Expression of mangrove allene oxide cyclase enhances salt tolerance in Escherichia coli, yeast, and tobacco cells.
To analyze the mechanisms of salt tolerance in the mangrove plant, Bruguiera sexangula, functional screening for cDNAs encoding proteins essential for salt tolerance was performed using Escherichia coli as the host organism. A transformant expressing a protein homologous to Lycopersicon (tomato) allene oxide cyclase (AOC) displayed enhanced salt tolerance. However, this unusual trait is not conferred by Lycopersicon AOC or its Arabidopsis homolog. Analysis of the functional region revealed a sequence of only 70 amino acids, which contains an unusual sequence that is essential for the salt-tolerant phenotype. On the basis of its unusual function, the mangrove AOC homolog is designated "mangrin". Furthermore, expression of mangrin driven by the GAL1 promoter and the 35S cauliflower mosaic virus (CaMV) promoter in Saccharomyces cerevisiae and tobacco cell lines, respectively, also gave rise to enhanced salt tolerance. Mangrin transcripts increased in cultured B. sexangula cells in response to salt stress. We propose that mangrin plays an important role in the salt-tolerance mechanism of B. sexangula, and that the biosynthesis of mangrin might be an effective means of enhancing salt tolerance in higher plants.
Yamada
Akiyo
A
Department of Biotechnology, Faculty of Technology, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo, 184-8588 Japan. yamaden@cc.tuat.ac.jp
Saitoh
Takeo
T
Mimura
Tetsuro
T
Ozeki
Yoshihiro
Y
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D019746:Intramolecular Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D019684:Magnoliopsida / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000378:metabolism / Q000494:pharmacology*; D014026:Nicotiana / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D010940:Plant Proteins; D012333:RNA, Messenger; D012965:Sodium Chloride; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase