RUI: Chloroplast Movements as a Mechanism for Protection Against Radiation Stress

St Mary'S College Of Maryland, Saint Marys City MD

Investigators

Abstract

Photosynthesis, the process by which the sun's energy is converted to chemical form, supports most of the life on earth. In leaves, the chloroplasts (where photosynthesis occurs) can move within the cell, maximizing light absorption when light is dim and minimizing absorption when light is bright. Although these movements are common, the advantage they confer to plants in the field, if any, is unknown. One possibility is that these movements help protect chloroplasts from damage when visible or ultraviolet radiation is excessive. Radiation stress is common, and plants have evolved a variety of photoprotective mechanisms to cope, possibly including chloroplast movements. The PIs will use laboratory measurements to examine the extent to which chloroplast movements might be photoprotective, and field measurements to ascertain whether this advantage is actually realized in plants growing under natural conditions. In the laboratory the PIs will measure photosynthesis and assess damage to chloroplasts both when chloroplasts are allowed to move freely and when they are fixed in one position. For field measurements, the PIs have developed an instrument to monitor chloroplast movements under natural conditions. The PIs will examine the link between these movements and rates of photosynthesis. This work will determine whether chloroplast movements are part of the suite of adaptations plants use to adjust their photosynthetic apparatus to the unpredictable changes in light they experience each and every day. Results of this study will be important for understanding how plants deal with stress and variability in their environment, both in natural and agricultural systems. In addition, the work will significantly enhance the research infrastructure at St. Mary's College, a small, public, liberal-arts honors college with a strong emphasis on undergraduate research. Several students will be involved in the research during each academic year and at least one will participate in the field research each summer.