Molecular Ecology of nifH Genes and Transcripts Along a Chronosequence in Revegetated Areas of the Tengger Desert.
The colonization and succession of diazotrophs are essential for the development of organic soil layers in desert. We examined the succession of diazotrophs in the well-established revegetated areas representing a chronosequence of 0 year (control), 22 years (restored artificially since 1981), 57 years (restored artificially since 1956), and more than 100 years (restored naturally) to determine the community assembly and active expression of diazotrophs. The pyrosequencing data revealed that Alphaproteobacteria-like diazotrophs predominated in the topsoil of our mobile dune site, while cyanobacterial diazotrophs predominated in the revegetated sites. The cyanobacterial diazotrophs were primarily composed of the heterocystous genera Anabaena, Calothrix, Cylindrospermum, Nodularia, Nostoc, Trichormus, and Mastigocladus. Almost all the nifH sequences belonged to the Cyanobacteria phylum (all the relative abundance values >99.1 %) at transcript level and all the active cyanobacterial diazotrophs distributed in the families Nostocaceae and Rivulariaceae. The most dominant active cyanobacterial genus was Cylindrospermum in all the samples. The rank abundance and community analyses demonstrated that most of the diazotrophic diversity originated from the "rare" species, and all the DNA-based diazotrophic libraries were richer and more diverse than their RNA-based counterparts in the revegetated sites. Significant differences in the diazotrophic community and their active population composition were observed among the four research sites. Samples from the 1981-revegetating site (predominated by cyanobacterial crusts) showed the highest nitrogenase activity, followed by samples from the naturally revegetating site (predominated by lichen crusts), the 1956-revegetating site (predominated by moss crusts), and the mobile dune site (without crusts). Collectively, our data highlight the importance of nitrogen fixation by the primary successional desert topsoil and suggest that the N2-fixing cyanobacteria are the key diazotrophs to the nitrogen budget and the development of topsoil in desert, which is critical for the succession of the degraded terrestrial ecosystems.
Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China.|Laboratory of Plant Stress Ecophysiology and Biotechnology, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China.
Jin
J
Wang
Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China.|School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, 730050, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
Jing-Ting
JT
Bao
Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China. lxinrong@lzb.ac.cn.|Laboratory of Plant Stress Ecophysiology and Biotechnology, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China. lxinrong@lzb.ac.cn.
Xin-Rong
XR
Li
Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China.|Laboratory of Plant Stress Ecophysiology and Biotechnology, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China.
Yu-Bing
YB
Liu
D001426:Bacterial Proteins / Q000235:genetics*; D044822:Biodiversity; D044002:Bryophyta / Q000254:growth & development / Q000382:microbiology; D000458:Cyanobacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D003889:Desert Climate; D017753:Ecosystem; D008011:Lichens / Q000254:growth & development / Q000382:microbiology; D010088:Oxidoreductases / Q000235:genetics*; D010802:Phylogeny; D012988:Soil Microbiology
D001426:Bacterial Proteins; D010088:Oxidoreductases; C029130:nitrogenase reductase
Biological soil crust; Chronosequence; Diazotrophic community; Pyrosequencing; Revegetation