Poster: Water Relations

Abs # 224: Evaluation of LEA proteins Hydrophilins from Soy bean and Ice plant

Presenter:	Yang, Yongil , yyang@unr.nevada.edu
Authors	Yang, Yongil  (A)   Kim, Kangmin  (B)   Soulages, Jose L. (C)   Cushman, John C. (A)
Affiliations:	(A): Department of Biochemistry, University of Nevada, Reno, NV 89557-0014 (B): 193 E.R. Madigan Laboratory, 1201 W. Gregory Ave., Urbana, IL (C): Department of Biochemistry and Molecular Biology, 147 Noble Research Center, Oklahoma State University, Stillwater, OK 74078

Late embryogenesis abundant (LEA) proteins are ubiquitous in plants and accumulate during the later stages of seed maturation and in vegetative tissues following dehydration, osmotic and low-temperature stress or ABA application. Many LEA proteins are also considered to belong to a group of proteins called 'hydrophilins' due to their high hydrophilicity and glycine residue content, high degree of evolutionary conservation, and expression in response to cold, salinity, osmotic or stress. Certain classes of LEA proteins have been demonstrated to improve cold, osmotic, salinity, and drought tolerance in yeast and plants, however, the exact function of most LEA proteins remains unclear. Overexpression of a soybean group I (GmD-19) LEA protein in transgenic Arabidopsis improved fresh/dry weight under non-stressed conditions and improved germination rates and fresh/dry weight of plants under osmotic (sorbitol) stress conditions relative to control plants. Overexpression of a soybean group II (GmDHN1) LEA protein improved only fresh/dry weight under osmotic stress conditions relative to control plants. We have also identified six novel hydrophilins from M. crystallinum based on their extreme hydrophilicity. Hydrophilins with high glycine content (7.5-28%) have between 5-50% alpha-helical content, whereas proteins with low glycine content (3-5%) have high (98%) alpha-helical content. Two of these glycine-rich proteins are being evaluated for potential use in engineering improved abiotic stress tolerance. In planta functional analyses are being complemented by both structural and biophysical analyses of purified, recombinant proteins. Possible mechanisms for improved abiotic stress tolerance conferred by selected hydrophilins are discussed.