Red and green algal monophyly and extensive gene sharing found in a rich repertoire of red algal genes

CHEONG XIN CHAN, EUN CHAN YANG, TITAS BANERJEE, HWAN SU YOON, PATRICK T. MARTONE¬, JOSÉ M. ESTEVEZ, & DEBASHISH BHATTACHARYA.

CURRENT BIOLOGY

CELL PRESS

Año: 2011

0960-9822

The Plantae comprising red, glaucophyte, and green algae (including land plants) is postulated to have a single common ancestor that is the founding lineage of photosynthetic eukaryotes [1, 2]. Recent multi-protein phylogenetic analyses have however provided little [3, 4] or no support [5, 6] for this hypothesis. These results may reflect the limited genome data available from red algae, currently only the highly reduced genome of Cyanidioschyzon [7], a reticulate gene ancestry [5], or significantly different gene divergence rates that mislead phylogenetic inference [8]. Here using novel genome data from the mesophilic taxa Porphyridium cruentum and Calliarthron tuberculosum, we increase by >5X the number of available red algal genes to assess support for the monophyly of the red + green (RG) algae and their extent of gene sharing with other lineages. Using a gene-by-gene approach, we find an emerging signal of RG monophyly (supported by ~50% of the examined protein phylogenies) that increases with the number of distinct phyla and terminal taxa in the analysis. A total of 1,808 phylogenies show evidence of gene sharing between Plantae and other lineages. We demonstrate that a rich, mesophilic red algal gene repertoire is crucial for testing controversial issues in eukaryote evolution and for understanding the complex patterns of protist gene inheritance.