Cytogenetic development in the genusLachenalia

Abstract

The genus Lachenalia, tribe Hyacintheae, sub-family Hyacinthoideae, family Asparagaceae, presents an extraordinary amount of variation when comparing traits among its species. Traits, such as morphological variation, environmental differences, and chromosome evolution, have been extensively studied to determine how these variations originated in the genus Lachenalia. Phylogenetic development of the DNA gene regions (rbcL and trnL-F) was compared with basic chromosome numbers, to infer a cytogenetic evolutionary history for the genus Lachenalia. Bayesian inference methods based on molecular sequence data from the rbcL and trnL-F gene regions and basic chromosome number values, were used to generate a cytogenetic phylogeny for the genus Lachenalia. Basic chromosome numbers groups Lachenalia into three distinct clades. The ancestral basic chromosome number for Lachenalia is suggested to be x=9 and could be the direct result of why Lachenalia presents so many cytogenetic variations. The ancestral basic chromosome numbers for the tribe Hyacintheae could be dibasic, x=4 and x=5. Understanding chromosome number evolution is essential to understand the extraordinary amount of cytogenetic variations seen in Lachenalia. It is crucial to obtain new species samples, sequence datasets and any additional data, such as chromosome numbers and ploidy levels, before any taxonomic revision of the genus is done again.