全 文 ：中国细胞生物学学报 Chinese Journal of Cell Biology 2012, 34(3): 279–285 http://www.cjcb.org
Received: August 9, 2011 Accepted: January 10, 2012
This work was supported by the National Natural Science Foun-
dation of China (No.31071818)
*Corresponding author. Tel: 86-571-28865327, E-mail: pangren-
shuiliang@yahoo.com.cn
High-frequency Floral Bud Regeneration from Petal Segment Cultures of
Sinningia speciosa Hiern
Pang Jiliang1*, Wang Lilin1, Xiang Taihe1, Zhong Dan1, Yu Hong2
(1College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China;
2Institute of Biotechnology, Hangzhou Academy of Agricultural Science, Hangzhou 310024, China)
Abstract The infl uence of gibberellin and cytokinin on the regeneration of fl oral bud from petal segments
of Sinningia speciosa Hiern in vitro was studied here. Two types of regeneration were regeneration of fl oral buds
only (designated BF), and regeneration of both fl oral and vegetative buds (designated BF+V). The capacity of fl oral
bud regeneration was infl uenced by light, the size of the fl oral bud and exogenous gibberellin (GA3) and cytokinin
in the media. In MS basic medium containing 1.0 mg/L GA3, the addition of 6-benzyladenine (BA, 0.5 mg/L) sig-
nifi cantly increased the frequency of total (BF+BF+V) fl ower bud formation to 100%. The culture was in darkness,
the frequency of BF regeneration was up to 93.4%. The highest percentage of BF was 86.7% formed in petal seg-
ments from 7 mm fl oral buds in diameter. Morphological changes in tissue structure of petal segment cultures were
observed at several stages (0 to 30 d) under the light microscopy.
Key words Sinningia speciosa Hiern; petal segment culture; direct regeneration of fl oral buds; gibberellin;
benzyladenine; darkness
In vitro direct regeneration of fl ower buds plays
important roles not only on the application in biotech-
nological industry but also on the understanding of the
mechanism of fl oral bud differentiation. In vitro direct
regeneration of fl ower buds was successfully achieved
in only over twenty of species in past long period[1-3].
In most of these species such as Nicotiana tatbacum[4],
Hyccinthus orientalis[5], Lycopersucun esculentum[6],
applications of auxin and cytokinin have been used in
vitro to induce direct regeneration of fl oral buds with
different combinations. Only in few species, such as
Torenia fournieri[7], applications of gibberellin and
cytokinin in vitro induced direct regeneration of fl oral
buds. We have successfully induced the direct forma-
tion of male and female fl owers from excised cotyle-
dons of cucumber[8], and induced fl owering of in vitro
cultures from a hybrid of Cymbidium goeringii and
C.hybridium[9].
Our recent studies show that GA3 combinated
with cytokinin promotes the direct regeneration of
floral buds from cultured floral buds and sepal seg-
ments in Sinningia speciosa Hiern[10-11]. Sinningia is
a day-neutral ornamental fl owering plant with a short
(3~4 months) vegetative phase. In sinningia genetic
transformation is performed easily[12], possibly making
it an ideal species for further study of the mechanism
of synergistic promotion by GA and cytokinin on fl oral
bud differentiation. To optimize the experimental sys-
tem, we further investigated the optimal conditions for
fl oral bud regeneration from petal segment cultures of
sinningia under different light, fl oral bud size and the
combinations of GA3 and cytokinin.
1 Materials and Methods
1.1 Plant material
Floral buds with diameters of about 7 mm and
young leaves were excised from flowering plants of
280 ·Research paper·
S. speciosa Hiern. The excised fl oral buds and young
leaves were sterilized in 0.1% (v/v) mercuric chloride
for 8 min and then rinsed three times with sterile dis-
tilled water. This was followed by cutting the detached
petal into four segments longitudinally and cutting the
young leaf into 5 mm2 segments.
