Cryptic Species in the Fern Ceratopteris thalictroides (L.) Brongn. (Parkeriaceae). II. Cytological Characteristics of Three Cryptic Species

2005·3.6 MB·English

by  Masuyama, Shigeo

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ISSN 1346-7565 ActaPhytotaxG.eobot.56(3)2]31-240(2005)

CrypticSpeciesinthe Fern Ceratopteritshatietroide(sL.B)rongn.

(ParkeriaceIaI.eC)yt.ologicaClharacteristicsThree Cryptic
of
Species

SHIGEO MASUYAMAi *and YASUYUKI WATAN02
iDepartment qfMatheniatic asnd Ndturat Sciences, Cotleg eoL.fD]eAprat rantsdni Senctiences ,7bkyo llloma 'ns Christian
Un i v e r si t y Z e m p uk a g ' i 2 -6 - 1 , S u gi n a m i , 7 1 ) k} ) oJ 6 7 - 85 8 5 , J c r p an , qfBotan) ;fttcul toyfScien cChei,ha
Univensiov }keyoich o1-33 ,lnage ,Chiba 263-8522 ,,1opan
Ceratop)te rtihsaiictroide hsas been reported to contain three cryptic species, called thc south type, the
north typc and thc third type. To obtain a clear understanding oflhesc cryptic species, the somatic and
meiotic chromosomes were exarnined in 1 8 sporophytes from differe nlteealit iaends threc hybrid ssyn-
thesized among thc thrcc types, The examinations revealed that the north typ eand the third type are
tetraploids with 2n =-, 156 and n = 78 chrernesomcs, whercas the south type i sa hypotctraplo iwidth
2n = 154 and n == 77 chromosemes. Severa pleculia crenfigurations were occasionally observed at diaki-
nesis in all three type ss:ingle rope-shaped bivalen twisth acrosyndcsis, split bivalen twisth acrosyndetic
coimections, and quadrivalent or quadrivalent- lcionkfeigurations, Occasiona qluadrivalen itnsdica tthee
presence ofseveral homologie swithin the genomes of the three tspe sM.any univalents were observed
at metaphase I in the hybri dbetween the south and north typcs w,hereas only a few univalents wcrc occa-
sionally observed in the hybrid sbctwccn thc third and north types, for which a partia lcross-sterility had
been reported, This suggests that the chremosemal structure has difTerentia tleidtt lbeetween thc
genomes of the third typ eand the north typ eand that the partia lcross-sterility is mostly due to genic dir
ferentiatiboentweenthem.

Key words: Cb"utopter tihsalictroide scr,yptic species, cytology, fern,hybrid sterilitM Parkeriaceae ,pely-
ploid ,quadrivalent
The lates ttaxonomic revision of the fern genus troides, however ,is inconclusi vaes ,Pal (195 9an)d
Cevatqpter iwass canied out by Lloyd (197 4H)e, Pal & Pal (1963 d)ocumented 2n - 80 and Ninan
recognized fbur species in the genus :C. cornuta (195 6an)d Hickok (197 9re)portcd 2n == 154 fbr this
(Pa lB.eauv.) Le Prieur ,C pteridoides CHook.)species, indicatin gthe presenc eof intraspecific
Hieron,, C, richardii Brongn. and C. thalictroides polyploid asnd aneuploids. In the previou sstudy
CL, B)rongn. Among them C, thalictroides is char- (Masuya meta al. 2002) ,we revealed the presence of
acteristically highly polymorphic. Most ofthe cytQ- three distinc tentities in C. thalictroides, which we
logica sltudies of Ceratopter ihsave shown that the called the south type, the north typ eand thc third
fbrmer thre especies are diploi dwsith 2n = 78 chro- type T.hey were regarded as independe nsptecies for
mosomes and the remaining one, C thaiictroid eiss, two reasons. One was that the ywcrc suMciently dif
tetraploi dwith 2n = 156 chromosomes (L6v eet feren tin molecular characteristics, including
al. 1977). The cytological evaluation of C. thalic- allozymc coinposition and nuclcotidc sequcnccs of
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232 APG Vdl,56

