DOCSLIB.ORG

Phytophthora Root and Stem Rot of Soybean in Iowa

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Phytophthora Root and Stem Rot of Soybean in Iowa View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Digital Repository @ Iowa State University Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 2007 Phytophthora root and stem rot of soybean in Iowa: minimizing losses through an improved understanding of population structure and implementation of novel management strategies Sarah Marie Cerra Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agricultural Science Commons, Agronomy and Crop Sciences Commons, and the Plant Pathology Commons Recommended Citation Cerra, Sarah Marie, "Phytophthora root and stem rot of soybean in Iowa: minimizing losses through an improved understanding of population structure and implementation of novel management strategies" (2007). Retrospective Theses and Dissertations. 14837. https://lib.dr.iastate.edu/rtd/14837 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Phytophthora root and stem rot of soybean in Iowa: minimizing losses through an improved understanding of population structure and implementation of novel management strategies by Sarah Marie Cerra A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Plant Pathology Program of Study Committee: Alison Robertson, Major Professor Silvia Cianzio Edward Braun Iowa State University Ames, Iowa 2007 Copyright © Sarah Marie Cerra, 2007. All rights reserved. UMI Number: 1443152 UMI Microform 1443152 Copyright 2007 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI 48106-1346 ii Table of Contents Abstract iii Chapter 1. Introduction and literature review of Phytophthora sojae 1 Introduction 1 Phylum Oomycota: the Oomycetes 1 Phytophthora versus Pythium 2 Phytophthora sojae: classification and biology 3 Phytophthora Root and Stem Rot disease cycle 6 Managing Phytophthora Root and Stem Rot 8 My Project 13 Justification for research 13 Literature 14 Chapter 2. Within field diversity of Phytophthora sojae populations in production soybean fields in Iowa 19 Abstract 19 Introduction 20 Materials and Methods 23 Results 28 Discussion 37 Appendix 2.1 41 Literature 44 Chapter 3. Search for new sources of resistance to Phytophthora sojae in soybeans 47 Abstract 47 Introduction 47 Materials and Methods 49 Results 52 Discussion 59 Literature 60 Chapter 4. Use of mefenoxam in combination with soybean genotype as a Phytophthora disease management tool in Iowa 62 Abstract 62 Introduction 62 Materials and Methods 65 Results 67 Discussion 73 Appendix 4.1 76 Literature 82 iii Abstract Phytophthora root and stem rot (PRR), caused by the oomycete Phytophthora sojae, is an economically important soybean disease in the North Central Region of the United States, including Iowa. Management of PRR includes the use of specific resistance (Rps genes), partial resistance, and seed treatment fungicides. We had three objectives specific to PRR in Iowa; i) to determine the within field population diversity of P. sojae in fields with a history of PRR, ii) to screen 32 PI lines identified with unique resistance to P. sojae with isolates from Iowa and determine their value for future breeding efforts and iii) to determine if seed treatment fungicides in combination with partial resistant cultivars of soybean would be a useful management tool against PRR. Previous surveys in Iowa recovered 12 races of the pathogen between 1966 and 2004. These surveys collected a single isolate from each site. We proposed multiple races could be identified from a single site, based on evidence from Ohio, Arkansas and Australia surveys. Three fields in Iowa with a history of PRR were extensively sampled. Soil samples were baited using leaf disc and seedling baiting methods. A total of 36 isolates of P. sojae were collected. Of those, 32 were identified to race or pathotype. We found multiple races and pathotypes in two fields sampled. Eleven races and 13 pathotypes are reported new to Iowa. Rps genes generally are defeated by P. sojae populations between 8 and 15 years after deployment. Due to the pathogen’s ability to defeat Rps genes, new sources of resistance need to be discovered and incorporated into commercial soybean lines. As part of a collaborative study with the North Central Soybean Research program, we screened 32 previously identified plant introduction (PI) lines against isolates of P. sojae collected iv in Iowa to identify potential resistance beneficial to Iowa soybean