Botanical Journal of the Linnean Society, 2016, 181, 532–541. With 3 figures
Chromosomal features of Fosterella species
(Bromeliaceae, Pitcairnioideae)
1
Departamento de Gen
etica, Centro de Ci^
encias Biol
ogicas, Universidade Federal de Pernambuco, CEP
50670-420 Recife, PE, Brazil
2
Department of Sciences, Institute of Biology, University of Kassel, D-34132 Kassel, Germany
Received 9 August 2015; revised 1 December 2015; accepted for publication 20 January 2016
Fosterella (Bromeliaceae) comprises 31 species with rosulate leaves and mostly small, whitish flowers. Previous
karyological studies were restricted to chromosome counts. In the present study, chromosomal variation in
Fosterella was analysed using CMA3/DAPI staining and/or fluorescence in situ hybridization (FISH) using 45S
and 5S rDNA probes, generating data for nine taxa with either 2n = 50 or 100 chromosomes. A single
chromosome pair containing one CMA+/DAPI band was identified in all diploid species. In the tetraploid
Fosterella hatschbachii one pair had a CMA+/DAPI band, whereas the other tetraploid studied, Fosterella
yuvinkae, had two pairs with proximal bands. The presence of two CMA+/DAPI pairs in F. yuvinkae may
indicate a recent polyploidization event. This paper also reports the application of FISH in Bromeliaceae. FISH
using 45S rDNA as the probe revealed one pair of terminal sites in most species and a co-localization with CMA+/
DAPI bands in all analysed species. The 5S rDNA sites were terminal in the tetraploid F. hatschbachii and
proximal in all other species studied. Our data indicate that Fosterella species have little heterochromatin and it
is largely restricted to the vicinity of the nucleolus organizer region. The data also indicate that
hybridization (sometimes associated with polyploidy) has probably played an important role in the evolution of
Fosterella. © 2016 The Linnean Society of London, Botanical Journal of the Linnean Society, 2016, 181, 532–541
ADDITIONAL KEYWORDS: diploidization – fluorescence in situ hybridization – NOR-associated
heterochromatin – polyploidy – rDNA sites.
INTRODUCTION
Bromeliaceae are among the major families of
Neotropical plants, with c. 3300 species in 58 genera (Luther, 2012). The natural distribution area of
the family ranges from the south-eastern United
States south to northern Chile and Argentina. A
single species is found in West Africa [Pitcairnia
feliciana (A.Chev.) Harms & Mildbr.], where it
probably arrived as a consequence of long-distance
dispersal (Jacques-Felix, 2000; Givnish et al., 2004).
Representatives of Bromeliaceae generally have
showy inflorescences and leaves arranged in
rosettes that often form a water and nutrient
reservoir, a so-called tank (Benzing, 2000). Waterimpounding tanks not only confer tolerance to
*Corresponding author. E-mail: brasileirovidal.ac@gmail.com
532
drought, but they also constitute a microenvironment inhabited by a variety of animals, such as
ants, frogs, arachnids and snakes (Reitz, 1983;
Benzing, 2000).
According to the most recent classifications by
Givnish et al. (2007, 2011), Bromeliaceae are
divided into eight monophyletic subfamilies, Brocchinioideae, Lindmanioideae, Navioideae, Tillandsioideae, Hechtioideae, Puyoideae, Bromelioideae
and Pitcairnioideae. Fosterella L.B.Sm. belongs to
the last of these, in which it forms a well-supported monophyletic group (Rex et al., 2009; Givnish et al., 2011). The genus comprises 31 species
distributed from southern Argentina to northern
Peru, with a disjunction in Mexico and a centre of
diversity in the Bolivian Andes (Rex et al., 2009;
Wagner et al., 2013). Fosterella species are terrestrial herbs with small leaves arranged in rosettes
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~ VASCONCELOS1, ANA
HEVILA
MENDES DE LIMA SILVA1, EMANUELLE VARAO
1
2
MARIA BENKO-ISEPPON , NATASCHA WAGNER , KURT WEISING1 and ANA
CHRISTINA BRASILEIRO-VIDAL1*
CHROMOSOMES OF FOSTERELLA
MATERIAL AND METHODS
PLANT MATERIAL
Chromosome numbers were counted for 11 accessions from nine Fosterella species. Eight of these species were analysed by CMA3/DAPI staining and
seven by FISH (for details see Table 1). Seeds or
fixed roots were sampled from the living collection
kept at the Institute of Biology, Department of
Sciences, University of Kassel (Kassel, Germany),
and were preserved in the germplasm collection of
the Laboratory of Plant Genetics and Biotechnology,
Department of Genetics, UFPE (Pernambuco, Brazil). Vouchers of the analysed accessions have been
deposited in the herbaria listed in Table 1.
