Evaluating disease reaction of western Canadian spring wheat cultivars (Triticum spp.) to natural and artificial infection with Claviceps purpurea (Fr.) Tul. A Thesis Submitted to The College of Graduate Studies and Research In Partial Fulfillment of the Requirements For the Degree of Master of Science In the Department of Plant Sciences University of Saskatchewan Saskatoon, Saskatchewan By Lisa Malo © Copyright Lisa Malo, July 2013. All Rights Reserved. PERMISSION TO USE In presenting this thesis in partial fulfilment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or to make other use of material in this thesis in whole or part should be addressed to: Head of the Department of Plant Science 51 Campus Drive University of Saskatchewan Saskatoon, Saskatchewan S7N 1N8 i ABSTRACT Ergot, caused by the fungal pathogen Claviceps purpurea (Fr.) Tul., attacks the floral organs of many grassy species resulting in sclerotia production rather than grain. Infection causes reduced yields, downgrading, and poisoning if consumed by humans or animals. Few recent studies have been conducted on ergot in wheat (Triticum spp.), and prevention is the only means of control. The objectives of this study were to determine if western Canadian spring wheat differed in reaction to infection with C. purpurea and if levels of inoculum would affect disease intensity in a field setting. Three variables were measured for the field experiments to determine disease reaction, including percent sclerotia by weight, number of sclerotia per spike, and weight per sclerotium. In the first experiment, nine wheat cultivars were tested using three inoculum levels. No significant differences were detected among inoculum levels. In the second and third experiments, ninety-two cultivars were studied in field and controlled conditions. Honeydew production, sclerotial size, and the percent of florets aborted were added as variables in the growth chamber experiment. Pearson correlations were calculated using cultivar means for the field and controlled environments. Results indicate that there are differences in disease reaction among cultivars and market classes, but these differences varied depending on the evaluation method used. In the field, CWAD wheat had the smallest sclerotia, but had more per spike compared to the CWRS and CWES market classes. There were no significant differences among these market classes for percent sclerotia by weight. In the growth chamber, CWAD wheat generally had the lowest ergot infection levels. When comparing the market classes within T. aestivum (CWRS, CPS, and CWES), there were no significant differences except for honeydew production. The correlation between environments was not significant for any of the variables, suggesting alternate resistance mechanism expression. In the field, reduced infection may be due to an escape mechanism, while artificial inoculation in a controlled environment may detect a physiological resistance mechanism. However, a group of cultivars with Grandin parentage showed promising results in both environments, and might confer resistance that could be integrated into disease resistance breeding programs. ii ACKNOWLEDGEMENTS I would like to thank my supervisor Dr. Pierre Hucl for his continued guidance, assistance, and valuable knowledge during the course of this project, as well as my advisory committee members Dr. Sabine Banniza, Dr. Randy Kutcher, and Dr. Bruce Coulman for their help in my thesis. I would also like to acknowledge the technical assistance of Mike Grieman, Glen Trowell and the bread wheat field research group; Tim Dament and the flax/cereal pathology group; and Dr. Jim Menzies (CRC-AAFC). I appreciate the financial support provided by the Robert P. Knowles Scholarship (College of Graduate Studies and Research) and the Syngenta Sustainable Agriculture Scholarship (College of Agriculture and Bioresources), as well as the research funding provided by NSERC and The Saskatchewan Ministry of Agriculture through the Agriculture Development Fund (ADF). I would also like to include a special thanks to my family for their support throughout my schooling, and for all of their love and encouragement that has gotten me to where I am today. iii TABLE OF CONTENTS PERMISSION TO USE ..................................................................................................... i ABSTRACT ....................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................ iii TABLE OF CONTENTS ................................................................................................ iv LIST OF TABLES ......................................................................................................... viii LIST OF FIGURES ........................................................................................................ xii LIST OF ABBREVIATIONS ....................................................................................... xiii 1.0 INTRODUCTION....................................................................................................... 1 2.0 LITERATURE REVIEW .......................................................................................... 5 2.1 Canadian Wheat Production: A Look at the Host ..................................................... 5 2.2 Ergot Disease ............................................................................................................ 8 2.2.1 Historical Significance ....................................................................................... 8 2.2.2 Current Significance .......................................................................................... 9 2.3 Claviceps purpurea (Fr.) Tul. Disease Epidemiology ............................................ 12 2.3.1 Biology ............................................................................................................. 12 2.3.2 Life Cycle......................................................................................................... 14 2.3.3 Symptoms in Cereals ....................................................................................... 18 2.3.4 Sources of Inoculum ........................................................................................ 19 2.4 Influence of Environmental Conditions on Infection ............................................. 20 2.4.1 Temperature ..................................................................................................... 20 2.4.2 Moisture ........................................................................................................... 21 2.5 Influence of Flowering on Infection ....................................................................... 22 2.5.1 Floret Morphology and Male-sterility ............................................................. 22 2.5.2 Flowering Habit ............................................................................................... 23 2.5.3 Effect of Fertilization ....................................................................................... 24 2.6 Ergot and Soil Micronutrient Deficiencies ............................................................. 25 iv 2.7 Analyses of Ergot Infection in Cereals ................................................................... 27 2.7.1 Inoculating Technique ..................................................................................... 27 2.7.2 Differentiating Market Classes and Cultivars .................................................. 28 2.8 Control Options ....................................................................................................... 31 3.0 MATERIALS AND METHODS ............................................................................. 35 3.1 Introduction ............................................................................................................. 35 3.2 Site Information for Field Experiments .................................................................. 35 3.3 Field Experiment #1 – Reaction of Cultivars to Varying Levels of Inoculum ....... 38 3.3.1 Plant Material ................................................................................................... 38 3.3.2 Experimental Design ........................................................................................ 38 3.3.3 Data Collection ................................................................................................ 39 3.3.4 Data Analyses .................................................................................................. 40 3.4 Field Experiment #2 – Disease Reaction Differences among Wheat Species,