Larry D. Dunkle was born in 1943 in Helena, OK. He received his B.S. degree in biology in 1965 from Colorado State College (now the University of Northern Colorado), where his interest in fungi was cultivated by J. Gapter. He received his M.S. degree in 1968 and his Ph.D. degree in 1970 from the University of Wisconsin, under the direction of P. J. Allen, working on wheat stem rust urediospore germination and germ tube differentiation. He was an NIH postdoctoral fellow with J. VanEtten at the University of Nebraska, studying biochemistry of fungal spore dormancy and germination. In 1971, he became assistant professor in the Department of Plant Pathology at Nebraska, investigating root and stalk diseases of corn and sorghum and teaching a course in introductory plant pathology. In 1978, he moved to Purdue University to his current position with the USDA-ARS as a research plant pathologist and adjunct professor in the Department of Botany and Plant Pathology.
Dr. Dunkle’s research interests include the physiology and biochemistry of fungal pathogens and host-pathogen interactions. His research involves investigations of phytotoxic metabolites produced by fungi. He has studied the structure, biosynthesis, mechanism of action, and role in pathogenesis of host-selective toxins produced by pathogens of corn and sorghum. His work involves a variety of approaches, including classical field studies, biochemical and physiological studies, genetic analyses, and molecular investigations. His studies on the mechanism of action of purified and chemically characterized preparations of peritoxin challenged the generally held hypothesis that damage to the plasma membrane resulting in loss of cellular electrolytes is the primary cause of toxin-induced cell death and disease symptoms. His demonstration that disease symptoms could be induced without detectable damage to cell membranes or impairment of their function indicated that other effects of the toxin, such as alterations in gene expression and signal transduction, are more significant to disease development.
Dr. Dunkle’s studies on the toxin produced by Cochliobolus carbonum and its role in pathogenesis of maize demonstrated localized induced resistance, previously undescribed in maize, and indicated the toxin binds to DNA, alters protein synthesis in susceptible maize genotypes, and prevents synthesis of an antimicrobial compound by infected maize leaves. His recent studies indicate the genes controlling toxin production by the fungus are expressed during conidial germination, and the synthesis and release of the toxin by germinating conidia are regulated by morphogenesis of the germ tube during penetration of the maize leaf.
In addition to his research, Dr. Dunkle has supervised graduate students and postdoctoral associates, who he enjoys engaging in critical discussions of pathological principles and fallacious dogma. He has been active in APS, as well as the American Society of Plant Physiologists (ASPP) and the Mycological Society of America (MSA). He has served as member and chair of committees in APS and MSA, as a member of the Editorial Board of APS Press, and as senior editor or associate editor of Phytopathology and Plant Physiology. He has been invited to contribute book chapters and discuss his research findings in seminars, symposia, colloquia, and Gordon Conferences. He is recognized for his work on host-selective toxins and has been invited to participate in and organize national symposia on topics dealing with biochemical and molecular aspects of plant pathogenesis as well as on host-selective toxins.