Botanical Studies (2006) 47: 45-50.
*
Corresponding author: e-mail: hshige@agbi.tsukuba.ac.jp;
Tel & Fax: +81-29-853-4603.
BIOCHEMISTRY
A glycolipid involved in flower bud formation of
Arabidopsis thaliana
Yosuke HisamaTsu
1
, Nobuharu GOTO
2
, Koji HasEGaWa
1
, and Hideyuki sHiGEmORi
1,
*
1
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
2
Department of Biology, Miyagi University of Education, Sendai 980-0845, Japan
(Received December 21, 2004; accepted september 27, 2005)
ABSTRACT.
We searched for bioactive substances involved in flower bud formation of Arabidopsis
thaliana. some significantly decreasing HPLC peaks were detected in the extract of flower buds-forming
A. thaliana compared with that of the non-flower bud-forming stage. Compound 1, which corresponded to
the most decreased HPLC peak, was isolated from aerial parts of A. thaliana. From NmR and ms data,
compound 1 was identified as one of the monogalactosyl diacylglyceride (mGDG). Compound 1 induced
flower bud formation of A. thaliana exposed to long day condition for only 1 day. These results suggest that
compound 1 as a precursor or a substrate of flower bud-forming substances plays important roles in the flower
bud formation of A. thaliana.
Keywords: Arabidopsis thaliana; Bioactive substance; Flower bud formation; Long day condition; mGDG;
short day condition.
IntroductIon
Flower bud formation is one of the most important
physiological process for higher plants, and the flowering
time is influenced by photoperiod, vernalization, drought
stress, and so on. Chailakhyan demonstrated that
flowering was regulated by the bioactive substances,
which were produced in leaves that were subjected
to favorable photoperiods, and the substances were
transported to the shoot apex to induce flower bud
formation. He named the substances "flower-inducing
hormone" or "florigen" (Chailakhyan, 1936). Since then,
studies on isolation of substances inducing flower bud
formation have been carried out with a large number
of plant species. For example, when the water solution
prepared by immersing Lemna paucicostata exposed
to drought, heat, or osmotic stress, were incubated with
(-)-norepinephrine, the water solution showed strong
flower inducing activity of L. paucicostata (Takimoto
et al., 1994). They found that FN1, the tricyclic α-ketol
fatty acid derived from (-)-norepinephrine and 9, 10-ketol-
octadecadienoic acid (KODA), induced flower formation
of Lemna (Yamaguchi et al., 2001). On the other hand,
to analyze the molecular processes that initiate flower
bud formation and trigger the change from vegetative
to reproductive growth, biologists have performed
intensive genetic studies of flowering time in model plant
A. thaliana. as a result, there was discovery of many
genes about the regulation of flowering time and the
development of a lot of genetic models (Bastow and Dean,
2003). However, bioactive substances involved in flower
bud formation of A. thaliana have been hardly reported.
In this paper, we report the isolation and identification of
a bioactive substance (compound 1) involved in flower
bud formation of A. thaliana and the flower buds-forming
activity of compound 1.
MAterIAlS And MethodS
equipment
Optical rotations were measured with a JasCO
DiP-370 polarimeter.
1
H an d
13
C NmR spectra were
measured and recorded on a Buker aVaNCE-500 in
CD
3
OD. The resonances of CD
3
OD at δ
H
3.35 ppm and
δ
C
49.8 ppm were used as internal standards for NmR
spectra. Esims were recorded on a Waters platform
LC. HPLC was performed using a system composed
of a TOsOH DP-8020 pump and a TOsOH PD-8020
photodiodearray detector or a TOsOH Ri-8021 refractive
index detector.
Plant materials
The seeds of Arabidopsis thaliana cv. Columbia
were provided by the sendai Arabidopsis seed stock
Center (sassC, Japan). The seeds were immersed in
the water for 2 days before sowing on rock wool (Rock
fiber, NITTOBO, Japan). They have been cultured in the
growth container (24°C, ca. 3,800 lux) under short day
condition (8 h-light and 16 h-dark, sD) for 26 or 30 days.