Karen Schumaker

Karen Schumaker

Professor

Degree(s)

  • B.S., Plant Sciences, University of California, Davis
  • M.S., Plant Breeding and Genetics, Oregon State University
  • Ph.D., Botany, University of Maryland
  • Post-doctoral Fellow, Cellular and Molecular Physiology, Yale University School of Medicine
Research

Our research is focused on understanding how cellular energy transduction is regulated and the molecular evolution of genes that control plant adaptation. These two projects intersect in their importance for plant growth in saline environments.

Interests

UNDERSTANDING HOW SEEDS SENSE THE OSMOTIC ENVIRONMENT More than 25 percent of the world’s agriculture is grown in areas of severe water stress. This figure doubles when irrigated cropland, which produces 40 percent of the global food supply, is included. It has been estimated that the demand for water will increase 50 percent by 2030, and that water supply will not grow in parallel. Agriculture will be responsible for nearly half of the additional demand, because global food production must increase almost 70 percent to feed 9.6 billion people by 2050. To meet future food demand, farmers must increase crop yields -- essential to achieving this goal will be the identification and development of crops with improved ability to grow during drought (osmotic) stress. Seed germination is a critical part of the plant’s life cycle, insuring survival of all plant species. Because of its role in stand establishment, seed germination remains key to agricultural productivity. Therefore, a fundamental understanding of germination is essential for crop production. While much is known about the mechanisms that underlie seed germination under well-watered conditions, little is known about the extent of genetic variability for germination during osmotic stress. Comparative studies of seed germination in the salt-sensitive plant Arabidopsis thaliana (Arabidopsis) and its salt-tolerant relative Eutrema salsugineum (Eutrema) identified genetic variability for seed germination during osmotic stress. Seed germination is similar for the two species in the absence of osmotic stress (without salt) -- seeds from both species germinate and seedling growth takes place. However, when seeds are germinated in the presence of salt, very different responses are observed in the two species. At low concentrations of salt, Arabidopsis seeds germinate and seedlings quickly die, while at high concentrations of salt, seeds do not germinate even when they are subsequently transferred to media without salt. Eutrema has a consistent pattern at both levels of salt -- it does not germinate on media with salt; however, when seeds are transferred to media without salt, germination and seedling growth take place. These studies indicate that Eutrema has a unique ability to sense its osmotic environment and delay germination until conditions are favorable for growth. We are characterizing the sensor at the physiological level and working to uncover its molecular identity. Results from these studies will contribute to understanding of the regulation of seed germination, link environmental sensing to plant adaptation to abiotic stress, and identify a molecular determinant for our toolkit for crop improvement during drought stress.

Teaching

PLS/MCB/EEB 440/540, Mechanisms of Plant Development
PLS/MCB/EEB 560, Current Topics in Plant Biology