Comparative karyotypic analysis and cytotaxonomy in the Alstroemeria ligtu L. (Alstroemeriaceae) complex of Chile

Due to the variability in morphology and color of the flowers as well as the excellent post-harvest durability of Alstroemeria, many species are cultivated as ornamental and cut flowers. Alstroemeria ligtu L., endemic to Chile, has also been a source of artificial hybridizations for development of new cultivars. Cytogenetic studies provide clues for possible breeding programs and taxonomically useful data to clear up infraspecific relationships of Chilean native populations. Three subspecies are recognized within A. ligtu: subsp. ligtu, subsp. splendens Munoz-Schick, and subsp. simsii (Sprengel) Bayer. The objective of this paper is to characterize karyotypically these subspecies and to clarify their taxonomic status. Fourteen populations were collected throughout its distributional range. Chromosome number, karyotypic formulae, karyotypes, ideograms, intrachromosomal asymmetry index MCA, and interchromosomal asymmetry index CVCL were calculated. All studied populations showed 2n = 2x = 16 chromosomes. Subspecies ligtu and simsii are clearly differentiated from each other in MCA and together from subsp. splendens with CVCL. Intrachromosomal asymmetry index revealed two populational groups within subsp. splendens. These populations also differ in karyotypes formulae, habitat, soil type, and distribution. We concluded that a fourth subspecies should be described from populations located in the lower part of the cordillera de los Andes in the Region of Maule. Populations of higher elevations correspond to those already described as subsp. splendens.