INTERACTIONS BETWEEN STRAINS of SQUASH MOSAIC VIRUS in PUMPKIN and CANTALOUPE PLANTS by Jos6 Albersio De Aratijo^Lima a Thesis S
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Interactions between strains of squash mosaic virus in pumpkin and cantaloupe plants. Item Type text; Thesis-Reproduction (electronic) Authors Lima, José Albersio de Araújo, 1940- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 01/10/2021 08:47:18 Link to Item http://hdl.handle.net/10150/554643 INTERACTIONS BETWEEN STRAINS OF SQUASH MOSAIC VIRUS IN PUMPKIN AND CANTALOUPE PLANTS by Jos6 Albersio de Aratijo^Lima A Thesis Submitted to the Faculty of the DEPARTMENT OF PLANT PATHOLOGY In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 7 2 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of re quirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judg ment the proposed use of the material is in the interests of scholar ship. In all other instances, however, permission must be obtained from the author. SIGNED: APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: mz. MERRITT R. NELSON Date Professor of Plant Pathology ACKNOWLEDGMENTS The author wishes to express his sincere gratitude and appre ciation for the counsel and helpful guidance of Dr„ Merritt R. Nelson, Professor of Plant Pathology, The University of Arizona, under whose leadership this investigation was conducted. Appreciation is extended to Dr. Milton Zaitlin and Dr. Richard B. Hine for their useful advice and efforts in criticizing the manuscript. The author also thanks Mr. Wilbur R. Hague for his helpful contributions in the greenhouse works. Gratitude is extended to Dr. William G. Matlock, Campus Co ordinator, AID Brazil Program, The University of Arizona/University of Ceara Contract, and to his secretary, Mrs. Evelyn Jorgensen, for their understanding and cooperation. The author was supported by funds from the United States Agency for International Development (US AID), The University of Arizona/Univer sity of Ceara Contract, to whom sincere appreciation is expressed. Special recognition is given to my wife, Diana, whose patience and support made this work possible. TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS. v LIST OF TABLES .................... vi ABSTRACT. ........................ vii INTRODUCTION AND LITERATURE REVIEW .. 1 MATERIAL AND METHODS . .. ........ 12 Virus Strains and Hosts „ . .............. 12 Virus Purification and Inoculation Methods ........ 13 Cross-protection Experiments between Strains of SMV in Pumpkin and Cantaloupe . „ . „ „ . 14 Squash M osaic Virus Strain Dominance in Simultaneously Inoculated Plants .... „ „ . 16 Concentrations of Strains of Squash Mosaic Virus in Pumpkin and Cantaloupe............... 17 RESULTS ............ ........... 18 Virus Strains and Hosts ................. 18 Cross-protection between Strains of SMV in Pumpkin and Cantaloupe . ...... .. 22 Squash M osaic Virus Strain Dominance in Simultaneously Inoculated Pumpkin and Cantaloupe Plants................... 24 Squash Mosaic Virus Strain Concentration in Pumpkin and Cantaloupe............... 26 DISCUSSION . ...... 28 REFERENCES. ...... ". „ . 32 iv LIST OF ILLUSTRATIONS Figure Page 1 „ Systemic Symptoms in Leaves of Cucurbita pepo L. Inoculated with Strains of Squash M osaic Virus . 19 2. Symptoms of Strains of Squash M osaic Virus in CuCumis melo L „ „ .... 20 3. Local Lesions on Cotyledons of Citrullus vulgaris Schrad. Caused by IH Strain of Squash Mosaic Virus ...................... 21 4. Results of Intragel Cross-absorption Tests with Purified SMV Suspension Obtained from Pumpkin Plants Inoculated First with IIA and 10 Days Later with IH Strains . 21 v LIST OF TABLES Table Page 1 „ Dominance of One SMV Strain over the Other When Different Concentrations of IH and IIA Strains Are Simultaneously Inoculated into Pumpkin and Cantaloupe Plants ................ 25 2. The Relative Concentrations of IH and IIA Strains of Squash M osaic Virus in Pumpkin and Canta loupe Plants Grown in Greenhouse and Growth Chamber. .................... 27 v i ABSTRACT Interactions between strains IH and IIA. of squash mosaic virus (SMV) in pumpkin (Cucurbita pepo L„) and cantaloupe (Cucumis melo L.) plants were studied. Complete reciprocal cross-protection was observed in pumpkin. In cantaloupe, strain IH was able to overcome any initially suppressive effect of IIAi This phenomenon in cantaloupe is believed related to the fact that strain IH was determined to be capable of multi plication to twice the extent of strain IIA. In pumpkin, the relative ex tent of multiplication of the two strains is roughly equal. The detection of cross-protection, when the challenge strain is the milder of the two, was accomplished by utilizing host range differ ences and the intragel absorption technique, When opposite cotyledons of pumpkins were inoculated simul taneously with equal concentrations but different strains of purified virus, each strain dominated in roughly 50 percent of the plants to the exclusion of the other. When the concentration of one strain was reduced in relation to the other, the number of double-inoculated plants in which it dominated was reduced proportionately. Identical experiments with cantaloupe resulted in almost complete dominance of strain IH even when one-tenth of the concentration of strain HA was used. INTRODUCTION AND LITERATURE REVIEW Biological properties of viruses can and have been used exten sively to determine the relationship between strains of plant viruses. According to Matthews (1970), differences and similarities in the bio logical properties of virus isolates are probably related to functions of the viral genome not involved with viral coat protein synthesis. Among the biological properties of viruses, cross-protection studies have been widely and successfully used by several workers to demonstrate identity and strain relationships of some plant viruses. The phenomenon in which plant tissues infected with one strain of a virus are protected against related strains of the same virus was first observed by McKinney (1929). Since then the interaction between virus strains in plant tissues has received wide attention. Ainsworth (1934) compared potato viruses isolated from Cana dian tomato material with standard English material. The fact that mild strains conferred immunity in tomato against a virulent strain was con sidered as strong evidence of close relationship of the two isolates. Kunkel (1934) demonstrated that leaves of Nicotiana sylvestris Spegaz. and Comes mottled by tobacco mosaic virus (TMV) strains were protected against the aucuba mosaic strain of TMV. He also showed that viruses unrelated to TMV gave no protection against the aucuba . mosaic strain of TMV, suggesting a certain degree of specificity in the protection process. Similar results were obtained by Price (1935). He observed that leaves of Zinnia elegans Jacq. systematically invaded by 1 any one of four different mottling strains of cucumber mosaic virus (CMV) were protected against a strain of CMV which produced necrotic lesions in healthy zinnia plants but not against a necrotic-type TMV strain. He also found that leaves of plants mottled by TMV strains became immune from the necrotic-type TMV but not from a necrotic-type CMV. He further demonstrated the specificity of the protection action in zinnia for both CMV and TMV by demonstrating that plants infected with viruses unre lated to CMV or TMV were susceptible to the necrotic-type strains of both. The results obtained by Price (1936) evidenced the specificity of acquired immunity from tobacco ring spot diseases. Strains of tobacco ring spot virus protected tobacco plants against each other but did not confer protection against unrelated viruses. From cross-protection studies between lily mosaic virus and CMV in zinnia plants, Price (1937) concluded that the two viruses were closely related and that lily mosaic virus should be classified in the cucumber mosaic virus group. Again, Price (1941) observed that zinnia plants infected with Hawaiian commelian mosaic virus were protected against the indicator strain of CMV, thus demonstrating that the virus was a strain of CMV. Using insect inoculation and graft transmission, Crowdy and Posnette (1947) carried out experiments on cross-immunity reactions between viruses attacking Theobroma cacao L. The results revealed some degree of protection afforded by one virus against infection with the other. 3 Strains of alfalfa mosaic virus (AMV) have been identified by- cross-protection tests. The results obtained by Berkeley (1947) in to bacco plants indicated that a pepper virus was closely related to the AMV. Oswald (1950) used cross-protection studies to identify a strain of AMV which was causing vine and tuber necrosis in potato . Because common bean mosaic and yellow mosaic viruses were very similar