Seven gene phylogeny of heterokonts.

Nucleotide ssu and lsu rDNA sequences of all major lineages of autotrophic (Ochrophyta) and heterotrophic (Bigyra and Pseudofungi) heterokonts were combined with amino acid sequences from four protein-coding genes (actin, beta-tubulin, cox1 and hsp90) in a multigene approach for resolving the relationship between heterokont lineages. Applying these multigene data in Bayesian and maximum likelihood analyses improved the heterokont tree compared to previous rDNA analyses by placing all plastid-lacking heterotrophic heterokonts sister to Ochrophyta with robust support, and divided the heterotrophic heterokonts into the previously recognized phyla, Bigyra and Pseudofungi. Our trees identified the heterotrophic heterokonts Bicosoecida, Blastocystis and Labyrinthulida (Bigyra) as the earliest diverging lineages.