9630407 Dure The Lea Proteins are late-embryogenesis abundant. Although first recognized in cotton seeds, homologs of many of the cotton Leas have been found in embryos of other species, both monocot and dicot. Thus, their occurrence in higher plant seeds is probably universal. Subsequently, it was observed that the Lea proteins accumulate in all tissues of the maturing embryo, indicating that the induction of their genes is not tissue or organ specific, but a whole-plant response. More recently, several lea genes homologous to cotton lea families have been shown to be induced into high levels of expression in non-seed tissue by subjecting the plant or organ to a water stress or exposing it to exogeneous ABA. Even more recently, some of these genes have been shown to be induced into high expression by salt stress or cold stress, both of which force a water-loss stress. Finally, proteins homologous to two Lea families have been found to increase in leaves of the desiccating "resurrection plants." The common aspect of late embryogenesis and these stresses is the loss of waters from plant cells. Several of the Lea proteins have regions of amino acid sequence that strongly suggest secondary and tertiary structures. These structures in turn suggest functions in handling the molecular problems encountered when cells lose 50-90% of their total water. Our present goal is 1) to determine the 3D structure and other biophysical properties of these Lea proteins under various intracellular conditions with the hope of implicating their cellular function in so doing. 2) Concomitantly, we wish to test the protective effect of several of these purified proteins on cellular entities (organelles, membranes, enzymes) subjected to drought stress. In short, the PIs intend to describe the phenomenon of desiccation tolerance/water stress survival in terms of the properties of the proteins evoked by the stress. Implicit in this research is the fact that understanding the function of these drought-in duced proteins would seem to be a requisite for manipulating drought tolerance in crop plants in a sophisticated manner.
