Dataset Information

Co-Regulations of Spartina alterniflora Invasion and Exogenous Nitrogen Loading on Soil N2O Efflux in Subtropical Mangrove Mesocosms.

ABSTRACT: Both plant invasion and nitrogen (N) enrichment should have significant impact on mangrove ecosystems in coastal regions around the world. However, how N2O efflux in mangrove wetlands responds to these environmental changes has not been well studied. Here, we conducted a mesocosm experiment with native mangrove species Kandelia obovata, invasive salt marsh species Spartina alterniflora, and their mixture in a simulated tide rotation system with or without nitrogen addition. In the treatments without N addition, the N2O effluxes were relatively low and there were no significant variations among the three vegetation types. A pulse loading of exogenous ammonium nitrogen increased N2O effluxes from soils but the stimulatory effect gradually diminished over time, suggesting that frequent measurements are necessary to accurately understand the behavior of N-induced response of N2O emissions. With the N addition, the N2O effluxes from the invasive S. alterniflora were lower than that from native K. obovata mesocosms. This result may be attributed to higher growth of S. alterniflora consuming most of the available nitrogen in soils, and thus inhibiting N2O production. We concluded that N loading significantly increased N2O effluxes, while the invasion of S. alterniflora reduced N2O effluxes response to N loading in this simulated mangrove ecosystem. Thus, both plant invasion and excessive N loading can co-regulate soil N2O emissions from mangrove wetlands, which should be considered when projecting future N2O effluxes from this type of coastal wetland.

SUBMITTER: Jia D

PROVIDER: S-EPMC4701003 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Co-Regulations of Spartina alterniflora Invasion and Exogenous Nitrogen Loading on Soil N2O Efflux in Subtropical Mangrove Mesocosms.

Jia Dai D Qi Fei F Xu Xia X Feng Jianxiang J Wu Hao H Guo Jiemin J Lu Weizhi W Peng Ronghao R Zhu Xiaoshan X Luo Yiqi Y Lin Guanghui G

PloS one 20160104 1

Both plant invasion and nitrogen (N) enrichment should have significant impact on mangrove ecosystems in coastal regions around the world. However, how N2O efflux in mangrove wetlands responds to these environmental changes has not been well studied. Here, we conducted a mesocosm experiment with native mangrove species Kandelia obovata, invasive salt marsh species Spartina alterniflora, and their mixture in a simulated tide rotation system with or without nitrogen addition. In the treatments wit ...[more]

PMID: 26727205

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Project description:Hundreds of plants and half a kilogram of seeds of Spartina alterniflora, which were collected from Morehead City in North Carolina, Sapelo Island in Georgia, and Tampa Bay in Florida, were introduced to China in 1979. However, according to documented records, S. alterniflora from different origins were introduced to different areas when the species was first introduced to the coastal areas of China in the 1980s. In order to understand the relationship between the invasive S. alterniflora populations of China and the native S. alterniflora populations of the United States, and whether the genetic structure and genetic diversity of the invasive populations of China were affected by different introductions in the 1980s, molecular markers were used to determine the levels of gene flow and its effect on population differentiation. A total of 715 samples of S. alterniflora were collected from nine invasive populations in China and nine native populations from the United States. The genetic diversity and genetic structure of invasive and native populations were compared using microsatellite markers. The heterozygosity of Chinese invasive populations of S. alterniflora (HO = 0.538, HE = 0.725) were similar with those of native populations (HO = 0.530, HE = 0.744), which may attribute to its multiple introductions with the multisource populations from different geographic areas of the United States. However, the lower allelic diversities of Chinese invasive populations were detected, which may be due to the founder effect, or the bottleneck, which supports the theory that the allelic diversity is more sensitive to population bottlenecks than heterozygosity. The results of the STRUCTURE analysis among all sampling sites showed that the value of ?K was largest when K = 2, which indicated that the invasive S. alterniflora populations in China had completed differentiated from the native populations of the United States. This may be because of admixture and hybridization of three non-overlapping original populations, or the postintroduction rapid evolution in China, and reproductive isolation under long-term geographic isolation. There was significant differentiation among invasive populations, which was mainly affected by different human-mediated introductions in 1980s. Significant genetic structure (K = 7) and high genetic differentiation (Fst = 0.30193) were detected in Chinese invasive populations, which may due to the low natural gene flow among populations. The genetic structure of the invasive populations in China was still affected by the human-mediated introductions in the 1980s, and the different initial introductions might promote differentiation among the invasive populations. In fact, the human-mediated long-distance dispersal should take the most of responsibility for the rapid spread of S. alterniflora along the coast of China. Multisource introductions of S. alterniflora are perhaps helpful for local adaptation but itself cannot cause rapid spread along the whole coast of China. Meanwhile, we suggest that the prevention of gene exchange among populations of S. alterniflora is the first and most important step in the control of the species on the coast of China, because admixture and hybridization of isolated populations might generate new heterosis and increase the difficulty of managing S. alterniflora in China.

