DOCSLIB.ORG

AR TICLE an Expanded Phylogeny for the Genus Phytophthora

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
AR TICLE an Expanded Phylogeny for the Genus Phytophthora ·PSSPM! doi:10.5598/imafungus.2017.08.02.09 8(#('*$"*1'" Phytophthora ARTICLE Xiao Yang1, Brett M. Tyler2, and Chuanxue Hong1 1Hampton Roads Agricultural Research and Extension Center, Virginia Tech, Virginia Beach, VA 23455, USA; corresponding author e-mail: [email protected] 2Center for Genome Research and Biocomputing, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA )#A comprehensive phylogeny representing 142 described and 43 provisionally named Phytophthora species 3*4 is reported here for this rapidly expanding genus. This phylogeny features signature sequences of 114 ex-types and oomycetes numerous authentic isolates that were designated as representative isolates by the originators of the respective species. systematics Multiple new subclades were assigned in clades 2, 6, 7, and 9. A single species P. lilii was placed basal to clades 1 to taxonomy 5, and 7. Phytophthora stricta was placed basal to other clade 8 species, P. asparagi to clade 6 and P. intercalaris to evolution clade 10. On the basis of this phylogeny and ancestral state reconstructions, new hypotheses were proposed for the plant pathology evolutionary history of sporangial papillation of Phytophthora species. Non-papillate ancestral Phytophthora species were inferred to evolve through separate evolutionary paths to either papillate or semi-papillate species. $1 Submitted: 8 June 2017; Accepted: 31 October 2017; Published: 21 November 2017. INTRODUCTION A sound taxonomic system is foundational for correctly identifying Phytophthora species and safeguarding The genus Phytophthora has had profound impacts on agriculture, forestry, and natural ecosystems. Traditionally, human history by causing agriculturally and ecologically taxonomy of the genus was based on morphological important plant diseases (Erwin & Ribeiro 1996). Among OHBDBO@GD?& [=LVB>GL@BX ><DMH<X<ZWFB?GV OXB??E[OB@E<L the most notorious Phytophthora species is P. infestans, of Phytophthora species was established by Waterhouse cause of the late blight disease, which was the primary IH<OXB??E[GV@HG?MGOEG?EL@<?EZD<=M?FB?GV<L@HG cause of the Irish potato famine from 1845 to 1852 in which ><DMH<X<ZW<[?M<DBLZEBH<><@HBXXE?>BLVO<L[Z=DB@E<L<[ approximately one million people died and 1.5 million antheridia. However, plasticity in morphological characters emigrated from Ireland (Turner 2005). Another example B><LZ?@ E?<XB@G? <[ ELVEEV=BX ?MGOEG? E? ?EZLE[OBL@ ?< is the sudden oak death pathogen, P. ramorum, that has is homology or homoplasy among different species. For killed millions of coast live oak, tanoak and Japanese larch example, isolates of P. constricta (Rea et al. 2011), P. trees, and has permanently altered the forest ecosystems gibbosa (Jung et al. 2011), P. lateralis (Kroon et al. 2012), in California and Oregon, USA (Goheen et al. 2002, Rizzo P. mississippiae (Yang et al. 2013), and P. multivesiculata et al. 2002, Rizzo et al. 2005). Other species, such as P. (Ilieva et al. 1998) all produce a mixture of semi-papillate cinnamomi, P. nicotianae, and P. sojae, can also cause and non-papillate sporangia. Many non-papillate species highly destructive plant diseases (Erwin & Ribeiro 1996). recovered from irrigation water such as Phytophthora The impact caused by Phytophthora species has continued hydropathica (Hong et al. 2010) and P. irrigata (Hong et al. to increase with the emergence of new pathogens and 2008) were morphologically inseparable from P. drechsleri, diseases. The number of species known in the genus has while sequence analyses demonstrated that they are distinct doubled during the past decade due to extensive surveys in species. Also, production of many morphological structures previously unexplored ecosystems such as natural forests BLV MHW?E<X<ZEOBX [GB@=DG? LGGV? ?MGOE[O GLED<L>GL@BX (Jung et al. 2011, 2017, Rea et al. 2010, Reeser et al. 2013, conditions, while observation of these features requires Vettraino et al. 2011), streams (Bezuidenhout et al. 2010, ?