Testimonials for Pioneer Member Marc Allan Cohn

Steve Footitt – Marc’s interest in seed biology, studying imbibitional chilling damage in maize seeds, started as a graduate student with Prof Ralph Obendorf at Cornel University (1973-76). Then, Ph D in hand (his “license to practice” as he would say), he arrived at Louisiana State University in 1978, where he worked on seed dormancy in red rice, a serious weed in rice-growing areas. Aware all research needs a solid foundation, he developed a simple robust test system to characterized the role of temperature and seed moisture content on dormancy. At that time there was great interest in the dormancy breaking ability of chemicals both for weed control and for understanding the mechanism of dormancy-breaking. Marc made major contributions to our understanding of how these chemicals work. He showed for the first time that nitrogen dioxide gas broke dormancy in dry seeds. He also showed the dormancy breaking activity of weak acids and bases was pH-dependent. That Marc was the first to do this in seeds was, he commented, a reflection of biologists’ general lack of education in chemistry. Investigating the chemical properties important for dormancy breaking was perhaps his biggest contribution to the field. He demonstrated that lipophilicity, functional groups, and their position, even molecular size control dormancy breaking activity. Further work showed that dormancy-breaking chemicals induced acidification of the embryo and activated metabolism prior to breaking dormancy; this refuted the anesthetic hypothesis for the dormancy-breaking activity of alcohols by showing they had to be metabolized before dormancy-breaking occurs.

The arrival of molecular biology mainly ended interest in how dormancy-breaking compounds work. But despite the advances in understanding the genetics of dormancy and identifying the large number of genes involved, we still do not know how these compounds break dormancy.

During Marcs’ career, it was noticeable that papers on seed research increasingly provided more detail on experimental systems, including the pH of test solutions. This was due to the impact of his research and the fact that he was a prolific reviewer for journals. Such was Marcs’ dedication that as the editor of Seed Science Research, he read almost every paper submitted. His enthusiasm never seemed to diminish, and to those who knew him, he was a constant source of advice (at times brutally honest) and encouragement.

Being Marc’s doctoral student (1986-92) was as challenging as it was exciting. His encyclopedic knowledge of and passion for seed biology was infectious. I also quickly realized that Jazz was the other passion in life. He was always asking questions because he was always interested in what you were doing. At one seed conference, I attended with him, over 5 days he asked every speaker a question. In the final session, the moderator (Prof Cees Karssen) asked if anyone else would like to ask the first question. He once told me “there are no answers, only better questions to ask”. As a scientist, I came to appreciate how right he was. Working with Marc opened up a whole new way of thinking.

One invaluable skill Marc taught was the forensic reading of research papers, stating the Discussion was the authors’ opinion, so look at the results as data does not lie. Marc could quickly spot missing controls and key points in the data whose significance the authors may have missed. When designing experiments Marc was clear you needed a question and must use all possible controls to give a clear cut answer. His mantra on this was “garbage in, garbage out”. Rigorous attention to detail and record keeping in lab books, which he read, was paramount.

Changes in cell development often involve changes in cellular pH; when I had the idea of looking at changes in embryo pH as a marker of chemically induced dormancy-breaking, he encourage me to go for it. A year of hard work and failure brought me to within days of giving up. All the time, Marc advised and encouraged me and the technique was finally perfected. The next four years were truly as exciting as only science can be, as we generated unique data showing for the first time changes in seed embryo pH, metabolic activation and the metabolism of dormancy breaking chemicals during dormancy breaking. Marc encouraged debate and many hours were spent discussing what these data meant. Near the end of the project, he said to me one day “I feel sorry for the seeds because you never give up”.

Overall, as a scientist and thinker he was exceptional. A phrase he would often repeat was “seeds don’t care what we think they are doing, they just do what they do. Our job is to listen to what they tell us”.  Eventually, we worked together more as colleagues. And on Fridays, Marc would occasionally join me and other grad students in a local bar for a quick beer and a game of table football. When harvesting red rice each year, he would keep the sun and mosquitoes off with a sombrero and a cigar, as we sweated away in the field. We kept in touch and occasionally met at conferences, enjoying long conversations on life. As I look back on my career as a seed biologist, I see that the insight he gave me still guides me. He gave me a chance when no one else would, for that I owe him everything.

Julia Frugoli – When I first became involved with Southern Section ASPB, as part of the planning committee for a meeting, I had the opportunity to sit in on the Executive Committee meeting that was held before the meeting started. That was the first time I met Dr. Cohn in person, and he seemed to be the source of all history and record keeping for the Southern Section. That first impression turned out to be true. Over the next few years as I became more involved and hosted a Section meeting at my university, I discovered that even from semi-retirement he continued to be a leader in the Section -a point of continuity as elected officers changed. The Southern Section of ASPB would not have survived without his initial leadership and his mentorship of future leaders.

Gordon E. Holcomb – Marc was a friend and colleague in a department where I was a plant pathologist and and Marc a plant physiologist. I knew him as a dedicated scientist, teacher and long-time editor Seed Science Research.

Karen Koster – Marc Cohn was one of the first seed biologists who welcomed me into the field when I was a graduate student, and over the years, I learned to respect him as a role model, mentor, and friend. Marc was a champion of seed science and a generous collaborator who was always happy to share his knowledge and advice. He was a reliable presence at professional meetings, a supporter of our professional societies, and mentor to many young scientists. Marc’s knowledge of the history and literature in the field, his understanding of how research questions in seed biology have evolved, and his high standards and honesty about what constitutes good science made him a respected colleague whose advice and opinions were valued greatly. He is sorely missed.

Jeff Kuehny – Marc was a great scientist who contributed significantly to seed biology, but more importantly he provided inspiration and guidance to numerous graduate students. He encouraged students to research the topics of their projects and quizzed them with his dry sense of humor to make sure they had done a thorough job of it. Students and faculty alike appreciated his honesty and integrity, which made us all better contributors to science and society.

Mautusi Mitra – Marc was an awesome mentor to all graduate students at LSU and genuinely cared about professional growth of his students. He was very passionate about plant biology and shared his passion throughout his life with the budding plant biologists.

Mel Oliver – There is a Marc sized hole in the heart of the Southern ASPB Section that will never be filled, and my world was a better place for knowing Dr. Marc Cohn (Dr. Jazz).

Paxton Payton – Dr. Cohn was an outstanding example of what it means to be a mentor, teacher, and leader in plant biology, as well as servant to the community at-large. As a graduate student attendee at ASPB Southern Section meetings, I found he was someone I admired and later on, was fortunate enough to work with when I became and officer in the Southern Section. He was a steadfast supporter of ASPB, especially for the Southern Section and young scientists in plant biology throughout his career. It was an absolute privilege to know and work with Dr. Cohn in the Southern Section of ASPB, and I was proud to consider him a mentor and friend. This is a well deserving accolade for his contributions.

Tim Sherman – Marc Cohn was an ardent supporter of the Southern Section of ASPB for many years. He was a young faculty member at LSU when I met him as a graduate student at the section meetings in the mid-1980’s. Marc was one of group of young, active, and extremely supportive faculty members who attended the meetings at that time. It was impressive to me as a student that he cared to spend time with us and would remember us from year to year when we would see him at the meetings. As I progressed through my career as a young, I continued my involvement with the Southern Section and offered my own services as an officer. As such, I gained a greater appreciation for the role that Marc played in the Section, particularly with regard to making sure that the Section’s finances were in order. Marc took an active role in the Southern Section throughout is professional career and then some. The Southern Section, in large part, is the well organized and soundly funded body that it is due to Marc’s efforts and devotion. His presence will be sorely missed.