Poster: Salinity

Abs # 98: Comparison of betaine aldehyde dehydrogenase activity in leaves under salt and heat stresses between sheep grass and spinach

Presenter:	Ozaki, Keiko , i021006d@mbox.nagoya-u.ac.jp
Authors	Ozaki, Keiko  (A)   Hibino, Takashi  (B)   Takabe, Teruhiro  (B)   Takabe, Tetsuko  (A)
Affiliations:	(A): Nagoya University (B): Meijo University

Glycinebetaine is one of the most important osmoprotectants. It is synthesized by a two-step oxidation of choline; the first step of which is catalyzed by choline monooxygenase and the last step by betaine aldehyde dehydrogenase in chenopods. Glycinebetaine synthesis pathway, however, is not well known in other plants. Sheep grass [Aneurolepidium chinense (Trin.) kitag] that grows in semi-arid areas, is tolerant towards various stresses and accumulates glycinebetaine at a high level (more than 100 μmol/gFW) under salt stress. We isolated two types of BADH genes, AcBADH1 and AcBADH2, from gray type of sheep grass, which is more tolerant towards the stresses than that of green type. AcBADH1 had the transit peptide targeting to peroxisome and was induced under various stresses. AcBADH2, which is expected to be localized in the cytosol, was also somewhat induced under various stresses, but the transcript level was constitutively high. To characterize the AcBADH2 enzyme activity, we transformed AcBADH2 into E. coli and compared AcBADH2 with spinach BADH. AcBADH showed more tolerant towards heat stress than spinach BADH when glycinebetaine was added. While spinach BADH uses some of amino-aldehydes, AcBADH used betaine aldehyde more specifically than spinach BADH. Total BADH proteins were extracted from leaves of sheep grass and spinach. The BADH activity of sheep grass was five times higher than that of spinach.