KARYOTYPES OF MUHLENBERGIA RIGIDA (POACEAE: CHLORIDOIDEAE) FROM NORTH CENTRAL MEXICO

2013·5.2 MB·English

by  O Rosales Carrillo

CHLORIDOIDEAE)
OF MUHLENBERGIA (POACEAE:
KARYOTYPES RIGIDA
FROM NORTH CENTRAL MEXICO
Herrera Arrieta
Rosales
O. Carrillo Y.
Durango
IPNCIIDIR
Durango
IPNCIIDIR
Sigma 19 Fracc 20 de Nov.
Sigma 9 Fracc. 20 de Nov. 1 II
1 1 II
MEXICO
MEXICO Durango, Durango, 34220
Durango, Durango, 34220
Almaraz Abarca
Gonzalez Elizondo N.
M.S.
Durango
IPNCIIDIR
Durango
IPNCIIDIR
Nov
Sigma 9 20 de
Nov Fracc. II
Sigma 9 20 de 1 1
Fracc.
1 1 II
MEXICO
Durango, 34220
Durango,
MEXICO
34220
Durango, Durango,
Vanzela
Al. Laforga
Mayek
Perez
N.
IPNCBG
de Citogen^tica e Diversidade Vegetal
Laboratorio
Blvd.del Maestro s/n esq. Elias Pina
BRAZIL
86051-970, Londrina, PR,
Mendoza
Narciso
Col.
MEXICO
88710
Reynosa, Tamaulipas,
INTRODUCTION
^
.*s„„eof.he.arges.gene«cf.hePoaceaetaily,wi.happn«*
and
temperate forests &
>»ose, 150 mainly the
are distributed in AnnaWe
Peterson
& ^
f
Renvotze
1986;
only (Clayton
six endemic South Asia
species are to
&
Ml;
Petenmn
Peterson
Orttz-Diaz 1998;
some
”™j“^;,r!“merica“and Northern Mexico, of
Southern
33species ofMuhlenbergia native to the
^
(25)^lh
Amenca
them and South J
even America
reaching Central (38)
^
Espejo
‘n Mexico 2000;
(Beetle 1986 Espejo-Serna et al.
Peterson
Peterson 2003;
2001;
; ^ j
neta&delaCerdaLemusl995;HerreraArrieta&Petersonl992^Petersone
&Valdes-Reyna Muhlenl^rgiaisagenusvdt^^^^^^
1999).
tive plants (5 to
small
characters, ranging from very
^
rieida(Kunth)Trin.haspopulations
^
M.robusta(E.Foum.)Hitchc.Furthermo '
ones cm ’
(150-300
in
tall)
and which
that differ in plant habit as well as in the shape size of their inflorescence, can be compact
(dense)
or
loose (open), large or small. This creates taxonomic confusion and problems with the
specific
delimitation.
Few
chromosome
studies have been carried out on the genus Muhlenbergia. Soderstrom
(1967)
stated
Avdulov was who new
that (1931) the first reported cytological information as a basis for a classification
system
of Poaceae. Although Sodertstrom (op. did not carry out cytological studies, he does mention
cit.) the
results
from several studies which reported a base chromosome number Muhlenbergia x =
for of or
9, 10, 21. These
studies included the 2n chromosome number
for the species of sect. Epicampes. Peterson (1988) studied
the
chromosome number
25 annual
of Muhlenbergia species, reporting for the time the chromosome number
first
of nine of them. Noteworthy among
these are Muhlenbergia biloba Hitchc. and M. shepherdii (Vasey) Swallen
since they are n = 8. Herrera (1995) published the chromosome number of three species of the M. montm
complex
(Nutt.) Hitchc. [(M. montana, M. quadridentata (Kunth) and M. (Kunth)
Trin., y^irescens Trin.)], re-
cording for the first time the chromosome number of M. quadridentata, the disploid chromosome number ofM.
and
virescens confirming
the tetraploid condition of M. montana. Gould (1966) carried out karyotyping of 60
genera and 149 species Mexican
of grasses, eight of which belong to Muhlenbergia. However, M. rigida was not
included
in Gould’s study.
Muhlenbergia SW
rigida is a grass with widespread distribution in the United States and ranges south to
and
Central South
America. In Mexico found from
it is Baja California to Chiapas. The grass can be found
m
growing
pine-oak and
forests grasslands,
sporadically at the edge of roads, and at elevations between 1280-
m &
2550
(Herrera Arrieta
Peterson
2007).
