Application Of Denaturing Gradient Gel Electrophoresis In The Study Of Microalgae Identification And Phytoplankton Genetic Diversity

Denaturing gradient gel electrophoresis (DGGE) is an important molecular polymorphism technique. It has been widely used in the study of species identification and plankton community composition. In this study, DGGE was applied to the identification of microalgae. It was also applied to the analysis of phytoplankton community diversity in the East China Sea, Yellow Sea and Yangtze River. Additionally, the linkage of environmental factors and phytoplankton community was analyzed by the ordination technique of canonical correspondence analysis (CCA). The results are summarized as below:(1) Specific primers for amplification of the 18S rDNA, 28S rDNA and rDNA ITS gene were developed for the analysis of microalgae by DGGE. By optimization of PCR reaction conditions, partial fragments of the 18S rDNA and 28S rDNA sequences were selected as characteristic gene domain. Denaturing gradient and electrophoresis time were optimized by perpendicular electrophoresis and time travel experiment. Fortunately, unique bands were obtained for most microalgae studied here. A database was constructed for microalgae of China coast, providing a new method for microalgae identification.(2) Phytoplankton samples were collected from 24 stations of the East China Sea and Yellow Sea in November 2007. Genetic diversity of phytoplankton communities were investigated with DGGE fingerprinting. It was suggested that each group resulted from UPGMA clustering analysis of DGGE profiles showed good consistency with the eco-environmental characteristics of the sea area they belonged to. The Relationship of phytoplankton diversity to environmental factors was statistically analyzed with CCA. Temperature, DIN and silicate-Si were found to be significantly related to the phytoplankton community composition. (3) Surveys were conducted during April (dry season) and September (rainy season) 2006 along 25 stations of the Yangtze River. Phytoplankton community structure was analyzed by DGGE of 18S rRNA genes. It was shown that application of DGGE could reflect regional phytoplankton community distribution in the Yangtze River. CCA was further applied to reveal the relationships between phytoplankton diversity and environmental factors. Results showed that the phytoplankton community was primarily correlated with silicate-Si and SPM in April. In September, silicate-Si and Ammonium-N were found to be significantly related to the phytoplankton community composition.