| Laminaria is one of the most important economic marine macroalga. Its farming area and yield-production both rank first in the whole world. Laminaria has a wide range of application including food industry, chemical materials and marine drugs. As a result, it plays an irreplaceable role in the national economy and people's well-being. In addition, Laminaria is an important part of the primary productivity of the subtidal area,taking care of the marine environment and maintaining ecological balance. To some extent, our work leads in the field of Laminaria breeding from the start, and some improved varieties have been raised gradually. Laminaria cultivar with a single high-yield property can not meet the diverse market demands. A leap from quantitative change toward qualitative change is sure to occur. In order to solve those problem and to develop the breeding theory, modern Laminaria farming industry must focus on breeding, germplasm resources and the corresponding molecular biology research.Sequence-related amplified polymorphism (SRAP) is a novel molecular marker technique based on the polymerase chain reaction (PCR). Primers are designed to amplify open reading frames (ORFs), for the fact that GC is rich in exonic regions while AT is rich in intronic regions and regions with promoters. As a result, the forward primers amplify exonic regions and the reverse primers amplify intronic regions and regions with promoters. The observed polymorphism originates in the variation of the length between these extrons, introns, promoters and spacers, both among individuals and among species. SRAP has been applied extensively in genetic linkage map construction, genetic diversity analysis and comparative genetics of different species. But when it comes to the algae-related reseach, SRAP has only been uesd to explore the genetic diversity and genetic linkage map construction of Porphyra.SRAP marker analysis is applied to assess genetic structure between seven Chinese Laminaria cultivars (169 samples in total). Fifteen out of eighty-eight SRAP primer combinations are selected in the experiment. A total of 246 reproducible loci ranging from 100 to 900 bp are obtained, among which 226 are polymorphic, with an average of 16.40 loci and an average of 15.07 polymorphic loci per primer combinations. The percentage of polymorphic loci (P) of seven populations ranges from 54.07% to 63.41%, while Nei's genetic diversity (H) is between 0.2003 and 0.2292, and the Shannon's Information index (I) ranges from 0.2962 to 0.3406, and the average of P, H, I was 57.67%, 0.2139 and 0.3162, respectively. It is revealed all the seven populations show high standard of genetic diversity, with the highest in the Shengchanzhong population (as contral) and the lowest in the Rongfu population. At the species level, the percentage of polymorphic loci (P), Nei's genetic diversity (H) and Shannon's Information index (I) is 91.87%, 0.3143 and 0.4691 respectively. Unweighed pair group method with arithmetic averages (UPGMA) dendrograms is constructed based on genetic distances among populations. Analysis of molecular variance (AMOVA) demonstrates that the major genetic variation is originated from intra populations, accounting for 61.52%. At the same time, only 38.48% of variations occur in inter populations. The genetic differentiation among populations is highly significant (P<0.01). The Gst value is 0.3176, consistent with Fst (0.3848), and the gene flow (Nm) is 1.0743, indicating genetic differentiation and gene exchange exists among populations.SRAP is applied in the area of Laminaria research for the first time, providing a new tool for the genetic diversity analysis, germplasm identification and other molecular biological research of Laminaria. Fully convinced, SRAP can guide the genetic breeding of Laminaria in the future. |
PDF Full Text Request