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17
1. Introduction
The subgenus Cerasus of the genus Prunus includes
more than 50 species, most of which are distributed in
temperate areas in the Northern Hemisphere, especially
in China, where 33 wild species occur (Yu and Li, 1986).
In Japan, nine native species are recorded: P. jamasakura
Sieb. ex Koidz., P. sargentii Rehder, P. verecunda (Koidz,)
Koehne, P. incisa Thumb. ex Murray, P. nipponica Mat-
sum., P. apetala (Sieb. et Zucc.) Fr. et Sav., P. lannesiana
(Carr.) Wilson var. speciosa (Koidz.) Makino, and P. pen-
dula f. ascendens (Makino) Ohwi. In addition, three wild
species, P. pseudo-cerasus Lindl., P. cerasoides D. Don
and P. campanulata Maxim., have been popularly cultivat-
ed since their introduction from China, Taiwan, and Nepal,
respectively (Kawasaki, 1991).
Several classifications based on morphological obser-
vations have been proposed for Japanese flowering cher-
ries (Kawasaki, 1991; Kobayashi, 1992; Ohba, 1992), and
they have been classified into five sections: Apetalae (P.
apetala), Incisae (P. incisa and P. nipponica), Sargentiella
(P. jamasakura, P. sargentii, P. verecunda, and P. lannesi-
ana), Phyllomahaleb (P. maximowiczii), and Microcalym-
ma (P. pendula). The phylogenetic relationships among
these taxa have been investigated using restriction fragment
length polymorphism (RFLP) analysis of chloroplast DNA
(Kaneko et al., 1986), randomly amplified polymorphic
DNA (RAPD) analysis (Shimada et al., 2001), and analyses
of rDNA ITS sequences (Lee and Wen, 2001), SSR markers
for nuclear DNA (Ohta et al., 2005), and plastid subtype
identity (PSID) sequences (Ohta et al., 2006).
More than 250 cultivars of flowering cherries, includ-
ing Prunus × yedoensis Matsum. ‘Somei-yoshino’ (Ik-
etani et al., 2006), have been created through repeated
natural and artificial hybridizations among wild Cerasus
species (Kawasaki, 1993). ‘Somei-yoshino’ was first pro-
posed to have arisen as a hybrid between P. lannesiana
var. speciosa and P. pendula f. ascendens (Wilson, 1916).
Takenaka (1962, 1965) produced hybrids between the
two species and noted that they had similar morphologi-
cal characters to ‘Somei-yoshino.’ However, these hybrid
plants, such as ‘Amagi-yoshino’ and ‘Izu-yoshino,’ were
taller and produced many more flowers with white pet-
als than ‘Somei-yoshino.’ Based on SSR marker analysis,
Iketani et al. (2007) pointed out clonal status of ‘Somei-
yoshino,’ which has been propagated by grafting.
Origin of Prunus × yedoensis ‘Somei-yoshino’ based on
sequence analysis of PolA1 gene
Nakamura I.(1)*, Takahashi H.(1), Ohta S.(2), Moriizumi T.(3), Hanashiro Y.(4), Sato Y.-I.(5), Mii M.(1)
(1) Graduate School of Horticulture, Chiba University, Matsudo, Matsudo 271-8510, Japan.
(2) Department of Agriculture, Shizuoka University, Ohya, Shizuoka 422-8529, Japan.
(3) Bex Co. Ltd., Itabashi, Tokyo 173-0004, Japan.
(4) Ocean Exposition Commemorative National Government Park Management Foundation, Kunigami,
Okinawa 905-0206, Japan.
(5) Future Center, Kyoto Sangyo University, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.
Key words: Flowering cherry, phylogenetic relationships, PolA1 gene, RNA polymerase I largest subunit.
Abstract: Prunus × yedoensis ‘Somei-yoshino’ is the most popular cultivar of owering cherry in Japan. Although the
origin of this cultivar has been considered hybrid between P. pendula f. ascendens and P. lannesiana var. speciosa, the
paternity of P. lannesiana has not been clearly proven by molecular analysis. To reveal the origin of ‘Somei-yoshino,’ we
analyzed sequences of intron 19 and exon 20 of PolA1, a single-copy nuclear gene encoding the largest subunit of RNA
polymerase I. One of two exon 20 sequences found in ‘Somei-yoshino’ was the same as that of P. pendula, whereas the
other sequence was shared with several taxa in seven wild species, including P. jamasakura and P. lannesiana. ‘Somei-
yoshino’ contained two different haplotypes of the intron 19 sequences; one was the same as that of P. lannesiana, which
is endemic to the Izu and Boso Peninsula in Japan. While another haplotype of ‘Somei-yoshino’ was different from that of
P. pendula by two SNPs but identical to one of two haplotypes of P. pendula ‘Komatsu-otome,’ which is a cultivar found in
the Ueno Park, Tokyo. These results indicated that ‘Somei-yoshino’ probably originated by the hybridization of cultivars
derived from P. pendula and P. lannesiana.
