Bol.Soc. Argent.Bot. 35 (3-4): 269-273. 2000
CYTOLOGICAL
NOTES
ONFIVE
SPECIES
OFTHEGENERA
DANAEA
ANDADIANTUM
(PTERIDOPHYTA)FROMNORTHEASTERN
BRAZIL*
ANA MARIA BENKO-ISEPPON1 and ELIZABETHRODRIGUES
DA FONSÊCA DIAS2
Summary:Cytologicalobservations -includingchromosome number, size, condensingbehavior andtypeof interphasenuclei-are givenfor fivespecies ofthegeneraDanaea (Maratiaceae)and Adiantum(Pteridaceae)
collected inthe Gurjaú Natural Reserve, an areaofAtlanticforest inthe state ofPernambuco, Brazil. Both Danaeaspeciesstudied (D. nodosa,2n =160andD.elliptica,2n=158-160) aretetraploidconfirming the base numberx =40, previouslyproposedforthegenus. The sameploidylevelwas found for three analyzed speciesofthegenusAdiantum(A.glaucescens,2n =118-120;A.obliquum, 2n =120,andA.pulverulentum,
2n =120), considering thebasenumberx=30 previously suggestedforthegenus. All analyzedspecies
presented semi-reticulated interphasenuclei andhomogeneouscondensing behaviorin prophase to prometaphase.Onthe base ofkaryologicaldata,thehypothesisthat the genus Danaeashould be isolated
fromtheMaratiaceae inan own family (Danaeaceae) is not supported,since bothtaxa presentsimilar
chromosome numbers and thesame base number (x=40). ' Keywords: chromosomes,Pteridophyta,Danaea, Adiantum,Northeastern Brazil.
Resumo: Notascitológicaspara cinco espécies dosgênerosDanaeae Adiantum ( Pteridophyta)do nordeste
Brasileiro.Observações citológicasincluindo númeroe tamanhocromossômico, comportamentodecondensação
ecaracterizaçãodos núcleosinterfásicos são fornecidaspara5 espéciesdos gênerosDanaeae Adiantum, coletadasna Reserva Natural de Gurjaú, urnaárea preservadadeflorestaAtlánticano estado de Pernambuco, Brasil. As duas espécies do géneroDanaea estudadas(D. nodosa,2n =160eD.elliptica,2n =158-160) são
tetraplóides, confirmandoonúmero básicox=40,propostoanteriormente paraogênero. Omesmonivel de ploidiafoiobservadoparatrês espéciesdogêneroAdiantum (A.glaucescens, 2n =118-120; A.obliquum, 2n=120e A. pulverulentum, 2n =120), considerando-se o númerobásico x =30,previamentesugeridopara ogênero.Todasasespéciesanalisadas apresentaram núcleosinterfásicossemi-reticuladosecomportamento
decondensação homogéneonas fases deprófaseà prometáfase.Do ponto devistacariológico,a hipótese de queo gênero Danaea deveria ser isoladoda família Maratiaceaeem uma famíliaà parte (Danaeaceae) não pôdeser confirmada, em vista dasemelhançade números cromossômicose por apresentar o mesmo
número básico(x=40).
Palavras-chave: chromosomos,Pteridophyta,Danaea, Adiantum,Nordeste Brasileiro.
INTRODUCTION
thepaleotropics, mainly in índia and Himalayas(Sharma, 1996).
The first report oncytological data regarding. neotropical Pteridophytawasgivenby Walker(1966)
which,together with other information about the ferns of Jamaica,reported chromosome numbers for 270ofthe about540 species of this island. Other works contributed forabetterunderstanding ofthe cytogeneticsof CentralAmerican pteridophytes,as the workof Wagner(1980)with ferns ofCostaRica and the studies of Walker(1985)including155 spe¬ cies of Trinidad. The cytogenetics of the South American fernsis,onthecontrary,scarcely known (Walker,1984). Sotadelaet al. (1987) studied3 species of Argentina belonging to the genera Microgramma and Thelypteris. The only known study including Brazilianspecieswascarriedoutby The ferns are arepresentative group ofplants
including about 10,000-13,000 speciesamong the Pteridophyta. A very common trend in the cytoevolution of ferns seems tobe the polyploidy, observedin about90%of thepreviously studiedspe¬ cies (Walker, 1979,1984).Walker (1984) estimated that only 2,500 (19-25%) of the known fern species had been analyzed. Many of thesearedistributed.in
* Dedicated to Prof.Dr,Juan H. Hunzikeron the ocassionof his75th anniversary.
1Universidade Federal de Pernambuco, CCB/Genética,Av.
Prof.MoraesRego,s/no.,CEP 50732-970, Recife,PE, Brazil.
