Poster: Late and Moved Abstracts

Abs # 983: CaLEA1 encoding a hydrophobic LEA protein confers increased tolerance to heat stress in addition to drought and salinity stress

Presenter:	Joe, Anna , ynhong@snu.ac.kr
Authors	Joe, Anna  (A)   Kim, Hyung-Sae  (A)   Lee, Jee Hyun  (A)   Jun, Sung-Soo  (A)   Hong, Young-Nam  (A)
Affiliations:	(A): Seoul National University
Web Site:	http://biosci.snu.ac.kr

In our previous study, a dehydration-responsive cDNA clone named as CaLEA1 (Capsicum annuum Late Embryo Abundant) for a novel gene encoding LEA protein in hot pepper was isolated from a cDNA library constructed from leaves of 4-week old hot pepper plants subjected to 10% (w/v) PEG-treatment up to 48 h. The ORF of CaLEA1 encoded a putative cytoplasmic polypeptide of 164 amino acids with a calculated Mr of 18 kDa and a theoretical pI of 4.63. The predicted CaLEA1 protein was highly hydrophobic except C-terminal region and its deduced amino acid sequence and hydropathy plot were similar to the other atypical group of hydrophobic LEA proteins. CaLEA1 was not initially expressed in the leaves, but heavily up-regulated by both PEG-treatment and NaCl-treatment, evoking cellular dehydration. Furthermore, CaLEA1-overexpressing tobacco plants exhibited enhanced tolerance against dehydration and salinity stresses. In this study, we demonstrate that CaLEA1 is also responsive to heat stress and is up-regulated by heat treatment. In addition, CaLEA1-overexpressing tobacco plants exhibit enhanced tolerance and improved maintenance of photosynthetic capacity against heat stress. The results indicate that the protective role of LEA proteins is not confined to dehydration stress but may extend toward other various abiotic stresses.