The broad goals of Dr. Davies' research program are to understand the plant response to wounding all the way from the initial chemical (or electrophysiological) signal produced by the wound, through intracellular regulatory mechanisms, to alterations in the expression of specific genes responsible for the plant's adaptive response. He has observed that within a few minutes after a wound, a number of specific messenger RNAs can be detected, and there is an increase in polysome formation. Unexpectedly, however, even though new messages can be detected within a few minutes of the wound, overall protein synthesis drops by 75%. Dr. Davies has formulated several alternative hypotheses as to mechanisms that might account for this. One of the hypotheses is that there is a regulated translocation of polysomes from one subcellular site at which they are active, to another site where they are inactive. Consistent with this possibility is his observation of a shift in the way polysomes from wounded and unwounded plants sediment. After wounding, a large fraction of polysomes pellet with larger cellular structures. The short-term goals of this project are to identify and localize the proteins that are encoded by the wound- responsive genes and the polysomes that appear after wounding. In particular he will attempt to determine whether the shift in sedimentation properties of the polysomes is caused by association with the cytoskeleton. The question of whether polysome association with the cytoskelton is a biologically significant phenomenon has been controversial for a long time. The results of this project will make a two-fold contribution. First, they may resolve the long- standing controversy over whether association of polysomes with the cytoskeleton in plant cells occurs under physiological conditions (but this is high risk). Second, the results should establish the location of polysomes involved in translation of wound inducible gene products and so enhance knowledge of the translation stage of the wound response.