thc chloroplast DNA. The second was that crossing study (Masuya meta al. 2002), all but IN3 (Indo-
tests indicate drigi dcross-sterilit byetween the south nesia) and TW1 ([Ilat wierwea nex)amined cytologi-
type and the other two and panial cross-sterility cally (1la t1b) ,tTehe Japanes esporophytes O, M, F
between the north typ eand the third type. and Yl ofwhich the fbrmer two and the latt etrwo
These studies tead to the fo11owing previsionswere frem population swith allozyme compositions
with respect to the cytological characteristics of of the south type and the north type, respectively
the three types :1) they may diffe nrot only in mol- (Watan &o Masuyama 1994) ,were also examined.
ecular characteristics but also in chromosome num- Additiona lobservations were made ofmeiosis in the
ber ;2) differe nltevel osf cross-sterility among the hybrid sbetween the third and north type s(IN 1 × N
three type msay be related to differe pnltoid ylevels and IN2 ×N) and between the south and north types
or to aneuploidy. The purpos eof this study is to (IN ×4 N) that had been synthesized in the previous
show evidence fbr or against these prevision sby study. All the sporophytes but O, M, F and Y have
examining the chromosomes of the three types of been cultivated successively through asexual repro-
Ceratopter ithsalictroides. ductio nby gemmae since the previou sstudy. The
sporophytes O, M, F and Y were obtained through
Materials and Methods mixed matings of gametephyte sgenerating from
spores, fo11owin tghe method describe pdreviously
Of the sporophytes that were used in the previous (Masuyam a1996). For examination of somatic
ZNBLE 1.Code names, ]ocaliti eansd molecular characteristic softhe sporophytcs cxamined.
Code Spore collection Sequenceof
1)namcLecality number chloroplastDNAZ)AllQzyme composition]}
soMTHIDINO4nNnGaGsYoNnF, YOTkWi2nTaW3wHa WPIrHeWf2, GJAaIpNa1nIN2 S. Masuyama 2611 South typc South type
Ootomi, hiomote Isl. ,Okinawa Pref, Japan S. Masuyama 2877 South type
Motonagur aI,shiga kIsil .O,kinawa Pref. J,apan S. Masuyama 2876 South type
Khao Taln, Chumphon, Thailand S. Masuyama 3107 South type South type
Mirzapur ,Uttar Pradesh ,India S. Masuyama 2741 South type South type
Gnung Batu, Bogor, Indonesia S. Masuyama 2599 South type Seuth type
Hisue, Kairuku, New Guinea S. Masuyama 2737 South type South typc
Georgetown, Guyana S. Masuyarna 2740 South type South type
Nagareyama, Chiba Pref, Japan S. Masuyama 2869 North type Nenh type
Fukiage ,Kagoshima Pref, Japan S. Masuyama 1293 Nemh type
Yanyu, Amami Isl ,K,agoshima Pref, Japan S.Masuyama2131 Nonh type
Tali ,Taichung Pref i, Taiwan S, Masuyama 2700 North type North type
Taichung, Taichung Pref, T,aiwan S.Masuyama2681 Nonh type
Hanapepe Riv. ,Kauai H,awaii U,SA S. Masuyama 2736 North typc