=F?@BL@EBX @DBELELZ BLV GMGD@E?G *E[[O=X@W EL <F@BELELZ Brazee et al. 2017, Reeser et al. 2007, Yang et al. 2016), important morphological data can impair accurate species riparian ecosystems (Brasier et al. 2003a, 2004, Hansen EVGL@E[OB@E<L et al. 2012), and irrigation systems (Hong et al. 2010, With the advent of DNA sequencing, the taxonomic 2012, Yang et al. 2014a, b). The total number of formally concept for the genus has evolved from morphology to named species in the genus was about 58 in 1996 (Erwin & molecular phylogeny-based (Blair et al. 2008, Cooke et al. Ribeiro 1996), but now is more than 150. In addition, some 2000, Kroon et al. 2004, Lara & Belbahri 2011, Martin et provisionally or informally named species are also expected al. 2014, Martin & Tooley 2003, Robideau et al. 2011, Villa to be formally described in the near future. et al. 2006). In particular, the availability of whole genome © 2017 International Mycological Association You are free to share - to copy, distribute and transmit the work, under the following conditions: Attribution: 7<=>=?@B@@DEF=@G@HGI<DJEL@HG>BLLGD?MGOE[GVFW@HGB=@H<D<DXEOGL?<DF=@L<@ELBLWIBW@HB@?=ZZG?@?@HB@@HGWGLV<D?GW<=<DW<=D=?G<[@HGI<DJ Non-commercial: 7<=>BWL<@=?G@HE?I<DJ[<DO<>>GDOEBXM=DM<?G? No derivative works: 7<=>BWL<@BX@GD@DBL?[<D><DF=EXV=M<L@HE?I<DJ For any reuse or distribution, you must make clear to others the license terms of this work, which can be found at http://creativecommons.org/licenses/by-nc-nd/3.0/legalcode. Any of the above conditions can be waived if you get permission from the copyright holder. Nothing in this license impairs or restricts the author’s moral rights. VOLUME 8 · NO. 2 355 ?#" et al. sequences from P. sojae, P. ramorum (Tyler et al. 2006) and that were designated as representative isolates by the P. infestans (Haas et al GLBFXGV@HGEVGL@E[OB@E<L<[ originators of the respective species names (Table 1). The genetic markers useful for multi-locus phylogenies (Blair et majority of these isolates were provided by the originators of al. 2008). the respective species, while the rest were purchased from Cooke et al VGGX<MGV @HG [D?@ ><XGO=XBD the Westerdijk Fungal Biodiversity Institute (CBS), Utrecht, ARTICLE phylogeny for the genus by analyzing sequences of the The Netherlands. internal transcribed spacer region (ITS) of 51 species. Kroon et al. (2004) constructed a phylogeny based on sequences =8# of four nuclear and mitochondrial genes of 48 species, and To extract genomic DNA (gDNA), an approximately 5 × 5 Blair et al. (2008) produced a sophisticated phylogeny based mm culture plug of each isolate was taken from the actively on sequences of seven nuclear genetic markers. That multi- growing area of a fresh culture. This was then grown in 20 % locus phylogeny divided 82 Phytophthora species into 10 OXBDE[GV­FD<@HXE>BFGBLFD<@H[<DZD<IELZBP. infestans phylogenetically well-supported clades. Martin et al. (2014) isolate 27A8) at room temperature (ca. 23 °C) for 7–14 d analyzed sequences of seven nuclear and four mitochondrial to produce a mycelial mass. The mass was then blot-dried genes of 90 formally named and 17 provisional species and using sterile tissue paper and then lysed in liquid nitrogen provided phylogenies including 10 clades, almost identical to or using a FastPrep®-24 system (MP Biomedicals, Santa that of Blair et al. (2008), except that P. quercina and P. sp. Ana, CA). gDNA was extracted using the DNeasy® Plant Mini ohioensis were excluded from clade 4 and grouped into a kit (Qiagen, Valencia, CA) or the Maxwell® Plant DNA kit in potentially new clade. combination with a Maxwell® Rapid Sample Concentrator A comprehensive molecular phylogeny is required (Promega, Madison, WI). to understanding the evolution of Phytophthora species. Although discordance has been found between the molecular =#%($##@" phylogeny and the morphology-based taxonomy (Cooke et al. A set of primers for seven genetic markers were used for 2000, Ersek & Ribeiro 2010), correlations have been observed *& B>MXE[OB@E<L ELOX=VELZ ©EF<?