PREPARATION
AND STAINING OF METAPHASE CHROMOSOMES
For mitotic chromosome preparations, root tips
obtained from plants cultivated in pots or from germinated seeds were pretreated with 2 mM 8-hydroxyquinoline at 8 °C for 24 h, fixed in absolute ethanol/glacial
acetic acid (3:1, v/v) for 6 h at room temperature, and
stored at 20 °C until use. Fixed materials were
washed three times in distilled water, followed by
digestion in a 2% (w/v) cellulase (Onozuka R-10, Serva)
and 20% (v/v) pectinase (Sigma-Aldrich) solution for
5 h at 37 °C. Slides were prepared according to Carvalho & Saraiva (1993), with minor modifications. After
staining with DAPI solution (2 lg mL–1)/glycerol (1:1,
v/v), slides were destained and fixed in ethanol/glacial
acetic acid (3:1, v/v) for 30 min and transferred to absolute ethanol for 1 h, both at room temperature. After
air drying, the best slides were stored at 20 °C until
further experiments were performed.
Chromosome staining with DAPI allows characterization of AT-rich (DAPI+) or AT-poor (DAPI–) heterochromatic regions, and CMA3 preferentially binds to GC-rich
DNA (CMA3+) (Schweizer, 1976; Barros e Silva &
Guerra, 2010). For CMA3/DAPI staining, air-dried slides
were aged for 3 days at room temperature. Staining was
then performed with CMA3 (0.5 mg mL 1, 1 h) and
DAPI (2 mg mL 1, 30 min), mounted in McIlvaine’s
buffer (pH 7.0)/glycerol (1:1, v/v) and stored for another
3 days (Schweizer & Ambros, 1994). After image capture, slides were destained as previously described and
stored at 20 °C for use in FISH experiments.
RDNA PROBES
The probes for FISH were R2, a 6.5-kb fragment of the
18S–5.8S–25S rDNA repeat unit from Arabidopsis
thaliana (L.) Heynh., and D2, a 400-bp fragment containing two 5S rDNA repeats from Lotus japonicus
(Regel) K.Larsen (Pedrosa et al., 2002). Plasmids were
isolated using the Plasmid Mini Kit (Qiagen) and
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and mostly whitish flowers. The fruit is a dehiscent
capsule that releases winged, wind-dispersed seeds
upon dehiscence (Ibisch et al., 2002; Peters, 2009).
Fosterella differs from closely related genera by
having nude petals and anthers that join the filament at their base (Ibisch et al., 2002). Molecular
phylogenetic analyses based on plastid DNA have
shown that Fosterella is subdivided into six wellsupported evolutionary lineages (Rex et al., 2009;
Wagner et al., 2013).
To date, chromosome counts are available for
only c. 10% (c. 390 species) of species of Bromeliaceae (Gitaı et al., 2014) and triple staining with
the fluorochromes chromomycin A3 (CMA3), actinomycin and 40 ,6-diamidino-2-phenylindole (DAPI) has
only been carried out in three species (Gitaı, Horres & Benko-Iseppon, 2005). This scarcity of data
reflects the difficulty of analysing extremely small
chromosomes, which in the family range from 0.21
to 2.72 lm (Zanella et al., 2012). The basic chromosome number in the vast majority of species of
Bromeliaceae is x = 25, with the majority of species
analysed being diploids (68% of analysed species).
Nevertheless, polyploids have been reported for
several genera from three of the eight subfamilies
of Bromeliaceae. Tetraploids (12 species) have been
observed in Tillandsioideae, and tetra- and hexaploids have been found in Bromelioideae (nine tetraploids and three hexaploids) and Pitcairnioideae
(six tetraploids and two hexaploids). Further polyploids will probably be detected if additional species are analysed (Gitaı et al., 2014).
In Pitcairnioideae, chromosome counts indicative
of polyploidy have so far been reported for some species of Fosterella (Delay, 1947a, b; Brown & Gilmartin, 1986; Brown, Palacı & Luther, 1997) and
Deuterocohnia Mez and Pitcairnia L’Her. (Gitaı
et al., 2005, 2014). In Fosterella, chromosome numbers have so far been determined in just six accessions from four species, with three polyploid
accessions: (1) F. penduliflora (C.H.Wright) L.B.Sm.
