Phylogeny and Character Evolution in Allium Subgenus Amerallium (Amaryllidaceae)

2012·2 MB·

by  Li Qin-Qin

植 物 分 类 与 资 源 学 报 ,34 ( ):
摇 2012 2 107~119
Plant Diversity and Resources :
摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 DOI 10.3724/SP.J.1143.2012.10259
葱属 Amerallium 亚属 (石蒜科) 的系统发生与性状进化*
李琴琴, 周颂东, 何兴金**, 魏先芹
四川大学生命科学学院 四川成都
( , 摇 610064)
摘要: 运用贝叶斯和简约法对葱属 Allium Amerallium亚属的核糖体 内转录间隔区 进行了
( ) DNA (ITS)
分析 对该亚属的系统发生进行了推测 系统分析证实 Amerallium是单系的 并表明该亚属由三个隔离的
, 。 ,
地理群组成 北美Ameralliums 地中海区Ameralliums和东亚Ameralliums 性状进化的重建表明鳞茎是原
: , 。
始或祖先状态 根状茎和肉质增粗的根是衍生状态且在Amerallium这个亚属的类群中独立进化发生了几
,
次 重建也表明该亚属的原始染色体基数x 其它染色体基数 x 是由它转化而来的
。 =7, ( =8,9,10,11) 。
在北美类群中 异基数性相当罕见 而多倍性似乎是一个相对频繁的进化事件 在地中海区类群和东亚类
, , 。
群中 异基数性和多倍性是染色体进化的两个主要驱动力
, 。
关键词: 葱属 Amerallium 性状进化 系统发生
; ; ; ITS;
中图分类号: 文献标识码: 文章编号:
Q948.2, Q942摇 摇 摇 摇 A摇 摇 摇 摇 摇 2095-0845(2012)02-107-13
Phylogeny and Character Evolution in Allium Subgenus
Amerallium Amaryllidaceae
( )
**
LI Qin鄄Qin, ZHOU Song鄄Dong, HE Xing鄄Jin , WEI Xian鄄Qin
SchoolofLifeSciences SichuanUniversity
( , ,Chengdu610064,China)
Abstract
: Bayesian and parsimony analyses of the nuclear ribosomal DNA internal transcribed spacer (ITS) were
Allium Amerallium Amerallium
used to infer the phylogeny of subgenus . Phylogenetic analyses corroborate that is
Amerallium
monophyletic and the results indicatethat composedofthreeisolatedgeographicalgroups:NorthAmeri鄄
Ameralliums Ameralliums Ameralliums
can , the Mediterranean region ,and eastern Asian . Reconstruction of charac鄄
ter evolution suggests bulbs as a primitive or ancestral state, and rhizomes and thick fleshy roots as derived states
Amerallium
which haveevolvedanddevelopedseveraltimesindependentlywithinthegroupsof ,andthebasicchro鄄
x x
mosome number =7 is the primitive state and other basic chromosomes numbers ( =8,9,10,11) are derived
x Ameralliums
from =7. Within North American , dysploidy is a rather rare evolutionary event and polyploidy seems
Ameralliums
to bearelativelyfrequentevolutionaryevent. WithintheMediterraneanregionandeasternAsian ,both
dysploidy and polyploidy are two primary driving forces in their chromosome evolution.
Key words Allium Amerallium
: ; ; Character evolution; ITS; Phylogeny
Allium
摇 The genus L. consists of approximately lected Plant Families maintained by Royal Botanic
et al
more than 800 species according to Fritsch . Gardens, KEW (UK, http:/ /apps. kew. org/wcsp/
(2010). To some extent, this is consistent with the reportbuilder. do), which recognizes 881 species.