<>BX MD<@GEL between molecular phylogenies and individual morphological FG@B@=F=XEL$@=FGX<LZB@E<L[BO@<D BXMHB) and physiological traits. Recent studies indicated that enolase (Enl), heat shock protein 90 (HSP90), 28S ribosomal species in individual clades or subclades are mostly identical DNA (28S), and tigA gene fusion protein (TigA) as indicated in sporangial papillation, and optimum and maximum growth in Blair et al. (2008). PCR reaction mixtures were prepared temperatures (Cooke et al. 2000, Kroon et al. 2012, Martin with the Takara Taq DNA polymerase (Takara Shuzo, Shiga, et al. 2012, Yang 2014). However, there was limited to no Japan) according to the manufacturer’s instructions. The correlation between phylogeny and the morphology of PCR cycling protocol was the same as indicated by Blair ?G=BX <DZBL? ?=OH B? BL@HGDEVEBX O<L[Z=DB@E<L (<<JG et et al. (2008), except that the Eppendorf® Mastercycler® Pro al. 2000, Kroon et al. 2012, Martin et al. 2012, Yang 2014). thermal cycler (Eppendorf, Hamburg) was used in this study. These studies have implied that divergence in sporangial &XX (©MD<V=O@?IGDGGBX=B@GV[<D?=OOG??[=XB>MXE[OB@E<L morphology and variation in environmental specialization using agarose gel electrophoresis. Unsuccessful PCR may be the keys in the evolutionary history of Phytophthora B>MXE[OB@E<L? IGDG DGMGB@GV =?ELZ B ><VE[GV MD<@<O<X @< species. Nevertheless, these hypotheses need to be further B@@G>M@ ?=OOG??[=X B>MXE[OB@E<L? FW <M@E>EELZ BLLGBXELZ tested and the exact evolutionary history of the genus temperature using gradient PCR (typically with lower Phytophthora warranted more investigation. annealing temperatures) or using the GoTaq® Flexi DNA In this study, an expanded phylogeny, including more Polymerase (Promega, Madison, WI) PCR mixture system.
Load more

Recommended publications
  • Phytopythium: Molecular Phylogeny and Systematics
    Persoonia 34, 2015: 25–39 www.ingentaconnect.com/content/nhn/pimj RESEARCH ARTICLE http://dx.doi.org/10.3767/003158515X685382 Phytopythium: molecular phylogeny and systematics A.W.A.M. de Cock1, A.M. Lodhi2, T.L. Rintoul 3, K. Bala 3, G.P. Robideau3, Z. Gloria Abad4, M.D. Coffey 5, S. Shahzad 6, C.A. Lévesque 3 Key words Abstract The genus Phytopythium (Peronosporales) has been described, but a complete circumscription has not yet been presented. In the present paper we provide molecular-based evidence that members of Pythium COI clade K as described by Lévesque & de Cock (2004) belong to Phytopythium. Maximum likelihood and Bayesian LSU phylogenetic analysis of the nuclear ribosomal DNA (LSU and SSU) and mitochondrial DNA cytochrome oxidase Oomycetes subunit 1 (COI) as well as statistical analyses of pairwise distances strongly support the status of Phytopythium as Oomycota a separate phylogenetic entity. Phytopythium is morphologically intermediate between the genera Phytophthora Peronosporales and Pythium. It is unique in having papillate, internally proliferating sporangia and cylindrical or lobate antheridia. Phytopythium The formal transfer of clade K species to Phytopythium and a comparison with morphologically similar species of Pythiales the genera Pythium and Phytophthora is presented. A new species is described, Phytopythium mirpurense. SSU Article info Received: 28 January 2014; Accepted: 27 September 2014; Published: 30 October 2014. INTRODUCTION establish which species belong to clade K and to make new taxonomic combinations for these species. To achieve this The genus Pythium as defined by Pringsheim in 1858 was goal, phylogenies based on nuclear LSU rRNA (28S), SSU divided by Lévesque & de Cock (2004) into 11 clades based rRNA (18S) and mitochondrial DNA cytochrome oxidase1 (COI) on molecular systematic analyses.
