Physiology and Genetic Studies of the Hard Maple Group
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PHYSIOLOGY AND GENETIC STUDIES OF THE HARD MAPLE GROUP by Whitney April Jackson A dissertation submitted to the School of Graduate Studies Rutgers, The State University of New Jersey In partial fulfillment of the requirements For the degree of Doctor of Philosophy Graduate Program in Plant Biology Written under the direction of Dr. Jason Grabosky And approved by New Brunswick, New Jersey May 2020 ABSTRACT OF THE DISSERTATION Physiology and Genetic Studies of The Hard Maple Group by Whitney April Jackson Dissertation Director: Dr. Jason Grabosky The hard maple group is comprised of several taxonomically ambiguous, phenotypically plastic, and genetically variable taxa, native (mainly) to the United States. Northern Sugar Maple, Acer saccharum Marsh, the most recognizable group member, is culturally, ecologically, and economically important in that region. Southern hard maples have adapted to climates defined by increasing thermal loading and extended periods of drought. Understanding southern hard maple behavioral response is needed in planning future efforts on developing strategies to sustain the role of northeastern sugar maple. I provide brief overview of hard maple taxonomy, silviculture, and relevant studies. I then describe a greenhouse study in which I compare the quantified mechanical drought response of hard maple populations from range extremes. I found differential drought response to be higher among northern trees than southern trees. Southern hard maples modified stomatal aperture earlier than did northern trees, and water use efficiency was highly correlated with provenance of study groups. Next, I describe a study to better understand environmental boundaries of southern hard maples, where I quantify processes associated with plant biochemistry to determine differential drought response among southern hard maples exposed to extreme neglect during a summer heat wave. Southern trees did not exhibit significant differentiation in biochemical study parameters among taxa, but population means were influenced by time, suggesting a tight genetic link to ii seasonality in the southern cohort. I also undertook a genotyping analysis of hard maple germplasm tissue that I collected from field campaigns and the drought studies to determine the correlation between drought response and genotype among taxa. Relative genetic variance was highest for individuals within provenances, followed by variance among taxa, with provenances within taxa showing the least variation. All populations were shown to be significantly different genetically. Groupings resulting from population pairwise comparisons from the drought study (Tukey’s HSD) were compared to those for the genotype AMOVA (PT). Groupings were not consistent between the drought study and the genotype analysis. These results suggest that in terms of breeding and selection programs for improving sugar maple industry stock, it is important to consider provenance location as an important indicator of plant performance. Genetic affinity is only part of the story. iii Acknowledgements The dissertation would never have happened without the support of the people who believed in me. I am more than thankful to my committee chair, Dr. Jason Grabosky, for his ongoing encouragement and out of the box character. Jason has created a culture in the Urban Forestry Lab that could not have been a better place for me to “grow more rows of teeth” and “develop thicker skin.” Thank you to Dr, Bingru Huang. Her work in plant stress physiology was the inspiration underlying my choice to conduct my own studies looking at drought response in trees. I appreciated the level of organization and thorough quality of her studies, and always will. Dr Peter Smouse was critical in helping me speak the language of science through writing. His ability to keep up with my warp speed editing pace the six months prior to my defense deserves a medal of honor. Peter was there with every anecdotal bit of advice I ever needed, though he may not have realized it. I will strive to accomplish the magnitude of his enthusiasm for sharing science and the value he places on “the question.” Dr Cecil Konijnendijk van den Bosch, who’s European class in governance played a major role in how I saw the implications of my work in the bigger picture., thank you for supporting me throughout my non-traditional graduate program. I want to thank Dr. A.J. Both for taking his time to get to know me over pizza and connect me to the Urban Forestry Lab. Also, for patiently directing me as I drove in circles around Cook Campus upon my initial visit to Rutgers. We do not have “jug handle” left turns in