1.2 Culture of explants in media supplemented
with GA3 and BA
To investigate the effects of combinations of
GA3 and BA on regeneration of floral buds, three in-
dependent experiments were carried out. Firstly, petal
segments were cultured on modifi ed MS medium (Mu-
rashige and Skoog, 1962) containing 1.0 mg/L GA3
and a range of concentrations of BA (0, 0.1, 0.2, 0.3,
0.4 and 0.5 mg/L) in the light or in darkness. Secondly,
young leaf segments were cultured on modified MS
medium containing 1.0 mg/L GA3 and a range of con-
centrations of BA (0, 0.3 and 0.5 mg/L) in the light or
in darkness. Thirdly, petal segments were cultured on
modifi ed MS medium with combinations of 0.3 mg/L
BA and a range of concentrations of GA3 (0, 0.5, 1.0,
2.0, 3.0 and 4.0 mg/L) in the light.
1.3 Culture of petal segments from fl oral buds of
different diameters
To investigate the effect of fl oral bud size on re-
generation, petal segments from fl oral buds of a range
of diameters (5, 7, 9, 12, 16, 30 mm) (Fig.1A) were
cultured on modified MS medium with combinations
of 1.0 mg/L GA3 and 0.3 mg/L BA. In each experiment
described above, GA3 was always added to the me-
dium after fi lter sterilization. Each treatment consisted
of 60 explants and the experiment was repeated twice.
The explants were cultured in a growth room at 25 °C,
and examined using a Zeiss Stemi 2000-C Stereomi-
croscope equipped with a Canon PowerShot G5 camera
after 30, 40, 50, 60 d of culture.
1.4 Histological analysis
After 0, 8, 15, 20, 24, 30 d of culture, petal seg-
ments were fi xed in FAA (formaldehyde/acetic acid/al-
cohol) for 48 h. Conventional paraffi n embedding and
sectioning was used for the preparation of slides. Sec-
tions of 8 μm thick were stained in HEIDENHAIN’S
haematoxylin[13] and viewed with a microscope (Zeiss
AXIO Imager A1), and micrographs were obtained us-
ing a Zeiss AxioCam MRc5 camera.
2 Results
2.1 External morphological and internal struc-
ture changes in direct in vitro floral bud regen-
eration from petal segments
The cut edges of explants swelled after 15 d of
culture with many fl oral organ primordia appearing at
the segment edges and on the surfaces on 30 d (Fig.1B).
On 40 d small fl oral buds formed (Fig.1C). The fl oral
buds were about 4 mm to be seen by the naked eye on
50 d (Fig.1D). After 60 d, the buds opened revealing
many petals (Fig.1E). The regeneration of two types of
fl oral buds from petal segment cultures was observed:
fl oral buds (designated BF) only (Fig.1D) and both fl o-
ral buds and vegetative buds (designated BF+V) (Fig.1E).
Only vegetative buds were regenerated in the cultures
of young leaf segments (Fig.1F).
The histological studies revealed the origins and
early development process of the fl oral buds regener-
ated in vitro directly from petal segments. Sections of
petal segments before culture showed the cells of the
petal segment tissues to be arranged regularly with no
cell division (Fig.2A). After 8 d of culture some highly
meristematic centers of dividing cells appeared on the
cut edges and under the epidermis (Fig.2B). After 15 d
of culture, the meristematic centers became larger and
formed meristematic protuberances (Fig.2C). By 20 d,
fl oral organ primordia differentiated on the meristemat-
ic protuberances (Fig.2D). The fl oral organ primordia
grew larger by 24 d (Fig.2E). Floral buds with petals
and stamen primordia were observed on 30 d (Fig.2F).
