Afforestation increases microbial diversity in low-carbon soils

Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of plantings on soil microbial diversity.The results showed that the overall effect of afforestation on soil microbial diversity was positive across the country.Random forest algorithm suggested that soil carbon was the most important factor regulating microbial diversity and the positive response was only found with new plantings on low-carbon bare lands but not on high-carbon farmlands and grasslands.In addition,afforestation with broadleaved species increased microbial diversity,whereas planting with conifers had no effect on microbial diversity.This study clarified the effects of plantings on soil microbial diversity,which has an important implication for establishing appropriate policies and practices to improve the multiple functionalities(e.g.,biodiversity conservation and climate change mitigation)during plantation establishment.

Human adipose, placenta, and umbilical cord-derived mesenchymal stem cells ameliorate imiquimod-induced psoriatic mice via reducing T cells infiltration

Psoriasis is an autoimmune-related chronic inflammatory disease with an approximate prevalence of 2–3%around the world,involving increased keratinocyte proliferation.Indeed,Th17 cells and IL-17 play critical roles in the pathogenesis of psoriasis.The monoclonal antibodies against cytokines have been shown to have effectively immunosuppressive effects on human psoriasis.However,there are still some patients that have no response to these treatments.Some patients have even serious side-effects which may affect their life.Mesenchymal stem cells have the ability of immunosuppressive and anti-inflammatory effects,which may be an alternative therapy with more safety and efficacy for human psoriasis.Moreover,the underlying mechanisms by which the MSCs prevent or ameliorate psoriasis are still poorly understood.Here,we first isolated and characterized human adipose,placenta,and umbilical cord-derived mesenchymal stem cells(haMSCs,hpMSCs,and huMSCs).After that,the animal model of imiquimod(IMQ)-induced psoriasis in C57BL/6 mice was confirmed.We investigated the impact of haMSCs,hpMSCs,and huMSCs on this model by H&E staining,immunohistochemistry staining,and quantitative real-time PCR.Data analysis showed that mice subcutaneously injected with these MSCs had a significantly decreased epidermal thickness,which was caused by obviously reduced hyper-proliferation of keratinocytes.Furthermore,our findings revealed that the infiltration of T cells to psoriatic lesions in IMQ-induced psoriasis mice was markedly downregulated by intradermal administration of haMSCs,hpMSCs,and huMSCs,respectively.Consequently,the production of IL-17 from Th17 cells was reduced,which inhibits the proliferation of keratinocytes in lesioned skin of IMQ-induced psoriasis mice.These data suggest that haMSCs,hpMSCs,and huMSCs can inhibit the effects of proinflammatory Th17 cells on the development of psoriasis,which may be potential therapeutic candidates for skin inflammatory disease or other autoimmune diseases.

N-cycle gene abundance determination of N mineralization rate following re-afforestation in the Loess Plateau of China

Afforestation effectively improved soil microbial communities and significantly increased soil nitro-gen mineralization rate(Rm).Soil microorganisms drive Rm by regulating soil N-cycling genes.Soil nitrification genes had a major effect on soil Rm than denitrification genes after afforestation.Assessing the function of forest ecosystems requires an understanding of the mechanism of soil nitrogen mineralization.However,it remains unclear how soil N-cycling genes drive soil nitrogen mineralization during afforestation.In this study,we collected soil samples from a chrono-sequence of 14,20,30,and 45 years of Robinia pseudoacacia L.(RP14,RP20,RP30,and RP45)with a sloped farmland(FL)as a control.Through metagenomic sequencing analysis,we found significant changes in the diversity and composition of soil microbial communities involved in N-cycling along the afforestation time series,with afforestation effectively increasing the diversity(both alpha and beta diversity)of soil microbial communities.We conducted indoor culture experiments and analyzed correlations,which revealed a significant increase in both soil nitrification rate(Rn)and soil nitrogen mineralization rate(Rm)with increasing stand age.Furthermore,we found a strong correlation between soil Rm and soil microbial diversity(both alpha and beta diversity)and with the abundance of soil N-cycling genes.Partial least squares path modeling(PLS-PM)analysis showed that nitrification genes(narH,narY,nxrB,narG,narZ,nxrA,hao,pmoC-amoC)and denitrification genes(norB,nosZ,nirK)had a greater direct effect on soil Rm compared to their effect on soil microbial communities.Our results reveal the relationships between soil nitrogen mineralization rate and soil microbial communities and between the mineralization rate and functional genes involved in N-cycling,in the context of Robinia pseudoacacia L.restoration on the Loess Plateau.This study enriches the understanding of the effects of microorganisms on soil nitrogen mineralization rate during afforestation and provides a new theoretical basis for evaluating soil nitrogen mineralization mechanisms during forest succession.

Unique genes carried by abundant species enhance CH_(4) emissions during the growing season at the Tibetan Plateau

CH_(4) emission rates followed an increased pattern during the growing season at Tibetan Plateau.•Unique genes carried by abundant species were positively correlated with CH_(4) emission rates.•Climate factors influenced CH_(4) emission rates by regulating microbial community and their genes.Microorganisms play pivotal roles in soil methane(CH_(4))emissions and their functional genes are origins of a key mechanism for soil CH4-cycling.However,understanding of the roles of specific genes(e.g.,unique or shared genes carried by species)underlying CH_(4)-cycling remains elusive.Here,we measured CH_(4) emission rates and investigated variations in microbial community and the abundance of genes carried by species during the growing season in alpine meadow on the Tibetan Plateau.We discovered that CH_(4) emission rates increased from 394.4,745.9,and 1092.7µg CH4 m−2 h−1,in April,June,and August,respectively,and had a positive correlation with unique genes carried by abundant species during the growing season.Moreover,we found that unique genes carried by abundant species involved in methanogenesis processes have a higher abundance than methanotrophic processes.Further analysis indicated that climate factors(i.e.,mean monthly temperature(MMT)and mean monthly precipitation(MMP))influenced microbial community and their functional genes,and therefore affected the CH_(4) emission rates.Overall,the present study provides a novel insight into the variation of soil CH4 emissions from a functional gene perspective,highlighting the important roles of unique genes carried by abundant species in CH4 emissions in the Tibetan Plateau under seasonal variation.