Adv. Hort. Sci., 2015 29(1): 17-23
* Corresponding author: inakamur@faculty.chiba-u.jp
Received for publication 14 November 2014
Accepted for publication 13 February 2015
18
Adv. Hort. Sci., 2015 29(1): 17-23
Previously, Kaneko et al. (1986) showed that P. pen-
dula might be the maternal parent of ‘Somei-yoshino’
based on RFLP patterns of chloroplast DNA. A recent
analysis of PSID sequences provided additional support
that ‘Somei-yoshino’ had the 10A-T-4A haplotype spe-
cific to P. pendula, but not the 14A haplotype for P. lan-
nesiana and P. jamasakura (Ohta et al., 2006). Recently,
Roh et al. (2007) proposed that variations for nuclear ISSR
markers and two plastid DNA sequences of the P. yedoen-
sis population on Korean Jeju Island overlapped those of
‘Somei-yoshino.’ Their data, however, did not prove the
paternal origin of ‘Somei-yoshino.’ Utilizing the associa-
tions of nuclear DNA markers dispersed over the genome,
it is especially difficult to identify the paternal parent in
Cerasus species. Because the Cerasus species have com-
plete self-incompatibility, those DNA markers recombine
every generation.
To resolve the paternity of ‘Somei-yoshino,’ we decid-
ed to compare a relatively short sequence within a single-
copy gene, because a short DNA sequence is thought to be
a block consisting of many closely linked DNA markers,
for which recombination is difficult. Sang (2002) stated
that the sequences of single- or low-copy nuclear genes
are particularly helpful for understanding the inter- and in-
traspecific relationships of various plant groups. Recently,
we were interested in PolA1 as a candidate single-copy
gene, which encoded the largest subunit of the RNA poly-
merase I complex. The DNA sequences of intron 19 of the
PolA1 gene were highly polymorphic whereas the exon 20
sequences showed species-specific variations in the gen-
era Petunia (Zhang et al., 2008), Oryza (Takahashi et al.,
2009), and Triticum (Takahashi et al., 2010).
The present study was initiated to reveal the origin of
‘Somei-yoshino’ through the analysis of intron 19 and
exon 20 sequences in PolA1 gene.
2. Materials and Methods
Plant material
Most of the DNA samples used in this study were pro-
vided from the Faculty of Agriculture, Shizuoka Univer-
sity, and some DNA samples were extracted from leaves
of the clonally propagated plants that were maintained
in the Tama Forest Science Garden, Tokyo, Japan. A to-
tal of 42 individuals of nine wild species native to Japan
(Table 1) were analyzed; P. apetala (three individuals), P.
incisa (four), P. nipponica (four), P. jamasakura (eight), P.
sargentii (two), P. verecunda (four), P. lannesiana (three),
P. maximowiczii (three), and P. pendula (six), and three
alien wild species, P. campanulata (two), P. cerasoides
(two), and P. pseudo-cerasus (one) (Table 1). Two culti-
vars, ‘Somei-yoshino,’ P. pendula f. ascendens ‘Komastu-
otome’ Hayashi & Nshida (Hayashi, 1989), and five Edo-
higan trees were collected in Ueno Park, Tokyo, Japan.
One individual of apricot (Prunus armeniaca L.) was also
analyzed as out-group material.
