Molecular phylogenetic relationships among Lachenalia, Massonia and Polyxena (Liliaceae) on the basis of the internal transcribed spacer (ITS) region

Abstract

A molecular phylogenetic analysis based on internal transcribed spacer (ITS) sequences in 31 species, four varieties and four cultivars of Lachenalia, two species of Massonia and three species of Polyxena was made. These three genera have been considered as closely related with each other. The ITS sequence data confirmed that Massonia was clearly different from Lachenalia and Polyxena. Polyxena constructed one clade distinguished from Lachenalia. The species of Lachenalia used showed a correlationship between ITS sequence data and karyotypes, excepting the species with the basic chromosome numbers x=7 and x=8 did not show any correlationship with those with the other basic chromosome numbers. Similarities of their arrays of ITS sequence data among species with x=8 were greater than those among the species with x=7. Lachenalia pusilla and L. muirii which had x=7 formed a clade with the species with x=8. Differences in The species with the basic chromosome numbers of X=7 and 8 showed less differences in correlationship between ITS sequence data and karyotypes than those with other basic chromosome numbers It was suggested that the species of Lachenalia with the basic chromosome numbers of x=7 and 8 might be originated from a common ancestor, while the other species of the genus with basic chromosome numbers other than x=7 and 8 might be originated from other ancestor-else. Lachenalia is an important genus in the Liliaceae, sometimes placed in the Hyacinthaceae. The genus is endemic to the western part of southern Africa and consists of approximately 115 species (Duncan 1998). Since the genus has subtle, morphological differences in rather small area, it has been classified into numerous species. However, it has been difficult to study phyloge-netic relationships, speciation and other species biology. The previous cladistic analyses by Duncan (1988) and Duncan et al. (2005) made in 73 characters included flowers, bulbs and seeds in the members of the genus indicated that all those morphological data could be inadequate to clarify and justify the species relationships. They suggested that molecular comparisons in Lachenalia. Molecular data in atpB and trnL-F chloroplast DNA sequence data were studied in six species in the tribe Massonieae, the family Hyacinthaceae by Pfosser et al. (2003) suggesting Massonia and Polyxena were closely related to Lachenalia. Chromosome numbers of 61 species and eight varieties in Lachenalia documented showed aneuploid chromosome numbers of 2n=10 Karyotypes of 35 species and four varieties of the genus were studied and classified into nine groups (Hamatani et al. 1998, 2004, 2007), however, they were not consistent with those of the cladistic analysis of Duncan et al. (2005). More deep studies in their karyotypes deposited problematic with patterns such as intermediate karyotypes among certain groups, triploid-like and natural hybrid-like karyotypes, non-uniformity of intraspecific karyotypes. It seemed that morphological and karyomorphological data were not sufficient to construct phylogenetic relationships of the species in Lachenalia. The present phylogenetic study was conducted in the internal transcribed spacer (ITS) region in nuclear DNA sequences in 31 species, four varieties and four cultivars in Lachenalia, two species of Massonia and three species of Polyxena.