growers. We screened the PIs in four fields as well as in the greenhouse using four layer tests with multiple combinations of isolates. We found six PI lines (PI 398693, PI 399079, PI 408029, PI 424487B, PI 567374, and PI 407974B) with possible new sources of resistance to be incorporated into Iowa soybeans. Partial resistance does not become active until the VC growth stage of the soybean, causing the seed and seedling to be susceptible to disease at planting and early stages of growth. Application of fungicide seed treatments, including the active ingredients metalaxyl and mefenoxam, are suggested in areas of strong disease pressure and favorable environmental conditions for disease development. We evaluated the use of fungicide seed treatments in combination with partial resistance as a potential effective management tool, as part of a collaborative study of the North Central Soybean Research Program. Three fields with a history of PRR were identified and field trials were conducted over two years in a split plot design, with the main plot including cultivar of soybean (2 susceptible; Sloan and Williams, 2 reportedly partial resistant; Stine 2402 and S27-T7, and 2 with Rps genes; Archer with Rps1k and 6 and 2834RR with Rps1k). The subplot included three seed treatments; a control untreated, Apron XL® and Apron XL® plus Apron Maxx®. Evaluations included initial stand counts, disease incidence taken twice in the growing season, final stand counts and yields. Disease pressure was low due to unfavorable environmental conditions for P. sojae development. As results of these conditions, we are unable to make any conclusions to the effectiveness of using fungicide seed treatments in combination with partial resistance as an effective management tool. 1 Chapter 1: Introduction and literature review of Phytophthora sojae Introduction Phytophthora root and stem rot (PRR) of soybean, Glycine max (L.) Merrill, is caused by the oomycete, Phytophthora sojae Kaufmann & Gerdemann (26). The disease is the second most important disease of soybean in the United States after soybean cyst nematode (24, 41). Phytophthora sojae causes disease in every soybean growing state in the United States as well as Canada, China, Argentina, Australia, Hungary, Russia and Italy (29, 40). The disease was first described in 1948 in Indiana, followed by identification in Ohio and North Carolina in the early 1950’s (11, 19). PRR was first identified in Iowa in 1966 (35). In 1998, PRR caused 1113.6 x 103 metric tons of yield loss in the north central region of the United States (41). In Iowa, PRR of soybean is a destructive seedling disease present in over 63% of the soybean fields (30, 49). During 1998 - 2002, the estimated annual loss in Iowa averaged 92,480 metric tons of soybeans with an approximate value of $6 million (41). Greater yield losses can occur during years with favorable environmental conditions for disease development. Phylum Oomycota: the Oomycetes Phytophthora sojae is a water mold in the phylum Oomycota. Molecular phylogenetic analysis has shown that the oomycetes are more closely related to the diatoms, brown and golden brown alga in the kingdom Chromista (Stremenophila) than to the true fungi kingdom Eumycota (1, 25). Oomycetes have diploid nuclei in their hyphae and the only haploid state occurs in the gametes (1, 3, 25). Hyphal cell walls contain cellulose-like glucans instead of chitin (1, 3, 25). The hyphae are aseptate (1). Oomycetes produce zoospores with heterokont flagella that point in opposite directions 2 of the spore, one tinsel flagellum pointing forward and one whiplash flagellum pointing to the rear (3, 25). Oogamous sexual reproduction occurs in the oomycetes. Fertilization between distinct oogonia and antheridia results in the formation of a thick walled oospore (1, 3, 25). There are five orders in the phylum Oomycota but only two are economically significant, Saprolegniales (water molds) and Peronosporales, which include many plant pathogens such as Pythium spp., Phytophthora spp., Peronospora spp. (downy mildews) and Albugo spp. (white rusts) (3, 25). Phytophthora versus Pythium Phytophthora and Pythium belong to the family Pythiaceae. Both genera are closely related and often times it is difficult to distinguish between the two. Both have coenocytic mycelium, produce zoosporangia and produce a single oospore per oogonium (12). The major difference between Phytophthora and Pythium is zoospore formation in relation to the sporangium.