Allium
current online version of the World Checklist of Se鄄 is a member of order Asparagales, family
基金项目 国家自然科学基金资助项目 教育部博士点基金资助项目 中国科学院
* : (31070166,31100161); (20090181110064);
大科学装置开放研究项目 资助 科技部科技基础性工作专项重点项目
(2009鄄LSF鄄GBOWS鄄01) ; (2007FY110100)
**Authorforcorrespondence; E鄄mail:[email protected]
Receiveddate: 2011-04-29, Accepteddate: 2012-01-25
作者简介 李琴琴 女 博士研究生 主要从事葱属植物的系统发育与分子进化研究
: (1983-) , , 。 E鄄mail:[email protected]
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Allium Allium
Amaryllidaceae J.St.鄄Hil.,subfamily Allioideae Herb., subgenus into six subgenera namely ,
Amerallium Bromatorhiza Caloscordum
tribe Allieae Dumort. (Fay and Chase,1996; APG, , Ekberg,
et al Melanocrommyum
2009; Chase ., 2009). After Fay and Chase (Herb.) R. M. Fritsch, (Webb
et al et al Rhizirideum
(1996), Friesen . (2000) and Chase . & Berth.) Rouy and (G.Don ex Koch)
Allium Caloscordum Mi鄄 Nectaroscordum
(2009), (including Herb., Wendelbo, while excluded from
lula Nectaroscordum Allium
Prain and Lindl.) is the only classifications of the genus . Recently, molec鄄
genus in tribe Allieae. Previous molecular data sug鄄 ular approaches such as chloroplast DNA and nucle鄄
Allium
gested that evolution proceeded in three sepa鄄 ar ribosomal DNA (nrDNA) have been applied to
rate evolutionary lines (Fritsch, 2001; Fritsch and understand the evolutionary processes and taxonomic
et al et al Allium
Friesen, 2002; Friesen ., 2006; Li ., relations within the genus and also in subge鄄
Amerallium Amerallium
2010) and Traub is the largest subgenus nus . A first approach to structuring the
Allium
in the most ancient line comprising around 135 spe鄄 genus itself by molecular markers was pub鄄
et al
cies occurring in North America (New World), the lished by Linne von Berg . (1996). The resul鄄
Mediterranean region and eastern Asia (Old World) ting phenogram largely confirmed the subgeneric
et al
(Traub, 1968; Friesen ., 2006). Members of classification based on an integration of morphologi鄄
Am鄄
this subgenus are extremely diverse in ecology and cal and other methods, but found that subgenus
erallium Bromatorrhiza
grow in dry stony slopes, Mediterranean garigues, and could not be clearly dis鄄
Bromatorrhiza
cliffs, river banks, prairies, mountains and subal鄄 tinguished. The subgenus (including
et al Bromatorrhiza Coleoblastus
pine meadows (Hanelt .,1992). The subgenus section Ekberg, Ekberg,
Cyathophora
is very diverse in cytology and contains all the basic R.M. Fritsch), originally circumscribed
Allium
chromosome numbers in the genus . The most by Ekberg (1969) by the presence of fleshy roots as
x
common basic chromosome number is =7, and yet storage organs and the lack of true storage bulbs or
x
other numbers ( =8,9,10,11) also exist (Traub, rhizomes, again proved to be paraphyletic and had to
et al et al et al
1968; Sen,1974; Yan .,1990; Huang ., be cancelled in other studies (Samoylov .,
et al et al et al et
1995; Huang ., 1996a, b; Xu ., 1998; 1995, 1999; Mes ., 1997, 1999; Friesen
et al al et al
Ni, 1999; Xu and Kamelin, 2000; Dale ., ., 2000). Later, Friesen . (2006) presented
et al Allium
2002; Zhang and Xu, 2002; Zhang ., 2008, a new classification of genus consisting of 15
et al Nectaroscordum
2009; Wei ., 2011). subgenera (including ) based on
Historically, Traub (1968, 1972) proposed their phylogenetic study, in which they confirmed
Allium Bromatorrhiza
classifying the 600 or so species under three the artificial character of subgenus
Allium Amerallium Nectaroscor鄄 Bromatorrhiza Amer鄄
subgenera: L., and and placed section in subgenus
dum allium Cya鄄
(Lindl.) Asch. et Graebn. In Traub爷s classi鄄 and other two sections in subgenus
Allium siculum thophora et al
fication, Ucria was the type species (R. M. Fritsch) R. M. Fritsch. Li .
Nectaroscordum Amerallium
of subgenus ; subgenus (2010) again corroborated the artificial character of
Bromatorrhiza
united the North American species with the Mediter鄄 subgenus and agreed with their taxo鄄
Alliums Molium Amerallium
ranean classified under section nomic treatment. The distribution of spe鄄
Endl. and species that are now classified under sec鄄 cies between Old World and New World was well re鄄
Arctoprason Briseis
tions Kirschl. and (Salisb.) flected in the phylogenetic data (Dubouzet and Shi鄄
et al et al et al
Stearn (Hanelt ., 1992); and the rest of the noda, 1999; Friesen ., 2006; Nguyen .,
Allium et al
species were lumped together in subgenus . 2008; Li ., 2010), and the origin and migra鄄
et al Amerallium
Based on a multidisciplinary approach, Hanelt . tion about has been long in dispute.
et al Ameralliums
(1992) reassembled the species pooled by Traub in Hanelt .(1992) postulated that the
期 et al Allium Amerallium
2 摇 摇 摇 摇 摇 LI Qin鄄Qin .: Phylogeny and Character Evolution in Subgenus …摇 摇 摇 摇 摇 摇 1摇09
had its origins in Asia and spread to North America age organs and chromosome numbers evolution in
Amerallium
via the Bering Land Bridge, but they did not discuss under the phylogenetic framework.
