Molecular phylogenetic analyses of the Japanese Ulva and Enteromorpha (Ulvales, Ulvophyceae), with special reference to the free-floating Ulva

Abstract

SUMMARY In order to elucidate the species composition of free‐floating Ulva that cause green tide in several bays in Japan, and to clarify the generic status of Ulva and Enteromorpha (Ulvales, Ulvophyceae), the nuclear encoded internal transcribed spacer (ITS) region including the 5.8S gene and the plastid encoded large subunit of ribulose‐1, 5‐bisphosphate carboxylase/ oxgenase (rbcL) gene sequences for 15 species were determined. Both ITS and rbcL analyses indicate that free‐floating Ulva samples are divided into four different lineages that correspond to Ulva lactuca Linnaeus, U. pertusa Kjellman, U. armoricana Dion etal. and U. fasciata Delile. These four species are distinguished by cell morphology including the arrangement of cells, the shape and size of cells and the position of chloroplasts. Molecular data also indicated that Ulva and Enteromorpha are not separated as respective monophyletic groups within a large monophyletic clade and congeneric as shown by previous molecular studies using the ITS sequences alone. This strongly suggests that these genera are congeneric and Enteromorpha should be reduced to the synonym of Ulva.

Genetic variation of Ulva (Enteromorpha) prolifera (Ulvales, Chlorophyta)—the causative species of the green tides in the Yellow Sea, China

“…Most previous studies focused on the species identification of bloom-forming algae using molecular markers, such as sequences of the ribosomal DNA internal transcribed spacers 1 and 2 (ITS1 and ITS2), the 5.8 S gene, and the plastid rbcL sequence (Blomster et al 2000;Shimada et al 2003;Jiang et al 2008;Shimada et al 2008). Microsatellite (simple sequence repeat, SSR) markers have been used to study the genetic structure of the U. intestinalis populations in the Gulf of Finland (Alström-Rapaport and Leskinen 2002; Kostamo et al 2008).…”

The dominant Ulva strain of the 2008 green algal bloom in the Yellow Sea was not detected in the coastal waters of Qingdao in the following winter

“…Species in the genus Ulva are widely distributed in marine and brackish water environments all over the world (Hayden and Waaland 2002;Shimada et al 2003;McAvoy and Klug 2005). Recently, molecular phylogenetic analyses and culture data provided convincing evidence that Ulva and Enteromorpha are not distinct evolutionary entities and should be recognized as one genus of the Ulvophyceae, Ulva (Tan et al 1999;Hayden et al 2003;Shimada et al 2003).…”

“…Recently, molecular phylogenetic analyses and culture data provided convincing evidence that Ulva and Enteromorpha are not distinct evolutionary entities and should be recognized as one genus of the Ulvophyceae, Ulva (Tan et al 1999;Hayden et al 2003;Shimada et al 2003). Ulva species are highly tolerant of variations in salinity, temperature, irradiance, and water quality (Taylor et al 2001;Dan et al 2002;Cohen and Fong 2006;Conley et al 2009).…”

“…This high level of plasticity often leads to difficulties in species identification when only based on morphological and cytological features (Blomster et al 2002;Leskinen et al 2004). In view of these facts, molecular methods were introduced on the basis of sequence comparisons of the nuclear encoded internal transcribed spacer DNA (ITS nrDNA) region, including the 5.8S gene, the more conserved plastid encoded large subunit of the ribulose-1,5-bisphosphate carboxylase/oxgenase (rbcL) gene, and the 5S spacer region (Marks and Cummings 1996;Leskinen and Pamilo 1997;Blomster et al 1998;Woolcott and King 1999;Shimada et al 2003Shimada et al , 2008Hayden and Waaland 2004).…”

Seasonality and thallus ontogeny of edible seaweed Monostroma latissimum (Kützing) Wittrock (Chlorophyta, Monostromataceae) from Tosa Bay, Kochi, Japan

“…A region of approximately 293 bp encompassing the partial ITS 1 sequences was PCR amplified and sequenced. Methods for PCR amplification and sequencing were as described by Shimada et al (2003). DNA sequences were deposited in GenBank.…”