(one diploid accession, 2n = 2x = 50; one tetraploid,
2n = 4x = 100; and one hexaploid, 2n = 6x = 150); (2)
F. rusbyi (Mez) L.B.Sm. (2n = 2x = 50); (3) F. villosula (Harms) L.B.Sm. (2n = 6x = 150); and (4) F. weberbaueri (Mez) L.B.Sm. (2n = 2x = 50) (Delay,
1947a, b; Brown & Gilmartin, 1984, 1986, 1989;
Brown et al., 1997).
In the present work, we applied CMA3/DAPI
staining of metaphase chromosome preparations
from nine Fosterella species and fluorescence
in situ hybridization (FISH) with 5S and 45S
rDNA probes to reveal additional features of infrageneric chromosomal diversity in Fosterella. In
addition, we report new chromosome counts for
eight species.
533
534
SILVA ET AL.
Table 1. Analysed species of Fosterella with specimen numbers of permanent herbarium vouchers, phylogenetic groups
(according to Rex et al., 2009; Wagner et al., 2013), ploidy (PL), chromosome numbers (2n), quantity and localization of
CMA+ bands, and 45S and 5S rDNA sites
PL 2n
CMA+
(pair)
B, WU, HEID, albicans
CUZ, LPB
2x 50
1 terminal 1 terminal 1 proximal 1A/2A
KAS, LPB
micrantha
2x 50
1 terminal 1 terminal 1 proximal 1B/2B
P. Ibisch & LPB, FR, SEL, micrantha
C. Nowicki
USZ, WU
98.0173
NiSch
CICY, KAS
micrantha
11-12
2x 50
1 terminal 1 terminal 1 proximal –
2x 50
1 terminal n.a.
Specimen
Herbarium
F. robertreadii
Ibisch &
J. Peters
F. christophii
Ibisch, R.V
asquez
& J. Peters
F. christophii
Ibisch, R.V
asquez
& J. Peters
F. micrantha
(Lindley)
L.B. Smith
F. gracilis
(Rusby)
L.B. Smith
F. floridensis
Ibisch &
E.Gross
F. hatschbachii
L.B. Smith &
R.W. Read
F. rusbyi (Mez)
L.B.Smith
F. spectabilis
H. Luther
F. spectabilis
H.Luther
F. yuvinkae
Ibisch,
E. Gross &
Reichle
Rauh
20866
NW
09.030
Group
45S rDNA 5S rDNA
(pair)
(pair)
n.a.
Figures
CMA/FISH
1C/–
NW
09.022
LPB, KAS
penduliflora 2x 50
1 proximal 1 proximal 1 proximal 1D/2C
NW
09.003
LPB, KAS
rusbyi
2x 50
n.a.
Leme
7100
KAS
rusbyi
4x 100 1 proximal 1 proximal 1 terminal 1E/2E
NW
09.009
Peters
06.0048
Peters
06.0046
Reichle
P-SR1
LPB, KAS
rusbyi
2x 50* 1 proximal 1 proximal 1 proximal 1F/2F
FR
rusbyi
2x 50
1 terminal n.a.
LPB
rusbyi
2x 50
1 terminal 1 terminal 1 proximal 1G/2G
LPB
rusbyi
4x 100 2 proximal n.a.
1 terminal n.a.
n.a.
n.a.
–/2D
–
1H/–
B, Herbarium Berolinense, Botanical Garden Berlin, Germany; CICY, Herbarium of the Centro de Investigaci
on
Cientıfica de Yucat
an, Mexico; CUZ, Vargas Herbarium of the University of Cuzco, Peru; FR, Herbarium Senckenbergianum Frankfurt/Main, Germany; HEID, Herbarium of the Botanical Garden Heidelberg, Ruprecht-Karls-University,
Germany; KAS, Herbarium of the University of Kassel, Germany; LPB, Herbario Nacional de Bolivia, Universidad
Mayor de San Andr
es, La Paz; SEL, Marie Selby Botanical Gardens, Sarasota, Florida; USZ, Herbario del Oriente Boliviano, Museo de Historia Natural Noel Kempff Mercado, Universidad de Santa Cruz (Aut
onoma Gabriel Ren
e Moreno);
VASQ, Herbarium Vasquezianum, Santa Cruz, Bolivia (private collection Roberto Vasqu
ez); WU, Herbarium of the
University of Vienna, Institute of Botany, Austria; n.a., not analysed.