Genomic DNA isolation and PCR amplification
Genomic DNA was extracted from ca. 50 mg of young
leaves using a modified CTAB method (Doyle and Doyle,
1987). The forward primer designated as 19ex5P (5’- CTC-
GCTGGACGGGGTGAGATGAATG-3’) and the reverse
primer designated as 21ex3P (5’-ATTTACTGGCAATC-
CAAGACAGAT-3’) were designed based on PolA1 gene
(GenBank accession No. NM_125397) of Arabidopsis
thaliana and EST (GenBank accession No. BQ641151)
of almond (Prunus dulcis Mill.), respectively. DNA frag-
ments containing intron 19 and exon 20 sequences of
PolA1 gene were amplified by PCR using a pair of 19ex5P
and 21ex3P primers (Fig. 1). The reaction mixture of 25
µl contained 10-50 ng of genomic DNA, 1 unit of Ex Taq
DNA polymerase (TaKaRa Co., Japan), 2.5 µl of 10× buf-
fer (100 mM Tris-Cl, 500 mM KCl, and 15 mM MgCl2,
pH8.0), 2 µl of 2.5mM dNTPs, 1 µl of 2.0 µM each primer
(19ex5P and 21ex3P), and 17.5 µl of distilled water. PCR
was performed with a condition of 35 cycles of 94°C for 1
min denaturation, 58°C for 1 min annealing, and 72°C for
2 min elongation in PTC200 Thermocycler (MJ Research
Co., USA).
Direct sequencing of PCR products containing the intron
19 and exon 20
The amplified PCR products were subjected to 1.2%
agarose gel electrophoresis, purified using QIAquick
PCR Purification Kit (Qiagen Co., USA), and directly se-
quenced with 19ex5P or 21ex3P primer used for the PCR-
amplification by ABI3100 Automated DNA Sequencer
with a BigDye Terminator Cycle Sequencing Kit (Life
Technologies Co., USA). Either 20ex3P (5’-TTGAAGAT-
GTTCAGGTATGGGGAG-3’) or 20ex5P (5’-ATAAGTT-
GAAGAAAATCAC TGTGG-3’) primer were also used
as an internal sequencing primer. The two internal primers
were designed based on the partially determined sequenc-
es of PolA1 exon 20 of Cerasus in this study.
The determined sequences of the intron 19 and exon
20 of PolA1 gene were analyzed using a NCBI web-based
Blast server (Altschul et al., 1990), and aligned using web
server of Mafft ver 6.0 (Kato and Toh, 2008), and then the
aligned sequences were subjected to phylogenetic analy-
sis using UPGMA software, with bootstrap analysis using
1,000 replicates, in the Mega 4.0 (Tamura et al., 2007).
Fig. 1 - DNA fragments containing intron 19 (PI19) and exon 20 (PE20)
of PolA1 gene were amplified using a pair of 19ex5P (PE19)
and 21ex3P (PE21) primers. The sequences were determined
by direct sequencing using primers for the initial amplification
and internal sequence primers, 20ex5P and 20ex3P.
19
Nakamura et al., Origin of Prunus × yedoensis ‘Somei-yoshino’ based on sequence analysis of PolA1 gene
Table 1 - Samples used in this study
Species Name (Z) Locality PI19 (y) PE20 (y)
Prunus apetala (Sieb. et Zucc.) Fr. et Sav. TJ063 Kawaguchiko, Yamanashi 507 nd.
TJ093 Chino, Nagano 507 847
TJ164 Hachioji, Tokyo (TFSG) 507 847
P. incisa Thumb. MM048 Gotenba, Shizoka 507 847
MM131 Fujimi, Nagano 507 847
MM160 Amatsukominato, Chiba (TFSG) 507 847
MM165 Fujiyoshida, Yamanashi (TFSG) 507 nd.
P. nipponica Matsum. TK077 Shizuoka, Shizuoka 507 nd.
TK113 Ashiyasu, Yamanashi 507 nd.
TK140 Fujimi, Nagano 507 847
TK188 Kusatsu, Gunma 507 847
P. jamazakura Sieb. ex Koidz.YM001 Morimachi, Shizuoka 507 nd.
YM011 Ishikawa Forest Exper. Station 485,507 nd.
YM038 Amagiugashima, Shizuoka 485 823
YM154 Hachioji, Tokyo (TFSG) 507 nd.
YM245 Kushikino, Kagoshima 507 847
YM256 Izumi, Kumamoto 507 847
YM272 Kinkai, Nagazaki 507 nd.
YM277 Yayoi, Notsu, Oita 485,507 nd.
P. sargentii Rehder OY024 Ishikawa Forest Exper. Station 507 nd.
OY162 Mamurogawa, Yamagata (TFSG) 507 847
P. verecunda (Koidz.) Koehne KS016 Ishikawa Forest Exper. Station 507 847
KS136 Fujimi, Nagano 507 nd.
KS183 Yahiko, Niigata 507 nd.