Ameralliums
the origins of the Mediterranean . The
1摇 Materials and methods
alternate hypothesis is a predominantly unidirectional
1.1摇 Taxon sampling
migration via the land bridges at Bering and North
et
Atlantic (Dubouzet and Shinoda,1999). Nguyen Our sampling scheme was designed to cover
al Amerallium
. (2008) investigated the evolutionary history of those taxonomic and geographic groups,
Alliums
in western North America (especially in Ca鄄 and 64 taxa from North America (47 out of about81
lifornia) and their adaptation to serpentine soils. species), the Mediterranean region (10 out of about
Their results also represent a first attempt at initia鄄 46 species), and eastern Asia (18 samples, repre鄄
ting a more detailed study on the biogeography of senting 5 species and 2 varieties out of about 8 spe鄄
Amerallium Allium
subgenus in North America and imply cies) were included in the present study.
Ame鄄 bulgaricum A.siculum
that two separate biogeographic patterns led to (Janka) Prod佗n, Ucria, and
rallium A.monanthum
diversi覱cation in North America. Based on Maxim., were designated as outgroups
et al
those researches, Li . (2010) further examined according to previous studies (Fritsch,1988,2001;
Ameralliums et al
the migration route of the by the inclu鄄 Fritsch and Friesen, 2002; Friesen ., 2006;
et al et al
sion of species endemic to eastern Asia that have of鄄 Nguyen .,2008; Li .,2010). The sources
ten been excluded from previous analyses. They pro鄄 of ITS sequences obtained from original materials
Amerallium
posed that the ancestor of originated in and GenBank accession numbers for all other species
Amerallium
eastern Asia and one lineage of likely included in this investigation are listed in the Ap鄄
spread eastward to North America via the Bering pendix 1. All accessions in the collection stem from
Land Bridges and expanded their range southward, populations collected during field trips. Voucher
Amerallium
while the other lineage of expanded its specimens were deposited in the herbarium of the Si鄄
range from east to west and ended up in the Mediter鄄 chuan University (SZ).
1 2摇 DNA extraction amplification and sequencing
ranean region, not across the North Atlantic. . ,
All the above鄄mentioned works have been useful Genomic DNA was extracted from silica gel鄄
Amerallium
in understanding of phylogeny and bioge鄄 dried or fresh leaves by using the method of Doyle
ography, but the diversity of cytological data and other and Doyle (1987). The ITS region was amplified
et al
character have not been tested in a phylogenetic with primers ITS4 and ITS5 (White ., 1990).
framework to date. In order to better understand the The PCR parameters were as follows: 94益 for 5
Amerallium
character evolution of ,speciesendemic to min; 30 cycles of 94益 for 45 s, 55益 for 45 s,
eastern Asia were again incorporated in the present 72益 for 1 min; and 72益 for 7 min. PCR products
study, but we still lack samples of the Mediterranean were separated by 1. 5% (w/v) agarose TAE gel
Amerallium
which are also poorly sampled in the pre鄄 and purified using Wizard PCR preps DNA Purifica鄄
vious studies. Nevertheless,it seems appropriate now tion System (Promega, Madison, WI, USA) follow鄄
to publish the results of our study, partly because ing manufacturer爷s instructions. The purified PCR
these are important for considerations of phylogeny products were analyzed in an ABI 310 Genetic Ana鄄
Amerallium
and character evolution of and partly be鄄 lyzer (Applied Biosystems Inc.) in both directions
cause we hope our results will stimulate further stu鄄 using the PCR primers.
13摇 Sequence comparisons and phylogenetic analyses
dies. The goals of the present study were to:(1) con鄄 .
