INTRODUCTION
Ramie (Boehmeria nivea Gaud), commonly known
as China grass, is a perennial fiber plant in Urticaceae,
which has been grown in China for thousands of years and
was used for Chinese burial shrouds over 2,000 years. It
is used for the production of textiles and ropes because
it is extremely absorbent, dries quickly, dyes fairly easy,
resists shrinkage, and is unusually tolerant with bacteria,
mildew and insect attacks. Ramie is frequently used in
fabric blends due to its poor elasticity and brittleness.
Consequently, when added to cotton, ramie can increases
strength, color and luster without compromising the
flexibility of the fabric.
Improvement of ramie mainly focused on fiber quality,
yield and resistance. However, traditional breeding of
ramie is limited owing to its complex genetic background.
Comparatively, in vitro techniques can provide alternative
means for cultivar improvement via Agrobacterium-
mediated transformation. Successful application of in vitro
methods is largely dependent on a reliable regeneration
Botanical Studies (2007) 48: 173-180.
*
Corresponding author: E-mail: dxpeng@mail.hzau.edu.
cn; Tel: +86-27-87280550; Fax: +86-27-87281311; Dr. Bo
WANG: E-mail: wangbo@webmail.hzau.edu.cn.
system, which, nevertheless, has not been established in
ramie. Since the first publication on tissue culture of ramie
was reported over two decades ago (Zhou et al., 1980),
efforts have been made to regenerate ramie plantlets
from different explants such as cotyledons (without
regeneration data) (Huang et al., 1980), stem segments
(Pan et al., 1995), hypocotyls (Huang et al., 1981) and
leaves (Guo et al., 1998; Pan et al., 1995). It is noted that
in all of the above studies plants were regenerated via
morphogenesis from callus induced from the explants. The
callus was always subcultured for several cycles before
plant regeneration. One disadvantages of such process
is the recalcitrance of the callus to differentiation (Pan
et al., 1995), which negatively affected the regeneration
efficiency. Furthermore, a low rate of regeneration (not
more than 50%) in these studies limited the application of
previous protocols in genetic transformation, which, so far,
has been performed in work (Dusi et al., 1993). Therefore,
it is necessary to establish a reliable and efficient
regeneration system of ramie, which can be employed for
genetic transformation in the future.
Cotyledon, which has been widely used for many other
plants (Colijin-Hooymans et al., 1994; Yang et al., 2001;
Han et al., 2004; Sul III-Whan et al., 2004; Zhang et al.,
2005), was scarcely used in ramie tissue culture. Thidi-
azuron (TDZ), a substitute urea with both cytokinin activ-
phySIOlOgy
An efficient adventitious shoot regeneration system for
ramie (Boehmeria nivea
gaud) using thidiazuron
Bo WANG, Dingxiang PENG*
,
Lijun
LIU, Zhenxia SUN, Na ZHANG, and Shimei GAO
College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China
(Received May 22, 2006; Accepted October 25, 2006)
ABSTRACT.
An efficient culture system for direct adventitious shoot regeneration of plantlet from cotyledon
of ramie (Boehmeria nivea Gaud) was established and factors affecting shoot regeneration efficiencies were
evaluated. Cotyledons excised from 4-day-old seedlings showed the highest regeneration capacity. Various
concentrations of thidiazuron (TDZ) and indoleacetic acid (IAA) gave rise to adventitious shoots with differ-
ent efficiencies. The cultures of cotyledons from 4-day-old ramie seedlings on MS medium supplemented with
2.27 £gM TDZ and 0.057 £gM IAA were shown to have the highest efficiency (83.6%) of shoot regeneration
among the four auxin supplements (2,4-D; IAA; IBA; NAA). Regeneration of shoot in six cultivars was geno-
type-dependent, ¡¥5041-3¡¦ being the most responsive one. The regenerated shoots were transferred to hormone-
free medium for shoot elongation, after successfully rooted on half-strength MS medium supplemented with
0.27 £gM NAA. The rooted plantlets with 4-5 leaves were transplanted to greenhouse for further growth. To
our knowledge, this is the first report on efficient regeneration of plantlet from cotyledon of ramie, which will
be of value for genetic improvement in the near future.
Keywords: Boehmeria nivea Gaud; Cotyledon; Organogenesis; Ramie; Thidiazuron.
Abbreviations: BA, Benzyladenine; FCM, Flow cytometry; 2, 4-D, 2, 4-Dichlorophenoxyacetic acid;
IAA, Indoleacetic acid; IBA, Indolebutyric acid; MS medium, MS medium basal medium; NAA,
£\-Naphthaleneacetic acid; TDZ, thidiazuron (N-phenyl-N¡¦-1,2,3-thidiazol-5-ylurea).