This grow
capacity to in such
extensive areas with
diverse habitats translates into a great morphological
diversity within the
species
This
(rigida).
diversity of and
traits is reflected mainly in the shape size of leaves
and
inflorescences, with vanation among
the type
of
inflorescence (compact or loose) being particularly noto-
nous. However,
there no
is correlation between k-
morphotypes and
habitats or geographical distribution as
quently both^orphotypes^can
be found
growing On
in the same morphological
location. the basis of the great
study, the aim of the ^
present study
compare
is to the karyotyproTt^moi^hm^^^^^ of
rigida located in north
central Mexico.
This comparison
will reveal any between the karyotype
relationship
and
the morphological
differences within
the species
as well as other relevant variations that allow the distinc-
tion of groups among
the studied
populations,
or otherwise
distinguish between two morphotypes.
the
MATERIALS AND
METHODS
I
d
was
collected from
27
locations
(Fig. and following
30
1) populations of Muhlenbergia rigida,
—
^ ^ Chihuahua,
Durango,
and
Zacatecas, Guanajuato, Jalisco-
Aguascalientes,
Mexico
(Table Live
plants were
1).
collected
(bunches) from under
natural and
populations cultivated
and
localities(mcludmggeographical
coordinates and
elevation) in which thestudiedplam^
Karyotyping
a.4C
12 hours
for
followed
IvhydrolysUwUh
three
passes using dLuied 30-min„.eimc™^^
water
at
hen
acid
hydrolyias using
O.IN
HCI, and
tcd-
citrates 41
buffer 30 miLtes usinga
for
then digestion
a final
enzyme
lulase mixture
"Onozuka h-al
R-10 23U
(Serxa)” and 1% pectin^ Y h Ph rrcal) for
1
we«
removed
to^ after the samples Preparations
were kept -84°C.
at
for^l^v
left
Chromosomes reagent
were acetocarmine
CountinJatlLt stained using the
H
,an
gr y
I^ierptetationofthechromosomes(in7-10metaphaseslides)wascarriedoutusingan
383
hup;//www.colostaie.edu/
software
Axioskop camera.
Zeiss microscope with digital
fitted
o e
lengt
the
measuring
^tsmiology/MicroMeasure) was used for nomer
the
arm)
^^ort
arm: ^ ^
The chromosome arms (long ^
ratio of the (r)
propt^
was that
morphology
for describing chromosome stanc
Stebbins’
^ 00-6.99).
^
:00;l-69),sm = submetacentric(r=1.70-2.99),andst
=
accordi g
’on chromosomes
(1938) was
used
classifying
for
5-9 pm, pm,
medium-large; >9 large.
karyotypes
t
of the
,
In
order
to carry out the quantitative
<
384
m
2014
23°45'51.6”N 104‘’25'29"W,
y
m
Parte alta de la Canada el Caj6n, Santa Maria, Oro, Durango, 25°24'42.8"N 104'’57'28.4"W, 1914
El y
Entronque m
Otinapa-Autopista Durango-Mazatlan, Durango, Dgo. 23°58'35.0"N KM'Se'SOJ'W, 2446
y
Km
m
25 Autopista Durango-Torreon, Durango, Dgo. 24°1 1'12.0"N y104‘’29'31.7"W, 1864
Por la carretera 1 05, rumbo a la presa Bayacora, Durango, Dgo., 34°54'44.1 "N 04°44'46.9"W, 21 85 m
y 1
de m
Cerro Los
Gallos, Aguascalientes, Ags. 2r40'03.6"N 102'’1 3'1 5.8"W, 21 91
y
de m
Cerro Los
Gallos, Aguascalientes, Ags. 2r40'03.6"N 102‘‘13'15.8"W, 2191
y
m
Entronque
a
Milpillas, Jesus Maria, Ags. 2r55’28.6"N 102“33’57.7''W, 21 86
y
m
Cerro Roble,
El Jesiis Maria, Ags., 2r47'30.7"N 102°31 '26.3"W, 201 9
y
km
6 antes de caseta de cobro por
la la autopista Aguascalientes-Zacatecas, Guadalupe, Zac.,
m
22’’39'19.6"N 102°26'45.5"W, 2305
y
Ciudad de m
jr la Guerrero, Guerrero, Chih. 28“30'1 5.8"N 107°29'00.3"W, 2045
y
m
c, Chih. 28“24'09.4"N 107“34'57.0"W, 2277
y
m
norte deTemochi, y107“49'26.0"W, 2075
c, al Chih., 28‘’21 '20.7"N
chromosome
calculated:
(1) total length (LTC); mean chromosome index
centromere
(2) length (LMC);
(3)
mean
(short arm/total chromosome
=
length x
100 [Cl]); intra-chromosomal asymmetry index (Al)
(4)
where and B
1- [I(b/B^), b are the measures
of
the short and long arm each homologous chromosome pair re-
of
and
spectively n is the total number of homologues; where
=
(5) inter-chromosomal asymmetry index (A2) s/x,
s IS the standard deviation and x mean
is the chromosome CVCL CVCVlOO
length; Paszko Index Al = x
(6)
CVCL=
where
(SC17XCL) x
100
the
is relative variation of chromosome CVCI = (SCl/XCl) x 100 is
length,
the relative vanation of the centromere
XCl
length, XCL and
respectively, mean chromosome length
the
is
Cl mean.