Michigan, thankfully. Thank you to my course instructors: Dr. Lena Stuwe, Dr. Ning Zhang, Dr, Eric Lam, Dr. Peter Oudemans, Dr. Nilgun Tumer, Dr. Donald Kobayashi, Dr. Brad Hillman, and Dr. Stacy Bonos. I learned so much from all of you and I appreciate all that you do iv for the Plant Biology program at Rutgers. The administrative staff in Plant Biology , as well as, the administrative staff in Ecology, and Natural Resources have my sincere gratitude. The support these people provide their programs is second to none. I would like to thank the staff at the research greenhouse, Joe Florentine, Mark Pecos, and Jeffery Akers, as well as Nicki Graf at the Floriculture Greenhouse. Thank you to Josh Honig and his team in the DNA Genotyping Lab in Foran Hall for your great work and insights. Dr Joan Bennett helped me through hurricane Sandy when we were displaced form our home for two weeks. She has also been a wonderful support as I worked towards finishing my studies. Joan is a class-act, kind, and honest. I am so grateful to have met and gotten to know her. I must acknowledge the staff of several institutions that made my field campaigns and research a success. The staff at the Secrest Arboretum in Wooster Ohio, who helped in the re-discovery of Howard Kriebel’s original maple trial was helpful with everything from a bucket truck to Fels Naphtha to combat the sea of poison ivy overlaying the entire plot. At Steven F. Austin University Dr. David Creech and the SFA Gardens team who provide the space and materials to process and ship leaf tissue back to Rutgers for DNA analysis. Thank you to Ted Stephens, native plant specialist and host during my field campaign to South Carolina, for sharing your knowledge of southern hard maples. Thanks to Ed Gilman for your time and expertise at the University of Florida-Gainesville. The undergraduate students that I met and worked with throughout my program were critical to the execution of my studies, they were enthusiastic, intelligent, and hard- working. Ross Whitehead, Kate O’Connell, Megan Kelly, Shirley Zhao, Booker George, Jessica, and John. You all have my best wishes for the future. v Thanks to fellow students who showed me not only how to be a college student again but also supported me through some difficult times; Shannon, Allyson, Ive, Josh, Jess, Jennifer, Brit, Nelson, and Clayton. You all have a place in my heart. I will also thank those who did not see my potential and/or did not believe I had what it takes to be a PhD. Names are not necessary, as you are not likely to read these pages, but you should know that the challenge only helped me want to accomplish this goal even more and now the end is all the sweeter. I wish you all the best. To my family and all of the crazy we have been through, I want to thank you for your belief in me and helping me build the resilience I needed to finish. Nothing about us is traditional and I have come to learn that this is normal and beneficial when facing what seems to be impossible circumstances. The future is bright. To Chris, thank you for doing your best to support me. Sometimes it was tough, and I am grateful to have you in my life. Well…….this brings me to the last and most important thank you of all. To my son Jackson Warner Morton, As of today (April 27, 2020), you are 12 years old, with 13 right around the corner. We started on this journey exactly 10 years ago, after tragedy struck your dad and we lost him. I packed up the car (Dory) and we drove out to New Jersey, not knowing a soul. You embraced the entire adventure with positivity and trust. You were speaking mandarin at 3 years old. You hated bedtime and loved to use a magnifying glass. We lived in the family dorms on Busch Campus and the outdoor soccer field was our back yard. You loved going to the ocean and running away from the waves. You have always been my favorite person and my motivation. My wish for you is that you remain true to yourself and fight for the ability to do so, not matter what. I hope that I have shown you self-worth and resilience, vi perseverance, and love. You deserve anything you ask the universe to provide, all you need to do is ask. I truly believe that I would not have been able to get through all life has put us through without you. You have made me the best mom I can be, which for me means that I am the beast me I can be. The state of change that COVID-19 has put at your feet is not what you deserve. But I know that, like the sword of Gryffindor, that you only take on that which makes you stronger. You are strong, funny, caring, and kind. You see the goodness in everything. Things seem unfair at the moment, but this is temporary, and you are a master (though you do not know it yet) at making friends wherever you go.