Project description:Spartina alterniflora, marsh grass, is a vegetative apomicticly-reproducing halophyte native to marshes along the east coast of the United States and invasive across the world. S. alterniflora provides many ecosystem services including, but not limited to, water filtration, habitats for invertebrates, and sediment retention. Widespread diebacks of longstanding marsh grass colonies launched extensive investigations into probable mechanisms leading to patchy diebacks. There is still current debate as to the causes of a marsh dieback but environmental stress is acknowledged as a constant. Spatial epigenetic variation could contribute to variation of stress susceptibility, but the scale and structure of epigenetic variation is unknown. The current study investigates patterns of epigenetic variation in a natural population of S. alterniflora. This study examines variation of global DNA methylation within and among clones of the marsh grass Spartina alterniflora using an ELISA-like microplate reaction and observed significant heterogeneity of global DNA methylation within and among clones of S. alterniflora across the North Inlet basin, as well as significant differences of global methylation between adults and sexually produced seedlings. The present study also characterized differences for plants in a section of the population that experienced an acute marsh dieback in the year 2001 and have subsequently recolonized, finding a significant positive correlation between cytosine methylation and time period of colonization. The significant heterogeneity of global DNA methylation both within and among clones observed within this natural population of S. alterniflora and potential impacts from hypersaline environments at North Inlet suggests the need for more in-depth epigenetic studies to fully understand DNA methylation within an ecological context. Future studies should consider the effects of varying saline conditions on both global DNA and gene specific methylation.

Project description:BACKGROUND:Asparagine (N)-linked glycosylation is one of the most crucial post-translational modifications, which is catalyzed in the lumen of the endoplasmic reticulum (ER) by the oligosaccharyltransferase (OST) in eukaryotic cells. Biochemical and genetic assay leads to the identification of the nine subunits (Ost 1-6, Stt3, Swp1 and Wbp1) of the yeast OST and in which Stt3p is proposed playing a central and conserved role in N-glycosylation. Two STT3 isoform genes, STT3A and STT3B, exist in the plant and mammal genomes. OST with different catalytic STT3 isoforms has different enzymatic properties in mammals. The mutation of STT3A in Arabidopsis thaliana causes a salt hypersensitive phenotype the inhibited root growth and swollen root tips suggesting protein N-glycosylation is indispensable for plant growth and development. Spartina alterniflora is widely used for shoreline protection and tidal marsh restoration due to the strong salt tolerance although the exact molecular mechanism is little known. To explore the possible biological roles of N-glycosylation in plant adaptive resistance to salinity stress, we cloned the STT3 genes from S. alterniflora and heterogenously expressed them in Arabidopsis mutant to observe the functional conservation. RESULTS:SaSTT3A and SaSTT3B genes were cloned from Spartina alterniflora. SaSTT3A genomic sequences spanned over 23 exons and 22 introns, while SaSTT3B had 6 exons and 5 introns. The gene structures of both genes were conserved among the analyzed plant species. Subcellular localization and transmembrane structure prediction revealed that these two genes had 13 and 11 transmembrane helices respectively. The functional complementation in which the cDNA of SaSTT3A and SaSTT3B driven by CaMV 35S promoter completely or partially rescued Arabidopsis stt3a-2 mutant salt-sensitive phenotype, indicating STT3A functions conservatively between glycophyte and halophyte and N-glycosylation might be involved in plant resistance to salinity. CONCLUSIONS:Two STT3 isoform genes, SaSTT3A and SaSTT3B, were cloned from S. alterniflora and they were evolutionally conserved at gene structure and coding sequences compared with their counterparts. Moreover, SaSTT3 genes could successfully rescue Arabidopsis stt3a-2 salt-sensitive phenotype, suggesting there exists a similar N-glycosylation process in S. alterniflora. Here we provided a first piece of evidence that the N-glycosylation might be involved in salt tolerance of halophyte.

Dataset Information

Co-Regulations of Spartina alterniflora Invasion and Exogenous Nitrogen Loading on Soil N2O Efflux in Subtropical Mangrove Mesocosms.

Publications

Co-Regulations of Spartina alterniflora Invasion and Exogenous Nitrogen Loading on Soil N2O Efflux in Subtropical Mangrove Mesocosms.

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