Load more

Recommended publications
  • Phytophthora Damping Off and Root Rot of Soybean Anne E
    FACT SHEET Agriculture and Natural Resources AC-17-09 Phytophthora Damping Off and Root Rot of Soybean Anne E. Dorrance and Dennis Mills Department of Plant Pathology The Ohio State University hytophthora damping off and root rot have been increased use of no-tillage and reduced tillage residue Pthe most destructive diseases of soybeans in Ohio management systems, however, Phytophthora damp- for more than 50 years. When rainfall saturates fields ing off and root rot has become a serious problem in soon after planting, severe seedling kill can result other areas of Ohio as well. The soil-borne pathogen in yield losses greater than 50% in individual fields. that causes this disease (Phytophthora sojae) can be Phytophthora seed rot and pre-emergence damping found in most agricultural soils in the state. off are one of the major causes of replanting on heavy soils. Historically, statewide yield losses average 11% Symptoms in years with wet springs and 8% in years with more Phytophthora normal planting seasons. can attack soy- The disease is most severe in poorly drained soils bean plants at any with high clay content. Traditionally, the northwest stage of develop- section of the state has had severe problems with ment. Symptoms Phytophthora damping off and root rot. With the in young plants include rapid yel- lowing and wilt- ing accompanied by a soft rot and collapse of the root. More ma- ture plants gener- ally show reduced vigor and may be gradually killed as the growing Figure 2. Phytophthora stem season progresses. rot—adult plant showing stem Figure 1.
    [Show full text]
  • Review Ten Things to Know About Oomycete Effectors
    MOLECULAR PLANT PATHOLOGY (2009) 10(6), 795–803 DOI: 10.1111/J.1364-3703.2009.00593.X Review Ten things to know about oomycete effectors SEBASTIAN SCHORNACK1, EDGAR HUITEMA1, LILIANA M. CANO1, TOLGA O. BOZKURT1, RICARDO OLIVA1, MIREILLE VAN DAMME1, SIMON SCHWIZER1, SYLVAIN RAFFAELE1, ANGELA CHAPARRO-GARCIA1, RHYS FARRER1, MARIA EUGENIA SEGRETIN1, JORUNN BOS1, BRIAN J. HAAS2, MICHAEL C. ZODY2, CHAD NUSBAUM2, JOE WIN1, MARCO THINES1,3 AND SOPHIEN KAMOUN1,* 1The Sainsbury Laboratory, Norwich, NR4 7UH, UK 2Broad Institute of MIT and Harvard, Cambridge, MA 02141, USA 3University of Hohenheim, Institute of Botany 210, 70593 Stuttgart, Germany sity of Wales, Bangor, UK, summed up the general feeling by SUMMARY declaring the oomycetes to be a ‘fungal geneticist’s nightmare’ Long considered intractable organisms by fungal genetic (Shaw, 1983). research standards, the oomycetes have recently moved to the In 1984, 1 year after David Shaw’s gloomy quip, Brian centre stage of research on plant–microbe interactions. Recent Staskawicz, Doug Dahlbeck and Noel Keen reported the first work on oomycete effector evolution, trafficking and function cloning of a plant pathogen avirulence gene from the bacterium has led to major conceptual advances in the science of plant Pseudomonas syringae pv. glycinea (Staskawicz et al., 1984). pathology. In this review, we provide a historical perspective on This landmark event ushered in a golden age for research into oomycete genetic research and summarize the state of the art in plant–microbe interactions during which bacteria and a handful effector biology of plant pathogenic oomycetes by describing of fungi became the organisms of choice for molecular studies what we consider to be the 10 most important concepts about on host specificity and disease resistance (see other reviews in oomycete effectors.mpp_593 795..804 this issue).
    [Show full text]
  • Appl. Environ. Microbiol. 60:2616–2621
    APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Mar. 1998, p. 948–954 Vol. 64, No. 3 0099-2240/98/$04.0010 Copyright © 1998, American Society for Microbiology PCR Amplification of Ribosomal DNA for Species Identification in the Plant Pathogen Genus Phytophthora JEAN B. RISTAINO,* MICHAEL MADRITCH, CAROL L. TROUT, AND GREGORY PARRA Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695 Received 7 August 1997/Accepted 15 December 1997 We have developed a PCR procedure to amplify DNA for quick identification of the economically important species from each of the six taxonomic groups in the plant pathogen genus Phytophthora. This procedure involves amplification of the 5.8S ribosomal DNA gene and internal transcribed spacers (ITS) with the ITS primers ITS 5 and ITS 4. Restriction digests of the amplified DNA products were conducted with the restriction enzymes RsaI, MspI, and HaeIII. Restriction fragment patterns were similar after digestions with RsaI for the following species: P. capsici and P. citricola; P. infestans, P. cactorum, and P. mirabilis; P. fragariae, P. cinnamomi, and P. megasperma from peach; P. palmivora, P. citrophthora, P. erythroseptica, and P. cryptogea; and P. mega- sperma from raspberry and P. sojae. Restriction digests with MspI separated P. capsici from P. citricola and separated P. cactorum from P. infestans and P. mirabilis. Restriction digests with HaeIII separated P. citro- phthora from P. cryptogea, P. cinnamomi from P. fragariae and P. megasperma on peach, P. palmivora from P. citrophthora, and P. megasperma on raspberry from P. sojae. P. infestans and P. mirabilis digests were identical and P. cryptogea and P.
    [Show full text]
  • Abstract Book
    6-8/6/2010 Salons Marengo Médiathèque José Cabanis, Toulouse, France Oomycetes are a diverse class of microorganisms comprising more than 600 species that have major impacts on plant and animal health. In the time between 1975, when Noel T Keen introduced the concept of race-cultivar specific elicitors, and present times, the deciphering of the molecular interactions between the oomycetes and their hosts has entered the genomic era. Scientists are now able to study a variety of molecules, such as PAMPs and hundreds of putative cytoplasmic effectors, all potentially interacting with components of their hosts' immune systems. A research community of the highest scientific quality has grown, focused on studying the molecular biology of oomycetes, and which the US National Science Foundation has funded to organize dedicated meetings since 2002. This international community now alternates its annual meeting between the USA and Europe. After Wageningen (The Netherlands) in 2006 and Birnam (Scotland) in 2008, the French "Ville Rose" welcomes you to discuss the latest exciting developments in oomycete molecular genetics and genomics, and also to discover some of the many still obscure aspects of their cell biology, evolution and ecological impact. Les oomycètes sont les microorganismes pathogènes les plus dévastateurs des cultures dans le monde, et comptent des parasites majeurs d'animaux. Un effort de recherche important est nécessaire au niveau international pour mieux connaître les mécanismes de leur pouvoir pathogène et mieux contrôler ces parasites. Un réseau collaboratif de recherche, intitulé « Oomycete Molecular Genetics Network » (OMGN), est financé par la « National Science Foundation » aux Etats-Unis depuis plusieurs années.
    [Show full text]
  • The Phytophthora Cactorum Genome Provides Insights Into The
    www.nature.com/scientificreports Corrected: Author Correction OPEN The Phytophthora cactorum genome provides insights into the adaptation to host defense Received: 30 October 2017 Accepted: 12 April 2018 compounds and fungicides Published online: 25 April 2018 Min Yang1,2, Shengchang Duan1,3, Xinyue Mei1,2, Huichuan Huang 1,2, Wei Chen1,4, Yixiang Liu1,2, Cunwu Guo1,2, Ting Yang1,2, Wei Wei1,2, Xili Liu5, Xiahong He1,2, Yang Dong1,4 & Shusheng Zhu1,2 Phytophthora cactorum is a homothallic oomycete pathogen, which has a wide host range and high capability to adapt to host defense compounds and fungicides. Here we report the 121.5 Mb genome assembly of the P. cactorum using the third-generation single-molecule real-time (SMRT) sequencing technology. It is the second largest genome sequenced so far in the Phytophthora genera, which contains 27,981 protein-coding genes. Comparison with other Phytophthora genomes showed that P. cactorum had a closer relationship with P. parasitica, P. infestans and P. capsici. P. cactorum has similar gene families in the secondary metabolism and pathogenicity-related efector proteins compared with other oomycete species, but specifc gene families associated with detoxifcation enzymes and carbohydrate-active enzymes (CAZymes) underwent expansion in P. cactorum. P. cactorum had a higher utilization and detoxifcation ability against ginsenosides–a group of defense compounds from Panax notoginseng–compared with the narrow host pathogen P. sojae. The elevated expression levels of detoxifcation enzymes and hydrolase activity-associated genes after exposure to ginsenosides further supported that the high detoxifcation and utilization ability of P. cactorum play a crucial role in the rapid adaptability of the pathogen to host plant defense compounds and fungicides.
