Poster: Hormones

Abs # 592: Studies on glycolipids concerning with flower bud formation from flower-forming Arabidopsis thaliana

Presenter:	Hisamatsu, Yosuke , s025416@ipe.tsukuba.ac.jp
Authors	Hisamatsu, Yosuke  (A)   Shigemori, Hideyuki  (B)   Goto, Nobuharu  (C)   Hasegawa, koji  (B)
Affiliations:	(A): Graduate school of Life and Environmental Sciences, University of Tsukuba (B): Institute of Applied Biochemistry, University of Tsukuba (C): Department of Biology, Miyagi University of Education

We demonstrated the search for bioactive substances concerning with flower bud formation from Arabidopsis thaliana. A. thaliana (Columbia), grown under short day condition (SD, 8h-light and 16h-dark) were transfered to long day condition (LD, 16h-light and 8h-dark) or kept under SD. The aerial parts were extracted with MeOH and the MeOH extracts were analysed by reversed phase HPLC. When compared HPLC chromatograms of each extract, some significantly decreasing peaks were detected in the long day-treated sample. For the purpose of identifying them, large amounts of flower-forming A. thaliana were extracted with MeOH. The MeOH extracts were partitioned with EtOAc and water. The EtOAc soluble layers were purified by silica gel column chromatography and reversed phase HPLC. The isolated sample was determined by LC-MS and 2D NMR as monogalactopyranosyl diacylglycerol (MGDG). Whether or not this substance causes flower bud formation of A. thaliana was determined. Thirty-day-old Arabidopsis plants cultured in SD were used for bioactive assay. Before its application, one group of the assay plants was exposed to LD for one day. Twenty-days after the onset of application, the number of plants formed flower bud was counted. In consequence, the substance induced flower bud formation of A. thaliana, which was treated to long day for 1day just before onset of its application, whereas the control showed weak activity. On the other hand, the applied plants in SD were not induced flower bud formation. These results suggest that MGDG as precursors or substrates of flower bud-forming substances plays important roles in the flower bud formation of A.thaliana. We will also report two new glycolipids, arabidopsides A and B isolated together with MGDG from flower-forming A. thaliana.