MOLECULAR PHYLOGENY OF THE GREEN ALGAL ORDER PRASIOLALES (TREBOUXIOPHYCEAE, CHLOROPHYTA)¹

Abstract

The systematics of the Prasiolales was investigated by phylogenetic inference based on analyses of the rbcL and 18S rRNA genes for representatives of all four genera currently attributed to this order (Prasiococcus, Prasiola, Prasiolopsis, Rosenvingiella), including all type species. The rbcL gene had higher sequence divergence than the 18S rRNA gene and was more useful for phylogenetic inference at the ranks of genus and species. In the rbcL gene phylogeny, three main clades were observed, corresponding to Prasiola, Prasiolopsis, and Rosenvingiella. Prasiococcus was nested among species of Prasiola occurring in subaerial and supralittoral habitats. Trichophilus welckeri Weber Bosse, a subaerial alga occurring in the fur of sloths in Amazonia, was closely related to Prasiolopsis ramosa Vischer. The species of Prasiola were grouped into three well-supported clades comprising (i) marine species, (ii) freshwater and terrestrial species with linear blades, and (iii) terrestrial species with rounded or fan-shaped blades. Sequence divergence was unexpectedly low in the marine group, which included species with different morphologies. For the 18S rRNA gene, the phylogenetic analyses produced several clades observed for the rbcL gene sequence analysis, but, due to very little sequence variation, it showed considerably lower resolution for inference at the species and genus levels. Due to the low support of some internal branches, the results of the analyses did not allow an unambiguous clarification of the origin and the early evolution of the Prasiolales.

Phylogeny and Molecular Evolution of the Green Algae

“…Since 1990 rapid advancements in techniques in molecular biology (e.g., the utilization of PCR) and bioinformatics made it possible to generate and analyze larger datasets. Nuclear-encoded 18S rDNA sequences have been, until recently, the primary source of data for inferring phylogenetic relationships among green algae (Pröschold & Leliaert, 2007), supplemented by 28S rDNA (e.g., Shoup & Lewis, 2003), actin and the chloroplast genes rbcL, tufA and atpB (e.g., Daugbjerg et al, 1994;Daugbjerg et al, 1995;McCourt et al, 2000;Hayden & Waaland, 2002;Nozaki et al, 2003;Zechman, 2003;Rindi et al, 2007).…”

“…The Prasiola-clade is the morphologically and ecologically most diverse trebouxiophyte lineage, including unicellular (e.g., Pseudochlorella, Pseudomarvania, Stichococcus), filamentous (e.g., Rosenvingiella, Raphidonema) and blade-like (e.g., Prasiola) forms growing in freshwater, marine and terrestrial habitats (Karsten et al, 2005;Rindi et al, 2005;Rindi et al, 2007;). …”

Leptochlorella corticola gen. et sp. nov. and Kalinella apyrenoidosa sp. nov.: two novel Chlorella-like green microalgae (Trebouxiophyceae, Chlorophyta) from subaerial habitats

“…Chlorella, Marinichlorella, Meyerella, Parachlorella and Picochlorum, which typically inhabit various freshwater and, to a lesser extent, marine habitats, either as free-living organisms or as endosymbionts of protists and metazoans (Henley et al, 2004;Krienitz et al, 2004;Fawley et al, 2005;Aslam et al, 2007;Bock et al, 2011;Pröschold et al, 2011). Additional Chlorella-like lineages were recently classified as separate trebouxiophycean genera Elliptochloris, Pseudochlorella and Xylochloris (Rindi et al, 2007;Letsch et al, 2009;Darienko et al, 2010;Neustupa et al, 2011).…”

Molecular diversity of green corticolous microalgae from two sub-Mediterranean European localities

“…Several relatively well-defined green algal phylogenetic lineages frequently occur in subaerial habitats, such as Trentepohliales (Printz, 1939), Trebouxiales (Škaloud & Peksa, 2010), Klebsormidiales (Rindi et al, 2011), Prasiolales (Rindi et al, 2007), and Coccomyxaceae (Ettl & Gärtner, 1995). A number of new taxa of chlorelloid green microalgae, isolated from various corticolous biofilms, were recently described taxonomically and defined by molecular phylogenetic methods (e.g.…”