KS211 Nishiki, Yamaguchi 507 847
P. lannesiana (Carr.) Wilson var. speciosa (Koidz.) Makino OS017 Ishikawa Forest Exper. Station 507 847
OS166 Miyake, Tokyo (TFSG) 507 847
OSMTD Matsudo, Chiba 507 nd.
P. maximowiczii Rupr. MY076 Shizuoka, Shizuoka 507 823
MY139 Fujimi, Nagano 498 nd.
MY158 Chichibu, Saitama (TFRG) 507 823
P. pendula Maxim. f. ascendens (Makino) Ohwi. EH015 Ishikawa Forest Exper. Station 506 nd.
EH149 Ochiai, Okayama (TFRG) 506 nd.
EH150 Takekawa, Yamanashi (TFRG) 506 823
EH155 Oya, Hyogo (TFRG) 506 nd.
EH163 Oguchi, Kagoshima (TFRG) 506 823
EHFSG a mountain behind TFRG 506 nd.
P. pseudo-cerasus Lindl. Shinami SN009 Ishikawa Forest Exper. Station 507 823
P. campanulata Maxim. KN014 Ishikawa Forest Exper. Station 507 823
KN101 Tsukubo Botanical Garden 507 nd.
P. cerasoides D. Don. HM001 Katomandu, Nepal (Shizuoka U.) 507 823
HM002 Katomandu, Nepal (Shizuoka U.) 507 nd.
P. armeniaca L. ANZ Chiba University 510 823
P. × yedoensis Matsum. ‘Somei-yoshino’ Chiba University 505, 507 823, 847
P. pendula Maxim. ‘Komatsu-otome’ Ueno Park, Tokyo 505, 506 823
(Z) Nos. are according to Ohta et al. (2006).
(y) length (bp).
Nd= not determined.
20
Adv. Hort. Sci., 2015 29(1): 17-23
3. Results
Polymorphisms of the PolA1 intron 19 sequences
Using total DNA extracted from 43 individuals in
ten species as template, ca. 2.2-kb-long DNA fragments
containing intron 19 and exon 20 of the PolA1 gene were
clearly amplified by PCR (Fig. 2). The PolA1 intron 19
sequences of most Cerasus species were 507 bp in length
(Table 1). All six individuals of P. pendula contained 506
bp because of a one-base insertion at position 49 and a
two-base deletion at position 349-350. One individual
(YM038) of P. jamasakura and one individual (MY139)
of P. maximowiczii had shorter intron 19 lengths of 485
and 498 bp, respectively. Two individuals (YM011 and
YM277) of P. jamasakura had two intron 19 sequences
of different lengths (485 and 507 bp), although these se-
quences could not be confirmed.
The DNA sequences described in this paper have
been deposited in DDBJ DNA database (accession nos.
LC010372- LC010416).
Polymorphisms of the PolA1 exon 20 sequences
Prunus pendula, P. maximowiczii, P. pseudo-cerasus,
P. campanulata, P. cerasoides, and P. armeniaca (out-
group) contained an 823-bp exon 20 (Table 1), whereas,
seven species (P. apetala, P. incisa, P. nipponica, P. ja-
masakura, P. sargentii, P. verecunda, and P. lannesiana)
showed a long 847-bp-long exon 20 with a 24-bp inser-
tion. One individual (YM038) of P. jamasakura had the
short exon 20 (823 bp), and two individuals (YM011 and
YM277) possessed both long and short exons 20 (Table 1).
The DNA sequences described in this paper have
been deposited in DDBJ DNA database (accession nos.
LC010540 - LC010565).
Phylogenetic tree of the PolA1 intron 19 and exon 20 se-
quences
The 41 sequences determined for intron 19 and the 23
sequences for exon 20 were aligned using Mafft and sub-
jected to phylogenetic analysis using the UPGMA method
in MEGA 4.0 with 1,000 bootstap replicates. In the phy-
logenetic tree for exon 20, the nine Japanese wild species
were classified into two groups, Jamasakura and Pendula
(Fig. 3). Prunus campanula belonged to a distantly-related
clade. In the Jamasakura group, P. jamasakura, P. nippon-
ica, P. incisa, P. lannesiana, and P. apetala shared a long
exon 20 and formed a closely-related clade, and ten indi-
viduals of these five species contained the same sequence
for the exon 20. One individual (KS016) of P. verecunda
and one individual (OY162) of P. sargentii also shared an
identical exon 20. One individual (YM038) possessed the
short exon 20 and was distantly related to the other indi-
viduals in the Jamasakura group. The remaining two spe-
cies, P. pendula and P. maximowiczii, formed the Pendula
Fig. 2 - PCR products (arrow) of DNA fragments containing intron 19
and exon 20 of PolA1 gene in the Cerasus species, 1: Prunus
lannesiana var. speciosa, 2: P. pendula f. ascedens, M: marker
(λDNA/HindIII plus øx144 DNA/HaeIII).