Amerallium
struct phylogenetic relationships within ; DNA sequences were initially aligned using the
(2) elucidate possible patterns of underground stor鄄 default pairwise and multiple alignment parameters
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et al et al et al
in Clustal X (Jeanmougin .,1998) and then re鄄 Zhang ., 2008, 2009; Wei ., 2011).
checked and adjusted manually as necessary using Three states were chosen for underground storage or鄄
et al
MEGA 4 (Tamura ., 2007). Gaps were posi鄄 gans: bulbs (0), rhizomes (1), and thick fleshy
tioned to minimize nucleotide mismatches and trea鄄 roots (2), and five states were chosen for basic
ted as missing data in phylogenetic analyses. chromosome numbers: 7 (0), 8 (1), 9 (2), 10
Phylogenetic analyses were conducted by emplo鄄 (3) and11 (4). To infer ancestral character states,
ying maximum parsimony (MP) criteria and Bayes鄄 Parsimony optimizations were performed in the soft鄄
*
ian Inference (BI), using the programs PAUP ver鄄 ware Mesquite v. 2.01. (Maddison and Maddison,
sion 4.0b10 (Swofford,2003) and MrBayes version 2007). Considering all accessions of the same spe鄄
3.1.2 (Ronquist and Huelsenbeck,2003), respec鄄 cies composed a well鄄supported clade, a reduced
tively. For MP, heuristic searches were carried with taxonomic subset was obtained and then phylogenetic
1000 random addition sequence replicates. One tree analysis was conducted by employing BI with the
was saved at each step during stepwise addition, and methods described above. Optimizations were run on
tree鄄bisection鄄reconnection (TBR) was used to swap the 50% majority rule tree from Bayesian analysis
branches, and the maximum number of trees was set and the character states were treated as “unordered冶
to 10000. All characters were unordered and equal鄄 (i.e., allow free transformation of a character state
ly weighted. Gaps were treated as missing data. to any other states).
Bootstrap values were calculated from1000000 rep鄄
2摇 Results
licate analyses using “fast冶 stepwise鄄addition of taxa
2.1摇 Sequence analyses
and only those values compatible with the majority鄄
rule consensus tree were recorded. Prior to a Bayes鄄 The ITS region varied in length from 589 bp
A.shevockii A.hoffmanii
ian analysis, MrModeltest version 2. 2 (Nylander, ( McNeal) to661bp ( Own鄄
2004) was used to select a best鄄覱t model of nucleo鄄 bey ex Traub). After introducing the necessary
tide substitution, and the GTR+I+G model under the gaps, the ITS alignment was 706 bp in length and
AIC was selected. The Bayesian Markov Chain Monte resulted in 225 constant characters and 463 variable
Carlo (MCMC) algorithm was run for 2 000 000 characters of which390 were parsimony鄄informative.
generations with one cold chain and three heated The mean GC content of the ITS region was52.5%.
2 2摇 Phylogenetic analyses
chains, starting from random trees and sampling .
trees every 100 generations. The first 5 000 trees Trees inferred from Bayesian analysis and maxi鄄
were considered as the burn鄄in and discarded. A mum parsimony showed no significant difference in
50% majority鄄rule consensus tree of the remaining their topologies, therefore here the Bayesian tree with
trees was produced. posterior probabilities (PP) and bootstrap support
1 4摇 Estimation of ancestral character states
. values (BS) is shown in Fig.1. In all analyses, the
Amerallium
Selected characters, namely underground sto鄄 subgenus proved to be monophyletic.
Amerallium Ameral鄄
rage organs and chromosome numbers, were defined Within subgenus ,the New World
Alliums lium Amerallium
according to previous studies of these (Traub, clade is sister to the Old World
Am鄄
1968; Sen, 1974; Pastor and Vald佴s, 1988; Tza鄄 clade (PP=1.00, BS=99%). The New World
et al erallium
noudakis and Vosa,1988; Yan .,1990; Huang clade (PP=1.00, BS=97%) contains two
et al et al et al
., 1995; Huang ., 1996a, b; Ohri ., groups. One group (PP = 0. 55, BS = 53%) in鄄
et al
1998; Xu ., 1998; Ni, 1999; Xu and Kame鄄 cludes several subclades corresponding to sections
et al Amerallium Caulorhizideum Rhopeto鄄
lin, 2000; Dale ., 2002; Zhang and Xu, Traub+ Traub+
et al et al prason
2002; Ricroch ., 2005; Friesen ., 2006; Traub with species native to mid鄄western and
期 et al Allium Amerallium
2 摇 摇 摇 摇 摇 LI Qin鄄Qin .: Phylogeny and Character Evolution in Subgenus …摇 摇 摇 摇 摇 摇 1摇11
Amerallium
Fig.1摇 PhylogenetictreeresultingfromaBayesiananalysisoftheITSsequencesfromspeciesof andthreeoutgroup
etal
species. ThesubgenericandsectionalclassificationaccordingtoHanelt . (1992),DubouzetandShinoda(1999),Fries鄄
etal et al et al
en .(2006), Nguyen . (2008), and Li . (2010) is indicated on the right. Values along branches represent
Bayesianposteriorprobabilities(PP) andparsimonybootstrap(BS),respectively
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southwestern United States (with few exceptions, e. numbers (Fig.2B).
