By Massimo Pigliucci1,2, Randy Small1, and Janet Braam3 1University of Tennessee, Knoxville 2SUNY-Stony Brook 3Rice University
The relative importance of nature (genetics) and nurture (environment) has always been at the center of much curiosity and discussion among scientists, philosophers, and people in general. In the last two decades or so, the scientific study of nature-nurture or, as it is technically known, genotype-environment interactions, has become a prominent field of inquiry. Scientists are seeking a better understanding of how exactly organisms perceive and react to changing environmental conditions and to new stresses imposed upon them. In particular, scientists want to know what genes are involved in these complex responses, and how they evolve through time in different organisms. This research project aims at studying a particular kind of response to stress in plants: thigmomorphogenesis, or the reaction to mechanical contact. Plants experience all sorts of mechanical stimulation, from those exerted by wind and snow, to the contact elicited by neighboring plants (which indicates the density of other plants, and hence the degree of competition for common resources such as water and light), to that induced by insects poised to attack the plant, using it as food. Touch response, then, is a common reaction to changing environmental conditions, and plants have evolved ways of dealing appropriately with the challenges imposed by wind, snow, insects, etc. These responses include an alteration of the flowering schedule (to minimize competition with other plants), a thickening of the plant stems (to better withstand insect attacks or pressure from wind or snow), and an alteration in the production of branches (again to minimize the effects of competition). Much remains to be uncovered, however, on exactly what genes make all of this possible, and how such genes work within the broader context of plant development and life cycles. The investigators will conduct several experiments to elucidate the genetic basis of touch response in a common weed, the mouse-ear cress (a member of the mustard family), which has been extensively used for genetic and ecological research over the past decades. Different genetic strains of this plant will be exposed to varying environmental conditions (increasingly strong wind), and their response will be measured for a series of crucial characteristics representative of the morphology and life history of this plant. At the same time, characteristics will be measured of a series of genes already suspected to affect the ability of these plants to respond to mechanical stimulation, in order to test hypotheses about how many of these genes may be active, and how exactly variation at the genetic level of analysis corresponds to the observable variation exhibited by the whole plant when grown under ecologically realistic settings. Results from this project will help ecologists, evolutionary biologists, and molecular biologists better understand the complex relationship between genes, environments, and the way living organisms look and behave. This is a general goal being pursued by many laboratories throughout the world, and this research will allow the scientific community to make progress in this area because of the ease with which the particular plant and environmental change selected here lend themselves to precise quantitative analyses of genes and their effects. It is also important to note that response to mechanical stimulation has been implicated as one way to conveniently alter certain plant characteristics (e.g., stem thickness) to be able to better withstand attacks from insects. This has obvious practical applications for plants of commercial interest to humans.