the Karyotype asymmetry
IS was
determined A2 indite
using Al and
Stebbins'
categories
(1971),
(Romero-Zarco
1986) and the Al index
(Paszko asymme
2006). The Al
index
a quantification of Stebbins'
is
try categories. ranges between
0 and
It and
1, these are low when Basic
chromosomes metacentric.
be
tend
to
mtetpretanonofAlvaluesdeterminesthatthehigherthe
value, the higheristheheterogeneityofchm^^^
m
and/M
length
the centromere
index
a
studied
karyotype
(Garcfa-Barriuso
et 2010).
al.
In the Ideograms, homologue
chromosome
decieasiC
pairs were
ordered
according length in
to iheir
Four
size order. to seven metaphase
were f«
cells measured
from an average
various slides in order to obtain
constjmetion
of the ideograms.
Measurements
were
compared AlandAliodices
usingANOVA.
The TCL,
Cl,
chromosome
as well as number
were
considered
Chromosome studies Muhlenbergia
et in
Rosales al.,
Clustering analysis of the karyotype data was carried out in order to examine karyotype similitude
A
OTUs
was
among populations. data matrix of 30 (operational taxonomic units) and five variables construct-
The following variables were used: LMC, Cl, Al A2 and chromosome number. The first four variables were
ed.
,
because they are not influenced by chromosome number. Nevertheless, ploidy level was also used since
used
The
morphotypes being compared.
characteristics of various populations of Muhlenbergia rigida are
different
STATISTICA 2004) software package was used to normalize the data matrix, calculate the aver-
v.7.0 (StatSoft,
UPGMA
and an dendrogram.
Euclidean distance, generate
age
Also, in order to evaluate the contribution of each karyotype parameter to the population clustering, the
OTU
and
component (PCA) based on the 30 data matrix the afore-
were subject to a principal analysis
entities
with
The chromosome counts obtained from radicular cells of Muhlenbergia rigida in this study are consistent
=
which documented 2n
and Soderstrom both of
numbers reported by Herrera and Peterson (2007) (1967),
the
40 and 44. This study recorded 2n = 30, 40, and 44; marking the first report of triploidy in this species. It is
morphotype
noteworthy to mention that the 2n = 40 and 2n = 44 counts were found in the compact panicle
morphotype.
while the 2n = 30 count was present in the open panicle
x = with 2n = 40
number Muhlenbergia
of is 10,
Our support previous suggestions that the basic
results
morphotypes of M. rigida stud-
equally distributed in the
Polyploidy
occurring in the majority of the species. is
= 3x = and only 13.33%
= 4x = 43.33% are triploid (2n 30)
ied here: 43.33% of the plants are tetraploid (2n 40),
are disploid, derived from tetraploid (2n = 4x + 4).
chromosomes M.
We 30 in
formula of
report the time the karyotype
for
first
found
the ideograms representing the three ploidy levels (Fig. 2)
composed metac
were of
analyzed
As
a whole, the karyotypes of the species
were
among populations
The formulae triploid
predominant.
trie (sm) chromosomes, with the former being
25m 5sm 22m
and
and +
27m + 3sm (two populations),
30m 29m Ism populations),
(six populations), + (three
8sm
+ in the remaining two populations.
