THE POTENTIAL ROLE OF HIGH PHOTOSYNTHETIC CAPACITY IN PEST RESISTANCE MECHANISMS IN Fragaria chiloensis By ALEXIS R. VEGA A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN HORTICULTURE WASHINGTON STATE UNIVERSITY Department of Horticulture and Landscape Architecture MAY 2005 ii To the Faculty of Washington State University: The members of the Committee appointed to examine the thesis of ALEXIS R. VEGA find it satisfactory and recommend that it be accepted. _________________________________ Chair _________________________________ _________________________________ iii ACKNOWLEDGMENTS One of the most powerful factors in which science is based is people interconnections, in many different ways, directly, through discussion, teaching and even dreaming awake, or indirectly, through formal written communications along the time vector, producing a cumulative flux of expertise that goes beyond the grasp and life of any science worker. This flux sustains the exponential character of knowledge generation, a remarkable human capacity that is, in turn, the base for innovation, for make improvements even over the better, over and over again. A Ph.D. dissertation is part of that web of interconnections, both in it generation and consequences, and because of that, I would like to acknowledge the support of the members of my original committee (1994-2000), Drs. J. Scott Cameron (Chair), Patrick P. Moore, Lynell K. Tanigoshi and Stephen F. Klauer, with special mention to my former adviser, Dr. Cameron, who allow me to explore concepts and facts following my own holistic approach to reach the goals of my project. Also, I am grateful to Dr. Moore for his patience guiding me in the rigorousness and proper English language writings. I would also like to thank my new committee, integrated by Drs. John K. Fellman, (Chair), Kathleen Willemsen and Larry Hiller, which kindly accept the responsibility to guide a graduate student after several years of leave status, allowing me to finish this adventure. Special thanks are devoted to Dr. Fellman, who was a key person to solve many long-distance logistic problems and that endured many delays created by my parallel academic work for the University of Chile, 6.000 miles away from the WSU. iv I would also like to thank Dr. Chuhe Chen for his assistance in the photosynthesis and spectrum analysis area, as well, to the entire crew at the Washington State University-Vancouver Research and Extension Unit. Also, I thank to many students from Clark College (Vancouver, WA), that in a year and a half gave me an important help in tedious and lengthy laboratory protocols through their work-studies credits, with special thanks to Jamie McCall, for her invaluable assistance, even after finishing her work-studies’ assignment. Finally, I would like to thank many people that directly or indirectly helped me in my project or encouraged me to continue in spite of many extra-academic problems that plagued this work, among others, my fellow faculty friends at the University of Chile, and the wholehearted support and love of my family. v THE POTENTIAL ROLE OF HIGH PHOTOSYNTHETIC CAPACITY IN PEST RESISTANCE MECHANISMS IN Fragaria chiloensis Abstract by Alexis R. Vega, Ph. D. Washington State University May 2005 Chair: John K. Fellman Fragaria chiloensis (L.) Duch., a strawberry native from the Pacific coast of North and South America was one of the parent species, along with F. virginiana from North America, of the cultivated strawberry (F. x ananassa), which came from a single cross between both parents. This created a rather narrow genetic variation on the descendants of the original cross, allowing to some researcher to propose an expansion of the genetic base of F. x ananassa with native germplasm, which show several useful agronomic traits, among others, pest resistance and high photosynthetic capacity. A research was carried out to test the hypothesis that pest resistance mechanisms in the Fragaria genus are more likely to be present in genotypes with high photosynthetic capacity, as their require extra energy to be operative. It was confirmed previous findings communicated in the literature that the Fragaria genus has a high phenotypic variability in both traits under study if a wide range of genotypes are tested. Such variability follows a continuous distribution along the observed response ranges, suggesting polygene systems. No strong association between photosynthetic capacity and pest resistance variables was found, however, genotypes placed at the extreme of the observed response ranges, did show consistency vi with the hypothesis. Also, it was determined that the photosynthetic capacity did not segregate under the experimental conditions, however, it was demonstrated that most of the variability observed in photosynthetic capacity in Fragaria can be linked to the leaf residual conductivity to the CO2 (gr). Some pest resistance variables do segregate in the F1 generation from a single cross (total leaf phenolics concentration, total leaf protein and trichome density). Some pest resistance mechanisms appear to be elicited by the feeding upon plants by the arthropod Otiorhynchus sulcatus (L.) (Black vine weevil), some of them in a systemic fashion (phenolics). More studies are required to determine where the pest resistance mechanisms reside in the Fragaria genus. vii TABLE OF CONTENT Page ACKNOWLEDGMENTS ..................................................................................................... iii ABSTRACT ......................................................................................................................... v LIST OF TABLES .............................................................................................................… x LIST OF FIGURES ............................................................................................................... xiv DEDICATION ...................................................................................................................... xvi 1. INTRODUCTION ............................................................................................................ 1 2. LITERATURE REVIEW ......................................................... ........................................ 3 2.1. PHOTOSYNTHESIS – BREEDING ............................................................................. 3 2.2. PEST RESISTANCE – BREEDING ............................................................................. 7 3. MATERIAL AND METHODS .....................................................................................… 10 3.1. Physiological characterization of selected Fragaria genotypes ranging in pest resistance and photosynthetic capacity ............................................................................................. 10 3.2. Physiological characterization of two Fragaria genotypes, one pest resistant and the other pest susceptible, in response to black vine weevil fed upon foliage ................................. 19 3.3. Physiological characterization of progeny and parents of a cross between pest susceptible and pest resistant Fragaria genotypes ............................................................................... 21 4. RESULT AND DISCUSION .............................................................................................. 23 4.1. GAS EXCHANGE ........................................................................................................... 23 4.1.1. Selected pest resistant and pest susceptible Fragaria genotypes ................................... 23 4.1.2. Weevil-Plant interaction ................................................................................................. 35 . viii Page 4.1.3. Observation on progeny .............................................................................................. 35 4.2. FLUORESCENCE ......................................................................................................... 45 4.2.1. Selected pest resistant and pest susceptible Fragaria genotypes ............................… 45 4.2.2. Weevil-Plant interaction ...........................................................................................… 51 4.2.3. Observations on progeny ..........................................................................................… 53 4.3. LEAVES FOURTH DERIVATIVE CHLOROPHYLL'S ABSORBANCE SPECTRUM ................................................................................................................… 58 4.3.1. Selected pest resistant and pest susceptible Fragaria genotypes .............................… 58 4.3.2. Weevil-Plant interaction ............................................................................................… 62 4.3.3. Observations on progeny ..........................................................................................… 67 4.4. CHLOROPHYLL CONTENT ....................................................................................… 74 4.4.1. Selected pest resistant and pest susceptible Fragaria genotypes ............................… 74 4.4.2. Plant-weevil interaction ...........................................................................................…. 81 4.4.3. Observations on progeny ...........................................................................................… 85 4.5. LEAF PROTEIN ............................................................................................................ 89 4.5.1.