Hageman Lecturer
Dr. Brian A. LarkinsUniversity of Arizona April 20-21, 2000Lecture: "Molecular Genetic Approaches to Developing Quality Protein Maize" Colloquium: "Plant Genomics and Genetic Engineering in Agriculture" |
About the speaker
Brian A. Larkins was born in Belleville, KS. He obtained both his B.S. and his Ph.D. (in Botany, with Eric Davies) at the University of Nebraska, Lincoln. Following a year as a post-doctoral researcher at Purdue, he was appointed an Assistant Professor of Biochemical Genetics there, in the Department of Botany and Plant Pathology. There he remained until 1988, when he moved to the University of Arizona, Tucson, as Head of the Department of Plant Sciences. In 1995 Professor Larkins stepped down as Head and became Porterfield Professor of Plant Sciences. A long-time member of the American Society of Plant Physiologists, Dr. Larkins served as an Associate Editor of Plant Physiology at the time that The Plant Cell was established as a new journal. Following four years as an Associate Editor of that new journal he became Editor-in-Chief serving in that capacity from 1992-1998. In 1998, Dr. Larkins was President of the ASPP. Among his numerous honors and recognition, he received the Charles A. Shull award from ASPP in 1983, for his work on maize seed storage proteins, and the D.R. Hoagland award from ASPP in 1997. In 1996 Dr. Larkins was elected to the National Academy of Science.
Throughout his career, Professor Larkins has conducted fundamental studies on protein synthesis in plants. His dissertation work was a successful method for isolation of polyribosomes from peas, and characterization of their functionality. He then turned his interests to maize storage proteins, particularly zein in opaque-2 mutants, which have a modified storage protein composition. He has continued that interest to the present but, among his more than 100 peer reviewed papers, there are a significant number of other topics including barley yellow dwarf virus, oat seed globulins, soybean protease inhibitors, and transgenic gene expression. Recently Dr. Larkins was member of an NRC Committee dealing with "Technology and Intellectual Property Challenges Associated with Genetically Engineered Seeds."
Seed storage proteins have obvious economic connections and successful breeding or engineering of seeds with improved protein quality depends on understanding cellular control of the program of gene expression during seed development. Dr. Larkins began examining the regulation of such gene expression more than 20 years ago and has received major support from industrial sources, as well as USDA, NSF, DOE, and private foundations. Some of his most recent grants are for study of modifier genes of opaque-2 and regulation of protein body formation in the maize endosperm. He is also an active participant in a major NSF multi-institutional grant for "Maize Gene Discovery, Sequencing and Phenotypic Analysis".
A very interesting finding is that a protein first identified as essential in protein synthesis, eEF-1A, is strongly linked to lysine content of maize seeds even though it can contribute only a few percent of the total seed lysine. Protein eEF-1A serves multiple roles within the cell and must in some way serve to recruit high lysine proteins.
Further complexity is added to attempts to engineer seed amino acid content by the finding that many transgenes which may be expressed under seed-appropriate promoters, end up producing polypeptides that are unstable in the species into which they are introduced. Stability of the seed storage proteins is context-dependent, with some combinations of expressed proteins being stable and others not. Thus, some obvious strategies to enhance lysine or methionine content of seeds have proven difficult to put into practice. Professor Larkins and his associates have made many useful discoveries on the road to that goal of designing quality protein seeds.