Cloning and Sequence Analysis of 18S rRNA Gene from Laminaria japonica Gametophytes and Its Application as an Internal Standard

18S rRNA gene sequence of Laminaria japonica was obtained by 18S rRNA gene cloning and sequencing(GenBank accession number:EU293553).The phylogenetic analysis among 8 spieces and an outgroup(Nostoc sp.PCC7120)were constructed based on 18S rRNA gene sequences by neighbor-joining(NJ)method.Based on the result,the genetic distance from L.japonica of Phaeophyta to Nostoc sp.PCC7120 of Cyanophyta,Griffithsia japonica of Rhodophyta and Chlamydomonas reinhardtii of Chlorophyta,was 0.819,0.303 and 0.219 in turn.While among chromophytes the longest genetic distance was 0.201 from Laminaria japonica of Phaeophyta to Rhodomonas sp.CS24 of Cryptophyta,the shortest was 0.103 from L.japonica to Heterosigma carterae of Xanthophyta.Using 18S rRNA gene as internal standard,semi-quantitative RT-PCR result revealed the expression of lhcf6 gene increased with enhanced light intensity.