A Lucid key to the Common Phytophthora species J. Beagle Ristaino and Julia Hu. Dept. Pathology, North Carolina State University, Raleigh, NC. 27695

OBJECTIVE Our overall objective was to use to produce a simple, ABSTRACT portable and accurate taxonomic tool that can be THE LUCID KEY (Cont.) The Key to the Common Phytophthora species (Lucid v 3.4) is a used to identify common species in the genus matrix-based computerized identification key and includes Phytophthora by morphology and diagnostic DNA We have obtained copyright permission from CABI to publish important morphological and molecular characters that are sequences (ITS and cox 1). We have developed “A Elizabeth Blackwell’s beautifully illustrated “Terminology in useful for identification of 54 species. A set of features and Lucid Key for Identification of Common Species of Phytophthora”. We also have several hundred images in the fact sheets character states are used to make a correct species identification Phytophthora” that with permission kindly given from Phytophthora experts worldwide. Some of the cultures provided for this work were from Gallegly and of an unknown culture. The user enters responses to known is soon to be published by APS Press. Hong (2008) were used in their dichotomous key. Matt Ryan of CABI feature state options into Lucid Player and the correct species is and Peter Bonants of PRI, NL kindly provided cultures. identified. Illustrations of feature state options are included We beta tested the key first at California Department of where applicable in the key and a glossary of terms to guide the Agriculture (Cheryl Blomquist), Univ. Florida (Carrie Harmon), Purdue user is included in the fact sheets. The main features included in University ( Gail Ruhl) and USDA APHIS. We plan to develop quick the key are: asexual structures, sexual structures, molecular diagnostic assays that can be used with the key in future chlamydospores, hyphae and cultural characteristics, work (Cooke, Bonants and Ristaino). The key will then be made temperature requirements, and host pathogenicity. The user can available through APS Press. The key should provide a useful tool in read an illustrated “Fact Sheet” on each species of interest. A research, teaching, diagnostic and regulatory labs. The current version cross-linked glossary of terminology is included in the “Fact of the key contains 55 common species. It can be easily expanded over sheets”. In addition, a FASTA file of the ITS and Barcode of time as species of regulatory importance are described. Waterhouse stated in her 1963 key “There has been a demand Life (5’ end of the cox1 gene) sequence for each species is for some time that a bold attempt should be made to formulate a key to attached in a file. The key was created to help provide the known species. It is only when such a key is available that it is individuals with easily accessible tools to distinguish species possible for workers to assess more precisely the similarities and based on a number of important morphological and molecular differences between closely related taxa”. The key is dedicated to Jean characteristics and will be available from APS Press. Stamps and Grace Waterhouse, two pioneers in Phytophthora that have left a lasting legacy to the research community. INTRODUCTION Fig. 1. The main features and character states included in the key are: The genus Phytophthora contains many destructive plant pathogens asexual structures (sporangium type, pedicel length, sporangium shape, Fig. 2. Lucid Builder Spreadsheet scoring. The spreadsheet LITERATURE CITED with great impact on agriculture (for example, P. infestans, Potato Late sporangium length breadth ratio, sporangium size, and scoring system in Lucid Builder allows 7 score types (vertical Bonants, P.J.M., van Gent-Pelzer, M.P.E., Hooftman, R., Cooke, D.E.L., Blight), floriculture (e.g., P. ramorum, Sudden Oak Death) and whole sporangiophores), sexual structures (reproductive behavior (homothallic icons – right side) including: absent, present, rarely present, Guy, D.C., and Duncan, J.M. 2004. A combination of baiting and ecosystems (e.g., P. cinnamomi in Australia). Phytophthora species continue or heterothallic), antheridia type, oogonia characters and size, oospore uncertain, present by misinterpretation, present by different PCR formats, including measurement of real time to cause significant damage to agricultural and nursery crops and natural characters and size, chlamydospores, hyphae and cultural misinterpretation and rare or not scored options to be quantitative fluorescence, for the detection of Phytophthora fragariae ecosystems on a global level (Brasier, 2008). Many species descriptions are characteristics, temperature requirements, host pathogenicity. DNA programmed. Each character state is illustrated with in strawberry . European Journal of Plant Pathology 110: 689- based on morphological characters that require an expert to observe and sequences (ITS and Barcode of life sequences) are also included for each photographs to walk the user through common morphological 702. discriminate. This presents a problem to regulatory officials who wish to species but are not used as a character state for selection. terminology in Phytophthora. Brasier, C. M. 2008. The biosecurity threat to the UK and the global safeguard against quarantine at the ports of entry, to survey for environment from international trade in plants. Plant Pathol. newly established locations, or who wish to make rapid diagnoses in high DOI.111/j.1365-3059.2008.01886. threat situations (Brasier, 2008). Early detection, accurate identification and Cline, E. T., Farr, D. F., and Rossman, A. Y. 2008. A Synopsis of the ability to trace pathogens back to their source and eliminate them are the Phytophthora with accurate scientific names, host range, and ultimate goals to reduce invasive species such as Phytophthora (Bonants et geographic distribution. Plant Health Progress. Doi:10.1094/PHP- al., 2004). Improved tools are needed for morphological and molecular 2008-0318-01-RS. identification of Phytophthora species (Cooke et al., 2000; Park et al., 2008). http:/www.plantmanagementnetwork.org/sub/php/review/2008/Phyto The well-authenticated and useable keys to species in the genus phthora/ Phytophthora developed by Grace Waterhouse, a British mycologist are still Cooke, D.E.L., Drenth, A., Duncan, J.M., Wagels, G., and Brasier, C.M. in use today (Waterhouse and Blackwell, 1954; Waterhouse, 1963; 2000. A molecular phylogeny of Phytophthora and related oomycetes. Waterhouse, 1970). Others have also developed dichotomous keys (Ho, Fungal Genet. Biol. 30:17-32. 