Epidemiology of Puccinia hordei and new sources of resistance in barley by Amor Hassine Yahyaoui A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Plant Pathology Montana State University © Copyright by Amor Hassine Yahyaoui (1986) Abstract: New virulence types of Puccinia hordei phenotypes were detected in various geographic regions in Tunisia. Highly virulent isolates able to overcome many sources of resistance were identified. The P. hordei virulence types reported in this investigation have not been previously identified. They are important not only because they are virulent on the commonly grown barley cultivars Martin' and 'Ceres', but also because many resistance (Pa) genes are ineffective against these isolates. The effectiveness of Pag to these virulence types is questionable. Pa3 and Pa7 were very effective against all P. hordei isolates tested. The naturally occurring Ornithogalum spp. , in Northern and Northwestern Tunisia, may be a breeding ground for new physiologic races of the P. hordei fungus. Isolates originating from the alternate host were as variable in virulence as those isolated from barleys in the same fields. New genes for resistance to P. hordei appeared to be common in several collections of barley (Hordeum vulgare L.) land race cultivars originating in Central and Southern Tunisia. Response of five land race cultivars to a number of different isolates of P. hordei from the Mediterranean region differentiated them from the known genotypes. A dominant resistance gene that behaved as Pa3 was found in Tu32. Three of the land race cultivars (Tu17, Tu27, and Tu34) each have a dominant resistance gene that is different from the previously known resistance genes. The dominant resistance genes identified in this study were as effective as Pa3 and Pag, and hence, should be considered as new sources of resistance. Further testing is needed to determine the genetic relationships between these genes. EPIDEMIOLOGY OF PUCCINIA HOJDEI AND NEW SOURCES OF RESISTANCE IN BARLEY by Amor Hassine Yahyaoui A thesis submitted in partial fulfillment of the requirements for the degree of . Doctor of Philosophy, in Plant Pathology MONTANA STATE UNIVERSITY Bozeman, Montana April I 986 ii APPROVAL of a thesis submitted by Amor Hassine Yahyaoui This thesis has been read by each member of the author's graduate committee and has been found to be satisfactory regarding content, English usage, format, citations, bibliographic style, and consistency, and is ready for submission to the College of Graduate Studies. ____ ___ Date / Chairperson, Gradua/e Committee Approved for the Major Department Date Head, Major Department Approved for the College of Graduate Studies Date Graduate Dean iii STATEMENT OF PERMISSION TO USE In presenting this thesis in partial fulfillment of the requirements for a doctorate degree at Montana State UniversityI agree that the Library shall make it available to borrowers under rules of the Library. Brief quotations from this paper are allowable without special permission, provided that accurate acknowledgement of source is made. Permission for extensive quotation from or reproduction of this thesis may be granted by my major professor, or in his absence, by the Dean of Libraries when, in the opinion of either, the proposed use of the material is for scholarly purposes. Any copying or use of the the material in this paper for financial gain shall not be allowed without my written permission. iv ACKNOWLEDGMENTS I wish to express my sincere appreciation and thanks to Dr. E. L. Sharp, my major advisor, for his interest, encouragement and guidance during my course work and the preparation of this thesis. I want to extend my sincere thanks to a long-time friend, Dr. A. Daaloul, for his \ encouragement, his unlimited support and for serving on my committee. Thanks are extended to Drs. R. Ditterline, D. Mathre, D. Sands, W. Alexander, A. Scharen, and J. Safford for serving on my graduate committee. I thank the faculty, staff and fellow graduate students for their friendship. A special acknowledgment to Bob Johnston and Lee Slater for assistance with the computer, to Chuck Juhnke and Sheila Neilsen for their help, and to Bernie Sally and Drs. H. Bockelman, M . Johnston for their assistance and patience. I wish to thank the entire Mork family, especially Joyce and Michael Bondurant for making my stay in ‘cold Montana' enjoyable. I would like to express my gratitude to the Tunisian government for supporting my research. Thanks to Linda Te wait, H. Shabaan,,Sarah Dixon, Drs, W. Prawl and H. Folks for their administrative assistance. Finally, a special thanks to my dear wife, Colleen, for her moral support and for typing this manuscript. V TABLE OF CONTENTS Page Approval..................................... ii Statement of Permission to O s e ................iii Acknowledgments.............................. iv Table of Contents.......................... v List of T a b l e s ............................. viii List of Figures.............................. xi A b s t r a c t ....................................xiii GENERAL INTRODUCTION ........................ I Part I: Epidemiology of barley leaf rust (PucGinia hordei Otth) in Tunisia ............ 4 I INTRODUCTION ................................. 5 II LITERATURE REVIEH............................. 7 Epidemiology Studies ........................ 7 Physiologic Specialization ................. 8 Differential Sets............................ 9 Life Cycle............. 10 Detection of New Virulences.................... 11 Control................................... 12 III MATERIALS AND METHODS........................... 13 Differential Hosts .......................... 13 Leaf Rust Cultures.......................... 14 Isolate Designation................. .. I 4 Inoculum............................ .. 16 Inoculation...................................I 6 Assessment of Reaction Types ............... 17 Classification and Analysis of the Isolates. 18 IV RESULTS.......................................... 20 Virulence Patterns of Puccinia hordei in Northern Tunisia................. 21 Site I: Mateur............................. 21 Site 2: BouRbia............................. 23 Virulence Patterns of Puccinia hordei in Northwestern Tunisia........................ 23 Site I : Beja............................... 23 Site 2: Le K e f ............................. 26 vi TABLE OF CONTENTS - continued Page Virulence Patterns of Pucoinia hordei in Central Tunisia.......................... 27 Site I : Kairouan......................... 27 Site 2: El J e m ........................... 28 Virulence Patterns of Puccinia hordei in Southern Tunisia.......................... 28 Site I: The Oasis......................... 28 Site 2: Mareth........... 30 Common Virulence Patterns............... .. 31 V DISCUSSION . .............................. 33 Virulence Patterns of Puccinia hordei in Various Regions................. 33 Common Virulence Patterns Across Regions . 36 Effectiveness,of Resistance Genes to Puccinia hordei in Tunisia ............. 37 Part II: New Sources of Resistance to Puccinia hordei Otth ,in Tunisian Barley Land Races................. 39 VI INTRODUCTION................................. HO VII LITERATURE REVIEH............................. 41 Importance of Barley in Tunisia........... 41 Disease Problems............................ 42 Sources of Resistance....................;■ 43 Inheritance an Resistance genes in barley. 45 Effectiveness of the Pa g e n e s ............. 46 VIII MATERIALS AND METHODS. .................... 48 Parent Selection . ...................... 48 Inoculum and Inoculation Technique......... 4 9 Statistical Analyses ............ 51 IX RESULTS...................................... 52 Parents..................................... 52 Segregation Patterns in Resistant x Susceptible Crosses........... 59 Segregation Patterns in Resistant x Resistant Crosses............. 60 Segregation in pB, and Backcross Generations . t ....... ............ 70 vii TABLE OF CONTENTS - continued Page X DISCUSSION................. 72 XI SUMMARY AND CONCLUSIONS....................... 83 REFERENCES CITED ............................. 86 APPENDICES................................... 93 viii LIST OF TABLES Tables Page I . Collection sites of Tunisian barley leaf rust, Puccinia hordei, isolates from I 980-1 9811....................................... 1 5 2. Assessment of reaction types of Puocinia hordei on host differentials.................. 17 3. Virulence patterns of sixteen Puccinia hordei isolates sampled at Mateur, Northern, Tunisia, in 1980, 1983, and 1984............................................ 22 4. Virulence patterns of two Puccinia hordei isolates sampled at BouRbia, Northern, Tunisia, in 1 9 82 ............... .. 24 5; Virulence patterns of sixteen Puccinia hordei isolates sampled at Beja, Northwestern, Tunisia, in 1 982 and 1 984 . 24 6 . Virulence patterns of nine Puccinia hordei isolates sampled at Le Kef, Northwestern, Tunisia, in 1 9 82 and 1 984 . 26 7. Virulence patterns of two Puccinia hordei isolates sampled at Kairouan in 1982, and one isolate sampled at El Jem in 1 983 , in Central Tunisia.................... 28 8. Virulence patterns of seven Puocinia hordei isolates sampled at the Oasis, Southern, Tunisia, in I 982 .................... 29 9. Virulence patterns of five Puccinia hordei isolates sampled at Mareth, Southern, Tunisia, in 1983 ........... 29 ix LIST OF TABLES - Continued Tables Page 10. Common virulence