Fig. 3 - Phylogenetic UPGMA tree of the exon 20 sequences in the
PolA1 genes from 22 individuals in nine Cerasus species. Indi-
viduals used are listed in Table 1.
PCR amplification
21
Nakamura et al., Origin of Prunus × yedoensis ‘Somei-yoshino’ based on sequence analysis of PolA1 gene
group together with P. pseudo-cerasus and P. cerasoides.
Unlike the species in the Jamasakura group, the four spe-
cies in the Pendula group were clearly differentiated from
one another (Fig. 3).
In the phylogenetic tree for intron 19, P. pendula was
positioned as the most distantly-related clade (Fig. 4) be-
cause this species contained a unique insertion (position
49) and a unique deletion (positions 349-350) (Fig. 5). Ex-
cept for P. pendula, the individuals in the Jamasakura and
Pendula groups formed two independent clades. Although
the species in the Pendula group were clearly differenti-
ated from one another, concurring with the results for exon
20, most individuals of the six species in the Jamasakura
group, except for YM038, shared similar sequences at in-
tron 19, and 14 individuals of the six species possessed the
same intron 19 sequence. Three individuals of P. lannesi-
ana had the same sequence and belonged to an indepen-
dent sub-clade (Fig. 4).
Analysis of the origin of P. × yedoensis ‘Somei-yoshino’
When the two allelic sequences of exon 20 of ‘Somei-
yoshino’ were determined, one was identical to that of P.
pendula, and the other was the same as that shared by five
species in the Jamasakura group. For the intron 19 sequence,
the (O) haplotype of P. lannesiana was distinguished from
the haplotypes of P. jamasakura by three unique single-
nucleotide polymorphisms (SNPs) (positions 25, 101, and
171), which were also found in one of two ‘Somei-yoshino’
haplotypes (Fig. 5). By contrast, the other (K) haplotype
was found to differ from the (E) haplotype of P. pendula
by one base deletion at position 49 and one base substitu-
tion of C to A at position 392 (Fig. 5). Consequently, we found that P. pendula f. ascendens ‘Komatsu-otome’ pos-
sessed two haplotypes (K and E): one was the same haplo-
Fig. 4 - Phylogenetic UPGMA tree of the intron 19 sequences in the
PolA1 genes from 40 individuals in nine Cerasus species. Indi-
viduals used are listed in Table 1.
Fig. 5 - Haplotypes (H) of the intron 19 sequences in the PolA1 genes among ‘Somei-yoshino’ (KO), P. pendula (EE), ‘Komatsu-otome’ (KE), P.
lannesiana (OO), and P. Jamasakura (YY), A: polymorphic bases and their positions in two haplotypes are shown, B: Sequence charts were
produced using 21ex3P primer and converted to the complementary charts using the 4Peak software.
22
Adv. Hort. Sci., 2015 29(1): 17-23
type of ‘Somei-yoshino’ and the other was identical to that
of a wild P. pendula individual. Except for cultivars derived
from ‘Somei-yoshino,’ we found that ‘Komatsu-otome’ and
two other trees (Nos. 142, 145) in Ueno Park had the same
haplotype as ‘Somei-yoshino’ (Fig. 6).
4. Discussion
Speciation of wild Cerasus species in Japan
Comparing the sequences of intron 19 and exon 20
(Figs. 3 and 4), the nine wild species of Japanese Cerasus
were clearly classified into two groups; the Jamasakura
group of seven species (P. apetala, P. incisa, P. nipponica,
P. jamasakura, P. sargentii, P. verecunda, and P. lannesi-
ana) and the Pendula group of two species (P. pendula and
P. maximowiczii). Although the former group had been
grouped into sections, Apetalae, Incisae, and Sargentiel-
la based on morphological differences (Kawasaki, 1966,
1991; Kobayashi, 1992; Ohba, 1992), all seven species
shared the same 24-bp insertion within the long exon 20
(847 bp), suggesting that they originated from the same
ancestor. The remaining two wild species, P. pendula and
P. maximowiczii, contained the short exon 20 (823 bp), in
common with three alien wild species (P. pseudo-serasus,
P. campanulata, and P. cerasoides), and with P. armenia-
ca (out-group). The results from the sequence analysis of
exon 20 were thought to be more reliable than those for
intron 19 for classifying the subgenus Cerasus, and poly-
morphisms found in intron 19 will be useful for discrimi-
nating among closely-related taxa and cultivars.