    [Show full text]
  • Phytophthora Plurivora T. Jung & T. I. Burgess and Other Phytophthora Species Causing Important Diseases of Ericaceous Plant
    Plant Protect. Sci. Vol. 47, 2011, No. 1: 13–19 Phytophthora plurivora T. Jung & T. I. Burgess and other Phytophthora Species Causing Important Diseases of Ericaceous Plants in the Czech Republic Marcela MRÁZKOVÁ1, Karel ČERNÝ1, Michal TOMšovsKÝ 2 and Veronika STRNADOVÁ1 1Silva Tarouca Research Institute for Landscape and Ornamental Gardening, Průhonice, Czech Republic; 2Mendel University in Brno, Brno, Czech Republic Abstract Mrázková M., Černý K., Tomšovský M., Strnadová V. (2011): Phytophthora plurivora T. Jung & T. I. Burgess and other Phytophthora species causing important diseases of ericaceous plants in the Czech Republic. Plant Protect. Sci., 47: 13–19. Ornamental nurseries, garden centres, public gardens and urban greenery in the Czech Republic were surveyed in 2006–2009 for the presence of Phytophthora spp. and the diseases they cause on ericaceous plants. Diseased plants such as Rhododendron spp., Pieris floribunda, Vaccinium sp., and Azalea sp. showed various symptoms including leaf spot, shoot blight, twig lesions or stem, root and collar rot. Nearly 140 Phytophthora isolates were collected from symptomatic plants in different areas of the country. Of the Phytophthora spp. on ericaceous plants or in their surroundings, P. plurivora appeared to be the most common species. Herein, we focus on the most frequently occurring species, P. plurivora, and describe its morpho-physiological and pathogenicity features and confirm its identity based on ITS sequences of rDNA. In addition, we give a list of other Phytophthora spp. including P. cactorum, P. cambivora, P. cinnamomi, P. citrophthora, P. megasperma, P. multivora, P. ramorum, and P. gonapodyides that we identified on the basis of their cultural and morphological characteristics and DNA sequences.
    [Show full text]
  • Detection and Quantification of Phytophthora Species Which Are
    Eur. J. For. Path. 29 (1999) 169–188 © 1999 Blackwell Wissenschafts-Verlag, Berlin ISSN 0300–1237 Detection and quantification of Phytophthora species which are associated with root-rot diseases in European deciduous forests by species-specific polymerase chain reaction 1 2 3 3 4 By R. SCHUBERT *, G. BAHNWEG *, J. NECHWATAL ,T.JUNG ,D.E.L.COOKE , 4 1 2 2 J. M. DUNCAN ,G.MU¨LLER-STARCK ,C.LANGEBARTELS ,H.SANDERMANN JR and 3 W. OßWALD 1Faculty of Forest Sciences, Section of Forest Genetics, Ludwig-Maximilians-University Munich, Am Hochanger 13, D-85354 Freising, Germany (R. Schubert for correspondence); 2GSF-National Research Center for Environment and Health, Institute of Biochemical Plant Pathology, Ingoldsta¨dter Landstr. 1, D-85764 Neuherberg, Germany; 3Faculty of Forest Sciences, Institute of Forest Botany, Phytopathology, Ludwig-Maximilians- University Munich, Am Hochanger 13, D-85354 Freising, Germany; 4Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK Summary Oligonucleotide primers were developed for the polymerase chain reaction (PCR)-based detection of selected Phytophthora species which are known to cause root-rot diseases in European forest trees. The primer pair CITR1/CITR2, complementing both internal transcribed spacer regions of the riboso- mal RNA genes, gave a 711 bp amplicon with Phytophthora citricola. The Phytophthora cambivora specific primer pair CAMB3/CAMB4, producing a 1105 bp amplicon, as well as the Phytophthora quercina specific primer pair QUERC1/QUERC2, producing a 842 bp amplicon, were derived from randomly amplified polymorphic DNA (RAPD)-fragments presented in this paper. All three primer pairs revealed no undesirable cross-reaction with a diverse test collection of isolates including other Phytophthora species, Pythium, Xerocomus, Hebeloma, Russula, and Armillaria.