Author for correspondence,e-mail:celisep@hotlink.com.br
2Universidade Federal de Pernambuco, CCB/Botânica, Recife,
Bol. Soc. Argent. Bot. 35 (3-4)2000
Morawetz &Samuel (1988).The chromosome sizes (maximalvalues in pm) wereestimated from the negative films usingamicrometric scale in thesame enlargement.PhotomicrographsweretakeninLeitz microscope with Agfa CopexPanfilm and enlarged inKodakKodabromide F3 orAgfaBrovira BN-4 andBW-5 paper.
Tiyonetal. (1975), including 11species of 4genera (
Schizala,
Trichomanes, Pityrogramma, and Lindsala) collected in the neighborhood of Manaus in thestateof Amazonas.Thepresent work aimstobring cytological in¬ formation concerning the genera Adiantum and
Danaea fromthe Atlantic forest of Pernambucoin
the northeastern Brazilian region.
RESULTS
MATERIAL
ANDMETHODS
The cultivation of the collected fernswasdiffi¬ cult. Of 19 plants of 10 speciescollected,only eight individuals of four speciessurvived.The best fixa¬ tionswereobtained from plants preserved in there¬ frigeratorforoneday withmeristematic tissuecol¬
lected andpretreated in the following day. Fixations donedirectlyin the field (withorwithoutpretreat¬ ment)presented only interphase nuclei andsome , prophases.
Chromosome numbers are summarized in Table 1 and illustrated in Fig. 1. All studied plants presented semi-reticulatedinterphasenuclei. In the genusDanaea(Fig. 1 A), fourtoeight larger
andmany small sharp delimited chromocenters could be observed presentingveryregulardistri¬ bution. On the opposite, the three analyzedspe¬ cies of Adiantum presented nebulous chro¬ mocenters exhibitingcloud-like formations in which two to four darker regions could be ob¬ served(Fig.1 B).
Ingeneral,thechromosomecondensingbehavior washomogeneous (Fig. 1C-E)withsomedarker,mostly interstitial regions, especially inDanaea(Fig. 1 D-E).
Evenafter different pretreatmenttimes with colchicine and 8-hydroxyquinoleine completelycon¬ densedmetaphase chromosomes with easilyrecog¬ nizable constrictions couldnotbe seenandmost
countshave been carriedoutinprometaphases. In thisstage,thechromosome sizewassimilar for both The studied specieswerecollectedinthe Gurjaú
Reserveinthe cityof Cabo,stateofPernambuco,
NortheasternBrazil. A list of the studied plants is giveninTable 1. Voucher specimensweredeposited inthe herbarium UFP of the Universidade Federal dePernambuco, Centro de Ciências Biológicas, Departamentode Botânica (Recife,Pernambuco,
Brazil).
Livingplantswerecollected togetherwith their substrata in dark plastic bags.Mostplantswerecul¬ tivated in the glasshouses of the Department of Ge¬ netics while other had theirroottips andapical mer-istems collected andpre-treatedimmediately inthe field. Somehave been maintained forasingle day inthe refrigerator and had their apical androot meristems collected and pretreated early in the fol¬ lowing day.
Youngroottipsormeristematic tissue of bacula primordiawerecollected andpretreated with 2 mM of 8-hydroxyquinoleineat 10-12 °C for 5-24 hor
0.2 %colchicine at2-5°C for 4-7h and fixed in Camoy (ethanol:acetic acid, 3:1).
Conventional
chro¬ mosome staining with Giemsaproceededas de¬ scribed by Guerra (1983), with modifications de¬ scribed byBenko-Iseppon & Morawetz (2000). De¬ scriptions of interphase nuclei followed thesystems ofD,elay (1947) and Guerra (1985). Classification ofthe chromosome condensing behavior followedTable1.Taxastudiedwithcollector,vouchernumber,andchromosomenumbers. Chromosome
number(2n) Taxon Collector,Voucher Number
Maratiaceae Danaea
BllipticaSm. inRees Fonsêca28, UFP-8324 158-160
nodosa(L.)Sm. Fonsêca13, UFP-8337 160
Pterldaceae
Adiantum
obliquumWilld. Fonsêca &Barros174,UFP-8352 120
qlaucescensT. Moore Fonsêca &Barros183,UFP-8381 118-120.
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Interphase nuclei and chromosomes ofDanaea (A,D-E) andAdiantum (B-C), after Giemsa standard staining. A:Interphasenuclei ofD. nodosa. B: Interphase nuclei of A.pulverulentum.C: Prometaphases of A. glaucescens. D: D.elliptica.E:D. nodosa. ArrowheadBol. Soc. Argent. Bot. 35(3-4)2000
Danaea species, withmaximal sizes varying from inthepresent work and considering the grade of 1.3to4.8 pm.Thechromosome size oftheanalyzed difficultytoobtaingood chromosome spreads-and
Adiantum species(Fig. 1 C) waslarger than that consequentlyaccurate chromosomenumbers-this
observedinDanaea(Fig. 1 D-E), having less size concept ofputative aneuploidracesinAdiantum variationwithin the chromosomecomplement (from should be revised.