1981; Ho et al., 1995; Leonian, 1934; Tucker, 1931; Gallegly and Hong, Gallegy, M., and Hong, C. 2008. Phytophthora: Identifying species by 2008). Jean Stamps and colleagues transformed Waterhouse’ keys into a morphology and DNA fingerprint. American Phytopathological “user friendly” tabular format in 1990. Gallegly and Hong (2008) recently Society Press, St. Paul, Mn.158pp. published a dichotomous “ Key for identifying Phytophthora species by Ho, H.H. 1981. Synoptic key to the species of Phytophthora. Mycologia morphology and DNA fingerprinting” and include single strand 73: 705-714. conformational polymorphism analysis as a tool to differentiate species. Ho, H., Ann, P. J., and Chang, H. S. 1995. The genus Phytophthora in Erwin and Ribiero’s book Phytophthora Diseases Worldwide remains a Taiwan. Inst Bot Academia Sinica Monograph Series No. 15, Taipei. useful bibliographic reference for Phytophthora species descriptions through Leonian, L.H. 1934. Identification of Phytophthora species. W, Va. Agric. 1996. Cline et al. (2008) have recently published a “Synopsis of Exp. Stn. Bull. 262. 36 pp. Fig. 3. Lucid Player is used by the user to make an Phytophthora with accurate scientific names, host range, and geographic Fig. 4. Lucid player also has a shortcut feature that narrows Park et al. 2008. Phytophthora Database: A Forensic Database Supporting identification. First a user must have a culture of the species of distribution down the list of character states needed to make a correct the Identification and Monitoring of Phytophthora. Plant Dis. 92: 966- interest. Features of the specimen are examined and character (http:/www.plantmanagementnetwork.org/sub/php/review/2008/Phytophthor identification of the species of interest. Note the short list of 972. states are entered into the key (upper left box). By a process of a). Kang et al. have developed a Phytophthora database for genotyping and stats needed to sort the four species (upper right box) in the 1c Stamps, D.J., Newhook, F.J., Waterhouse, G.M. and Hall, G. S. 1990. elimination, the species with the character states of interest are identifying species based on DNA sequences (Park et al., 2008). clade (center box). Revised Tabular key to the species of Phytophthora de Bary. C. A. B. selected (upper right box) while others are eliminated ( lower International Mycological Institute, Mycological Papers No. 162. boxes). Data does not need to be entered for each feature. Commonw. Mycol. Inst., Kew Surrey, England. 28 pp Tucker, C.M. 1931. The taxonomy of the genus Phytophthora de Bary, THE LUCID KEY Univ. Mo. Agr. Exp. Stn. Res. Bull. 153. 208 pp. Traditionally biological specimens have been identified through Waterhouse, G.M. and Blackwell, E.M. 1954. Key to the species of the use of dichotomous keys. With the advent of database and Phytophthora de Bary recorded in the British Isles. Mycological multimedia software, it is now possible to store large amounts of Papers 57. Commonw. Mycol. Inst., Kew, Surrey, England. 9 pp. biological data and to access the information through easy-to-use Waterhouse, G.M. 1963. Key to the species of Phytophthora de Bary. matrix-based keys. Matrix-based keys do not suffer from “the Mycol. Pap 92, Commonw. Mycol. Inst., Kew, Surrey, England. 22 unanswerable couplet problem” encountered in traditional dichotomous pp. keys. Lucid keys were developed at The Centre for Biological Waterhouse, G.M. 1970. The genus Phytophthora. Diagnoses (or Information Technology (CBIT), The University of Queensland in descriptions) and figures from the original papers. Mycol. Pap. 122, Commonw. Mycol. Inst., Kew, Surrey, England. 59 pp. Australia to train students in insect identification (www.Lucidcentral.org). Two components of Lucid keys include Lucid Builder for key development and Lucid Player for using the key. The ACKNOWLEDGMENTS key runs on a a PC from a CD drive. Fact Sheet Fusion can be used to Special thanks to H. H. Hon and Jean Stamps for providing many images from develop html documentation for the key. their previous Phytophthora keys and to the many Phytophthora researchers We used Lucid Builder and developed a set of features and worldwide who have contributed their images for fact sheets and are credited in the figure legends of the key. Dr. Charles Woloshuk served as editor for the character states with information necessary to make a correct project. Cheryl Blomquist, California Department of Food and Agriculture, Phytopphthora species identification for 55 common species (Fig. 1, 2). Fig. 6. An exported Fact sheet. Linked terminology is included in a glossary page that is accessible in the key. Each fact sheet includes an Carrie Harmon, coordinator of the Southern Plant Diagnostic Network, and Gail The user enters responses to known character state options into Lucid Ruhl, Purdue Univ. provided comments and beta tested the key. Gordon Gordh Fig. 5. Fact Sheet Fusion Builder was used to develop a species introduction that describes the first reports and nomenclature of each Player (Fig. 3, 4) and the correct is narrowed down by entries description page for each species. The fact sheet illustrates the at USDA APHIS and NSF REU provided financial support for the development species, cultural characteristics, reproductive structures (asexual and of the key. Thanks to the Australia-based Lucid development team including into the matrix and ultimately identified. Detailed fact sheets for each builder page for P. infestans. Each Fact Sheet is attached as an sexual), host range and distribution, symptoms, limited control strategies html page to each species in the key. Matt Taylor for technical assistance and Elaine Medowar and Marion Haege for species were also developed with Fact Sheet Fusion (Fig. 5, 6). and references. writing and editing work.