Plant Molecular Biology
My research focuses on the response of plants to environmental stress at the molecular, biochemical, and physiological levels, utilizing both crop and model plant species. Most of my research centers on non-biological stresses such as exposure to foreign compounds, or unfavorable temperatures (heat or chilling). The objective is to identify the basic mechanisms that limit a plant’s ability to withstand stress, and to devise strategies to overcome periods of stress. Many of my projects rely on the use of the model plant species, Arabidopsis thaliana, due to the many research tools and bioinformatics databases available for use with that species. I also use cotton, perhaps the most important and abundant fiber crop in the world. Most of all, I enjoy research projects that involve Grinnell students, and which address problems relevant to agriculture.
I am hoping to identify the molecular/genetic mechanisms that control the expression of genes important for stress tolerance. Published studies conducted at the USDA, and in my lab with Grinnell students, have examined the response of a key photosynthesis gene (Rubisco activase) to high temperature stress (DeRidder et al., 2012; DeRidder and Salvucci, 2007). It was discovered that heat stress affects the transcriptional mechanisms that control Rubisco activase gene expression. Grinnell students have engineered genetically-modified Arabidopsis plants that are helping us see and understand exactly how the activase gene responds to heat stress. We utilize modern molecular tools to clone genes, quantify their expression, and analyze their responses to stress.
I am also interested in the mechanisms that control the expression of genes involved in detoxification of toxic compounds in plants – an important feature for plant survival! One important example from agriculture involves chemicals called “safeners”, which are used to protect monocot crop species (maize, wheat, rice, sorghum) from injury by herbicides designed to kill weeds. Safeners do not afford protection from herbicides to dicot or monocot weed species, and earlier projects in my lab shed light on this discrepancy. Unexpectedly, we discovered that safeners can activate antioxidant systems in dicots, such as cotton, in addition to monocots. This finding opened up a number of projects in my lab that examine the use of safeners to induce antioxidant responses in plants.
A significant part of my research portfolio focuses on the negative effects of chilling stress on the growth and development of plants. Chilling temperatures hinder the productivity of warm-climate crop species such as maize and cotton, especially at the beginning of the growing season. One mechanism by which plants survive periods of chilling is by activating antioxidant systems, which serve to protect many important biological processes during stress. Many studies have examined plants exposed to stress later in the growing season, but little is known about those responses in younger plants. Other projects have attempted to protect cotton from chill stress by engineering plants to express individual parts (genes/proteins) of the antioxidant system, but with little success. Ongoing projects in my lab indicate that safeners can protect cotton by activating a more comprehensive antioxidant response. Stay tuned for exciting results! And, a new project is underway to explore whether safeners, by inducing antioxidants, can enhance elongation of cotton fibers. Together, these projects may have direct implications for agricultural biotechnology.
I gratefully acknowledge supports for my research from the National Science Foundation (NSF-RUI 0820877, NSF-MRI 0820756, NSF-MRI 0923422, NSF MRI 1428384, and NSF-MRI 1726941) and from the Grinnell College Committee for the Support of Faculty Scholarship.
Education and Appointments
B.S. Biology 1998, Calvin College
Ph.D. 2003, Purdue University
Postdoctoral Associate 2003-04, USDA-ARS Phoenix, AZ
Research Molecular Biologist 2004-06, USDA-ARS Phoenix, AZ
Grinnell College Biology Faculty 2007-present