A Study of Physoderma on Three Species of Portulacaceae

Brigham Young University BYU ScholarsArchive Theses and Dissertations 1958-06-01 A study of physoderma on three species of portulacaceae David L. Mumford Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd BYU ScholarsArchive Citation Mumford, David L., "A study of physoderma on three species of portulacaceae" (1958). Theses and Dissertations. 8095. https://scholarsarchive.byu.edu/etd/8095 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. A STUDYOF PHYSODERMAON THREESPECIES OF PORTULACACEAE A THESIS SUBMITTEDTO THE DEPARTMENTOF BOTANYAND THE GRADUATESCHOOL OF BRIGHAMYOUNG UNIVERSITY IN PARTIALFULFILLMENT OF THE REQUIREMENTSFOR THE DEGREEOF MASTER OF SCIENCE BY DAVIDL. MUMFORD BRIGHAMYOUNG UNIVERSITY JUNE 1958 ACKNOWLEDGEMENTS I wish to express my appreciation to all who have assisted in the completion of this project. Acknowledge- ment is made to Dr. C. V. Morton, Smithsonian Institution, for his prompt identification of host species. Apprecia- tion is expressed to Mr. Robert Eastmond for assistance with photographic work and to Margaret Mumford for typing the manuscript. I am especially grateful to my wife Joyce 1 for her help and encouragement in connection with this project. iii TABLEOF CONTENTS Page ACKNOWLEDGEMENTS• • • • • • • • • • • • • • iii LIST OF TABLES•• • • • • • • • • • • • • • • • V LIST OF ILLUSTRATIONS••• • • • • • • • • • • • • • 1ri Chapter I. INTRODUCTION • • • • • • • • • • • • • • • 1 II. MATERIALS ANDMETHODS • • • • • • • • • • • 4 Host Species Studies Physoderma Studies III. EXPERIMENTALDATA AND OBSERVATIONS •• • • • 11 Host Classification Activation and Growth of Host Species Signs and Symptoms of the Disease Activation of the Parasit e Inoculation Studies IV. DISCUSSION ••••• • ••••• • • • • • 26 The Parasites The Hosts v. SUMMARY.• • • • • • • • • • • • • • • • • 36 LIST OF REFERENCES. • • • • • • • • • • • • • • • • 42 iv LIST OF TABLES Table Page 1. Percentage of germination of three species of Portulacaceae •••••• , ••••• • • 14 2 . Average shoot growth from corms of £k_ lanceolata soaked in various concen - trations of ethylene chlorohydrin •• • • • • 15 3. Size of resting sporangia on leaves of 4 host species ••••••••••• • • • • 19 4. Measurements of resting sporangia from leaf and stem of Erocallis triphylla , • • • • • • 24 V LIST OF ILLUSTRATIONS Figure Page 1. Healthy and infected specimens of 0. py:gmaeum. • • • • • • • • • • • • • • • • Specimen of O. py;gmaeum showing infection , of the floral organs •••••••••••• 38 J. Specimens of E. triphylla showing leaf and stem infections ••••••••••••• 39 c. lanceolata, showing infection on leaves and sepals •••••••• • • • • • • 39 Longi-section through gall on stem of E;. triphylla showing hypertrophy~ •• • • • 40 Infected cells of o. py~maeum showing resting sporangia and r izomycelium~ • • • • 40 Physoderma on E. triEhylla, showing resting sporangium, rhizomycelium, and intercalary swelling ••••••••• • • • 41 Physoderma on E. triphylla, showing rhizomycelial strands and i ntercalary swellings ••••••••••••••• • • • 41 vi CHAPTERI INTRODUCTION Our knowledge of Physoderma on terrestrial plants dates from 1833 when Physoderma pulposum Wallroth was reported on members of the Chenopodiaceae, In general the species of Physo- derma on terrestrial plants have not been studied thoroughly, As pointed out by Karling (10) the genus now contains nearly eighty species, many which are of questionable validity because of lack of knowledge regarding them. Two species of the genus occur on economically important plants and have, therefore, received considerable attention in earlier studies, Physoderma alfalfae Pat. and Lagerh, previously known as Urophlyctis alfalfae (Lagerh.) Magnus causes a disease known as "crownwart" of alfalfa and can be very destructive when condi- tions are favorable for it. Physoderma maydis Miyabe causes a disease of corn sometimes referred to as "brown spot". Eddins (3) reported this as one of the most important diseases of corn in the southern United States. The first record of Physoder ma occurring on members of the Por tulacaceae is the report by Greene (5) describing Physoderma claytoni.;ma Greene on Cj.aytcmia virginic~ L. collected in Michigan and Ontario. The symptoms are described and information on resting spore measurements are given . 