Abstract:Soils – constituting the largest terrestrial carbon pool - are vulnerable to climatic warming. Currently existing uncertainties regarding carbon fluxes within terrestrial systems can be addressed by studies of past carbon cycle dynamics and related climate change recorded in sedimentary successions. Here we show an example from the Early Jurassic (early Toarcian, c. 183 mya) marginal-marine strata from Poland, tracking the hinterland response to climatic changes through a super-greenhouse event. In contrast to… Show more
“…Our study supports Hypothesis 2 that carbon-decomposing genes derived from fungi are more influenced by climate changes than bacteria, consistent with the previous finding that warming favours fungal-mediated decomposition of plant litter (Pienkowski, Hodbod, & Ullmann, 2016). Our finding that soil transplantation increased the relative abundance of fungal chitin-and lignin-decomposing genes ( Figure 3) is alarming because the loss of soil recalcitrant carbon can reduce soil carbon stability, particularly in high-latitude soils, which account for one-third of the global soil carbon pool (Biasi et al, 2005).…”
Section: Soil Transplantation Over Large Transects Reflect Abrupt CLIsupporting
Both fungi and bacteria play essential roles in regulating soil carbon cycling. To predict future carbon stability, it is imperative to understand their responses to environmental changes, which is subject to large uncertainty. As current global warming is causing range shifts toward higher latitudes, we conducted three reciprocal soil transplantation experiments over large transects in 2005 to simulate abrupt climate changes. Six years after soil transplantation, fungal biomass of transplanted soils showed a general pattern of changes from donor sites to destination, which were more obvious in bare fallow soils than in maize cropped soils. Strikingly, fungal community compositions were clustered by sites, demonstrating that fungi of transplanted soils acclimatized to the destination environment. Several fungal taxa displayed sharp changes in relative abundance, including Podospora, Chaetomium, Mortierella and Phialemonium. In contrast, bacterial communities remained largely unchanged. Consistent with the important role of fungi in affecting soil carbon cycling, 8.1%–10.0% of fungal genes encoding carbon‐decomposing enzymes were significantly (p < 0.01) increased as compared with those from bacteria (5.7%–8.4%). To explain these observations, we found that fungal occupancy across samples was mainly determined by annual average air temperature and rainfall, whereas bacterial occupancy was more closely related to soil conditions, which remained stable 6 years after soil transplantation. Together, these results demonstrate dissimilar response patterns and resource partitioning between fungi and bacteria, which may have considerable consequences for ecosystem‐scale carbon cycling.
“…Our study supports Hypothesis 2 that carbon-decomposing genes derived from fungi are more influenced by climate changes than bacteria, consistent with the previous finding that warming favours fungal-mediated decomposition of plant litter (Pienkowski, Hodbod, & Ullmann, 2016). Our finding that soil transplantation increased the relative abundance of fungal chitin-and lignin-decomposing genes ( Figure 3) is alarming because the loss of soil recalcitrant carbon can reduce soil carbon stability, particularly in high-latitude soils, which account for one-third of the global soil carbon pool (Biasi et al, 2005).…”
Section: Soil Transplantation Over Large Transects Reflect Abrupt CLIsupporting
Both fungi and bacteria play essential roles in regulating soil carbon cycling. To predict future carbon stability, it is imperative to understand their responses to environmental changes, which is subject to large uncertainty. As current global warming is causing range shifts toward higher latitudes, we conducted three reciprocal soil transplantation experiments over large transects in 2005 to simulate abrupt climate changes. Six years after soil transplantation, fungal biomass of transplanted soils showed a general pattern of changes from donor sites to destination, which were more obvious in bare fallow soils than in maize cropped soils. Strikingly, fungal community compositions were clustered by sites, demonstrating that fungi of transplanted soils acclimatized to the destination environment. Several fungal taxa displayed sharp changes in relative abundance, including Podospora, Chaetomium, Mortierella and Phialemonium. In contrast, bacterial communities remained largely unchanged. Consistent with the important role of fungi in affecting soil carbon cycling, 8.1%–10.0% of fungal genes encoding carbon‐decomposing enzymes were significantly (p < 0.01) increased as compared with those from bacteria (5.7%–8.4%). To explain these observations, we found that fungal occupancy across samples was mainly determined by annual average air temperature and rainfall, whereas bacterial occupancy was more closely related to soil conditions, which remained stable 6 years after soil transplantation. Together, these results demonstrate dissimilar response patterns and resource partitioning between fungi and bacteria, which may have considerable consequences for ecosystem‐scale carbon cycling.