*Chromosome number reported by Brown & Gilmartin (1984, 1989).
labelled by nick translation with digoxigenin-11-dUTP
and biotin-11-dUTP (both from Roche Diagnostics) for
45S and 5S rDNA, respectively. The manufacturers’
instructions for the kits were followed throughout.
FLUORESCENT
IN SITU HYBRIDIZATION
FISH pretreatment washes were based on PedrosaHarand et al. (2009), in which the 77% stringency
wash was performed with 0.19 saline sodium citrate
(SSC) at 42 °C. Chromosome and probe denaturation
and detection were performed according to HeslopHarrison et al. (1991). The hybridization mixture,
containing 50% (v/v) formamide, 29 SSC, 10% (w/v)
dextran sulphate and 5–10 ng lL 1 of that probe,
was denatured at 75 °C for 10 min. Each slide
received 10 lL of the hybridization mixture and was
hybridized for at least 48 h at 37 °C. Digoxigenin- or
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Species
CHROMOSOMES OF FOSTERELLA
biotin-labelled probes were detected using conjugated
anti-digoxigenin rhodamine (Roche Diagnostics) and
Alexa Fluor-conjugated streptavidin (Invitrogen),
respectively, in a solution containing 1% (w/v) bovine
serum albumin. Preparations were counterstained
and mounted with 2 lg mL 1 DAPI in Vector’s Vectashield (1:1, v/v).
ANALYSIS
Images of the best preparations were acquired using
a Leica DMLB epifluorescence microscope and a
Leica DFC 340FX camera with the Leica CW4000
software. Images were pseudo-coloured and optimized for contrast and brightness with the Adobe
Photoshop CS4 software (Adobe Systems).
RESULTS
A summary of the results obtained in the present
work is provided in Table 1. Chromosome counts
of the eight new analysed Fosterella species
revealed six diploid species (2n = 2x = 50) and
two tetraploid species (F. hatschbachii L.B.Sm. &
R.W.Read and F. yuvinkae Ibisch, E.Gross & Reichle,
2n = 4x = 100). Additionally, 2n = 2x = 50 chromosomes was found for F. rusbyi, as previously
described by Brown & Gilmartin (1984, 1989) (Supporting Information, Fig. S1).
Representative results obtained by CMA3/DAPI
staining (eight species) and FISH (seven species) are
shown in Figures 1 and 2, respectively. CMA3/DAPI
staining allowed the identification of one pair of
CMA+/DAPI (i.e. GC-rich heterochromatin) bands in
all diploid species (Fig. 1A–D, F, G), mostly in the terminal region. The exceptions are F. gracilis (Rusby)
L.B.Sm. and F. rusbyi, which had a pair of proximal
bands (Fig. 1D, Table 1). With regard to the tetraploid
species, in F. hatschbachii one pair of CMA+/DAPI
bands was evident in the proximal region (Fig. 1E),
whereas in F. yuvinkae two proximal pairs were
observed (Fig. 1H). For the latter species, different
chromosome sizes and band positions could be discerned (considering their distance from the telomere).
The FISH procedure revealed a single chromosome
pair carrying 45S and 5S rDNA in all analysed species, including the tetraploid F. hatschbachii
(Fig. 2E). Furthermore, 45S rDNA sites were co-localized with CMA+/DAPI bands (compare Figs 1B and
2B, 1E and 2E, and 1G and 2G). These results indicate that in Fosterella CMA+/DAPI heterochromatin
is exclusively associated with the nucleolus organizer
region (NOR).
The 45S rDNA signals were generally located in
terminal regions, except for F. gracilis (2n = 50;
Fig. 2C), F. hatschbachii (2n = 100; Fig. 2E) and
F. rusbyi (2n = 50; Fig. 2F), which displayed
hybridization signals at proximal sites. In contrast,
the 5S rDNA sites were generally located in the
proximal chromosome regions (Fig. 2A–D, F, G), with
the exception of F. hatschbachii (Fig. 2E) which displayed 5S rDNA sites in terminal regions.
