Small-subunit rRNA gene sequences from representatives of selected families of the Gigartinales and Rhodymeniales (Rhodophyta). 1. Evidence for the Plocamiales ord.nov.

Abstract

Nucleotide sequences of the nuclear, small-subunit (SSU) ribosomal RNAs, as inferred from polymerase chain reaction (PCR)-amplified products, are presented for Areschougia congesta (Turner) J. Agardh (Solieriaceae), Dasyphloea insignis Montagne (Dumontiaceae), Sarcothalia crassifolia (C. Agardh) Edyvane & Womersley (Gigartinaceae), Nizymenia australis Sonder (Nizymeniaceae), Phacelocarpus peperocarpos (Poiret) Wynne, Ardré & Silva (Phacelocarpaceae), Plocamiocolax pulvinata Setchell, Plocamium angustum (J. Agardh) J.D. Hooker, Plocamium cartilagineum (Linnaeus) Dixon (Plocamiaceae), Rhodymenia linearis J. Agardh (Rhodymeniaceae), and Sphaerococcus coronopifolius Stackhouse (Sphaerococcaceae). Phylogenetic analyses of the SSU sequences between the Plocamiaceae and members of the Sphaerococcaceae, Phacelocarpaceae, and Nizymeniaceae, with which the Plocamiaceae has been associated historically, show SSU differences of between 87 and 105 nucleotides and do not indicate a close relationship. A review of anatomical knowledge of the Plocamiaceae and Pseudoanemoniaceae and new information on vegetative and tetrasporangial development in Plocamium and Plocamiocolax are presented to buttress a case for the Plocamiales ord.nov. Representatives of the Nizymeniaceae and Phacelocarpaceae differ from one another by only nine nucleotides, suggesting that these two taxa are very closely related and perhaps not distinct at the family rank. Key words: Gigartinales, PCR, phylogeny, Plocamiales ord.nov., Pseudoanemoniaceae, Rhodophyta, small-subunit rRNA, systematics.

Combining small and large subunit ribosomal DNA genes to resolve relationships among orders of the Rhodymeniophycidae (Rhodophyta): recognition of the Acrosymphytales ord. nov. and Sebdeniales ord. nov.

“…The Plocamiales was removed from the Gigartinales based on a combination of molecular and anatomical data (Saunders & Kraft, 1994). Since then, molecular studies using SSU (Saunders & Kraft, 2002;, LSU (Harper & Saunders, 2001b) and combined SSU þ LSU analyses (Harper & Saunders, 2001b) have continued to support the independence of this order.…”

“…Saunders et al, 1994). Lindstrom (1987) proposed the monogeneric family Acrosymphytaceae removing Acrosymphyton from the Dumontiaceae (Gigartinales) based on differences in female reproductive structures and post-fertilization development.…”

“…The first in a series of SSU-based phylogenetic studies directed at the Florideophyceae combined molecular data with observations of reproductive structures and reduced the complexity of the Gigartinales by removing the Plocamiaceae, and (provisionally) the Pseudoanemoniaceae, to the Plocamiales (Saunders & Kraft, 1994). Two years later, Saunders & Kraft (1996) used SSU data to support Kraft & Robins' (1985) union of the Cryptonemiales and Gigartinales with the exception of the families Halymeniaceae and Sebdeniaceae, exemplars of Kylin's Cryptonemiales and Gigartinales, respectively.…”

Phylogenetic diversity in South AfricanPorphyra(Bangiales, Rhodophyta) determined by nuclear SSU sequence analyses

“…PCR amplification of the nSSU rDNA region was performed by amplification of two overlapping fragments. Fragment R, *1170 bp in size, was amplified by primers 18e (Hillis & Dixon, 1991) and NS4 (White et al, 1990) and fragment Qs, *850 bp in size, by primers G04 (Saunders & Kraft, 1994) and J04 (Broom et al, 1999) as shown in Fig. 2.…”

“…Reaction products were purified by PEG precipitation and sequenced on an ABI 377 automatic sequencer (Perkin Elmer Applied Biosystems, Foster City, CA, USA) utilizing standard methods. Where possible, after initial amplification of the Qs product, the 3' region of the nSSU rDNA was sequenced using primer G06 (Saunders & Kraft, 1994). This sequence, which spans approximately 450 bp and includes the V9 variable region of the gene (Neefs et al, 1993), has been found to be a useful proxy for overall variation in the whole nSSU in Porphyra (Broom et al, 1999).…”