A.validum
g., S. Watson). The other group (PP=
Lo鄄 3摇 Discussion
1.00, BS=66%) includes monophyletic section
phioprason 3.1摇 Phylogeny within the subgenus Amerallium
Traub with species restricted to western
A. cernuum Amerallium
North America (the only exceptions are spp. are extremely diverse in mor鄄
A. stellatum
Roth and Ker Gawler). Within the Old phology, in which some produce mainly rhizomes
Amerallium
World clade (PP=0. 88, BS=56%), and poorly developed bulbs and others form distinct
two sister subclades are evident: one with species bulbs and broad leaves similar to those common in
Melanocrommyum
from the Mediterranean region; the other with species the subgenus , or very narrow
Allium
from the Himalayas and South鄄West China. In the leaves as in the subgenus (Kamenetsky and
Narkissoprason
Mediterranean subclade, section Rabinowitch,2006). However, morphological syna鄄
Briseis Amerallium
Kam. is sister to a clade containing sections pomorphies for include one row of vascu鄄
Arctoprasum Molium
(Salisb.) Stearn, Kirschl., and lar bundles, absence of palisade parenchyma and
G. Don ex Koch (PP=1.00,BS=89%). In the Hi鄄 subepidermal position of laticifers (Traub, 1968,
A. wallichii
malayas and South鄄West China clade, 1972; Fritsch, 1988). Furthermore, strong serolo鄄
wallichii A. wallichii platyphyllum
var. Kunth, var. gical affinities and the dominating basic chromosome
A.macranthum x
(Diels) J.M. Xu and Baker are sister number of =7 strongly support its separate status.
A.omeiense A.fas鄄
to a clade comprising Z.Y. Zhu, The results presented here continue to support earlier
ciculatum A. hookeri hookeri Amerallium
Rendle, Thwaites var. 覱nding that is monophyletic (Samoylov
A.hookeri muliense et al
and var. Airy Shaw (PP=0.58, .,1995; Dubouzet and Shinoda,1999; Friesen
A. macranthum et al et al et al
BS<50%). The five accessions of ., 2006; Nguyen ., 2008; Li .,
composed a well鄄supported clade (PP=1.00, BS= 2010). In accordance with studies of Dubouzet and
100%) that wassister to a clade containing seven ac鄄 Shinoda (1999), our molecular data underline the
A. wallichii wallichii A.
cessions of var. and one of existence of two distinct biogeographic clades,
wallichii platyphyllum
var. (PP=1.00, BS=96%), namely the Old World clade and the New World
and these two clades constituted a weakly supported clade. Both clades are a monophyletic unit, which
A.omeiense A.hook鄄
clade (PP=0.65, BS<50%). , agrees with a uniform electrophoretic banding pattern
eri hookeri A. hookeri muliense
var. and var. form a of salt鄄soluble seed storage proteins (Maass, 1992).
Amerallium
trichotomy (PP=1.00, BS=99%) and this trichoto鄄 Furthermore, our results indicate that
A. fasciculatum
my is sister to (PP =1. 00, BS = composed of three isolated geographical groups: one
A. omeiense Allium
94%). the two accessions of formed a comprising almost all species native to North
strongly supported clade (PP=1.00, BS=99%). America (New World) and the remainder containing
2 3摇 Character state reconstruction
. two smaller groups from the Mediterranean region
Two morphological characters, underground sto鄄 and eastern Asia (Old World). In the well鄄suppor鄄
Amerallium
rage organs and basic chromosome numbers were op鄄 ted North American clade, the sister re鄄
Lophioprason Ameral鄄
timized onto the 50% majority rule tree. Parsimoni鄄 lationship of section to sections
lium Caulorhizideum Rhopetoprason
ous optimization suggested that bulbs are primitive, + + is well suppor鄄
Allium validum Caulorhizideum
and rhizomes and thick fleshy roots are derived states ted. from section is
Amerallium Caulorhiz鄄
within (Fig.2A). Optimization of chro鄄 sister to a clade containing the remaining
x ideum Amerallium Rhopetoprason
mosome numbers suggested =7 to be the ancestral + + . Thus, section
Caulorhizideum
basic chromosome number and the chromosome num鄄 is found to be non鄄monophyletic.
