Leaf and stem anatomy and essential oil composition of four Brazilian Aldama species (Asteraceae) and their taxonomic significance

Abstract

Aldama La Llave is one of several Asteraceae genera that pose phylogenetic problems. The close similarity between species, as well as the inconsistencies found in the most recent phylogenetic analysis, shows that new data are needed to help delimit group species. Aldama anchusifolia (DC) E.E.Schill. & Panero, Aldama megapotamica (Malme) Magenta & Pirani, Aldama nudibasilaris (S.F.Blake) E.E.Schill. & Panero and Aldama pilosa (Baker) E.E.Schill. & Panero are difficult to identify because they are very closely related. Therefore, the aim of this study was to detect anatomical and phytochemical characteristics to help elucidate phylogenetic issues raised by Aldama. Aerial vegetative organs were prepared using the standard histological techniques. Essential oils were obtained by hydrodistillation, and their components identified using a gas chromatograph coupled to a mass spectrometer and flame ionization detector. Each species presented a set of unique leaf and stem anatomical features. The front view of the epidermal cell walls in the leaves, the presence of secretory ducts in the phloem and medulla sclerification in the stems proved useful in delimiting these species. The essential oils were characterized by the predominance of sesquiterpenes such as t-caryophyllene, germacrene D and bicyclogermacrene. Some unique constituents in each species were also identified as potential chemical markers.

Extremely low nucleotide diversity among thirty-six new chloroplast genome sequences fromAldama(Heliantheae, Asteraceae) and comparative chloroplast genomics analyses with closely related genera

“…The fact that several repeat regions are present in more than one species is a good indication that they could be easily transferable across the genus, being useful for multi-species studies. While several Brazilian species complexes within Aldama have been the focus of detailed anatomical and phytochemical studies ( Bombo et al, 2012 ; Bombo et al, 2014 ; Silva & Appezzato-da Glória, 2014 ; Bombo, Filartiga & Appezzato-Da-Glória, 2016 ; Filartiga et al, 2016 ; Filartiga et al, 2017 ), populational studies based on these SSRs would greatly improve the understanding of population dynamics and microevolutionary processes in these species.…”