Teachers

Our laboratory performs research to acquire basic knowledge of the biological functions in nature. The emphasis includes scientific discovery and problem solving the global issues in ecosystems.

Seed development and germination represent a critical stage in the life cycle of higher plants and is an important ecological and commercial trait. Previous studies revealed many components that are required for the maintenance of dormancy and germination of plant seeds, including light, temperature, and plant hormones. In particular, the transition between seed dormancy and germination is determined by a balance of internal signals, associated with ABA and GA. We combine postgenomics, physiology and molecular genetics approaches and attempt to provide an insight to the molecular processes underlying seed biology of Rice and Arabidopsis. If we could understand how different internal and external signals take place within plant seeds, it would enable more rapid and significant improvement of crop yield, a major focus of breeding program.

Because of the availability of halogen ions in seawater, marine organisms, including algae, produce a diverse collection of halogenated natural products, ranging from peptides, polyketides, indoles, terpenes, acetogenins, and phenols to volatile compounds. Bromide is frequently used by algae for the biosynthesis of halogenated products, although chlorine occurs in higher concentrations (19 g/L) than bromide (65 mg/L) in seawater. The reason remains unclear, however, bromide appears to be used to increase biological activity of secondary metabolites. Previous investigations revealed that vanadium-dependent bromoperoxidase (V-BrPO) is able to catalyze the halogenation of organic compounds in the presence of halide ions and H₂O₂. These enzymes have received increasing attentions due to their ability to halogenate a wide range of organic compounds of commercial and pharmaceutical interest. We are trying to clone or isolate V-BrPOs from marine red algaeLaurencia sp. and examine whether they could catalyze the bromination of biological precursors of marine natural products. These studies may benefit to the novel biogenesis of halogenated organic compounds, combined with chemical methodologies.

References

• Holdsworth MJ et al. (2008) Molecular networks regulating Arabidopsis seed maturation, after-ripening, dormancy and germination. New Phytol, 179: 33-54.
• Washio K (2003) Functional dissections between GAMYB and Dof transcription factors suggest a role for protein-protein associations in the gibberellin-mediated expression of the RAmy1A gene in the rice aleurone. Plant Physiol, 133: 850-63.
• Washio K (2006) Common mechanisms regulating expression of rice aleurone genes that contribute to the primary response for gibberellin. Biochim Biophys Acta, 1759: 478-90.
• Roongsawang N et al. (2010) Diversity of nonribosomal peptide synthetases involved in the biosynthesis of lipopeptide biosurfactants. Int J Mol Sci, 12: 141-72.
• Cabrita MT et al. (2010) Halogenated compounds from marine algae.Mar Drugs, 8: 2301-17.