1 2 Sparrow (17) presents an amended description of Physoderma claytoniana Greene in which he indicates that the epibiotic, monocentric phase characteristic of the genus Physoderma is unknown for this species. Sparrow's (17) resting spore measurements are, on the average, much larger than those originally given for P. claytoniana by Qreene (5). Sparrow attributed this to immaturity of Greene's material, a possibility previously suggested. More recently, however, Savile and Parmelee (14), in a report on parasites of Portulacaceae, have reported that a difference does exist in size of mature resting sporangia. They have treated the larger-spored parasite studied by Sparrow as a new variety which they have called Phzsoderma claytoniana . R. C. Greene var. sparro~ii Savile and Parmelee. In a recent paper Karling (10) reported Physoderma on Claytonia megarrhiza Parry from Utah. The collection examined by Karling (10) is part of the material used in the present study. The host species has now been determined as Oreobroma pygmaeum (A. Gray) Howell (Lewi~ia pygmaea B. L. Robinson). The above review points out the limited number 6.f published records of Physoderma on different members of the Portulacaceae. Three species of the family Portulacaceae were collected during the summer of 1956, all showing signs of infection by what appeare.d to be a ehytrid parasite of the genus Physoderma. Since our present knowledge of Phzsoderma on members of the Portulacaceae is meager it seemed desirable to learn as much as possible about the parasite, its hosts, and the relationship between parasite and host. In addition preliminary observa- tion in the field showed considerable difference in -reaction of the host to the parasite. One host species showed marked hypertrophy near points of infection while the second exhibit- ed only discoloration with slight or no hypertrophy in infected areas. The thi rd host showed hypertrophy from stem infections but little or no hypertrophy from leaf infections. According to Karling (9) such differences in host reaction were used by Magnus in separating the genus Uro-ehlyctis from Ph1soder:na. A more recent Yie""Toint, however, holds that host rea,::tion is not sufficient reason for separating genera. Since the value of host reaction as a taxonomic character appears questionable a study of the above mentioned parasites was of particular note. From information based on the most thoroughly studied species Karling (9) in his monograph of the genus Physoderma has compil ed a general description of the Physoderma life cycle from wh~qh the following brief summary is taken. The par asite has two alternating phases of development, an endobiotic, polycentric phase and an epibiotio, monocentric , phase. The endobiotic phase is characterized by tha occurrence of large masses of chestnut colored resting sporangia produced on a delicate rhizomycelium. In the .spring zoospores from germ- inating resting sporangia produce the microscopic epibiotic phase. Several generations of the zoosporangia and zqospores, typical of the epibiotic phase, are produced. Later in the season these zoospores give rise to the endobiotic phase. CHAPTERII MATERIALSAND METHODS Host Species Studies Specimens of three species of Portulacaceae were collected in Utah for use in this study. Diseased specimens of Claytonia lanceolata Pursh., Oreobroma pygmaeum (A. Gray) Howell, and Erocallis triphylla (S. \vats .) Rydb. were collected and dried in a plant press. Specimens of .Q.:. lanceolata and O. pygmaeum were preserved in formalin- aceto -alcohol preservative. Collections of all three species were made in the Uinta Mounta ins near the adjacent corners of Wasatch, Summit, and Duchesne Counties. Collections were made at the following five locations along Highway 150: {1} Lodgepole pine forest on the north side of the highway, 200 yards east of "Provo River Overlook," (2) East and west side of Trial Lake, (J) Broadhead Meadows, Duchesne Co., approximately thirty-three miles northeast of Kamas, Utah, (4) Bald Mountain Summit, on the north side of the highway, (5) Utah State Fish and Game Station at the base of Haydn Peak. In addition, plants of C. lanceolata were collected at the Great Basin Research Center, Ephraim Canyon, Sanpete County, Utah. Large quantities of corms of c. lanceolata were collected at the latter site and used in experimental work. 5 Because it was necessary to have living material of all three host species, an attempt was made to preserve the perennating organs of each species. Corms and roots were placed about two inches deep in flats of moist sand. The flats were covered with cardboard to prevent rapid drying .and then stored at 65° F. until used. Seeds were collected from mature pressed material of all three host species. Attempts were made to induce germination of seeds of each of the host species by the following treatments: (l) subjection while dry to freezing temperatures for fourteen days, (2) immersion

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