Hanalei, Kauai, Hawaii, USA S. Masuyama 2868 Nonh type Nenh type
Mt. Santa Rosa, Yigo, Guam S, Masuyama 2964 North type Nerth type
Gnung Sal iS,. Salak I,ndenesia S. Masuyama 2701 Ihird type Third type
Pasir Kuda, Bogor, Indonesia S, Masuyama 2601 Third type Third type
1) The same as in the previou sstudy (Masuyam eat al. 2002) except O,M,F and Y,new codes fo radditional collections.
2) See the previou sstudy (Masuyam eat ai. 2002).
3) See the previou sstudies (Watan aond Masuyama 1 994, Masuyarna et al, 2002).
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fixedin Sporangia then in drop
chromosomes, roots ofthe sporophytes were were removed and placed a
Farmer' ssolution ( 3anhydreus ethyl alcohol:1 of aceto-camnin (45% acetic acid containing 1%
glaci aalcetic acid) after pretreatme nwitth 4 mM 8- carrnin) on slides and squashed under a cover glass
hydroxyquinoli nseolution fo rabout 6 hours F.or to provid estained spore mother cells ,Vbucher spec-
microscopic observations, the roots were put in imens ofthe sporophytes examined were deposited
45% acetic acid for more than 15 minutes, fbl- M KYO.
lowed by maceration in IN HCI solution at 60 OC
for 5 minutes. After a short rinse with 45% acetic Results
acid, the root tip was cut off and place din a drop of
aceto-orcein (45% acetic acid containing 2% orcein) Chromosome numbers determine din this study are
on slides. The material was spread by tapping on a summarized in Table 2. Representati v¢ehromo-
cover glas swith a stick and then squashed to provide some configurations are shown in Figs ,1 to 17.
stained somatic cells. For examination of meiotic Cytological feature sworthy of note in the three
chromesomes, young fenil eleaves were fixed in types and the hybrids are describe bdelow.
Farmer's solution. For observation, the leaves were
placed in 459r 6acetic acid for more than 1 5 minutes. TVie south mpe
All the sporophytes of the south type had 2n = 154
andror n = 77 chromosomes. In diakinesi osf meio-
TlxBL E2. Chromosome numbers of sporophytes of' Ceratopteris sis, some bivalen tshsowed a knotte drope-like con-
thatictroides. figurati owinth pairing at the terrninal regions of
CodenameLocalitySomatic Meiotic Fig. in text arms (Fi gI.b) .Occasionall ys,everal bivalents
no. no.
showed a single rope-like configuration with
South typc acrosyndesis, the pairin gat the ends of arms (Figs.
soMTHIDIN4NJGaGpYanJapanJap2ann=T1h5a4i2lna=n1nd5=I4=n7d7ni=a7I7nnd-7o7n1ne-=sa7i,7nab=,c,d,e 1c, 4 and 7b). Some of them paired furthe art their
2
ends with other normal bivalent rse,sulting in the
2n=1542n-1542n=1542n3-41556472-na=,1b54 fbrmatio nof taile dquadrivalent s(Fi gI.d) .There
bivalent
77n-77n==77n=77 was a split with an acrosyndetic connection

