Phylogeny of the genus Kluyveromyces inferred from the mitochondrial cytochrome-c oxidase II gene.

Abstract

A phylogenetic analysis of 17 species belonging to the genus Kluyveromyces and 12 reference and outgroup species was performed using mitochondrial cytochrome-c oxidase II gene sequences. The genus Kluyveromyces appears as a polyphyletic taxon formed by species included within the following four main groups. The Kluyveromyces phaffii group encompasses the species Kluyveromyces blattae, K. phaffii and Kluyveromyces yarrowii. The Kluyveromyces marxianus group is a monophyletic group consisting of the species Kluyveromyces aestuarii, Kluyveromyces dobzhanskii, Kluyveromyces lactis, K. marxianus and Kluyveromyces wickerhamii. The monophyletic Kluyveromyces thermotolerans group is formed by K. thermotolerans, Kluyveromyces waltii and Saccharomyces kluyveri (which appears in the mitochondrial tree as the sister clade of the K. marxianus group). Finally, the Saccharomyces cerevisiae group contains the remaining Kluyveromyces species, as well as the reference Saccharomyces species (sensu lato and sensu stricto) and Candida glabrata (the phylogenetic relationships within this group are unclear according to the bootstrap test). The phylogenetic relationships obtained for this mitochondrial gene are, for the most part, congruent with previous trees based on nuclear rRNA sequences, except for the position of K. yarrowii and the close relationship between the K. marxianus and K. thermotolerans groups. These differences, as well as the existence of these groups, are discussed in the context of previous studies based on phenotypic, genetic and molecular data. Although additional studies are required to decipher the phylogenetic relationships between the genus Kluyveromyces and the closely related genera Saccharomyces, Torulaspora and Zygosaccharomyces, future changes to their taxonomic status should take account of the existence of these four groups of Kluyveromyces species.

An analysis of inter- and intraspecific genetic variabilities in the Kluyveromyces marxianus group of yeast species for the reconsideration of the K. lactis taxon

“…Then, the difficulty of deducing convincing phylogenetic relationships could be evidence of a rapid radiation of the species K. dobzhanskii, K. lactis, K. marxianus and K. wickerhamii. In fact, short internode lengths and similar levels of sequence divergence among taxa have been also suggested as consistent with a hypothesis of rapid origin and radiation of lineages (Belloch et al, 2000).…”

“…The reconstruction of the phylogenetic relationships among species of the genus Kluyveromyces, either by 18S rRNA gene sequences (Cai et al, 1996;James et al, 1997), 26S rRNA gene sequences (Kurtzman and Robnett, 1998), restriction analysis of the 5.8S rRNA gene and the two ribosomal internal transcribed spacers (Molina et al, 1992;Shen et al, 1994;Belloch et al, 1998a) or mitochondrial COII gene sequences (Belloch et al, 2000), indicates that the Kluyveromyces is a polyphyletic genus formed by four groups of species.…”

“…The closer relationship between K. marxianus and K. dobzhanskii appears to be incongruent with the phylogenetic relationships obtained for the K. marxianus species group with the 26S rRNA gene Table 2) exhibited by Kluyveromyces lactis strains after chromosome DNA electrophoresis using running conditions, 600-1200 s, 75 V for 48 h, 120-400 s, 80 V for 48 h in 0.8% agarose gels 264 C. Belloch et al (Kurtzman and Robnett, 1998), in which the closest species are K. lactis and K. marxianus (BV 97%), and with the 18S rRNA gene (Cai et al, 1996;James et al, 1997), and the mitochondrial COII gene (Belloch et al, 2000), in which the closest species are K. dobzhanskii and K. lactis, with BVs of 84% in both trees. Alternative topologies representing all possible branching orders among these four species, compared by the test of Templeton (1983) and by the test of Kishino and Hasegawa (1989), were not significantly different, not only for the 5.8S-ITS region sequences but also for the 18S rRNA, 26S rRNA and COII gene sequences (not shown).…”

“…The investigation of the phylogenetic relationships among the members of the genus Kluyveromyces has revealed the existence of a monophyletic group, the so-called K. marxianus group, constituted by the species K. aestuarii, K. dobzhanskii, K. lactis, K. marxianus and K. wickerhamii (Lachance, 1989;Cai et al, 1996;Kurtzman and Robnett, 1998;Belloch et al, 2000). The closeness among these species has also been demonstrated by mating studies (Johannsen, 1980;Naumov, 1986Naumov, , 1988, DNA base composition and hybridization (Fuson et al, 1987;Vaughan-Martini and Martini, 1987), isoenzyme analysis Lachance, 1983, 1986), karyotypes (Sor and Fukuhara, 1989;Viljoen et al, 1989;Lehmann et al, 1992;Belloch et al, 1998b), restriction analysis of mtDNA (Ragnini and Fukuhara, 1988;Belloch et al, 1997), and RAPD-PCR analysis (Molnar et al, 1996).…”

Gene order evolution and paleopolyploidy in hemiascomycete yeasts

“…The phylogenetic position of C. glabrata is uncertain; different analyses have placed it at different positions relative to Saccharomyces and Kluyveromyces species, never with strong bootstrap support (4, 30 -32 (32). We therefore suggest that C. glabrata, as well as S. exiguus and S. servazzii, is related to S. cerevisiae as shown by the hypothetical species Y in Fig.…”