Studies On Molecular Systematics Of Eucheumatoideae

In this paper, using molecular markers to study the molecular systematics of Eucheumatoideae on the base of morphological characteristics.Firstly, Random Amplified Polymorphic DNA (RAPD) marker was used to estimate the population genetic diversity in six cultured populations of Kappaphycus alvarezii in Hainan provinces, China. 6 primers were selected out from 30 primers and amplified 43 reproducible and discernible loci and the fragments were from 300 bp to 3 kb. There were 42 polymorphic loci and the mean percentage of polymorphic loci is 98.27%. The POPGENE 32 software was used and the number (percentage) of polymorphic loci, Nei's (1973) gene diversity(H) , Shannon's information index(I), genetic distances and genetic identity of 6 populations of Eucheumatoid were 62.79% - 97.67%, 0.1455±0.1809- 0.2463±0.1797, 0.2291±0.2566 - 0.3808±0.2425, 0.0151- 0.1350 , and 0.8737 - 0.9851, respectively. And MEGA4 software was used for UPGMA dendrogram analysis, and the result showed that: S was clustered alone, and LA and XC first superficially clustered together, then ordinally clustered with LD, L and NC. It indicated that the genetic variations among populations were higher than those within populations, and the genetic diversity of Population S was the highest. The six populations really belong to the same species, Kappaphycus alvarezii, though they presented different in shape and color. This study would lay a foundation for further selection of good stains in Kappaphycus alvarezii cultivation production.Then,Random amplified polymorphic DNA(RAPD) was used to study the classification of 16 Eucheumatoid . 7 primers (S352, S384, S399, S1510, S1520, S2003, S2114) selected from 30 arbitrary primers were applied for amplifying the Eucheumatoid DNA. Total 96 bands were produce, among which 43 bands (44.79%) were polymorphic. A dendrogram showed that genetic relationships were constructed through an unweighted pair-group method UPGMA) based on the DNA polymorphism and the 16 Eucheumatoid were clustered into 2 main groups.Next,ISSR technique was used to investigate the genetic diversity of the genus Kappaphycus (Rhodopyta) and genus Eucheuma (Rhodopyta). Five primers (808, 841, 856, 880, 890) were selected from 30 primers and the proportion of polymorphic bands were 100% (40/40) in the genus Kappaphycus and 91.89% (34/37) in the genus Eucheuma. Selecting one specific primer 841 could be used for germplasm identification in the level of genus. It could amplify 600bp band in the genus Kappaphycus , 1000bp band in the genus Eucheuma, and two specific bands (750bp and 1570bp) in the Eucheuma xishaensis (XS, Xisha Island). By using software Popgen32, in the genus Kappaphycus and genus Eucheuma, Shannon's information indices (I) were 0.5667±0.1156 and 0.5205±0.1767; genetic distance were 0.0780-1.6094 and 0.0000-1.6650. MEGA4 software were used for UPGMA dendrogram analysis, each genus were clustered into 2 main groups.At last, using the psbA-trnH regions to analyze the sequence of the genus Kappaphycus (Rhodopyta) and genus Eucheuma (Rhodopyta). The results showed that the lengths of sequences about 670bp. The sequence similarity of two genus were both above 97%. The genetic distance of Kappaphycus and Eucheuma were 0.005-0.034 and 0.000. The GC content of six Kappaphycus was between 54.4%-56.0%, while two Eucheuma were 36.7%å'Œ37.3%.There was 29 difference base in six Kappaphycus, while eight in two Eucheuma. Combining of morphological features, the six Kappaphycus were all Kappaphycus alvarezii, two Eucheuma were Eucheuma denticulatum.