Abstract Detail

Systematics

Sassone, Agostina [1], Blattner, Frank R. [1].

Phylogenomics in South American garlics: preliminary results on diversification within Nothoscordum (Amaryllidaceae).

The New World genus Nothoscordum Kunth (Amaryllidaceae, Allioideae) is widely distributed in South America mainly in the extra-tropical regions, except for N. bivalve (L.) Britton, which reaches North America. The genus, as currently defined, encompasses two sections: the type section and N. sect. Inodorum Guagl. The sections differ in morphological, molecular, and cytological characters. The only taxonomic treatment of Nothoscordum is incomplete and includes 11 species. In the last two decades, 58 new Nothoscordum species were described, which often lacks the basic elements for taxon identification, resulting in ca. 100 names included within Nothoscordum. This created nomenclatural confusion and makes the identification of species a real challenge. For the first time, a phylogenomic analysis was carried out for Nothoscordum species, using genome-wide single-nucleotide polymorphism (SNP) data from genotyping-by-sequencing (GBS), a next-generation sequencing method. This approach allows us to investigate phylogenetic relationships and genomic variability of species. Together with other sources of evidence, we intend to reconstruct the history of the genus and delimitate species. We included materials to cover the morphological and geographical variation. Here we present preliminary results including 102 specimens. A total of 56,738 loci were retained for the ingroup after filtering, and a concatenated matrix of 5,092,996 bp length was generated. The level of missing data was lower than 90%. A Neighbor-Net network was constructed and phylogenetic reconstructions were performed using RAxML and tetrad. All analysis methods suggest that Nothoscordum sect Inodorum is recovered as monophyletic, including the weedy species N. gracile (Aiton) Stearn and N. nudicaule (Lehm.) Guagl. This section is characterized by the presence of white flowers and connate staminal filaments, and it distributed in northern Argentina, Bolivia, and Peru (generally in high elevation habitats). On the other hand, N. sect. Nothoscordum, including also the unifloral species (= Beauverdia Herter), is mostly distributed in southern Brazil and the Pampas region (Argentina and Uruguay) and is morphologically rather diverse. This section can be characterized by the presence of white, cream, and yellow flowers and free staminal filaments (with few exceptions). Our results support the hypothesis of reticulate evolution within the genus and current gene flow within species of N. sect Nothoscordum. The next steps of our in-progress-research will be testing these hypotheses.

1 - IPK Gatersleben, Experimental Taxonomy, Corrensstraße 3, Stadt Seeland OT Gatersleben, 06466, Germany

Keywords:
Allioideae
GBS
SNP
Taxonomy.

Presentation Type: Oral Paper
Session: SYS5, Systematics V: Gymnosperms to Monocots part A
Location: Virtual/Virtual
Date: Friday, July 31st, 2020
Time: 1:00 PM
Number: SYS5003
Abstract ID:242
Candidate for Awards:None