    [Show full text]
  • Predicting Lifestyle and Host from Positive Selection Data and Genome Properties in Oomycetes
    bioRxiv preprint doi: https://doi.org/10.1101/2021.01.12.426341; this version posted March 25, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC 4.0 International license. G´omez-P´erez and Kemen RESEARCH Predicting lifestyle and host from positive selection data and genome properties in oomycetes Daniel Gomez-P´ ´erez* and Eric Kemen *Correspondence: daniel.gomez- [email protected] Abstract Zentrum fur¨ Molekularbiologie der Pflanzen, Auf der Morgenstelle 32, Background: Host and niche shifts are a source of genomic and phenotypic 72076 Tubingen,¨ Germany diversification as evidenced in parasitism. Exemplary is core metabolism reduction Full list of author information is as parasites adapt to a particular host, while the accessory genome often available at the end of the article maintains a high degree of diversification. However, selective pressures acting on the genome of organisms that have undergone lifestyle or host change have not been fully investigated. Results: Here, we developed a comparative genomics approach to study underlying adaptive trends in oomycetes, a eukaryotic phylum with a broad range of economically important plant and animal parasitic lifestyles. Our analysis reveals converging evolution on biological processes for oomycetes that have similar lifestyle. Besides, we find that certain functions, in particular carbohydrate metabolism, transport, and signaling, are important for host and environmental adaption in oomycetes. Discussion: Given the high correlation between lifestyle and genome properties in our oomycete dataset and the convergent evolution of fungal and oomycete genomes, we have developed a model that predicts plant pathogen lifestyles with high accuracy based on functional annotations.
    [Show full text]
  • Seasonal Fluctuations in the Extent of Colonization of Avocado Plants by the Stem Canker Pathogen Phytophthora Citricola
    J. AMER. SOC. HORT. SCI. 120(2): 157–162. 1995. Seasonal Fluctuations in the Extent of Colonization of Avocado Plants by the Stem Canker Pathogen Phytophthora citricola Zeinah A. El-Hamalawi and John A. Menge Department of Plant Pathology, University of California, Riverside, CA 92521 Additional index words. Persea americana, amino acids, total soluble carbohydrates Abstract. At monthly intervals, plants and stem cuttings of avocado (Persea americana Miller) ‘Hass’ grafted on ‘Barr Duke’ rootstock and ‘Topa Topa’ growing in a lathhouse were wounded and inoculated with the stem canker pathogen, Phytophthora citricola Sawada. The seasonal changes (measured monthly) in the extent of colonization of the avocado plants by P. citricola followed a periodic pattern, with two peaks of colonization during an annual growth cycle. Concentration of free amino acids and total soluble carbohydrates in the plant tissues followed a periodic pattern with two peaks similar to that of canker growth. Months were significantly different for canker size, free amino acids, and total soluble carbohydrates of the bark tissues. The extent of colonization was highest during May-June, after the first vegetative flush, and during November-December, after the second vegetative flush. Total free amino acids of the hark tissue was highly correlated with canker size (r = 0.89). Although the total soluble carbohydrate of the bark tissue was also elevated during the periods of canker development, it showed lower positive correlation (r = 0.45) with canker size. Plants were relatively resistant to colonization through March-April, during the first vegetative flush, and through August-September, during the second vegetative flush.