    [Show full text]
  • Genetic and Phenotypic Variation of Phytophthora Crassamura Isolates from California Nurseries and Restoration Sites
    Fungal Biology xxx (xxxx) xxx Contents lists available at ScienceDirect Fungal Biology journal homepage: www.elsevier.com/locate/funbio Genetic and phenotypic variation of Phytophthora crassamura isolates from California nurseries and restoration sites * Laura L. Sims a, d, , Cameron Chee a, Tyler Bourret b, Shannon Hunter c, 1, Matteo Garbelotto a a Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, 94720, USA b Department of Plant Pathology, University of California, Davis, CA, 95616, USA c Department of Biology, School of Science, University of Waikato, Forest Protection, Scion, Rotorua 3010, New Zealand d Forestry Program, School of Agricultural Sciences and Forestry, Louisiana Tech University, LA, 71272, USA article info abstract Article history: Phenotypic and sequence data were used to characterize 28 isolates resembling Phytophthora Received 4 August 2018 megasperma from 14 host species in 2 plant production facilities and 10 restoration sites across the San Received in revised form Francisco Bay Area (California; USA). Size of the oogonia and DNA sequences (nuclear internal transcribed 22 October 2018 spacer (ITS) and mitochondrial cytochrome c oxidase subunit 1 (COX 1)) were compared, and sensitivity Accepted 27 November 2018 to mefenoxam and pathogenicity were measured. Based on ITS 61 % of isolates matched ex-type Available online xxx sequences of Phytophthora crassamura from Italy, and the remainder matched or were close to the P. Corresponding Editor: Nik Money megasperma ex-type. However, all California P. crassamura genotypes belonged to four unique COX 1 haplotype lineages isolated from both nurseries and restoration sites. Although lineages were sensitive to Keywords: mefenoxam, a significant difference in sensitivity was identified, and all continued growth in-vitro.
    [Show full text]
  • Phytophthora Sojae Infecting Soybean: Pathotype Diversity, New Sources
    South Dakota State University Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange Theses and Dissertations 2017 Phytophthora Sojae Infecting Soybean: Pathotype Diversity, New Sources of Resistance and Interaction with the Soybean Cyst Nematode Rawnaq Nazneen Chowdhury South Dakota State University Follow this and additional works at: http://openprairie.sdstate.edu/etd Part of the Agricultural Science Commons, and the Agronomy and Crop Sciences Commons Recommended Citation Chowdhury, Rawnaq Nazneen, "Phytophthora Sojae Infecting Soybean: Pathotype Diversity, New Sources of Resistance and Interaction with the Soybean Cyst Nematode" (2017). Theses and Dissertations. 1186. http://openprairie.sdstate.edu/etd/1186 This Dissertation - Open Access is brought to you for free and open access by Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, please contact [email protected]. PHYTOPHTHORA SOJAE INFECTING SOYBEAN: PATHOTYPE DIVERSITY, NEW SOURCES OF RESISTANCE AND INTERACTION WITH THE SOYBEAN CYST NEMATODE BY RAWNAQ NAZNEEN CHOWDHURY A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy Major in Plant Science South Dakota State University 2017 iii I would like to dedicate this thesis to my family; my mother Bilquis Alam Chowdhury, my father Raisul Alam Chowdhury, my sister Reema Najma Chowdhury and my brother Late Arif Alam Chowdhury. They have always encouraged me to pursue my passions. I am forever grateful for their never-ending love and support. iv ACKNOWLEDGMENTS With faith and gratitude to the almighty, I would like to express my earnest thanks to give me an opportunity to make my life meaningful in the world.