39m Ism
40m + (three
populations),
manner: (five
following
Tetraploid populations were present in the
m
32m 8sm popu
34m + ations.
6sm, five
32m +
8sm,
35m +
38m 37m 3sm, + 5sm,
populations), + 2sm, +
30m 35m
+
and + 14sm,
44m
populations)
(two
formulas:
karyotype
Disploid populations had the following
9sm
for the remaining two populations (Table
2).
^
, .
Stebbms
and ^m), according to
3.83
sLu (between 1.0
medium-small in size
Chromosomes and
were
pm pm. The centromere tndex
and
2.62
between 1.31
(LMC) ranged
(1938). The mean chromosome length
variedfrom
12.94 to 21.76. .. fo
. lA and, IB ot SteKbVnbimnsc
nnH categories
into
symmetrica fall
, , ,
moderately
In were
general the karyotypes
(1971).
shows three
similitudes (Fig. 3)
UPGMA karyotype “3
with
The
dendrogram constructed
wuh gro^
subgroups
composed of three
divided The group
into subgroups. is
first “yo “gs/
4215 4170,
by populations
formed
was
Group
populations and 4016. 1-2
4098,
4177,
Group 3982,
413942^^^^^^
..3wascomposedolpopulations4227
Sit
fimtroupTntains
IT " tTteTcroTelnSTcTraXw^^^
i
to the morphological characteris
population, while
and one tetraploid
nnp dditssnpltoaidd P
c one
has
group v,
dtapbid second
and
the
populations,
tetraploid
open
have p
that
populations
•Ito third group composed of triploid
completely
is
Journal of the Botanical Research
386 Institute of Texas
7(1)
Measurements from
and
triploid
tetraploid plants from the same compared re-
itically
1
suiting in
significant
differences (P <
0.05).
The
results obtained from
our study
of Muhlenbergia
rigida morphotypes confirms the previously re-
partially
ported chromosome
numbers
for this species by
several
authors.
Of
the 30 populations m
examined,
13 were
found
to be triploid, this being the report for triploidy
first
the species. Apart from
the
triploid cytotypes
this study also found and confirming
tetraploid disploid plants,
the results of previous The
studies. and
triploid while
tetraploid cytotypes are present in high frequency (86%)
disploidy(2n =
44)hadlowfrequency,beingfoundinonlyfour^pu,^^^^^^^
ThisstudypresentsploidylevelsfoundinM.rigidapopulationsinnorthcentralMexico.Italsoshows,for
the
first time, the karyotype and
ideograms
of the two and loose
Muhlenbergia morphotypes (dense
rigida
panicle) as well as the three
cytotypes within
the
species.
rPooilyyppilooiiudyy has
ppllaayyeedd aann
tias iimmppoorrttaanntt
rroollee iinn tthhee eevvoolluuttiioonn mmaannyy and the
ooff eeuukkaarryyootteess ((SSoollttiis et al. 1999),
inajontyofangiosperms(approximately7(m)have
r
have sshhoowwnn
nnl f ppoollyyppll^o^i^d^y during evolutionary proce:
their
n
: w
terson 11 999944)).. hhiigghhll, yy
IItt iiss nprroobbaahbllee tthhaatt fthhpe polyploidy of 1 . , , . i ;«nripin.
Muhlenbergia autopolyploidy ir
rigida of —
is
chromosomes. plan^
General morphology studied
of the
simuir^abk
very
2)
Thcj=sultsof.hiss.udyrevealade.ail£ddescrip,i„n„t,hechromosomalMUsof.woMukk«i^^
da morphotypes,
allowing
the
classification of chromosoa®
the karyotype
of M. The
rigida as symmetrical.
Steb-
of
the classification
^‘'‘^“fding to
bilsTwO
ancest*
when
polyploids compared disploid
to their
Stehto^ilqyT
c'
Stehbins(1971)recognuesfivetnaturitystagesof
polyploidy declining.*-!
complexes: iniL, young, mature,
5sis225S5:25?S3§l;:i595i2?s!s3
mmmmmmmnmrm
g
5s3|SiiliirJiisiii?isS2ilsiii
i
555S3553S5S3553SS5555S5555SSS5
3
ili!i!iiiii!il
1
iliilllliiiiiifflliiSi!
ii
i§islssiii§i§^^s3isissis=is2sl
si
s||SRS||?335?3iii22iii2s:25s:=
al
g
iiiiiiliiiSi
IlIliliiliilflilllttHiiHiHI
388
rehctual. According
to him,
the evidence
of
distribution polyploid)’
patterns indicates that the majority of
comp
exes
that are currently mature
originated
in the Pliocene or Pleistocene. Our finding of 100% polyploid)
frequency mjhe^uhlenbe^iari^^
indicates high
a evolutionary maturity.
