Study On Genetic Diversity Of Virioplankton In Napahai Wetland

Virioplankton is widely distributed in different habitats in nature. They show very important promoting effect on energy flow and material circulation on the planet. Bacteriophages are a large class of Virioplankton. With the development of molecular biology techniques, studies on the genetic diversity of virus are more and more. Wetlands are natural species gene pool. However, researches on genetic diversity of virioplankton are mainly focus on marine, freshwater lakes, terrestrial or paddy field environment. Natural wetlands have been poorly studied. Napahai wetland is a unique seasonal plateau wetland with low-latitude and high-altitude in China. In addition to the study on plants and animals, the research on genetic diversity of virioplankton has not been reported in Napahai wetlands.Different samples were collected in the rainy and dry season in Napahai wetland. First, the distribution of T4-type bacteriophage communities in Napahai wetland was detected by using the highly conserved biomarker gene of g23, which encodes the major capsid protein of T4-type bacteriophage, and can be amplified with primers of MZIAlbis and MZIA6 by PCR.122 different g23 clone sequences were obtained. The phylogenetic analysis showed it had rich T4 phage diversity and unique genetic diversity in Napahai wetland, and four unique groups, NPH-2, NPH-4, NPH-13 and NPH-14 were obtained. According to the PCoA analysis, T4 bacteriophages were widely distributed in different habitats, whereas it possed obvious difference between bacteriophage communities in different environments. Most T4 bacteriophages in Napahai alone clustered and were far apart with other habitats. They may be unique T4 bacteriophage communities in Napahai wetland. Correlation analysis of g23 genetic diversity and the environment physicochemical properties indicated that the element content, temperature, pH and concentration of chlorophyll play a significant role on diversity. Different environmental factors have different degree of influence on water and soil samples.Then the psbA gene encoding the photosynthetic proteins of cyanophage in Napahai soil were amplified by PCR using specific primers pro-psbA-F and pro-psbA-R. A total of 51 different psbA clone sequences were obtained. Phylogenetic analysis and PCoA analysis with other environments including marine, freshwater and paddy showed that the psbA gene sequences in Napahai were closed to Japanese rice field’s, but have a obvious different with the ocean, and most clustered cyanobacteria. It was deduced that NT-4 and NT-7 may be unique cyanophage groups in Napahai wetland, and were similar to cyanophage. Based on psbA sequences high similarity with cyanobacteria, it was speculated the existence of horizontal gene transfer between cyanophage and host.It revealed genetic diversity and distribution of phytoplankton virus in Napahai plateau wetland in this study, and provided scientific basis for further ilumination the function of phytoplankton virus in wetland ecosystem.