    [Show full text]
  • The XIII International Congress President’S Message
    Issue No. 3, 2007 International Society for Reporter Molecular Plant-Microbe Interactions IN THIS ISSUE Success in Sorrento— Success In Sorrento ................................ 1 The XIII International Congress President’s Message ................................ 2 The XIII International Congress of IS- MPMI arrived in Sorrento, Italy, on July New IS-MPMI BOD ............................... 2 21, remained for 5 full days packed with First IS-MPMI Awardee ......................... 3 an abundance of scientific, social, cultural, and gastronomic activity, and then left Interview with in a flurry on July 27 with the bustle of James C. Carrington ............................... 4 people, luggage, and buses. The final count Pierre De Wit Receives was about 1,245 registered participants, Noel T. Keen Award ............................... 5 originating from 59 countries worldwide! Meet IS-MPMI Members ..................... 6 This turnout reflected a good response of the MPMI scientific community to this event, Images from the XIII International even if only one and a half years have Congress ....................................................... 8 passed since the last occasion in Mexico. You Know You Attended the XIII Further, the registration discount offered Congress When ........................................ 9 when becoming an IS-MPMI member Past President Pierre de Wit, Congress Chair Matteo Lorito, and new President Federico Sanchez dancing Congress Award Recipients ............... 9 elicited about a 45% increase in the number of IS-MPMI
    [Show full text]
  • Identification, Validation, and Mapping of Phytophthora Sojae and Soybean
    Identification, Validation, and Mapping of Phytophthora sojae and Soybean Mosaic Virus Resistance Genes in Soybean Colin L. Davis Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Crop and Soil Environmental Sciences M. A. Saghai Maroof, Committee Chair John M. McDowell Bingyu Zhao Song Li May 10, 2017 Blacksburg, Virginia Keywords: Phytophthora sojae, Soybean Mosaic Virus, effectors, Glycine max, Soybean, R-genes, gene mapping Copyright © 2017, Colin Davis Identification, Validation, and Mapping of Phytophthora sojae and Soybean Mosaic Virus Resistance Genes in Soybean Abstract (Academic) Estimated at approximately $43 billion annually, the cultivated soybean Glycine max (L.) Merr., is the second most valuable crop in the United States. Soybeans account for 57% of the world oil-seed production and are utilized as a protein source in products such as animal feed. The value of a soybean crop, measured in seed quality and quantity, is negatively affected by biotic and abiotic stresses. This research is focused on resistance to biotic disease stress in soybean. In particular, we are working on the Phytophthora soja (P. sojae) and Soybean Mosaic Virus (SMV) systems. For each of these diseases, we are working to develop superior soybean germplasm that is resistant to the devastating economic impacts of pathogens. The majority of this research is focused on screening for novel sources of P. sojae resistance with core effectors to identify resistance genes (R-genes) that will be durable under field conditions. Four segregating populations and two recombinant inbred line (RIL) populations have been screened with core effectors.
    [Show full text]
  • Molecular Detection of Phytophthora Sojae in Glycine Max Through Conventional and Real-Time PCR J
    Molecular detection of Phytophthora sojae in Glycine max through conventional and real-time PCR J. C. Bienapfl, J. A. Percich, and D. K. Malvick Department of Plant Pathology, University of Minnesota, St. Paul 55108 INTRODUCTION Table 1. Isolates of Phytophthora sojae and other pathogens used to test specific primers PSOJF1- A B C PSOJR1 and results from the testing with conventional PCR (sPCR) and real-time PCR (qPCR) Phytophthora rot, caused by Phytophthora sojae Kaufmann & Gerdemann, is one of the most damaging diseases of soybean (Glycine max) in the U.S. (4). In 2005, P. sojae caused Genus and species Number of isolates sPCRa qPCRb,c an estimated yield loss of 1.1 million tons in the U.S. (7). Field diagnosis of Phytophthora Aphanomyces euteiches 1 - ND rot may be difficult due to symptoms resembling those caused by other pathogens such as Pythium or Diaporthe species. Symptoms include root rot and stem rot (Fig. 1). Methods to Diaporthe phaseolorum var. caulivora 2 - ND identify P. sojae involve direct isolation on semi-selective media. The development of a Fusarium acuminatum 2 - ND PCR-based assay for the rapid and sensitive detection of P. sojae could facilitate pathogen Fusarium equiseti 2 - ND identification and lead to more effective disease management. Fusarium graminearum 2 - ND PCR assays for rapid and specific detection of P. sojae using two sets of primers have been reported by other researchers, but they have limitations or have not been validated. PS1- Fusarium oxysporum 4 - ND PS2 were developed in China and PSOJF1-PSOJR1 were developed at Michigan State Fusarium proliferatum 2 - ND Fig.