DISCUSSION
Until now, there have been only a few cytogenetic
studies of the genus Fosterella, with previous reports
restricted to counts of meiotic bivalents or mitotic
chromosomes of four species (six accessions) (Delay,
1947a, b; Brown & Gilmartin, 1984, 1986, 1989;
Brown et al., 1997). Chromosome counts for eight
additional species are provided in the present work
(six diploids and two tetraploids), supporting previous studies concerning the predominance of diploid
species and confirming x = 25 as the basic chromosome number for the group (Brown & Gilmartin,
1984, 1986, 1989).
Fosterella species have high numbers of small
chromosomes (2n = 50, 100, 150), and this severely
complicates counting them and analysis by classical
and molecular cytogenetic techniques, such as FISH.
The latter technique was applied for the first time to
chromosomes of Bromeliaceae in this work.
Studies with base-specific fluorochromes have been
performed only in three species of Bromelioideae so
far. For two of them [Greigia sphacelata (Ruiz &
Pav
on) Regel and Ochagavia litoralis (Philippi)
Zizka, Trumpler & Zoellner, both with 2n = 50], the
presence of one pair of CMA+/DAPI bands was
reported (Gitaı et al., 2005), which is the same as the
CMA3/DAPI data obtained for the diploid species in
this work. In contrast, two pairs of CMA+/DAPI
bands were observed in metaphases of the diploid
Aechmea bromeliifolia (Rudge) Baker (Gitaı et al.,
2005), whereas in the present study two pairs of
CMA+/DAPI bands were observed only in the tetraploid F. yuvinkae. Two pairs are actually expected in
tetraploid species (2n = 4x = 100), but this feature
did not hold for the other tetraploid studied,
F. hatschbachii, which only had a single pair of chromosomes carrying CMA+/DAPI bands.
The FISH technique revealed that the number of
rDNA sites in Fosterella is well conserved, as all
analysed species had one pair of chromosomes carrying 45S rDNA and one pair carrying 5S rDNA for
diploid cells. The only exception was F. hatschbachii,
which had one pair of sites for each marker for
tetraploid cells. A similar conservation of rDNA
site number was observed when diploid and polyploid subspecies of Paspalum quadrifarium Lam.
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DATA
535
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SILVA ET AL.
B
C
D
E
F
G
H
Figure 1. Metaphase chromosomes of diploid (A–D, F–G) and tetraploid (E, H) Fosterella species stained with CMA
(yellow) and counterstained with DAPI (pseudocoloured in grey). A, F. robertreadii; B, F. christophii; C, F. micrantha;
D, F. gracilis; E, F. hatschbachii; F, F. rusbyi; G, F. spectabilis; H, F. yuvinkae. Arrows point to CMA3+ bands. Dotted
lines indicate distended secondary constrictions in H. The bar in H represents 5 lm.
(Poaceae; Vaio et al., 2005) and species of Daucus L.
(Apiaceae; Iovene et al., 2008) and Iris L. (Iridaceae;
Lim et al., 2007) were compared with each other.
The results obtained here for the tetraploid F.
hatschbachii could perhaps be explained by an ongoing diploidization process, possibly following silencing of some of the duplicated genes (Soltis & Soltis,
1999; Adams, Percifield & Wendel, 2004; see below).
If this explanation is correct, then the observation
that F. yuvinkae has two pairs of CMA+ bands suggests it might be a more recent polyploid than
F. hatschbachii. This suggestion is reinforced by the
observation that in F. yuvinkae both proximal CMA+
bands were observed on chromosome pairs that differ
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A
CHROMOSOMES OF FOSTERELLA
A
B
537
C
E
F
G
Figure 2. Fluorescence in situ hybridization of 45S (green) and 5S (red) rDNA probes in metaphase chromosomes of
Fosterella species counterstained with DAPI (pseudocoloured in grey). A, F. robertreadii; B, F. christophii; C, F. gracilis;
D, F. floridensis; E, F. hatschbachii; F, F. rusbyi; G, F. spectabilis. Arrows and arrowheads indicate 45S and 5S rDNA
sites, respectively. The bar in G represents 5 lm.
in size. This could in turn indicate that F. yuvinkae
arose from a hybridization step followed by allopolyploidy. If so, then this represents the first clear docu-
mented example of allopolyploidy in Bromeliaceae
that is supported by karyological evidence. Mirzaghaderi, Houben & Badaeva (2014) observed a
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D
538
SILVA ET AL.
similar size polymorphism for 45S rDNA sites in the
allotetraploid Aegilops triuncialis Ledb. ex Trautv.
(Poaceae) and suggested that the signal size reduction could be the result of a suppression of NORs
after hybridization.
