Research On Molecular Systematics And Asexual Reproduction Variation Of Four Solieriaceae Algae

Eucheuma, Kappaphycus and Betaphycus belong to Solieriaceae, Gigartinales,Florideophyceae, Rhodophyta, are the main economic tropical and subtropical redalgae producing carrageenan. In China, they are mainly distributed in Hainan Island,Taiwan island as well as Paracel Islands and Spratly Islands. In addition, Indonesia,Philippines, Malaysia etc are also of high yield of such seaweeds.At present, the development and application of molecular tools are expected tosupplement the traditional morphologic classification. Red seaweeds are mainlyconcentrated in the study of internal transcribed spacer in ribosomal18S and28S,23Sribosomal RNA gene, coxâ…  in mitochondrion, cox2-3spacer fragement,ribulose-bisphosphate carboxylase in Chloroplast, rbc spacer between the rbcS genes.In this study, five molecular markers of ITS, UPA (23S ribosomal RNA gene),mitochondrial cox2-3, rbc spacer and rbcL (chloroplast) were used and followed aPCR method to analyze the sequence characters of Betaphycus gelatinae, Eucheumadenticulatum, Kappaphycus sp. and Kappaphycus alvarezii. The results showed thatthe UPA gene of Betaphycus, Kappaphycus and Eucheuma were all326bp in length,and the GC content varies from46.0%to46.3%. cox2-3gene showed that thesequence length of these three genus were141bp,139bp,141bp, and the GC contentvaries from19.3%to23.7%. rbc spacer gene showed that the sequence length of thisthree genus were93bp,93bp,94bp, and the GC content varies from22.3%to23.7%.ITS gene showed that the sequence length of these three genus were1024bp,629bp-669bp,1001bp, and the GC content were from45.2%to52%. rbcL geneshowed that the sequence length of this three genus were all1467bp and the GCcontent were between37.1%and37.6%. Phylogenetic analyses of Solieriaceaeseaweeds conducted by PAUP4.0b10using NJ, MP and ML methods indicated thatEucheuma, Kappaphycus and Betaphycus were able to be obviously distinguished.Moreover, these three molecular markers can effectively distinguish two species from the genus of Kappaphycus. In addition, ITS fragment can also distinguish thevariation within the Kappaphycus genera. Moreover, this study compared thebioinformation points within different species of three algal genera of Solieriaceae,providing some data support for the research of molecular biology.Transposition phenomenon is an important mechanism which can cause epigeneticvariation in the clonal propagation. Retrotransposons is widely distributed ineukaryotic organisms. Retrotransposon-microsatellite amplified polymorphism(REMAP) is a kind of molecular marker technique has the advantages of easilyoperating, rich polymorphism, highly detection efficiency. In this study,20primerswere selected to conduct REMAP molecular marker study in five populations ofSolieriaceae seaweeds. The results showed that REMAP had better amplificationeffect in the selected five populations,500locis were amplified, and all of them werepolymorphism. The proportion of polymorphic loci was100%. The genetic distanceamong the five populations were between0.4861-0.7497. The results analyzed withArlequin software showed that contribution rates within populations and amongpopulations were7.38%and92.62%respectively, genetic differences amongpopulations was significantly higher than that within populations, showing greatresolving ability for species. The clustering results showed that these markers cansignificantly distinguish the five populations, and samples from the same populationall clustered together, showing better species specificity, moreover, for differentindividuals from same population, showed some extent amplified polymorphism,which revealed that transposable induced variation also existed. This study showedthat REMAP molecular marker has important research value on the identification andpopulation research of Solieriaceae species. Do further research on four differenttissue parts from3strians of Kappaphycus alvarezii, the results showed that theaverage proportion of polymorphic loci was26.65%, further confirmed the existenceof variation in the asexual reproduction, and these variation may be associated withretrotransposon activity.