Amerallium x Lophioprason
ber in evolved from =7 to other basic Section which comprises species that
期 et al Allium Amerallium
2 摇 摇 摇 摇 摇 LI Qin鄄Qin .: Phylogeny and Character Evolution in Subgenus …摇 摇 摇 摇 摇 摇 1摇13
are native to California or restricted to western North (Pastor and Vald佴s, 1985; Fritsch, 1988; Drusel鄄
et al
America in their distributions was found to be mono鄄 mann, 1992; Hanelt ., 1992; Kruse, 1992;
Amerallium et al Briseis
phyletic. Within the Old World clade, Samoylov ., 1995). Section was isolated
Bromatorrhiza Molium
the monophyletic section Ekberg was from on the basis of distinctive structure of
sister to a clade containing all other Mediterranean filaments and style and the presence of elaiosomes on
region sections. In the Mediterranean region taxa the the seeds (Stearn,1946) and their relationship is al鄄
Molium
species of section show greater affinity to so reflected in our phylogenetic studies. According to
et al Bro鄄
each other than to those of other sections including Li .(2010) and our present studies, within
Narkissoprason Briseis Arctoprasum Allium ur鄄 matorrhiza
, and . , two sister groups are evident, one with
sinum Molium A. wallichii wallichii A. wallichii
, while sister to the , is maintained as species var. , var.
Arctoprasum platyphyllum A.macranthum
a separate monotypic section , which is and , and the other with
A. omeiense A. guanxianense A.
also supported by various unique characteristics such species , J. M. Xu,
xiangchengense A.hookeri hookeri
as leaf morphology and anatomy, leaf sequence, J.M. Xu, var. and
A. hookeri muliense A. fasciculatum A. chien鄄
bulb morphology, secondarily reduced ovule number var. , ,
chuanense
and size, seedling morphology, cpDNA variability J.M. Xu.
Fig.2摇 EvolutionofcategoricalcharactersontheBayesiantopology:A,undergroundstorageorgans(bulbs,rhizomes,andthickfleshyroots);
B,basicchromosomenumbers(7,8,9,10,and11). Coloursareexplainedinthelegendofeachfigure
植 物 分 类 与 资 源 学 报 第 卷
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3 2摇 Character evolution in Amerallium
. The reason may be that both lineages distributed in
3.2.1摇 Underground storage organs the Himalaya and south鄄west china face similar envi鄄
Amer鄄
Within the New World (North America) ronmental challenges and selective pressures. Parsi鄄
allium Caulorhizideum Rhopheto鄄
, two sections, and monious optimization suggests bulbs as a primitive or
prason
with rhizomes and bulbs developed have a ancestral state, and rhizomes and thick fleshy roots
southernmost distribution in the New World in as derived states which have evolved and developed
Am鄄
Mexico and Guatemala whereas sections with true several times independently within the groups of
Amerallium Lophioprason erallium
bulbs ( and ) occur mainly (Fig.2A).
et
in mountains of western North America (Hanelt 3.2.2摇 Chromosome numbers
al et al
., 1992; Pistrick, 1992; Ohri ., 1998). In Former researchers have different views about
Ameralliums
the Mediterranean region , except for the evolution of basic chromosome numbers in the
Narkissoprason Allium
section , which also has rhizomes, all genus . Levan (1932, 1935) has suggested
the extra鄄Mediterranean sections have true bulbs. their origin in the form of an ascending series. Men鄄
Bulbs are dominant in these two regions, which may sinki (1940) has also put forward an alternative view
represent an adaptation to environments with a Medi鄄 according to which the basic numbers seven and nine
terranean type climate characterized by hot and dry have both arisen from eight. Brat (1965) considered
summers, but cool and moist winters favourable for that the basic numbers in different taxonomic groups
Allium
plant growth and development (McNeal and Own鄄 of the genus have arisen in independent or鄄
bey, 1973; Hanelt, 1990). Bulbs can float unim鄄 ders. Previous molecular studies have indicated that
Allium et al
paired for a long time in salt water (De Wilde鄄Duy鄄 is monophyletic (Friesen .,2006; Nguy鄄
et al et al
fjes, 1976; Stearn, 1978), which may also explain en ., 2008; Li ., 2010), so there should
the predominantly coastal distribution of Mediterra鄄 be a single primitive basic chromosome number for
Moliums
nean (Dubouzet and Shinoda,1999). Sec鄄 the entire genus although the primitive basic chromo鄄
Bromatorrhiza
tion is a small insufficiently studied some number may vary in different subgenera. It is
group occurring in ecologically mesophytic high regrettable that one cannot, at present, deduce with
mountain regions of western Himalaya and south鄄 confidence the primitive state of the basic chromo鄄
west China as a component of moist grassy slopes, some number and the direction of the basic chromo鄄
et al
rocks, and herb layer of forests (Hanelt ., some numbers changes within the phylogeny of the
Allium
1992). The special character of this group differing entire spp. We just infer the primitive basic
Amerallium
from the other sections in the is the pres鄄 chromosome number and the direction of the basic
ence of thick fleshy roots as storage organs, without chromosome number changes within the subgenus
Amerallium
true bulbs or rhizomes, and this special character al鄄 and the primitive basic chromosome
