| Molecular Ecological Studies on Genetic Variation and Salt-Resistant Characteristics of Several Species of MangrovesZhou Han-tao(School of Life Sciences, Xiamen University 361005)AbstractMangroves, the intertidal ecosystems occurring primarily in the tropical regions around the world, are valuable natural resources with high productivity and special wetland habitat. The plant species that are quite diversity to form a part of the ecosystem are constantly under environmental stress due to high saline conditions and extreme temperatures and have adapted themselves to these frequent and fluctuating changes at the special place or in the introduction. These plants, which are either bushy shrubs or small-to-large trees, are of great significance because of their potential in protecting coastlines by preventing sea water inundation; inspecting & purging the environmental pollution: and maintaining coastal ecological balance. However, detailed studies of these plants are lacking in major areas. Especially, the genetic polymorphism of the genomes of the plant species in the mangrove ecosystem is poorly understood, and the substantial accumulation of mucilage, latex, phenolics, tannins and other secondary metabolites in these plants make it a difficult system for the studies of molecular biology. In the study, the techniques of RAPD molecular marker .were established to analysis the genetic polymorphism and genetic relationship in mangroves. The technical systems of mRNA differential display were established to isolate the salt-resistant genes from Avicennia marina. The techniques of two-dimensional gel electrophoresis ~vere established to isolate the salt-resistant proteins from Avicennia marina, and the characteristics of these proteins were also analysed. The concrete results as followed:1.CTAB method used in the experiment of DNA extraction is an effective way to wipe off the substantial accumulation of mucilage, latex, phenolics, tannins and other secondary metabolites in mangrove, The obtainment of the DNA extraction has a high ratio I 2Oug DNA per-gram-fresh-weight leaves. The DNA extraction with value of A2~/A,80 between 1.6-1.8 indicates that it is purified enough for RAPD analysis. DNA bands are integral fragments with the size about 23Kb in 0.8% agarose gel. The DNA extraction can be used as the DNA template for RAPD analysis.To ensure that the results of RAPD will be reproductive and true in mangroves, themajor affecting factors in RAPD were studied. These factors included the concentrations of Taq polymerase enzyme, MgCl2, template, dNTPs, primer and thermal cycles, et aI. The final optimized RAPD conditions in mangoves were: each 25 11 I reaction solution was consisted of l0XBuffer (100mM Tris-HCI, pH8.O, 500mM KC1, 0.1%gelatin), SOng template DNA, 2mmol MgCl2, 0.2ismol/L dNTPs of each, 0.2~.t mol/L primer and O.5U Taq DNA polymerase. The amplification procedure conditions were : denature at 94~C I mm, annealing 36~Cfor I mm, extension 72'C for 2 mm, cycling 40 times, last extension at 72~C for 7 mm. The average amplified bands were 6-7. and the results can be repeated finely.2.DNAs of seven species of mangroves in Jiulongiiang Estuary in Fujian, which are Avicennia marina, Aegiceras corn iculatum, Sonneratia apelala, Kandelia candel, Bruguiera gymnorrhiza, Brziguiera sexangula and Bruguiera sexangula var. rhynchopetala , were extracted as the templates. RAPD analysises on genetic diversity of mangroves were conducted. 15 effective primers were screened from 30 10-oligonucleotide arbitrary primers, and a total of 630 DNA bands were amplified, among which 535 (84.92%) were polymorphic. Based on UPGA cluster analysis on DNA bands amplified by the 15 primers, a DNA molecular dendrogram was established. A standard delimit of genetic distance in mangroves was also established, and compared to the conventional classification, the molecular classification of mangroves was accurate.3.DNAs from 7 species in Rhizophpraceae of Dongzhai Harbour Mangrove Reserve in Hainan, which are Rhiz...
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