by a fain btridge w,hich appeare dlik etwo univalents
NewGuinea (Fi g.Ie) ,Quadrivalent -clonifikguerations, some
Guyana of which were probabl ytrue quadrivalen twesr,e
observed in many spore mother cells (Fig s1.c, le, 4
Northtype
NFYTW 2TW3HWJIaHpWa2nGJAapanJap2ann-T1a5i6w2ann=T1na5-i67w8an=n7U8SnA-U78SnA8=G-7ua8a,n=mb9 and 5) .The occurrence ef these variant configura-
tions was dependent on the spore mother cells, not
on the individu apllants ,Among the samples of the
south type, the sporophyte ofGuyana was peculiar
2n=156 78n=78n=7le8n=78 in having a single dot-lik echromosome in the
somatic cells (Fi g7.a). Although the dot-lik echro-
2n-1562n=IS6 1112
mosome was constantly observed among 154 regu-
lar did
chrornosomes, meiosis not appear abnor-
Third type mal and 77 normal bivalen wterse fbrmed (Fig.
MlIN2 Indonesia 2n=156 n=78 13-a,b14 7b),
Indenesia 2n=IS6 n=78
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7)l inoerth mpe which were called the south type t,he north type and
All the sporophytes ofthe north type had 2n - 156 the third type, Cytologic aalnalyses in the present
andforn =78 chrornosomes. As in the south type, study showed that the sporophytes regarded as the
occasional bivalen tsshowing acrosyndesis were south type had a complement of2n = 154 andlor n
observed at diakines iisn some spore mether cells = 77 chromosemes without exception, while those
(Fig8,b),Quadrivalent-like
configurations were regarded as the north type and the third typ ehad 2n
also observed in many spore mother cells (Fi g9.), = 156 and!or n =- 78 chromosomes. Tt is evident
from these results that both the north type and the
71ie thint mpe third type are characterized by the chromosome
Both sporophytes examined had 2n = 156 and n == number 2n = 156 andn == 78, whereas the south type
78 chrornosomes. As in the above two types, biva- is characterized by 2n = 154 and n = 77. In an
lent sshowing acrosyndesis (Fi g1.4) and quadriva- experimental study utilizing several sporophytes of
lent-li kcoenfigurations (Fig s13.b and 14) were the south type and thc north type, Masuyama &
occasionally observed at diakinesi sin meiosis. Watano (199 4re)ported both type sto have the same
chromosome number, 2n = 156. It appears that
71hedybrials
insurncien tobservations resulted in a miscount fbr
Three hybrids oftwo combinations were examined the south type. Sinc ethe chromosome number of2n
for the occurrence ofunivalents at metaphase I. In = 78 has been reported fbr diploi dspccies of
the hybrid INI XN (th ethird type × the north Ceratopteri s(L6v eet al. 1977), the count of2n =
type), 40 spore mother cells (SMCs )were examined. 156 in the north typ eand the third typ eis tetraploid
0ne and two univalents were observed in 12 and 2 and the count of 2n = 154 in the seuth type is a
SMCs, respectively (Fi gI.5); the rcmaining 26 hypotetraploid,
SMCs showed no univalents. In the hybri dIN2 ×N Ninan (195 6re)ported chromosome counts of
(th tehird type × the north type), 48 SMCs were 2n = 154 and n = 77 for Cleratopter ithsalicmoicles in
examined, One and two univalents were observed in India L.ate4 in a cytological study of seven different
13 and 1 SMCs, respectively; the rcmaining 34 collections ef Cl thatictroides, Hickok ( 1979) report-
SMCs had no uniyalents. In both hybrid sa,bnormal ed n = 77 fbr six colLections and n = 78 for one col-
bchavio rwas not d¢tected in chromosomal pairing lection ,The six collections with n =r 77 contained
at diakines i(sFi gI.6). In the hybrid IN4×N (the those from Malaysia and Surinam ,localit ineots
south type × the north type), a number of unjva- include din this study. The collection with n = 78
lent soccurred in metaphase I (Fi g17,). A rough was from Hawaii, the locali tinycluded in thi sstudy
estimation ofthe number ofunivalents was possible Combining these cytological data with the results of
in 5 SMCs, where at leas 2t2, 27, 31, 32 and 35 uni- this study, it appears that the south type with 2n =
valents were recognized. Pairin gbehavio rat diaki- 154 and n =: 77 is distribut ewiddely in trepical
nesis was irregul arers,ulting in a number ofuniva- and subtropical regions, and the north typ ewjth
lent sand multiva]ents arnong bivalents. 2n = 156 and n = 78 ranges from eastern Asia to
Micronesia, although their distribut iion nAfric ais