Coleoblastus Cya鄄 Allium
so exists in sections Ekberg and number of the entire is out of the scope of the
thophora
R. M. Fritsch which belong to subgenus present paper.
Cyathophora Amerallium
(R.M. Fritsch) R.M. Fritsch. Previ鄄 In the subgenus , most species are
et x
ous studies (Fritsch and Friesen, 2002; Friesen diploid with basic chromosome numbers of =7, 8,
al et al x
.,2006; Li .,2010) have indicated that sub鄄 9, 10 or 11; =7 being the most common. In addi鄄
Cyathophora
genus is one member of the third evolu鄄 tion to these differences in basic numbers,
Allium
tionary line in evolution. This may suggest polyploidy has proceeded on four basic series,7,8,
the process of convergent evolution, in which those 9 and11. The reconstruction of ancestral state in the
x
two distinct lineages evolve a similar characteristic present study suggested = 7 being ancestral and
x
(thick fleshy roots) independently of one another. other basic numbers ( =8, 9, 10, 11) being de鄄
期 et al Allium Amerallium
2 摇 摇 摇 摇 摇 LI Qin鄄Qin .: Phylogeny and Character Evolution in Subgenus …摇 摇 摇 摇 摇 摇 1摇15
rived (Fig.2B). Levan (1932, 1935) found arm鄄 and no linking dysploid numbers are known within
Ameralliums
length asymmetry is more pronounced in the “16冶 North American , which indicate that
and “18冶 鄄chromosomes types and took this to mean dysploidy is a rather rare evolutionary event in this
that the “14冶 鄄chromosome types were the most group. Compared with dysploidy, polyploidy origina鄄
primitive and that the “16冶 and “18冶 鄄chromosome ted via autoploidization or alloploidization occurs in
Ameralli鄄 Ameralliums
types were derived from them. In subgenus several North American and thus seems
um
, symmetrical chromosomes with median鄄subme鄄 to be a relatively frequent evolutionary event. Chro鄄
dian centromeres are most common in species with mosome structure, such as inversions and transloca鄄
x x
=7, while species with =8 have usually varying tions, seems to have acted as an important cytoge鄄
numbers of asymmetrical chromosomes and species netic mechanism in the evolution of the North Ameri鄄
x Amerallium Ame鄄
with =9, 10, 11 have entirely asymmetrical chro鄄 can , considering that 66 of the 81
rallium
mosomes with telocentric chromosomes (Brat,1965; species, i. e. 81.48%, are represented in
et al et al
Huang ., 1995; Xu ., 1998). According North America by diploid populations only (data
to the general principles (Stebbins, 1971; Hong, from the statistical results of the North American Flo鄄
et Allium
1990) and minimum interaction hypothesis (Imai ra for ). Considering all the available chro鄄
al Ameralliums
.,1986; Schubert,2007) of karyotype evolution, mosomal data, Mediterranean region
karyotype evolution in higher plants generally tends possess the abundant diversity for basic chromosome
x Ameral鄄
to develop from symmetry to asymmetry and tends to鄄 numbers ( =7,8,9, and11) in subgenus
lium Narkissoprason Arctopra鄄
wards an increasing number of acrocentric chromo鄄 , in which sections and
son x Briseis x
somes, thereby minimising the risk of deleterious re鄄 with =7, section with =7, 8, 9, and
Molium x
arrangements, while the opposite tendency, the re鄄 section with =7, 8, 9, and 11. The high
Briseis Moli鄄
duction of chromosome number and formation of karyotypic diversity encountered in and
um
metacentric chromosomes, is considered to be the might indicate rapid evolutionary episodes within
result of ‘rare back鄄eddies爷 that are generated at those two groups. Furthermore, polyploidy has taken
random and tolerated or even favoured when they place in the three series of basic chromosome num鄄
provide short鄄term advantages. Based on the cytolo鄄 bers, 7, 8 and 9. Thus, dysploidy and polyploidy
gical and molecular data, we propose that, in the seem to have acted as important cytogenetic mecha鄄
Amerallium
subgenus , the basic chromosome number nisms in the evolution of the Mediterranean region
x Ameralliums x
=7 is the primitive state and other basic chromo鄄 . Karyotype reconstruction suggests =7
x
somes number ( =8, 9, 10, 11) are derived from as a possible ancestral basic number for Mediterra鄄
Amerallium Ameralliums
it. The New World (North America) nean region and thus an ascending dys鄄