    [Show full text]
  • Project Title: Towards a Better Understanding of the Biology and Genetics of Phytophthora Rubi and Phytophthora Fragariae
    Project title: Towards a better understanding of the biology and genetics of Phytophthora rubi and Phytophthora fragariae Project number: CP 173 Project leader: Eleanor Gilroy, The James Hutton Institute (JHI), Dundee Report: Annual report, October 2019 Previous report: Annual report, October 2018 Key staff: Aurelia Bezanger (PhD student), Steve Whisson, Lydia Welsh, Ingo Hein Location of project: The James Hutton Institute, Dundee Industry Representative: Ross Mitchell, Castleton Fruit Ltd, Laurencekirk Date project commenced: October 2017 © Agriculture and Horticulture Development Board 2020. All rights reserved DISCLAIMER While the Agriculture and Horticulture Development Board seeks to ensure that the information contained within this document is accurate at the time of printing, no warranty is given in respect thereof and, to the maximum extent permitted by law the Agriculture and Horticulture Development Board accepts no liability for loss, damage or injury howsoever caused (including that caused by negligence) or suffered directly or indirectly in relation to information and opinions contained in or omitted from this document. © Agriculture and Horticulture Development Board 2018. No part of this publication may be reproduced in any material form (including by photocopy or storage in any medium by electronic mean) or any copy or adaptation stored, published or distributed (by physical, electronic or other means) without prior permission in writing of the Agriculture and Horticulture Development Board, other than by reproduction in an unmodified form for the sole purpose of use as an information resource when the Agriculture and Horticulture Development Board or AHDB Horticulture is clearly acknowledged as the source, or in accordance with the provisions of the Copyright, Designs and Patents Act 1988.
    [Show full text]
  • Tolerance Mechanism in Hybrid Citrus Rootstock Progenies Against Phytophthora Nicotianae Breda De Haan
    Indian Journal of Experimental Biology Vol. 59, March 2021, pp. 202-213 Tolerance mechanism in hybrid citrus rootstock progenies against Phytophthora nicotianae Breda de Haan Prashant Kalal1, RM Sharma1*, AK Dubey1, Deeba Kamil2, Lekshmy S3, Amrender Kumar4 & OP Awasthi1 Division of 1Fruits & Horticultural Technology; 2Plant Pathology; 3Plant Physiology; and 4AKM Unit, ICAR-Indian Agricultural Research Institute, New Delhi-110 012, India Received 27 August 2019; revised 20 November 2020 Phytophthora species is the major threat for world citrus industry in general, and for India, in particular due to commercial use of susceptible rootstocks. The resistant gene possessed by Poncirus genus may be of immense use, if transferred in a well acclimatized citrus species which can have good impact on fruit size of scion varieties. Being a soil borne problem, development of resistant/tolerant rootstock(s) is the most eco-friendly solution to combat with this deadly disease. The present study was conducted during 2016 to understand the tolerance mechanism in the intergeneric hybrids of citrus rootstocks against Phytophthora nicotianae. The materials of study consisted of 30 hybrids, ten each of Pummelo (P) × Troyer (T), Pummelo (P) × Sacaton (S) and Pummelo (P) × Trifoliate orange (TO) were tested against the inoculation of P. nicotianae, taking Pummelo, Troyer and Citrumelo as control treatments. Of the total hybrid progenies, only six hybrids (P × TO-103, P × TO- 112, P × S-117, P × S-119, P × T-125 and P × T-130) expressed resistance against P. nicotianae on the basis of lesion length (nil or <2.5 cm). Of the tested hybrids, P x S-117 had the highest photosynthetic rate (A) (8.12 µmol m-1s-1) followed by P × TO-112 and P × S-119.