2.2 Effect of combinations of GA3, cytokinin and
light on fl oral bud regeneration
To study the effects of GA3, cytokinin and light
on the effi ciency of direct fl oral bud regeneration from
petal segments, we used six different media in the light
and three different media in the dark (Table 1). The
frequencies of fl oral buds and vegetative buds regen-
erated directly from explants were calculated after
Pang Jiliang et al: High-frequency Floral Bud Regeneration from Petal Segment Cultures of Sinningia speciosa Hiern 281
A: fl oral buds from a to f are 5, 7, 9, 12, 16, 30 mm in diameter respectively; B: many fl oral organ primordia (arrow) formed on the edges and surface
of petal segments cultured for 30 d; Bar=0.5 mm; C: many fl oral buds (arrow) formed on the surfaces of petal segments cultured for 40 d; Bar=1.0 mm;
D: larger fl oral buds (arrow) could be seen with the naked eye after culture for 50 d; Bar=2.5 mm; E: both fl oral buds and vegetative buds (arrow) re-
generated from petal segments cultured for 60 d, and the fl oral bud opened; Bar=3.5 mm; F: only vegetative buds (arrow) regenerated from young leaf
segments cultured for 60 d; Bar=3.5 mm.
Fig.1 Direct regeneration of fl oral buds from petal segment cultures in Sinningia speciosa Hiern
60 d of culture. The results showed that no fl ower buds
were developed in the absence of BA in the light and
in the dark (Table 1). In the light, with 1.0 mg/L GA3
in the medium, the frequency of BF increased gradu-
ally with increasing concentrations of BA from 0 to
0.3 mg/L. The highest frequency of BF was 86.6%, but
the frequency decreased with BA over 0.3 mg/L in the
media. The frequency of (BF+BF+V) (total fl ower buds)
increased from 0 to 100% with increasing concentra-
tions of BA from 0 to 0.5 mg/L. In the dark, when the
medium was supplemented with 0.3 mg/L BA in com-
bination with 1.0 mg/L GA3, the frequency of BF was
up to 93.4%.
To study the effect of GA3, cytokinin and light on
282 ·Research paper·
A: the cells of petal segment tissues before culture arranged regularly with no dividing cells visible, 400×; B: small meristematic centers of dividing
cells at the cut edges and the lower epidermis of petal segment cultured for 8 d, 200×; C: after 15 d of culture, the meristematic centers grew bigger and
formed meristematic protuberances, 200×; D: by 20 d of in vitro culture, fl oral organ primordia had differentiated on the meristematic protuberances, 200×; E:
the fl oral organ primordia became larger after 24 d of culture, 100×; F: fl oral bud with petal, stamen primordia on a petal segment cultured for 30 d, 50×.
Fig.2 Sections of in vitro petal segments in Sinningia speciosa Hiern
organ regeneration from young leaf segments, we used
three different media in the light and in the dark, re-
spectively (Table 2). The results showed that no fl ower
buds were regenerated in these conditions, indicating
that the internal physiological condition of the explants
is very important for the regeneration of fl oral buds.
As shown in Table 1, the combination of 1.0 mg/L
GA3 with 0.3 mg/L BA resulted in the highest fre-
quency of pure fl oral bud regeneration (BF). To further
optimize the combination of BA and GA3, explants
were cultured on the medium containing 0.3 mg/L BA
with different concentrations of GA3 (0~4.0 mg/L)
in the light. After 60 d of culture, no fl oral bud forma-
tion was observed on explants grown on the medium
containing 0.3 mg/L BA without GA3. The addition of
0.5~4.0 mg/L GA3 in the medium containing 0.3 mg/L
BA clearly promoted floral bud regeneration (Table 3).
The highest frequency of BF was 83% at 1.0 mg/L GA3.