4.0 to 5.2 pm). Sometimes in Adiantum
pulverulentum, smallfragments (ca.1.6 mm)could obliquum are new reports. Itis noteworthy that be observed andwererecognizedasreleased satel- the Adiantumspecies here studiedaretetraploid, lites (Fig. 1 C). Accurateanalysesofchromosome contrasting with theliterature which reveals a
morphology were not possible,, since only higher frequencyofspecies with 2n=60forthe
prometaphases could be observed. In spite ofthat, Central American and also for thepaleotropical
manychromosomeswithprimary constrictions could regions (Kawakami, 1981;Walker,1985; Katoet beseen,mostofthem identifiedassubmetacentric al., 1992).
inDanaeaandacrocentricinAdiantum.
Thecounts forAdiantumglaucescensand A.
Both generapresenthomogeneous condensing behavior andsemi-reticulate interphasenuclei,but
diverge remarkablyregardingthe form anddistri¬
bution of chromocenters.This isnotsurprising,since theyarepositionedindifferent familiesandorders.
Thereare nopreviousobservationson
chromo-DISCUSSION
Thechromosomenumbers observed for both spe¬
cies ofthe genus Danaea agreewith previouslyre- somesize and morphology for both genera. It isre¬
portedmeioticnumbers fortwopopulations of the markable that both Danaea speciesare similarin
samespecies collectedinTrinidad (n=ca. 80and theseaspects.The sameobservationapplies tothe n=80,respectively) and also with the numbersgiven three Adiantum species, which grow sympatric in
for D. jenmanii L. Underw. from Jamaica and D. the-GmjaúReserve. Thiscouldbeanindicationthat,
simplicifoliafrom Suriname (Walker, 1985).
Walker (1985) suggested the
separation
ofthe number,therearemechanisms preventingthe hy-genus Danaea fromthe Maratiaceae,placing it inan bridization between thesespecies.isolated family (Danaeaceae)onthebasisofmor¬ phologicaland geographic evidences. This hypoth¬
esiscanbenotsupportedby thecytological data,since
CONCLUSIONS
inspite of thesimilarities in chromosomesize and
the basenumberx =40is similarlyobservedin
Danaea and inthe Maratiaceaeingeneral (e.g.,
Walker,1979, 1984; Smith &Mickel,1977).
Danaeaspecies studied(D.nodosa,2n= 160,
and D. elliptica, 2n=158-160)aretetraploid, con-Westudied three species ofAdiantum,all of them
firming
the base numberx=40.Bothspeciespresenttetraploid,consideringthe basenumberx=30 pro- comparablechromosomesizes (from 1.3to4.8pm) posed by Walker (1985). Previousreports onchro- andmorphology.
mosomenumbers of A. pulverulentum revealed2n
=60for twopopulations(Jamaica-Walker, 1973-and Trinidad-Walker,1985) suggestingtheexist¬
ence of different cytotypesbetweeri the Central American and Brazilian populations analyzed. In¬
terestingly,asingleoctoploid-dysploidindividual wasalso foundinTrinidad (n=122; 8x+2;Walker,
Adiantum speciesanalyzed(A.glaucescens, 2n =118-120, A.obliquum,2n=120,and A.
pulvè-rulentum,2n=120) aretetraploid, considering the base numberx=30. All ofthempresentchromosomes withless size variation (from 4.0to5.2 pm).
Allanalyzedspecies presented semi-reticu¬ latedinterphasenuclei and homogeneous condens-Walker(1984)postulated the base numbersx= ingbehaviorinprophasetoprometaphase. Both
gen-29,30,31withpredominance ofx=30.The author era differregarding the chromocenters. They are observed thatAdiantummaybeunique within pteri-
.
regularly distributed and sharply delimited indophytes intheextenttowhich aneuploidy abounds Danaea. In Adiantum theyconstituted cloud like and is frequently undetectablemorphologically.In formations inwhichtwotofourdarker regions could view of the frequent detachment of satellitesreported be observed.
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WALKER, T. G. 1979. TheCytogenetics ofFerns.In:DYER, A. F. (ed.),The ExperimentalByologyofFerns, pp. 87-132. Aca¬ demic Press, London.
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Recibidoel17deNoviembrede2000,aceptadoel30deNoviembrede2000. Thehypothesis that thegenus Danaeashould
be isolated from the Maratiaceae inan ownfamily (Danaeaceae)isnotsupportedby the karyological evi¬ dences, since itpresentssimilar chromosomenumbers and thesamebasenumber (x=40).
ACKNOWLEDGEMENTS
Wethank Dr.IvaCarneiro Leão and Dr. Marcelo Guerra for valuable suggestions and interesting dis¬ cussions. This study was supported by FACEPE (Projectno.
APQ.
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