The Response Of Soil Archaeal Community Structure Diversity To Natural Evolution In The Yellow River Delta

Since Woese first proposed the Three Domains in the biosphere, the theory of archaea considered to be the bacterial branch ended. With the application and development of molecular biology and microbiology uncultured technology in recent years, archaea have also been found widely distributed in a variety of environment, such as soil, lake, wetland and so on. The archaea is regarded as one of the important object by modern microbiology, environmental science and many other disciplines with its extreme living environment and unknown physiological processes and functions. Effects of archaea in the ecosystem for plant- soil- archaea are increasingly prominent. The research of archaeal community structure diversity is extremely weak compared with bacteria in the Yellow River Delta. Reports about the response of soil archaeal to the halophyte natural evolution are especially rare.In this paper, 0- 20 cm and 20- 40 cm soil layers under the bare board, Saline Seepweed, Angiospermae, Imperata and A. venetum in the Yellow River Delta were selected as research projects. Soil physical and chemical properties were measured in order to analyz and compare the response and trends in different soil depth and halophyte evolution stages. The archaeal community structure composition and relative content under different cover types were analyzed at horizontal and vertical distribution levels by using high-throughput sequencing technology. Then explored the response of soil archaeal community structure diversity to the halophyte natural evolution. Discussed the impacts of soil physical and chemical properties on changes of soil archaeal community structure diversity by analyzing the correlation between soil physical and chemical properties and soil archaeal relative content under different halophyte.The main research conclusions are as follows:(1) Compared soil physical and chemical properties in A and B layers respectively, in addition to the soil temperature in B layer and soil nitrogen, the rest showed significant differences. Compared soil physical and chemical properties in A and B layers as a whole, only soil temperature showed significant difference. In addition to soil moisture, the rest soil physical and chemical properties in A and B layers showed the same trends. With the salt vegetation forward succession, soil temperature and electrical conductivity(salinity) presented a decreasing trend, soil available phosphorus presented an increasing trend, the soil total nitrogen, soil available nitrogen and labile organic matter presented a first increasing and then decreasing trend. The contents of soil temperature, total nitrogen, available nitrogen and available phosphorus were higher in A layer than in B layer. While the contents of soil water, electrical conductivity(salinity) and labile organic matter were higher in B layer than in A layer. Bare board with no vegetation coverage had the highest soil electrical conductivity(salinity) and the lowest nutrient.(2) Valid sequence numbers of bare board and Angiospermae in A layer were higher than in B layer, and were higher of Imperata and A. venetum in B layer than in A layer. In addition to Imperata soil, OTU numbers of the rest in A layer were all higher than in B layer, in which the bare board soil had the highest OTU number, followed by A. venetum soil. The diversity index in A and B layers showed less differences. In addition to Imperata soil, the diversity index of the rest soil were higher in A layer than in B layer. Bare board soil with no vegetation coverage had the highest Shannon Index, ACE index and Chao1 index, corresponding to the highest soil archaeal community diversity and richness, followed by A. venetum soil.(3) Sequences of archaeal community under the five cover types mainly belonged to two phyla: Euryarchaeota and Crenarchaeota. Archaeal species in A layer were more than in B layer. Euryarchaeota was the advantage microflora in both A and B layers, and had significant differences with Crenarchaeota. Euryarchaeota had the highest relative content in bare board, followed by A. venetum soil. Soil archaeal community structure wasn't consistent strictly with halophytic vegetation succession. Soil archaeal community structure didn't showed obvious similarity when the halophytic vegetation succession at the same stage. Most soil archaeal community structure had differences at different successional stages, while the differences were not all greater when at different stages.(4) Soil temperature, electrical conductivity(salinity), total nitrogen, available nitrogen and labile organic matter had greater influences on soil archaeal community structure diversity in A and B layers. Each correlation between soil physical and chemical properties and soil archaeal community in A and B layers was different, and the consistency was higher in B layer. Most Euryarchaeota had positive correlations with soil temperature and electrical conductivity(salinity), and negative correlations with soil water content, total nitrogen, available nitrogen, available phosphorus and labile organic matter. And the positive correlation between archaea and soil conductivity(salinity) was more significant in B layer. Crenarchaeota in A layer had positive correlations with soil water content, total nitrogen, available nitrogen, available phosphorus and labile organic matter, and negative correlations with soil temperature and electrical conductivity(salinity). While correlations between archaea and soil physical and chemical properties in B layer were completely opposite to in A layer.