Molecular Systematic Studies Of Several Seaweeds In China

The dissertation consists of five chapters:In chapter one,the recent progress in molecular approaches in systematic studies of macroalgae e. g. DNA extraction,Restriction endonuclease fragment length polymorphisms (RFLPs),Random amplified polymorphic DNA (RAPD),gene sequencing,Intersimple sequence jepeats(ISSR),Amplified fragment length polymorphisms(AFLP) and Single strand.conformation polymorphisms (SSCP) were reviewed. The trend is refered to combine the evidence from several genes representing both nuclear and organella genomes with morphology,ontogeny and life history for systematic studies;While studies at the population level by applying molecular techniques with high differenciation lead an important direction.In chapter two,genomic DNA were extracted from three species of Ulva and Enteromorpha,respectively and from Cladophora sp. As a control with modified CTAB method. Sixties primers were used for DNA amplification and a total of 237 amplification products range from 450bp to 2500bp were generated. A similarity matrix for all pairwise comparisons was calculated using Nei and Li's formula and then transformed to distance matrix. Dendrograms were constructed by applying Unweighted pair-group arithmetic average (UPGMA) and Neighboring-jointing cluster analyses using the PHYLIP software. The results suggest:DNA samples that were extracted using the modified CTAB method were successfully amplified by RAPD;RAPD technique showed some potential to be useful in determining relationship between species within the two genera. The taxonomic position of ?linza,which is problematic based in morphological classification,showed a closer relationship with Ulva.In chapter three,genomic DNA were extracted from four individuals from Sinotubimorpha porracea and Grateloupia filicina,respectively and from G. livida as a control. Sixties primers were used for DNA amplification and a total of 120 amplification products range from 250bp to 2500bp were generated. Distance matrix and dendrograms were obtained as described in last paragraph. The results suggested that Sinotubimorpha porracea was not a variety of G. filicina,since the genetic difference between them was as large as two species or more.Morphological observations and rbcL sequence analyses of chondrus collected from Pingtan and Zhangpu of Fujian province,Qingdao of Shandong province and Dalian of Liaoning province were made. Total DNA were extracted from fresh or silica gel-desiccated plants and used as templates for polymerase chain reactions.Purified polymerase chain reaction products were directly sequcnced. The rbcL sequences were aligned using Clustal XI. 8 computer program ,then used to calculate di stance matrix with Kimura's two-parameter method and construct phylogenetic trees by applying neighbor-joining and Maximum Parsimony analyses using MEGA2. 1 computer program. Bootstrap analyses were carried out to evaluate statistical reliability based on 500 resamplings of the data set. The results indicated three Chondrus species in China:Chondrus ocellatus,Chondrus nipponicus and Chondrus armatus. The results also suggested that Chondrus ocellatus which was described from specimen collected at Southeast seashore of China should be Grateloupia imbricata and Chondrus yendoi which was described from specimen collected from Xiao Pingdao,Dalian should be Mazzaella japonica.In chapter five,morphological observations and ITS sequence analyses of Monostromaceae in China were made. Distance matrix and phylogenetic trees were obtained as described in last paragraph. The results supported the establishment of Protomonostroma and Kornmanniaceae and suggested Monostroma angicava should be merged with M. grevillei,with the older name M. grevillei taking priority. However,the taxonomic position of M. nitidumvas found to be questionable. We also described M. grevillei var. Vahlii the first time in China. The incongruous results based in DNA sequence analyses and morphological observations may be caused by morphological plasticity in environmental conditions. C...