Discussion
uncertain. The third type, another strain of 2n =
1 56, appears to be narrowly distribut eocdc,urring
Molecula ranalyses ofthe widely distribu tspeedcies only in Indonesi aand neighboring areas.
Ceratopter ithsalictroides (Masuya emt aat. 2002) Pal (195 9re)ported the chromosome number
revealed the presenc oef three distinc tentities, 2n = 80 and n == 40 i'o ran India nsporophyte iden-
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tific das Ceratepteris siliqt{osa, a synonym of C by the consistent occurrence of a single dot-like
thalictroides. Later ,Pal & Pal (196 3al)so reported chromosome among somatic chromosomes (Fig.
the same chromosorne number for C thatictroi idnes7a). The dot-li kcehromosome appears to be a B-
India .Judging from the nurnber reported, the spero- chromosomc because 77 norma] bivalent wser ¢
phyte sexamined appear to represent a strain derived constantly observed in meiQsis (Fi g7,b) .It is uncer-
from a diploi sdpecies of Ceratopteris. tain whcther the dot-li kcehromosome is charac-
In meiosis in the three type tsv,v' opeculia cron- terist iecf plants in Guyana or is only in the indi-
figurati oonfbsivalents were occasionaily observed: vidual examined,
single repe-shaped bivalents with acresyndesis Mating tests in our previous 6tudy (Masuyama
(Fig sIc., 4, 7b, 8b and 14) and split bivalen twisth et aL 2002) demonstrate tdhat when S (a sample of
an acrosyndetic connection (Fi gl,e) .The single the south type, see rfable 1) was utilized as a pater-
rope-shaped bivalent sappeared to be transformed nal tester ,spores of hybrid ssynthesized with the
configurations of knotte drope-shaped bivalents north type and those with the third type showed O to
(Fig l,b) after terminalizati oonfchiasma. SimilarIM 18% and 2 to 20% germination ,respectively, but
the split bivalen tapspear to result frem occasional when N (a sample of the north type) was paternal,
transformatio nof single rope-shaped bivalents, the spores ofhybrids with the south type and those
In addition to these peculia brivalcnt qsu,adri- with the thir dtype showed O to 209, 6and 37 to 69%
valent-like configurations (Fi gl,c, fbr example), germinatio nr,espectively, As selfed progeny ot-
includin tgaile dones (Fi gI.d) ,were occasionally each type showed 83 to 98% spore germination ,it
observed. Occasiona lquadrivalcnts have been was concluded that the spore germination rates of
reported fbr synthesized hybrid sbetween diploid hybrids noted above represented rigid cross-sterili-
species of Ceratopteri s(Hick o&k Klekowsk i1974, ty between the south type and the other two types
Hickok 1977) and crosses among differe ncotllec- and pania lcross-sterility between the third type
tions ef C thalictroides (Hick o19k79) .Most of and the nerth type (Masuyam eat al, 2002). In the
the sporophytes utilized in the presen tstudy, how- presen tstudy, a larg enumber ofunivalents consis-
ever, were not crosses but ordinary individuals, tentl yoccurred in metaphase 1 in the hybri dbetween
because i twas reported that their selfed progeny thc south type and the north type (Fi g1.7), This
formed viable spores at suMciently high frequenciesimplies that, in addition to chromosome number,
(Masuyama et al. 2002). Occasional quadrivalents,chromosomal structure and genic constitution have
therefore, appear not to be exclusive to crosses considerably differentia tbeedtween the genomes
between differen stpecies and forrn sbu,t to be rather ofthese types and have resulted in their rigi dcross-
common in the tetraploid species ef Ceratopteris.sterjlity, In contrast, one or two univalents occa-
Occasiona qluadrivalen tfbrmation in the tbree types sionally occurred in the hybrid sbetween the third
indicat tehsat some of differen ptair sofhomologous type and the north type (Fi g1.5) ,ln a cytological
chromosomes are ofhemoeologous origin and still study of synthesized hybrids among dipioi sdpecies
maintain homologie sat several sites .In seed plants,of Ceratopteris ,Hickok (1977 r)eported that the
occasional quadrivale nftbrmatio nhas been fre- hybrids showed 23 to 30% spore germinatio annd a
quently observed in polyploid taxa and explained in few univalents occurred only in les sthan 8% of
terms of the mechanism leadin gto stable bivalent the spore mother cells examined, a featu rseimilar to