Although the seven species in the Jamasakura group
have clearly different phenotypes, such as the apetala
flower of P. apetala and dwarf stature of P. incisa and P.
nipponica, these species have formed a large hybridizing
population because they share the same sequences for in-
tron 19 and exon 20. The short intron 19 found in three in-
dividuals (YM011, YM038, and YM277) of P. jamasakura
might have been derived from an ancestral cryptic species.
These results suggest that the classification of seven spe-
cies in the Jamasakura group remains to be revised based
on further molecular information.
Origin of ‘Somei-yoshino’
‘Somei-yoshino’ is the most popular flowering cherry
cultivar in Japan and the rest of the world. Ever since Wil-
son (1916) proposed a hypothesis for the hybrid origin of
‘Somei-yoshino,’ the biological and geographical origin of
this cultivar has been disputed in Japan. In this study, we
found that the O haplotype for intron 19 of P. lannesiana
contained three unique SNPs, and these SNPs were also
found in one of the two haplotypes (K and O) in ‘Somei-
yoshino’ (Fig. 5). This indicates that the paternal parent of
‘Somei-yoshino’ was P. lannesiana or its cultivars. As P.
lannesiana is endemic to the Izu Peninsula and the Izu Os-
hima Islands, ‘Somei-yoshino’ may have originated on the
the Izu Peninsula (Takenaka, 1962) or in Edo and Tokyo
(Iwasaki, 1989), and not on Jeju Island, Korea (Park et al.,
1984; Roh et al., 2007).
The other (K) haplotype of intron 19 in ‘Somei-yoshino’
was identical to that (E) of P. pendula, except for two SNPs
(Fig. 5). We also found that one of the two haplotypes (K and
E) for intron 19 of ‘Komatsu-otome’ was the same as that
of ‘Somei-yoshino.’ The original individual of ‘Komatsu-
otome’ grows inside the Ueno Park, Tokyo (Fig. 6) and has
a dwarf stature with pinkish flower petals. This implies that
the maternal origin of ‘Somei-yoshino’ is a cultivar related to
‘Komatsu-otome.’ Out of five trees grown in the same posi-
tion with ‘Somei-yoshino’ and ‘Komatsu-otome’ shown in
Figure 6, two trees (Nos. 142, 145) contained K haplotype
and three (Nos. 141, 142, 144) were hybrids between P. pen-
dula f. ascendens and P. lannesiana var. speciosa.
These results suggest that there were sufficient genetic
resources to develop ‘Somei-yoshino.’ Because P. pendula
and ‘Komatsu-otome’ bloom two weeks earlier than P.
lannesiana, ‘Somei-yoshino’ and ‘Komatsu-misaki’ were
probably produced in Tokyo through artificial hybridiza-
tions between ‘Komatsu-otome’ or a related cultivar, and
P. lannesiana or a related cultivar, before the end of the
Edo Period (Iwasaki, 1989).
Acknowledgements
We would like to express our sincere thanks to Pro-
fessor Dr. Toshio Ando of the Graduate School of Horti-
culture, Chiba University and Dr. Akira Kobayashi of the
Management Office of Tokyo Metropolitan Parks for their
kind assistance during the course of this research. This
work was supported by the Ocean Exposition Commemo-
rative National Government Park Management Founda-
tion, Okinawa, Japan.
Fig. 6 - Haplotype of the PolA1 intron 19 of trees (Nos. 135-145)
found around “Komatsu no miya” statue (S) in the Ueno Park.
‘Somei-yoshino’ (133, 134, 136, 138) and ‘Komatsu-otome’
(135) share a haplotype K, P. pendula (E), P. lannensiana (O).
IY, KN and KZ are flowering cherry cultivars, ‘Ichi-yo,’ ‘Kan-
zan,’ and ‘Kanzakura,’ respectively.
23
Nakamura et al., Origin of Prunus × yedoensis ‘Somei-yoshino’ based on sequence analysis of PolA1 gene
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