clade displays a uniform basic chromosome number ploid series for this group. Yet, the mechanism of
x
with =7. Within the 47 species investigated, 40 the dysploidy is still not well understood. Meiosis in鄄
species show a noteworthy constancy of chromosome volving irregular segregation, unequal translocation,
number represented by diploid populations only and centric fission are all possible causes of dysploid
x A. drummondii A. am鄄
(2 ), and four species ( , variations (Stebbins, 1971). Karyotype reconstruc鄄
plectens A. cratericola A. campanulatum x
, , ) contain tion indicates = 7 being ancestral for sections
x x x Narkissoprason Arctoprason Molium Bri鄄
both diploid and polyploid (2 , 3 , or 4 ) and , , and . For
A. canadense canadense A. seis x
three species ( var. L., , species with =7 are not included in the pre鄄
glandulosum A.validum
Link & Otto and ) exclusive鄄 sent study, so karyotype reconstruction did not pro鄄
x x x
ly polyploid populations (3 , 4 or 8 ). So, the vide any valuable information for the primitive basic
basic chromosome number found so far is very stable number in this section. Overall, relatively poor rep鄄
植 物 分 类 与 资 源 学 报 第 卷
摇116摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 34
resentatives in this region, do not allow us to pro鄄 sons for the diversity of basic chromosome number.
pose an unambiguous and credible scenario for kary鄄 Optimization of the chromosomal data onto the mo鄄
x
otype evolution within every section. Detailed sam鄄 lecular phylogenies reveals =7 to be the most likely
Bromatorrhiza
pling of Mediterranean region taxa would be necessa鄄 ancestral type in with other basic
Bro鄄
ry to elucidate the potential scenario. Section numbers being derived mainly through ascending
matorrhiza
is a small group restricted to the Himalayas dysploidy (Fig. 2B). The probable mechanism in鄄
and South鄄West China and reveals three different volved in the dysploid differentiation of chromosome
x Bromatorrhiza
basic numbers ( =7, 10 and 11), in which two numbers in is chromosome fission and
A. wallichii A. wallichii
species and one variety ( , the subsequent loss of chromosomes.
platyphyllum A. macranthum x
var. and ) with =7,
A.fasciculatum x 4摇 Conclusions
one species ( ) with =10, and four
A. guanxianense A.
species and one variety ( , Our present paper has provided insights into the
xiangchengense A. chienchuanense A. omeiense Amerallium
, , and phylogeny and character evolution of .
A. hookeri muliense x
var. ) with =11. Basic num鄄 Despite relatively lack samples of the Mediterranean
A. hookeri hookeri Ameralliums
bers for var. is complex. Except region , we have established evolution鄄
et
for few cytotypes recorded to have 33 (Huang ary patterns of underground storage organs and basic
al et al
., 1996b; Zhang and Xu, 2002; Wei ., chromosome numbers. However, a more detailed
et al
2011) and 44 chromosomes (Yan ., 1990; phylogenetic study including a larger sample of spe鄄
et al Ameralli鄄
Huang ., 1996b), twenty鄄two is the most com鄄 cies, especially the Mediterranean region
ums
mon number on record for this taxon (Sen, 1974; and additional molecular markers and further
et al et al
Yan ., 1990; Huang .,1996b; Zhang and studies focusing on their morphological characters,
n
Xu, 2002). According to existing researches, 2 = will be required to clarify the phylogeny and charac鄄
Amerallium
22 being off鄄types (trisomics) of segmental allotrip鄄 ter evolution of .
x et al n
loids with =7 (Sharma ., 2011), 2 =33 be鄄
x et al References
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A.wallichii walli鄄 BratSV,1965. Genetic systems in I. Chromosome variation
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Belmontia 7
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DoyleJJ,DoyleJL,1987. ArapidDNAisolationprocedureforsmall
and polyploidy are two primary driving forces in Phytochemistry Bulletin 19
Bromatorrhiza quantitiesoffreshleaf tissue [J]. , :
chromosome evolution of . Geological
11—15
history, unique ecological environment, and micro鄄 DruselmannS,1992. VergleichendeUntersuchungenanVertreternder
environmental diversity in this region could be rea鄄 AlliaceaeAgardh. 1. Morphologie der Keimpflanzen der Gattung