Karyology of Limonium (Plumbaginaceae) species from the Balearic Islands and the western Iberian Peninsula

Abstract

Somatic chromosome numbers, conventional karyotype features and idiograms are reported for 27 Limonium species inhabiting the Western Mediterranean basin (Iberian Peninsula and the Balearic Islands). The chromosome numbers of Limonium barceloi (2n = 36), L. ejulabilis (2n = 24), L. inexpectans (2n = 26), L. interjectum (2n = 24), and L. scopulorum (2n = 25) were determined for the first time. In addition, new aneuploid and/or polyploid cytotypes are reported in L. alcudianum (2n = 26), L. bonafei (2n = 26), L. camposanum (2n = 26), L. companyonis (2n = 26), L. dufourii (2n = 26), L. geronense (2n = 36), L. marisolii (2n = 54), L. migjornense (2n = 50), and L. pseudodictyocladon (2n = 16). A group of polyploid species showed karyotypes comprising homologous chromosomes in groups of three (L. antonii-llorensii, L. ejulabilis, L. interjectum, L. virgatum, and L. wiedmanii), four (L. geronense), or six (L. marisolii), which suggests an autopolyploid origin. Other polyploid species were characterized by the presence of two different chromosome sets (x = 8 and x = 9) in the genome. The species L . alcudianum, L. bonafei, L. camposanum, L. companyonis, L. dufourii, L. gibertii, L. girardianum, L. inexpectans, L. leonardi-llorensii, L. magallufianum, L. migjornense, L. minoricense, and L. scopulorum showed various combinations of paired and unpaired x = 8 and x = 9 chromosome sets, suggesting that they are allopolyploids.

Polyploid origin, genetic diversity and population structure in the tetraploid sea lavender Limonium narbonense Miller (Plumbaginaceae) from eastern Spain

“…allopolyploids) and autopolyploids, as confirmed in this study, exist in this genus, spanning from triploids to octoploids, as well as some diploid species. The number of taxa included in each category rapidly decreases with increasing ploidy levels, and the vast majority of Limonium species are triploids, which reproduce apomictically (Erben 1978(Erben , 1979Castro and Rosselló 2007). Therefore, genetic diversity in Limonium may be conditioned not only by extrinsic factors, such as distribution ranges, but also by intrinsic factors such as ploidy levels and reproductive system types.…”

“…The karyotype of L. narbonense lacks these long chromosomes and is composed of four sets of 9 homologous chromosomes. A hybrid allopolyploid origin between species of different chromosome base numbers can be discarded based on chromosome number and morphology (Erben 1979;Castro and Rosselló 2007). However, this does not imply directly autopolyploidy nor rules out a possible hybrid (allopolyploid) origin for the species, since hybridization could have occurred between parents with similar (x 1 = 9) karyotypes.…”

“…However, they are less frequent than triploids (Erben 1978(Erben , 1979. Tetraploids are the most abundant class among the higher-ploidy taxa (Erben 1978(Erben , 1993Castro and Rosselló 2007).…”

“…Typically, Limonium taxa have two basic chromosome numbers x 1 = 9 (2n = 2x 1 = 18) and x 2 = 8 (2n = 2x 2 = 16). The latter results from a chromosomal translocation, producing a longer marker chromosome that allows tracking this genome in other Limonium taxa (Erben 1979;Castro and Rosselló 2007).…”

Habitat requirements and population structure of the rare endangered Limonium girardianum in Mediterranean salt marshes

“…The recent existence of numerous taxa is related to frequent hybridization resulting in a high proportion of polyploids and especially triploid species, such as L. girardianum (Erben, 1993;Palacios et al, 2000). The ploïdy of L. girardianum (2n = 26 = 2 × 9 + 8) and its self-incompatible sexual reproductive system, -type A grain pollen and cob stigma - (Baker, 1966;Castro and Rosselló, 2007), bring about an obligate agamospermous reproduction, which leads to low genetic variability. This reproductive characteristic reduces the possibility of adaptation to changing habitat conditions, making L. girardianum a specialist species.…”