fbrmatio nin polyploid s(Drisc oetl lal, 1980, that in the abovc hybrid sbetween the third type
Watanabe 1981 ,Jackson & Casey 1982). and the north typc. From this pairin gbehavio rhe
The sporophyte from Guyana is characterized conc]uded that spore abortions ofthe hybrid swere
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TThhee JJaapapnaesneSeosciee tySociety ffoorr PPllanatnt SSyystsetmaetmicastics
240 APG Nlo1 .56
probabl ycaused not by chromosomal but by genic Hickok, L. G. 1977. Cytologic arlelationships between
imbalanc ein the spores after meiotic segregation. thre ediploi dspecies ofthe fer ngenus Ceratopteris.
The sarne cenclusion can be drawn fbr the above Can. J .Bot 55: 1660-1667.
hybrid sin this study. That is ,chromosomal stmcture , 1 979 .A cytological study ofintraspecific variation
may have differentia ltietdt lbeetween the genomes i1n7 0C0e.ratopter itshalietroide sC.an, J. Bot. 57: 1694-
of the third type and the north type and the partial & E. J. Klekowski, Jr .I974 ,Inchoate speciation in
sterility of the hybr{ds may be due mostly to diP Cleratopter Ains: analysis ofthe synthesized hybrid
feren tgenic constitutions of these types. C: riehaFdii × C. pteridoide sE,volutio n28: 439-
As noted in the bcgiming ,the south typ eof2n 446.
-: 154 is regarded as hypotetraplo iwdith a de- Jackson, R. C, & J .Casey .1982. Cytogeneti acnalyses of
bcree assueppdo sneudmber i no ft hceh rofmoosrommeas.tio n oTfX tvho ipsr oanceeupslsoeids ,can L l o yatduo , tRoo,cp toMolpy.lp ol1iodi9sd7.s4i .AS myMesortd.e emJla ,sBt oiant cdo.s f6t h9meei t4 hg8oed7ns-u5s0 1fC.oer mttrioppltoiedns's
One is the numerical loss ofchromosomes by fusion Brongn. (Parkeria cIeI a,faex)on,omy. Brittoni a26:
of two homologous pairs after formation of 139-160.
tetraploi dwsith 2n =: 156 chromosomes. ParticularL6ve, A., D. L6ve & R. E, G. Pichi Sermolli. 1977.
configurations indicativ eof chromosomal fusion, Cytotaxonomica latlas ofthe Pteridophyt Car.amer,
VZIduz.
however ,were not evident in somatic and meiotic M a su yama, S. 1996 .Progenesis as adaptive strategy i] tihe
chremosomes of the south type T.he other process is annual fern CeratctF)t ethrailsictroid eisn Japan .Plant
allotetraploid formation through hybridization Sp, Biol. 11: 225-232.
between ordinary diploid swith 2n = 78 and & Y Wbtano. 1994. Hybrid sterility betwce ntwo
unknown diploid swith 2n - 76, Pal (1959 a)nd isozymi ctypes ofthe fer nCtiratopte rthiaslictroidds
Pal & Pal (196 3re)ported a chromosome number 2n in Japan .J ,Plant Res. 107: 269-274.
=f i8n0d fibnrg Issnugdgiesatn sp otrhopaht ytseesveral of c yCteolroagitcaolpt evrari iTsahn.etsir C(, rLYy.. p )BYtraio tcsnapgebcnei.e , s(N P.i an Mtruhekr acfkorarimn Ciaec rI&ea. taMYooe.lp )etWc.eaurlt itaah.rnav ota,in ca2lty0rs0oe2is.des
may be present among diploid species of and cressing tests .J. Plant Res, 1 15: 87-97,
Ceratopter ialst,hough a chromosome number 2n = Ninan, C. A. 1956. Studie son the cytology and phy-
78 has been exclusively recognized fbr diploid logeny of the pteridophyte sI,V Systematic posi-
species so far (L6v eet al. I977) ,Funher cytological tion of Ceratopteris thalictroide s(L. B)rongn. J.
study of diploid sin Ceratopter imsay reveal an P a l ,SI.n d1i9a5n9 B. Coth. rSoomc.o s35o:m2e 5n2u-mb2e5r6. in (leratopte sriilisqtt-
outline ofthe origin ofthe south type and the other osa (L. C)opel .Curr, ScL 28: 455-456,
two types in C. thalictroides. Pal ,N. & S. Pal .1963 .Studie son rnorphology and aran-
it yofthe Parlceriac eIale .S.porogenesis ,development
Wc are indebted to Dr. Kuniaki Watanabe of Kobe of the gametophyte ,and cytolegy of Ceratopteris
Universi tfyor his valuable suggestions on the meiotic con- thalictroicl eBso,t, Gaz. 124: 405-412.
figuratio onbtsained in this study. Watanabe, K. 198 1 . Studies on the control ofdjploid-like
meiosis in polyploid taxa of ChTlysanthemum I,
References Hexaploi dCh.ymponens eNakai. Cytologi a46: 459-
498.

Watano, Y & S.Masuyama.1994,Geneticdifferentiation
D r i sMcIaoStl9hl- e,1Cm6.a 9t.Ji., cGs o.f Hc.hr oGmoosrodmeon & p aGi,r iKni gmG,beenre, t1i9 c89s05.: ithn ap loipc utlr oait die osin no sfJ atphae np .o Jl. yPmloar pnht Rice sf ,e1 r0 7nC:e1r3a9t-o1p4t6e.ri,y

Received,inn 3e, 2005; aecqptedJuly 22, 2005
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