Pang Jiliang et al: High-frequency Floral Bud Regeneration from Petal Segment Cultures of Sinningia speciosa Hiern 283
Table 1 Effects of combinations of 1.0 mg/L GA3 with different concentrations of BA on different organs regenerated directly
from cultures of petal segments in the light and in the dark
Illumination Growth regulator Frequencies of different organs regenerated directly(%)
GA3(mg/L) BA(mg/L) BF BF+V BV BF+BF+V BF/BT
Light 1.0 0 0 0 0 0 0
1.0 0.1 20.0±3.2a 0 0 20.0±3.2a 100 d
1.0 0.2 70.8±3.5b 0 0 70.8±3.5b 100 d
1.0 0.3 86.6±4.1c 0 0 86.6±4.1c 100 d
1.0 0.4 76.7±2.7b 6.7±1.6ab 0 83.4±2.1c 92±3.2bc
1.0 0.5 68.1±5.2b 31.9±4.5c 0 100d 68.1±5.2a
Dark 1.0 0 0 0 0 0 0
1.0 0.3 93.4±6.6d 1.7±1.7a 0 95.1±4.2d 98.2±1.8cd
1.0 0.5 86±5.8c 10.7±2.5b 3.3±3.3a 96.7±3.3d 86.0±5.6b
Explants were evaluated after 60 d of culture. BF: frequency of fl ower buds; BF+V: frequency of fl oral and vegetative buds; BV: frequency of only veg-
etative buds; BT: induction frequency (percentage of petal segments developing organs of the total petal segments plated). Each value represents the
mean±standard error of two replications, each with 60 explants. Means within a column followed by the same letter are not signifi cantly different using
Duncan’s multiple range test (P≥0.05).
Table 2 Effects of combinations of 1.0 mg/L GA3 with different concentrations of BA on different organs regenerated directly
from cultures of young leaf segments in the light and the dark
Illumination Growth regulator Frequencies of different organs regenerated directly(%)
GA3(mg/L) BA(mg/L) BF BF+V BV BF+BF+V BF/BT
Light 1.0 0 0 0 0 0 0
1.0 0.3 0 0 90.5±3.0a 0 0
1.0 0.5 0 0 91.7±2.5a 0 0
Dark 1.0 0 0 0 0 0 0
1.0 0.3 0 0 100b 0 0
1.0 0.5 0 0 100b 0 0
The note is the same as Table 1.
Table 3 Effects of combinations of 0.3 mg/L BA with different concentrations of GA3 on different organs regenerated directly
from the cultures of petal segments
Growth regulator Frequencies of different organs regenerated directly(%)
GA3(mg/L) BA(mg/L) BF BF+V BV BF+BF+V BF/BT
0 0.3 0 0 5.6±3.4a 0 0
0.5 0.3 53±3.6a 13.3±2.7b 3.3±1.7a 66.3±3.2b 76.1±5.2a
1.0 0.3 83±3.2c 0 0 83±3.2c 100b
2.0 0.3 72.2±4.5b 5.6±1.4a 0 77.8±3.0c 92.8±5.7b
4.0 0.3 50±2.3a 0 0 50±2.3a 100b
The note is the same as Table 1.
2.3 Effect of fl oral bud size on the direct regen-
eration of fl oral buds
Petal segments from fl oral buds of different diam-
eters (5~30 mm) were cultured on media supplemented
with combinations of 1.0 mg/L GA3 and 0.3 mg/L BA
for 60 d. It was signifi cantly different in the frequen-
cies of direct floral bud regeneration from petal seg-
ments of floral buds of different diameters (Table 4).
The frequency of BF regenerated from petal segments
from 7 mm fl ower buds was highest (86.7%), followed
by petal segments from 5 mm buds (80%) and petal
segments from 9 mm fl ower buds (75%) (Table 4). The
frequency of BF decreased with increasing floral bud
diameter from 9 to 30 mm.
284 ·Research paper·
3 Discussion
The genes of FLOWERING LOCUS T (FT),
SUPPRESSOR OF OVEREXPRESSION OF CO1/
AGAMOUS-LIKE20 (SOC1/AGL20) and LEAFY (LFY)
are the fl owering integrators that play the critical role
in the transition from vegetative to reproductive devel-
opment. GA promotes the expression of LFY, SOC1
and FT[14-16]. The combination of GA and BA enhances
SaSOC1 expression in the SAM of Sinapis alba[17].