“…8). This indicated that the evolutionary conservation of RNA editing is essential for only a few plastid editing sites, which is a common phenomenon among angiosperms and has been verified in many cases [39]. Fig.…”
BackgroundRNA editing is a posttranscriptional modification process that alters the RNA sequence so that it deviates from the genomic DNA sequence. RNA editing mainly occurs in chloroplasts and mitochondrial genomes, and the number of editing sites varies in terrestrial plants. Why and how RNA editing systems evolved remains a mystery. Ginkgo biloba is one of the oldest seed plants and has an important evolutionary position. Determining the patterns and distribution of RNA editing in the ancient plant provides insights into the evolutionary trend of RNA editing, and helping us to further understand their biological significance.ResultsIn this paper, we investigated 82 protein-coding genes in the chloroplast genome of G. biloba and identified 255 editing sites, which is the highest number of RNA editing events reported in a gymnosperm. All of the editing sites were C-to-U conversions, which mainly occurred in the second codon position, biased towards to the U_A context, and caused an increase in hydrophobic amino acids. RNA editing could change the secondary structures of 82 proteins, and create or eliminate a transmembrane region in five proteins as determined in silico. Finally, the evolutionary tendencies of RNA editing in different gene groups were estimated using the nonsynonymous-synonymous substitution rate selection mode.ConclusionsThe G. biloba chloroplast genome possesses the highest number of RNA editing events reported so far in a seed plant. Most of the RNA editing sites can restore amino acid conservation, increase hydrophobicity, and even influence protein structures. Similar purifying selections constitute the dominant evolutionary force at the editing sites of essential genes, such as the psa, some psb and pet groups, and a positive selection occurred in the editing sites of nonessential genes, such as most ndh and a few psb genes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0944-8) contains supplementary material, which is available to authorized users.
“…During the negative CIE, pulses of isotopically light C suggest enhanced input of CO 2 into the atmosphere from volcanic sources 25 leading to increased global temperatures 34 , sufficient to provoke methane (CH 4 )-hydrate dissociation 3 . This combined with an increase in terrestrial methanogenesis and a potential positive feedback associated with the decomposition of plant litter enabling further release of CO 2 and CH 4 from terrestrial sources (for example, refs 35,36), thus created the large negative CIE and enhanced CH 4 driven global warming. Coupled ocean-atmosphere models suggest an increase in global precipitation rates of þ 9 cm per year driven by the subsequent rises in CO 2 (ref.…”
The Toarcian Oceanic Anoxic Event (T-OAE) was characterized by a major disturbance to the global carbon(C)-cycle, and depleted oxygen in Earth's oceans resulting in marine mass extinction. Numerical models predict that increased organic carbon burial should drive a rise in atmospheric oxygen (pO 2 ) leading to termination of an OAE after B1 Myr. Wildfire is highly responsive to changes in pO 2 implying that fire-activity should vary across OAEs. Here we test this hypothesis by tracing variations in the abundance of fossil charcoal across the T-OAE. We report a sustained B800 kyr enhancement of fire-activity beginning B1 Myr after the onset of the T-OAE and peaking during its termination. This major enhancement of fire occurred across the timescale of predicted pO 2 variations, and we argue this was primarily driven by increased pO 2 . Our study provides the first fossil-based evidence suggesting that fire-feedbacks to rising pO 2 may have aided in terminating the T-OAE.
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