UTILITY OF THE MITOCHONDRIAL nad4L GENE FOR ALGAL AND PROTISTAN PHYLOGENETIC ANALYSIS¹

Abstract

Mitochondrial gene sequences, in contrast to their plastid counterparts, have been rarely exploited for use in determining algal phylogenetic relationships. Their utilization would prove advantageous particularly for the assessment of evolutionary relationships among protistan lineages that include photo synthetic species and their colorless heterotrophic dependents that contain only a reduced plastid genome as well as ancestral nonphotosynthetic relatives. Recent studies that have examined mitochondrial protein (coxl, cox2, cob, and nad5) rather than ribosomal RNA genes confirm that these algal sequences are sufficiently conserved to be used routinely in algal systematics. In this investigation, we sequenced the mitochondrial nad4L gene, encoding a small (ca. 99‐amino acid) polypeptide subunit of the NADH dehydrogenase complex, from two chromophytic algae and an oomycete to determine its suitability for use in determining algal and protistan evolutionary relationships. Our analysis demonstrated that nad4L could clearly resolve these three organisms as a distinct clade, the stramenopiles, to the exclusion of terrestrial plants/chlorophytes and eufungi. However, the position of deeply rooted species within the stramenopiles proved tenuous and would best be examined in conjunction with the analysis of longer mitochondrial protein gene sequences.

Mitochondrial genome sequences reveal evolutionary relationships of the Phytophthora 1c clade species

“…P. infestans and other oomycetes are members of the Stramenopila and are not true fungi (Chesnick et al 1996; Gunderson et al 1987; Föster et al 1990). P. infestans is closely related to four other Phytophthora species that infect different hosts.…”

Activity of some aminoglycoside antibiotics against true fungi, Phytophthora and Pythium species

“…Phytophthora and Pythium species are pseudofungi belonging to the phylum Heterokonta of the kingdom Chromista (Gunderson et al. 1987; Chesnick et al. 1996; Khulbe 2001) and as many as 95 Phytophthora and 100 Pythium species have been reported (Erwin and Ribeiro 1996; Kamoun et al.…”

New Frontiers in the Study of Dispersal and Spatial Analysis of Epidemics Caused by Species in the GenusPhytophthora

“…Plant diseases caused by species in the genus Phytophthora are responsible for significant economic losses on many important food, fiber, and ornamental crops (30). Phytophthora species are classified in the Kingdom Stramenopila and the phylum Oomycota and are actually more closely related to the golden brown algae than the true fungi (20,48). Phytophthora species have a diploid life cycle and contain cellulose in their cell walls unlike the true fungi.…”