Overview

Ralph L. Obendorf, Professor of Crop Physiology in the Department of Crop and Soil Sciences, is a specialist in Seed Biology with 40% teaching and 60% research responsibilities. His research addresses factors and functions that regulate seed growth, seed maturation, tolerance to desiccation, and seed performance. His work on soluble carbohydrates in seeds as related to desiccation tolerance and germination led to the discovery of new health-related compounds in seeds. One of these, fagopyritol A1, is isosteric to an insulin mediator believed to be deficient in subjects with non-insulin dependent diabetes mellitus (NIDDM or type II diabetes) and polycystic ovary syndrome (affecting 10% of women of reproductive age). Three genes have been cloned from buckwheat seeds and heterologously expressed in bacteria; the purified recombinant enzyme proteins catalyze the biosynthesis of fagopyritols and one may also catalyze the biosynthesis of a putative insulin mediator. Three patents were awarded in 2004. Obendorf's research emphasizes the training of 3-12 undergraduate students in research each semester. He had 13 undergraduates in his lab in 2007 and 21 undergraduate coauthors since 1997. Obendorf teaches Grains and Nutraceuticals (CSS 311), Seed Biology (CSS 612), Special Topics (CSS 691), Undergraduate Research (CSS 499; BioG 499; BioG 299), and Biology Seminar: Seed Biology & Health (BioG 125.1). His research and teaching are globally recognized. Obendorf is active in numerous professional societies nationally and internationally. He was president of the International Society for Seed Science (1999-2005) and is owner/editor (1995-present) of SEED-BIOLOGY-L@cornell.edu, a highly successful mailing list promoting global exchange of information on seed research among 450 subscribers residing in 50 countries and 45 states.

Research Focus

Biophysical, biochemical and genetic factors governing seed desiccation tolerance and longevity are studied in mutant soybean plants with altered accumulation of raffinose, stachyose, and phytin in seeds. The effects of these alterations on biosynthesis and accumulation of cyclitols and galactosyl cyclitols in seeds and the effect of altering seed composition on seed and seedling performance including seed desiccation tolerance, germination, vigor, and storability are studied. Changes in cyclitols, galactosyl cyclitols, raffinose and stachyose are assayed by gas chromatography analysis of seed extracts. Genes associated with seed development, germination, vigor and dormancy, are studied by feeding various substrates to isolated immature embryos and stem-leaf-pod explants of soybean with low-raffinose and low-stachyose or low-raffinose, low-stachyose, and low-phytin. The accumulated substrates and products, including sucrose, free cyclitols, galactosyl cyclitols, raffinose, and stachyose are studied in precociously matured seeds that carry genes regulating the accumulation of cyclitols, galactosyl cyclitols, raffinose, and stachyose. The role of specific genes in seed maturation, desiccation tolerance, and seed and seedling performance are extrapolated from the results. Certain low-raffinose, low-stachyose modifications to soybean seed can be implemented for improved feeding value to non-ruminant animals without loss in germination and agronomic seed performance.

Instruction Focus

Undergraduate and graduate courses in Grains and Nutraceuticals (CSS 311) and Seed Biology (CSS 612) emphasize the biology behind the production of food, feed and seed crops for improved yield, quality and agronomic performance. Obendorf emphasizes training of undergraduates (2-15 per year) in independent research through hands-on research laboratory experiences including course credit in CSS 499, BioG 299, BioG 499, BioG 498 and CSS 498. Three new courses were developed: BioG 125 Seed Biology & Health. This courses teaches first year students how to read and interpret scientific papers in current research literature (http://www.css.cornell.edu/courses/125/BioG125.html); CSS 211 Field Crop Systems. This course is part of the agriculture science program and provides a comphrensive introduction to field crops for food and feed (http://www.css.cornell.edu/courses/211/css211.html); CSS 405 Field Crop Systems. A comphrensive discussion of food and feed crops for graduate and advanced undergraduate students (http://www.css.cornell.edu/courses/405/css405.html).

Additional Links

• International Society for Seed Science
• Ralph L. Obendorf
• Link to CALS Research portal
• Link to CALS Impact statements

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