    [Show full text]
  • Pest Risk Assessment of Phytophthora Fragariae in Norway
    09-905-2_final Pest risk assessment of Phytophthora fragariae in Norway Opinion of the Panel on Plant Health of the Norwegian Scientific Committee for Food Safety 14.09.2010 ISBN 978-82-8259-003-7 VKM Report 2010: 26 1 09-905-2_final Pest risk assessment of Phytophthora fragariae in Norway Leif Sundheim Arild Sletten Trond Rafoss Arne Stensvand Citation: Sundheim, L., Sletten, A., Rafoss, T., Stensvand, A. (2010). Pest risk assessment of Phytophthora fragariae in Norway. Opinion of the Plant Health Panel of the Scientific Committee for Food Safety, 09/905-2_final, ISBN 978-82-8259-003-7 (Electronic edition). 54 pp. VKM, Oslo, Norway. 2 09-905-2_final SUMMARY The pathogen Phytophthora fragariae Hickman, causal agent of the red core disease of strawberry has been known to be present in a few limited areas in Norway since 1995. Surveys in recent years have revealed previously unknown infected places of production. In order to limit introduction and spread of the pathogen, import of strawberry plants is prohibited, plants to be traded must be tested and found to be free from the pathogen, and places of production where the pathogen has been detected are under strict regulations. The Norwegian Food Safety Authority (Mattilsynet) considers a revision of the phytosanitary measures and priorities related to red core, and has requested a pest risk assessment of P. fragariae from the Norwegian Scientific Committee on Food Safety (VKM) according to the international standard ISPM No. 11. The pest risk assessment was adopted by VKMs Panel on Plant Health in a meeting on 12th August 2010.
    [Show full text]
  • Of Phytophthora for More Accurate Morphological-Molecular Identification: the Importance of Types and Authenticated Specimens
    Abstracts: 5 th IUFRO Phytophthoras in Forests and Natural Ecosystems Auckland and Rotorua, New Zealand, 7-12 March 2010 Refined systematics (taxonomy, nomenclature and phylogenetics) of Phytophthora for more accurate morphological-molecular identification: The importance of types and authenticated specimens. Z. Gloria Abad 1, and Michael C. Coffey 2 1 USDA-APHIS-PPQ-RIPPS-MOLECULAR DIAGNOSTICS LABORATORY,Beltsville, Maryland, USA, 20705 2 WORLD PHYTOPHTHORA GENETIC RESOURCE COLLECTION, Department of Plant Pathology and Microbiology, University of California, Riverside, California, USA, 92521 Phytophthora with 98 species, is an ecologically important genus that has been well-studied. Although considerable advances in molecular systematics have been made there is still confusion in recognizing new species and difficulty in identifying described species. This is due in part to the number of sequences in GenBank that are from misidentified cultures or that are poorly annotated. Species complexes for P. capsici , P. citricola , P. cryptogea , P. dreschleri , P. megasperma , and others have been named due to the difficulties to identify the sensu stricto or extype clusters. The position of the extypes suggests the presence of few to several distinct species in each complex. Establishing a database of sequences from accurately identified material is vital so that others can use that tool to make correct molecular identifications. Ex types define the species so sequences from those isolates should be the primary reference in the database. The World Phytophthora Genetic Resource Collection (WPC) is a valuable biological resource containing many ex types and has been extensively used in the Phytophthora Database (PD) which is a web-based source of genotypic and phenotypic data for the international community.
    [Show full text]
  • Abstracts of Presentations at the 1989 Annual Meeting of the American Phytopathological Society
    Abstracts of Presentations at the 1989 Annual Meeting of The American Phytopathological Society August 20-24, 1989 Richmond Marriott Hotel and Richmond Convention Centre Richmond, Virginia The number above an abstract corresponds to its designation in the program of the 1989 APS Annual Meeting in Richmond, VA, August 20-24. If a presentation was not given at the meeting, the abstract is not printed among the following pages. The index to authors begins on page 1224. 1 lated peanut leaf and disease proportions are generated for early leafspot, late leaf spot, both leafspots mixed or peanut INFLUENCE OF TILLAGE SYSTEMS ON THE INCIDENCE AND SPATIAL PAT- rust. Pre-testing, drill and practice, and post-testing sessions TERN OF TAN SPOT OF WHEAT. Wolgang Schuh, Department of Plant were conducted in a 1-hr time period for introductory plant Pathology, The Pennsylvania State University, University Park, pathology students. Twenty of 22 students significantly improved PA 16802. their ability to estimate disease proportions of late leaf spot (random lesion sizes) as measured by (i) a higher coefficient of The incidence and spatial pattern of Pyrenophora tritici- determination relating the actual proportion (X) to the esti- repentis was assessed at four locations (two conventional & two mated value (Y) and/or (ii) a regression coefficient (slope) conservation tillage) two times during 1987 and three times which was closer to 1.0 in post-tests compared to pre-tests. during 1988. Tan Spot was detected earlier in 1988 and had a higher final disease incidence in both years under conservation tillage. Spatial pattern analysis, using Morisita's index of 4 dispersion, revealed a shift from clumped to random distribu- EFFECTS OF MAIZE INTERCROPS ON ANGULAR LEAF SPOT OF BEANS.
