Intraspecific Genetic Diversity of Undaria pinnatifida in Japan, based on the Mitochondrial cox3 Gene and the ITS1 of nrDNA

Abstract

The intraspecific genetic diversity of the kelp Undaria pinnatifida (Harvey) Suringar (Laminariales, Phaeophyceae) was investigated using DNA sequences of the mitochondrial cytochrome oxidase subunit 3 (cox3) gene and internal transcribed spacer 1 (ITS1) of nuclear ribosomal DNA in plants collected from 21 localities along the Japanese coast between 2001 and 2003. Morphological variation was also examined and compared with the genetic diversity. Cox3 analyses of 106 plants revealed 9 haplotypes (I-IX) that differed from each other by 1-7 bp (all synonymous substitutions). Haplotype I was distributed in Hokkaido and the northern Pacific coast of Honshu, while haplotype III was found along the Sea of Japan coast of Honshu. Other types were found along the central and southern coast of Honshu. ITS1 analyses of 42 plants revealed 0-1.7% nucleotide differences, but plants from the Sea of Japan coast and northern Japan had similar sequences. The lower genetic differentiation along the Sea of Japan and northern coasts might be due to the recent establishment (after the middle of the last glacial period) of the Sea of Japan flora. The cox3 haplotype of cultivated plants was found in natural populations occurring close to cultivation sites (Naruto, Tokushima Pref., and Hokutan, Hyogo Pref.). This suggests that cultivated plants possibly escaped and spread or crossed with plants of natural populations. Morphological analyses of variation in 10 characters were conducted using 66 plants. The results showed no significant local variation owing to the wide variation in each population and did not support any forma previously described. No correlations between the morphological characters and cox3 haplotypes were detected.

Phylogeography ofPadina boryana(Dictyotales, Phaeophyceae) around the Thai-Malay Peninsula

“…This could be a case of 'recent' hybridization in a contact zone, as these samples were all found in the lower Gulf of Thailand populations in the area of Surat Thani (SR), Nakhon Si Thammarat (NK) and Pattani (PT). Similar incongruence between nuclear and organellar markers has been noted in several algal studies (Uwai et al, 2006;Andreakis et al, 2007;Neiva et al, 2010).…”

Conservation and polymorphism of mitochondrial intergenic sequences in brown algae (Phaeophyceae)

“…Gielly & Taberlet, 1994), our mitochondrial intergenic spacers are very efficient and clearly evolve faster than previously used mitochondrial coding sequences of brown seaweeds (Ehara et al, 1999;Kogame et al, 2005;Muraoka & Saitoh, 2005;Coyer et al, 2006;Lane et al, 2006;Uwai et al, 2006a). Indeed, even within single loci, flanking coding sequences showed divergence values 2-to 12-fold lower than their corresponding non-coding spacer regions (results not shown).…”

“…In the Phaeophyceae, the existing repertoire of mitochondrial markers has generally been limited to conserved coding regions used for higher-order phylogenetics (Ehara et al, 1999;Lane et al, 2006;Oudot-Le Secq et al, 2006), detection of interspecific hybridization (Coyer et al, 2002a,b) and, more recently, for phylogeographic studies (Muraoka & Saitoh, 2005;Uwai et al, 2006a). However, for lower-level taxonomic and population-level studies, presumably neutral, non-coding regions, such as introns or intergenic spacers are preferable, to avoid the confounding effects of selection, which are particularly problematic in phylogeographic studies where patterns of gene flow must be inferred from gene genealogies.…”

Sperm Mitochondrial DNA Elimination in the Zygote of the Oogamous Brown Alga Undaria pinnatifida (Laminariales, Phaeophyceae)

“…Vegetative female and male gametophytes of U. pinnatifida, ooiso6-male, ooiso6-female, ooita5-male, and ooita5-female strains (Uwai et al 2006), were cultured in Fe-free ASP 12 NTA medium (Motomura and Sakai 1984). Gametogenesis was induced by transfer into PESI medium (Tatewaki 1966).…”

“…General primers (tTrpF1, tIleR1) and strain-specific primers (spacerF2t9, spacerR2t9, spacerF2t16, spacerR2t16) against mtDNA of U. pinnatifida were designed by referring to the mtDNA sequences of the tRNA coding regions in 2 strains of U. pinnatifida (AB240652, AB240659; Uwai et al 2006) (Table 1, Fig. 1).…”