Cytokinin activates TSF, FT homologue[18]. Floral
buds regenerated directly from sepals of 35S::CFL
(cucumber LEAFY homologue) Gloxinia in vitro[12]. So
GA and BA may promote synergistically the direct re-
generations of fl oral buds by promoting FT, SOC1 and
LFY expression.
Some long-day (Beta vulgaris) and short-day
(Pharbitis nil) plants flower in darkness[19-20]. Arabi-
dopsis could flower in complete darkness on liquid
mineral media[21] and solid medium supplemented with
sucrose[22]. Here fl oral bud regeneration from petal seg-
ments in darkness was also observed (Table 1). More-
over the regeneration frequency of BF from petal seg-
ments in darkness could reach 93.4% and much higher
than in the light. Arabidopsis lacking phytochrome B, re-
sults in higher gibberellin biosynthesis and sensitivity[23],
dark treatments of the upper shoots of rose signifi cantly
increased their cytokinin levels[24], possibly indicated the
culture of petal segments in darkness increases their gib-
berellin biosynthesis, sensitivity and endogenous cyto-
kinin levels, thus promoted fl oral bud formation.
In general, floral buds can only be regenerated
directly from explants from reproductive organs. In our
study, fl oral buds could not be regenerated directly from
cultures of young leaf segments (Table 2). It is further
confi rmed that there are some unknown substances in-
hibiting fl oral differentiation in vegetative organs.
Cytokinin activity in young rose petals is higher
than that in old ones[25]. In Cosmos sulphureus Cav,
cytokinin activity is low at early stage in fl ower devel-
opment and increases before full bloom, but decreases
at full bloom[26]. The highest concentration of free GA1/
GA3 was found in dormant flower buds of peach and
diminished thereafter. The highest concentration of free
GA1/GA3 did not increase immediately before fl ower bud
break[27]. Our experiment (Table 4) showed that the BF
frequency of petal segments changed according to the
size of fl oral buds, possibly mainly resulted from the dif-
ferences in the activity and content of endogenous cyto-
kinin and gibberellin in fl oral buds of different sizes.
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Table 4 Effects of fl oral bud size on direct regeneration of fl oral buds from the cultures of petal segments
Diameter of Frequencies of different organs regenerated directly(%)
fl oral buds(mm) BF BF+V BV BF+BF+V BF/BT
5 80±4.3bc 0 0 80±4.3bc 100b
7 86.7±3.8c 0 0 86.7±3.8c 100b
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The note is the same as Table 1.
Pang Jiliang et al: High-frequency Floral Bud Regeneration from Petal Segment Cultures of Sinningia speciosa Hiern 285
大岩桐花瓣切块离体培养高频率花芽再生
庞基良1*　王利琳1　向太和1　钟　丹1　余　红2
(1杭州师范大学生命与环境科学学院, 杭州 310036; 2杭州市农业科学研究院生物技术研究所, 杭州 310024)
摘要 该文报道了大岩桐花瓣切块离体培养再生花现象，花瓣切块再生花有两种方式: 一
种是仅再生花芽(命名为BF); 另一种是既再生花芽也再生营养芽(命名为BF+V)。花芽再生的能力与
光照、花芽大小及培养基中赤霉素和细胞分裂素浓度紧密相关。当培养基中含有1.0 mg/L GA3时，
BA的添加会显著增加总花芽(BF+BF+V)的形成率，添加0.5 mg/L BA时，总花芽形成率达100%。在
暗中培养时，BF达93.4%。不同大小花芽的花瓣再生花的能力不同，7 mm直径花芽的BF最高，达
86.7%。同时，对花芽再生过程中花瓣切块的组织结构形态变化也进行了观察。
关键词 大岩桐; 花瓣切块; 直接花芽再生; 赤霉素; 细胞分裂素; 黑暗
收稿日期: 2011-08-09　　接受日期: 2012-01-10
国家自然科学基金(No.31071818)资助项目
*通讯作者。Tel: 0571-28865327, E-mail: pangrenshuiliang@yahoo.com.cn
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