KENT BRADFORD, Derek Bewley Career Lecture, Sponsored by UNITED GENETICS

Tue Sep 12, 2017
10:15 AM - 11:00 AM




Bradford, K.J.

Department of Plant Sciences, Seed Biotechnology Center, University of California, Davis, California, USA

Contact: Kent J. Bradford,


Seeds offer a unique perspective from which to view biology. An individual seed is an autonomous biological entity that must rely on its own resources (and resourcefulness) to persist after dispersal and to time its transition to germination and seedling growth to coincide with environmental opportunities for survival. At the same time, much of what interests us about seed biology is determined by the behaviors of populations of individual seeds. The percentage of seeds in a population that is in a particular state (e.g., dormant, germinated, dead) at a given time is a fundamental metric of seed biology. This duality of individual diversity underlying consistent population-wide behavior patterns has been described using population-based threshold (PBT) models. While conceptually simple, these models can describe a wide diversity of behavior of seed populations in response to temperature, water potential, oxygen, hormones, light, and aging. Recently, this seed behavior has been linked to respiratory rates of individual seeds, indicating that basic metabolic processes within seeds vary among individuals in accordance with PBT principles. As we look more broadly to microbial, plant, and animal biology, examples of cellular diversity in function, hormonal sensitivity, gene expression, and developmental responses abound. Extension of the PBT approach to describe and understand how cells function in tissues could prove beneficial in understanding regulation of developmental patterns. Extending this even further, it is possible to conceive of the interactions of transcription factors and promoters, and even of enzymes and their substrates, as representing populations of molecules with defined means and variances of expression or function that do not represent error or noise, but rather a fundamental mechanism of biological functioning. Projecting this concept to seed and plant ecology, the interactions of individuals and populations with their environments can also be described by PBT models. Examples will be provided to illustrate how concepts and quantitative approaches developed for the analysis of seed populations could be applied across biological scales from molecules to ecosystems. By demonstrating how to understand and celebrate inherent variation, a seedcentric viewpoint could lead to novel experimental approaches and mechanistic insights into the nature of biology itself.


Kent Bradford
Professor, UC Davis

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