    [Show full text]
  • Biological Control of Phytophthora Root Rots on Alfalfa and Soybean with Streptomyces
    Biological Control 23, 285–295 (2002) doi:10.1006/bcon.2001.1015, available online at http://www.idealibrary.com on Biological Control of Phytophthora Root Rots on Alfalfa and Soybean with Streptomyces Kun Xiao,* Linda L. Kinkel,* and Deborah A. Samac*,† *Department of Plant Pathology and †USDA-ARS Plant Science Research, University of Minnesota, St. Paul, Minnesota 55108 Received May 11, 2001; accepted November 16, 2001 sojae was the second-most important yield-suppressing A collection of 53 antibiotic-producing Streptomyces disease in the north-central region of the United isolated from soils from Minnesota, Nebraska, and States. In 1994, an estimated 560,300 metric tons of Washington were evaluated for their ability to inhibit soybean were lost to P. sojae in the United States, plant pathogenic Phytophthora medicaginis and Phy- making it third among yield-suppressing diseases tophthora sojae in vitro. Eight isolates having the (Doupnik, 1993; Wrather et al., 1997). greatest pathogen-inhibitory capabilities were subse- Phytophthora root rots are difficult to control effec- quently tested for their ability to control Phytoph- tively. A variety of methods have been studied for use thora root rots on alfalfa and soybean in sterilized vermiculite and naturally infested field soil. The in control of Phytophthora root rots of alfalfa and soy- Streptomyces isolates tested significantly reduced root bean. Plant resistance is currently the major control rot severity in alfalfa and soybean caused by P. medi- method for Phytophthora root rots on both crops (Er- caginis and P. sojae, respectively (P < 0.05). On alfalfa, win and Ribeiro, 1996). Unfortunately, none of the isolates varied in their effect on plant disease severity, currently available resistant alfalfa cultivars is im- percentage dead plants, and plant biomass in the pres- mune to the disease, especially at high pathogen inoc- ence of the pathogen.
    [Show full text]
  • Phytophthora Palmivora–Cocoa Interaction
    Journal of Fungi Review Phytophthora palmivora–Cocoa Interaction Francine Perrine-Walker 1,2 1 School of Life and Environmental Sciences, The University of Sydney, LEES Building (F22), Camperdown, NSW 2006, Australia; [email protected] 2 The University of Sydney Institute of Agriculture, 1 Central Avenue, Australian Technology Park, Eveleigh, NSW 2015, Australia Received: 2 June 2020; Accepted: 7 September 2020; Published: 9 September 2020 Abstract: Phytophthora palmivora (Butler) is an hemibiotrophic oomycete capable of infecting over 200 plant species including one of the most economically important crops, Theobroma cacao L. commonly known as cocoa. It infects many parts of the cocoa plant including the pods, causing black pod rot disease. This review will focus on P. palmivora’s ability to infect a plant host to cause disease. We highlight some current findings in other Phytophthora sp. plant model systems demonstrating how the germ tube, the appressorium and the haustorium enable the plant pathogen to penetrate a plant cell and how they contribute to the disease development in planta. This review explores the molecular exchange between the oomycete and the plant host, and the role of plant immunity during the development of such structures, to understand the infection of cocoa pods by P. palmivora isolates from Papua New Guinea. Keywords: black pod rot; Oomycota; Theobroma cacao L.; infection; stem canker 1. Introduction Within the order Peronosporales, the largest genus with over 120 described species, Phytophthora is a hemibiotrophic phytogen capable of infecting a wide range of hosts, including many agricultural crops, worldwide [1,2]. One of the most economically important and delicious crops affected is cocoa (Theobroma cacao L.).
    [Show full text]