Late Embryogenesis Abundant Proteins

During the late maturation stage of seed development, water content decreases greatly. One of the most striking characteristics of mature orthodox seeds is their ability to withstand severe desiccation. Mechanisms of plant drought/desiccation tolerance have been studied by numerous groups, and a broad range of molecules have been identified to play some roles. Examples are proline, oligosaccharide, and late embryogenesis abundant (LEA)proteins, and so on. LEA proteins were first described from mature cotton seeds decades ago. Since then, many LEA proteins were identified from vascular and nonvascular plants, fungi, algae, and microbes, as well as anhydrobiotic animals such as protozoa, nematodes, insects, and crustaceans, and so on. The extensive distribution of LEA genes among diverse taxa implies that these genes might be primitive yet important and therefore maintained by these species. As a result of evolution, they may have a certain universal function-osmoprotection. Hydrophilic LEAproteins are members of natively unfolded proteins in solution. After the removal of bulk cytoplasmic water, the structures of LEA proteins undergo desiccationinduced folding. These biophysical features suggest that LEA proteins may carry out a bipartite function under diVerent water states. During drought, LEA proteins may establish a water shell and decrease ion strength. After esiccation, they may enhance the bioglass strength and act as a water replacement to stabilize cellular components.