular identification of Pythiogeton species Z. Gloria Abad USDA-APHIS-PPQ-PSPI, Beltsville, MD, USA Motoaki Tojo Osaka Prefecture University, Sakai, Osaka, Japan Cytoplasm evacuation of sporangium of Pythiogeton
  2. 2. Background and objectives 1. Pythiogeton in the Kingdom Straminipila with it's only nine species is a not widely studied genus. 2. In the USA, P. ramosum (Minden 1916) and P. autosytum (Drechsler 1932) have been reported. 3. Three putative new Pythiogeton species were isolated from ornamental plants (cypress, English-ivy and alyssum) which showed root rot symptoms during the summer 2003 in NC, USA. 4. These Pythiogeton species were characterized on morphology and the ITS rDNA sequences.
  3. 3. Kingdom: Straminipila Phylum: Heterokonta Class: Peronosporomycetes Order: Pythiales Family: Pythiaceae Genus: Pythium Phytophthora Halophytophthora Pythiogeton
  4. 4. Patterns of sporangium development in Pythiaceae Cysts Zoospores Flagellum Flagellum synthesis synthesis & & Vesicle Cytoplasmic Cytoplasmic cleavage cleavage Clear Flagellum Non or synthesis Unclear & Cytoplasmic cleavage Sporangium Pythium Phytophthora, Pythiogeton Halophytophthora
  5. 5. 0:00 0:30 1:00 1:30 2:00 3:00 Zoospore development in Pythiogeton sp. 1 4:00 5:00 18:00 Bars = 20μm
  6. 6. 0:00 0:10 0:20 0:30 0:40 0:50 Zoospore development in Pythiogeton sp. 3 0:60 1:20 2:00 Bars = 20μm
  7. 7. Sporagium of Pythiogeton sp. 1 produced in water culture Sporagium of Pythiogeton sp. 1 produced in radish root hairs. No obvious symptom was observed
  8. 8. Morphology of Pythiogeton sp. 1 1 7 1-5. Sporangia 6. Appressoria 7, 8. Cytoplasm evacuation and zoospore development 2 3 4 8 through vesicles (arrowhead) 9. Zoospore with flagella 10. Encysted and germinated 5 6 9 zoospores 11. Sporangia formed in cypress roots after artificial 10 inoculation (arrow heads) 12. Sporangia formed around cypress roots after artificial 11 12 inoculation Bars: 1-10 = 20 µm Bars: 11, 12 = 50 µm
  9. 9. Morphology of Pythiogeton sp. 2. 22 25 28 22-25. Sporangia 26. Appressoria 29 26 27, 28. Development of zoospores out and inside of sporangia 30 29. Empty sporangium 23 with a vesicle (arrowhead) 27 30. Encysted zoospores 31-33 Sporangia formed in and around English Ivy 24 roots after artificial inoculation 31 32 33 Bars: 22-30 = 20 µm Bars: 31-33 = 50 µm
  10. 10. Morphology of Pythiogeton sp. 3 34 38 41 34-39. Sporangia 40. Appressoria 39 41. Empty sporangium 35 with vesicle (arrowhead) 42. Encysted and germinated zoospores 36 37 40 42 31-33 Sporangia formed in and around root of Alyssum roots after artificial inoculation Bars: 34-42 = 20 µm 43 44 Bars: 43, 44 = 50 µm
  11. 11. P.arrhenomanes.39 P.volutum.64 P.vanterpoolii.61 P.periilum.54 P.graminicola.29 P.inflatum.63 P.aphanidermatum.71 P.deliense.42 P.porphyrae.06 P.destruens.74 P.insidiosum.64 P.grandisporangium.91 Pythiogeton.English.Ivy.03.287 Pythiogeton sp. 1 Pythiogeton.Cypress.02.1000 Ph.cambivora Ph.cinnamomi Ph.ilicis Ph.cactorum Ph.capsici Halophytophthora.batemanensis - P.viniferum.94 P.violae.63 . P.rhizosaccharum.78 P.ramificatum.17 P.middletonii.49 Pythiogeton sp. 2 P.rostratum.56 P.longisporangium.93 P.bifurcatum.35 P.orthogonon.53 P.nunn.51 P.campanulatum.04 P.acanthophoron.52 Pythium.sp.HS.66 P.ultimum.var.sporangiiferum.6 P.splendens.42 P.glomeratum.39 P.heterothallicum.62 P.undulatum.30 Achlya.bisexualis 0.1 Phylogenetic tree based in internal transcribed spacer ribosomal DNA region [ITS rDNA (ITS1, 5.8S, ITS2)] sequences constructed using Neighbour-joining analysis. Achlya bisexualis was used as outgroup.
  12. 12. Summary 1. Three putative new species, Pythiogeton sp. 1, 2 and 3 were isolated from ornamental plant roots in North Carolina, USA. 2. The all species infected to roots of their host plants and radish, but had no visible symptom in an inoculation test performed in Petri dish. 3. The phylogenetic tree based in ITS rDNA shows that all Pythiogeton are a solid species and the closest are members that belong to Pythium (P. grandisporangium) than Phytophthora.

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