Botanical Studies (2007) 48: 311-317.
*
Corresponding author: E-mail: msanso@vet.unicen.edu.ar;
Tel. +54-2293-439850.
INTRODUCTION
Alstroemeria andina Phil. var. venustula (Phil.) M.
Munoz (sub nom. A. andina Phil. subsp. venustula
(Phil.) Ehr. Bayer) is a perennial, small herb, 5-16 cm
tall, that occurs at 2,800-3,700 meters above sea level,
exceptionally at 2,300-2,400 meters above sea level, in
populations of limited distribution from Argentina and
Chile (Sanso, 1996). This taxon inhabits the IV Region of
Coquimbo in Chile and the departments of Iglesias and
Calingasta, San Juan province, in Argentina (Bayer, 1987;
Sanso, 1996). Its habitat comprises stony or sandy slopes
and screes of the Anden mountains (Sanso, 1996).
The basic karyotype structure in the entire genus
Alstroemeria is apparently uniform, and most species of
this one have normal male meiotic behaviour with eight
bivalents and the larger pair showing up to three visible
chiasmata (Sanso, 2002). The karyotype formula of A.
andina var. venustula was: 3 m pairs, 1 sm pair, 3 t and 1 t
(st) pair, with microsatellites observed on pairs n¢X 3 and n¢X
6. Chromosome lengths ranged from 5.55 £gm to 22.78 £gm
(Sanso, 2002).
This paper reports the first meiotic characterization of
a population of A. andina var. venustula, with results that
are totally different from all previous karyological studies
of the genus.
MATERIALS AND METHODS
Plant materials for this study were collected from
San Juan province, Calingasta department, Puesto de
Gendarmeria, Las Juntas, at 31¢X41¡¦49" S-70¢X14¡¦13" O,
Argentina. Voucher specimens, Fortunato & Kiesling
5631, were deposited at Herbarium of Instituto Darwinion
(SI).
Flower buds of individuals collected from the wild
population were fixed in ethanol-chloroform-glacial acetic
acid (6:3:1) and later transferred into 70% ethanol and
stored at 4-5¢XC. The cytogenetic analysis of this reduced
population of A. andina var. venustula revealed that
only five buds presented appropriate cells to analyze the
course of meiosis, even when flower and anther sizes were
suitable for it. Immature anthers were dissected out and
CYTOGENETICS
Meiotic irregularities in Alstroemeria andina var. venustula
(Alstroemeriaceae)
Andrea Mariel SANSO
1,2,
* and Arturo Federico WULFF
1
1
CONICET, Dpto. de Ecologia, Genetica y Evolucion, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos
Aires, 1428 Buenos Aires, Argentina
2
Laboratorio de ADN, Dpto. de Biologia, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la
Provincia de Buenos Aires, Campus Universitario, Paraje Arroyo Seco, 7000 Tandil, Argentina
(Received August 30, 2006; Accepted April 16, 2007)
ABSTRACT.
Alstroemeria andina Phil. var. venustula (Phil.) M. Munoz (sub nom. A. andina Phil. subsp.
venustula (Phil.) Ehr. Bayer) is a perennial, small herb, 5-16 cm tall, that occurs mainly at 2,800-3,700
meters above sea level, in populations of limited distribution from Argentina and Chile. The course of the
meiosis was analyzed in a population of this taxon (2n = 2x = 16), and it proved to be highly irregular. It was
characterized by presenting bridge and fragment configurations both at anaphases I and II. The highest number
of bridges at anaphase I found in one cell was two, suggesting heterozygosity for as many as two paracentric
inversions. Typical chiasmata were almost not detectable, even though they actually existed. The chiasma-
like structures observed may be regarded as concealed chiasmata as it has been described in cryptochiasmate
meiosis. A high frequency of tetrads with micronuclei was observed, implying significant levels of unbalanced
gametes. Pollen stainability ranged between 28 and 30%. In Alstroemeria species the meiotic behaviour is
highly regular, and the presence of rearrangements is very uncommon. The whole situation led us to suggest
that some environmental factors have drastically affected the chromosome structure and the control of the
meiotic process. The present study constitutes the first report of remarkable meiotic irregularities found in a
wild population of this genus.
Keywords: Alstroemeriaceae; Chromosomes; Cryptochiasmate meiosis; Meiotic behaviour; Pollen staining;
Structural heterozygosity.