    [Show full text]
  • Re-Evaluation of Phytophthora Citricola Isolates from Multiple Woody Hosts in Europe and North America Reveals a New Species, Phytophthora Plurivora Sp
    Persoonia 22, 2009: 95–110 www.persoonia.org RESEARCH ARTICLE doi:10.3767/003158509X442612 Re-evaluation of Phytophthora citricola isolates from multiple woody hosts in Europe and North America reveals a new species, Phytophthora plurivora sp. nov. T. Jung1,2, T.I. Burgess1 Key words Abstract During large-scale surveys for soilborne Phytophthora species in forests and semi-natural stands and nurseries in Europe during the last decade, homothallic Phytophthora isolates with paragynous antheridia, semi- beech papillate persistent sporangia and a growth optimum around 25 °C which did not form catenulate hyphal swellings, citricola were recovered from 39 host species in 16 families. Based on their morphological and physiological characters and decline the similarity of their ITS DNA sequences with P. citricola as designated on GenBank, these isolates were routinely dieback identified as P. citricola. In this study DNA sequence data from the internal transcribed spacer regions (ITS1 and forest ITS2) and 5.8S gene of the rRNA operon, the mitochondrial cox1 and -tubulin genes were used in combination with multivora β morphological and physiological characteristics to characterise these isolates and compare them to the ex-type and nursery the authentic type isolates of P. citricola, and two other taxa of the P. citricola complex, P. citricola I and the recently oak described P. multivora. Due to their unique combination of morphological, physiological and molecular characters phylogeny these semipapillate homothallic isolates are described here as a new species, P. plurivora sp. nov. Article info Received: 5 February 2009; Accepted: 26 March 2009; Published: 14 April 2009. INTRODUCTION dieback, respectively (Fig.
    [Show full text]
  • Major and Emerging Fungal Diseases of Citrus in the Mediterranean Region Mediterranean Region
    Provisional chapter Chapter 1 Major and Emerging Fungal Diseases of Citrus in the Major and Emerging Fungal Diseases of Citrus in the Mediterranean Region Mediterranean Region Khaled Khanchouch, Antonella Pane, Ali KhaledChriki and Khanchouch, Santa Olga Antonella Cacciola Pane, Ali Chriki and Santa Olga Cacciola Additional information is available at the end of the chapter Additional information is available at the end of the chapter http://dx.doi.org/10.5772/66943 Abstract This chapter deals with major endemic and emerging fungal diseases of citrus as well as with exotic fungal pathogens potentially harmful for citrus industry in the Mediterranean region, with particular emphasis on diseases reported in Italy and Maghreb countries. The aim is to provide an update of both the taxonomy of the causal agents and their ecology based on a molecular approach, as a preliminary step towards developing or upgrading integrated and sustainable disease management strategies. Potential or actual problems related to the intensification of new plantings, introduction of new citrus cul- tivars and substitution of sour orange with other rootstocks, globalization of commerce and climate changes are discussed. Fungal pathogens causing vascular, foliar, fruit, trunk and root diseases in commercial citrus orchards are reported, including Plenodomus tra- cheiphilus, Colletotrichum spp., Alternaria spp., Mycosphaerellaceae, Botryosphaeriaceae, Guignardia citricarpa and lignicolous basidiomycetes. Diseases caused by Phytophthora spp. (oomycetes) are also included as these pathogens have many biological, ecological and epidemiological features in common with the true fungi (eumycetes). Keywords: Plenodomus tracheiphilus, Colletotrichum spp., Alternaria spp., greasy spot, Mycosphaerellaceae, Botryosphaeriaceae, Guignardia citricarpa, Basidiomycetes, Phytophthora spp 1. Introduction Citrus are among the ten most important crops in terms of total fruit yield worldwide and rank first in international fruit trade in terms of value.
    [Show full text]