Stebbins’ terminology
(1971). All populations Mentrk
have predominamfy alesser
cLonl^some” to
!"nd,
degree
subrnetacentric
chromosomes.
The A1
index had a
fiuctuated 50% populations
for example, of the
0.1;
^
°
chromosomes,
the predominance
of metacentric
^
I
hi ngida
karyotype
constitutes Karyotype
the
karyotypic genus.
first description of the
asvmmer^
^ asymmetry between
f is type A1 and Bl. This degree of asymmetry
ppooppuullaattiioonnss h
high,
is reflecung low
i
specialization
(Stebbins
1971)
indicatingasimilarchroino-
The
aggl„me„ttve
clusuring
analysis (UPGMA) ih*'
revealed had greac«
tha. the parameters which
Chromosome Muhlenbergia 389
studies in
et
Rosales al.,
asymmetry
group and subgroup formation were the centromere index (Cl) and inter-chromosome
in
ence
The Cl values had an interval of 12.94 to 21.76 while the inter-chromosome asymmetry index values (A2)
(A2).
open
marking between morphotypes. Populations with the panicle
from 0.10 to 0.21, clear difference
range
A2 morphotype populations had
morphotype had the highest values (0.15 to 0.21) while the closed panicle
lowerA2values (0.10 to 0.16).
amount metacentric chromosomes in the cytotypes studied, suggest that the karyotype of this spe-
The of
become
tendency be symmetrical, indicating a trend to stable.
des shows a to
had compact indores-
morphotypes. Plants that
The ploidy levels of Muhlenbergia rigida are related to
=
were (2n
and = 40 and while those with loose inflorescence triploid 30).
were tetraploid disploid (2n 44)
cence
Knowledge on simple cytoge-
good complement taxonomic studies.
cytological data provides a to
Therefore,
chromosomes during meiosis,
chromosome number, behavior of the
such
of a species as
characteristics
netic
understanding of the pat-
and can contribute to a better
mode of reproduction of individuals their fertility
the
study con-
The obtained in this
taxonomic results
of morphological variation and help to define limits.
terns
and
morphological cytologi-
which maintain their
between two morphotypes of M. rigida,
firm the differences
However,
may two taxonomic entities.
and represent
when same
even growing the location,
cal features at
may support recognition at the species level.
further evidence be required to their
makes comparative study of karyo-
the
Muhlenbergia
The information on species of
lack of cytogenetic
of
on the possible participation
discussion
deeper
limiting
and
types their quantitative characteristics difficult,
some
and establishment of
the
processes,
speciation
chromosome changes in the evolution of the genus, in its
study (with
thorough cytogenetic
a
expected that
type of genome specialization in relation to the habitat. It is
M. da
evolutionary history of rig,
determine the
banding, FISH, or GISH) could provide more elements to
morphotypes.
ACKNOWLEDGMENTS
and
support, the
COFAA) financial
and for
We (CIIDIR-DGO, SIP,
want thank Nacional
to Instituto Politecnico
«^e„.o.hero.,owi„gpr„iec.s:S,P—
de
“Citologia
SIP-20110017
comunes ddee MMeexxiiccoo,,”
mas
pastos :s
ae) de Mexico,” SIP-20031025 “Estudio de los
lObSlTitodiversidad
y
and SIP-201
Mexico,”
de
c
Ciperaceas ae imporianc.a
y ^
graduate
the
CONACyT scholarship to
by
Many thanks to t
Ecosistemas de Madre Occidental.”
la Sierra tew
„
revis-
thank y
we want
to
Finally
student (CVU; present report.
V.11L vv- V u. 242097), nfirrsstt aauuttnhoorr ooif the
/ j, i
report.
ers and iched this
proof whose observatu
readers,
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'1«».W.D.,»SA G^neragramlnumigrassesof
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