It is well known that polyploid plants have a tendency towards returning to their original monoploid
DNA content during evolution. This process, named
diploidization (Wolfe, 2001; Leitch & Bennett, 2004;
Leitch et al., 2008), has been investigated in some
detail in soybean [Fabaceae, Glycine max (L.) Merr;
Schmutz et al., 2010]. Apparently, soybean has a
partially diploidized tetraploid genome, which is the
product of a diploid ancestor (n = 11) that later
underwent aneuploidy (n = 10), polyploidization
(n = 20) and diploidization (n = 20) (Shultz et al.,
2006; Schlueter et al., 2007; Schmutz et al., 2010).
Diploidization has been observed most often in polyploids that formed some time ago and hence have
had a sufficiently long time for evolutionary divergence [e.g. see evidence from FISH with a 45S rDNA
probe in Avena L. (Linares et al., 1996), Nicotiana L.
(Kovarik et al., 2008) and Aristolochia L. (Berjano
et al., 2009)]. In allopolyploids of Nicotiana, silencing
of 45S rDNA from one parent was confirmed to have
taken place during evolution, pointing to gene silencing as the major agent in the diploidization process
in the group (Kovarik et al., 2008). Additionally, if
transposable elements are found to be associated
with the rDNA sites, it is possible that they may contribute to the elimination of rDNA sequences. Such a
mechanism has previously been suggested as a
possible explanation of how rDNA sites were lost in
an allotetraploid species of Arabidopsis Heynh. in
Holl & Heynh. (Pontes et al., 2004) following
polyploidization.
The chromosomal localization of CMA+/DAPI
bands and 45S rDNA sites shows a certain preference for terminal regions, with some exceptions. In
angiosperms, a tendency has been observed towards
the localization of 45S rDNA sites in the terminal
region of the short arm, generally occupying the
whole short arm in acrocentric chromosomes, and of
5S rDNA sites in proximal regions (Roa & Guerra,
2012). A hypothesis for the preferentially terminal
position of the 45S rDNA was suggested in an
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Figure 3. Chromosomal positions of CMA+ bands and 45S and 5S rDNA sites for the studied Fosterella species, mapped
onto the proposed phylogenetic tree for the genus (modified from Wagner et al., 2013). Blocks in yellow indicate CMA+/
DAPI bands, blocks in green indicate 45S rDNA sites co-localized with CMA+/DAPI bands, and blocks in red indicate
5S rDNA sites.
CHROMOSOMES OF FOSTERELLA
CONCLUSIONS
In view of the data presented from both the current
work and the literature, the karyological features in
Fosterella can be summarized as: (1) a prevalence
for speciation at the diploid level, although polyploids can also arise (e.g. F. yuvinkae which may
have arisen through allopolyploidy and hybridization); (2) 2n = 50, 100, 150 corroborating x = 25 as
the basic chromosome number for Fosterella; (3) low
amounts of GC-rich heterochromatin (CMA+/DAPI )
associated with the NORs; (4) presence of a single
pair of chromosomes bearing 45S rDNA sequences
in diploid species, whereas polyploid species may
contain either one or two 45S rDNA sites, depending on the state of ongoing re-diploidization; and (5)
variation in the chromosomal position of rDNA marker sequences, with a prevalence for terminal positions for the 45S rDNA repeats (except in
F. hatschbachii, F. gracilis and F. rusbyi) and proximal positions for 5S rDNA repeats (except for
F. hatschbachii). Taken together, CMA/DAPI staining and FISH with 45S and 5S rDNA markers
appear to be useful approaches for tracking karyoevolution in Fosterella, facilitating, for example,
the identification of putative hybrids.
ACKNOWLEDGEMENTS
e and
We thank colleagues Diego S. B. Pinang
Rodrigo C. G. Oliveira for help during the collection
of seeds and root tips. We also thank CNPq (Con-
selho Nacional de Desenvolvimento Cientıfico e Tecogico,
Brazil),
DAAD
(German
Academic
nol
~o de AperExchange Service), CAPES (Coordenacßa
feicßoamento de Pessoal de Nıvel Superior, Brazil –
~o de
PROBRAL Program) and FACEPE (Fundacßa
Pesquisa do Estado de Pernambuco, BraAmparo a
zil) for financial support and fellowships.
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Additional Supporting Information may be found in the online version of this article:
Figure S1. Metaphase chromosomes of nine Fosterella species.
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SUPPORTING INFORMATION