Marc A. Cohn
Professor

Research interests: Seed Physiology/Weed Science
Mechanisms of seed dormancy
Physiological ecology of seed dormancy
Dormancy of recalcitrant seeds

Seed dormancy, a state of suspended animation, is advantageous to survival of native species, but presents serious problems for seed scientists and producers. In my program, research is focused on the mechanisms of seed dormancy and the physiological ecology of seed survival using red rice (Oryza sativa) as a model system. In collaboration with John Larkin, developmental geneticist in the Department of Biological Sciences, we have identified a highly dormant native ecotype of Arabidopsis thaliana, which will serve as an additional model system. Work has also begun on dormancy and viability studies of Spartina alterniflora, a marsh grass whose seeds cannot be dried. An accurate viability assay has been developed to pursue aspects of dormancy and recalcitrance.

Research Contribution:
Questions under current study:

• What are the structural features of a chemical that endow it with dormancy-breaking activity (structure-activity studies using computational chemistry and computer modeling of activity)?

• What is the metabolic fate of chemicals used to break dormancy, and what does this tell us about the dormancy-breaking mechanism(s)?

• What dormancy-breaking treatments stimulate germination of Spartina?

• Why do Spartina seeds die when they are dried?

• What are the best seed processing protocols to maximize the viability of Spartina seeds after harvest?

• What is the role of protein phosphorylation in signal processing during seed dormancy maintenance and termination?

• What are the QTLs that contribute to seed dormancy and weediness of red rice?

Questions for future study (examples):

• What are the effects of dormancy-breaking chemicals upon transcription and translation?
  How is intermediary metabolism repressed in dormant seeds, and how do dormancy-breaking chemicals activate it?

• What are the natural, environmental cues that stimulate germination under field conditions?
  Can dormancy-breaking treatments be successfully applied in crop production to reduce the size of the weed seedbank and reduce overall herbicide inputs?

Professional Experience

Miscellaneous Professional Activities
Dr. Cohn received his Ph.D. from Cornell University in 1977 under the guidance of Dr. Ralph Obendorf and has devoted over 3 decades to seed physiology research. He has served as Associate Editor of Crop Science and a scientific reviewer for numerous other journals and grant panels. Dr. Cohn is the Editor of Seed Science Research, the premier international journal devoted to basic seed biology. He is a regular participant at the International Seed Biology and Plant Dormancy Workshops and is a member of the W-1168 Regional Research Project, Seed Quality Investigations. He has authored or co-authored more than 50 research papers and book chapters, as well as an equal number of scientific abstracts. He has been an invited symposium speaker at the International Weed Science Congress, Weed Science Society of America national and regional meetings, as well as International Seed Science Society meetings and recently presented the keynote address at the 3rd International Plant Dormancy Workshop in the Netherlands. He has been an invited speaker at 40 universities and symposia worldwide. Dr. Cohn has been a member of the Executive Committee of the American Society of Plant Physiologists-Southern Division since 1988 and an emeritus member of the parent society's Executive Committee. He received the ASPP-Southern Distinguished Service Award in 2001. He was the co-recipient of the LSU College of Agriculture Distinguished Dissertation Award for his work with Steve Footitt in 1993. Dr. Cohn is a member of the Weed Science Society of America, Crop Science Society of America, American Society of Official Seed Analysts, a life member of the American Society of Plant Biologists and a charter member of the International Seed Science Society.

Former students of Dr. Cohn have published their own work in EMBO Journal, The Plant Cell, and the Proceedings of the National Academy of Sciences (USA). Dr. Cohn is a life-long jazz aficionado, has guest lectured in the Jazz History course at LSU, and was a volunteer jazz broadcaster for more than a quarter of a century. He is an accomplished French chef and dedicated servant of his cat.
 

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