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Alpine wetland degradation reduces carbon sequestration in the Zoige Plateau, China
No full textAlpine wetland plays an important role in the global carbon balance but are experiencing severe degradation under climate change and human activities. With the aim to clarify the effect of alpine wetland degradation on carbon fluxes (including net ecosystem CO2 exchange, NEE; ecosystem respiration, ER; gross ecosystem productivity, GEP, and CH4 flux), we investigated 12 sites and measured carbon fluxes using the static chamber method in the Zoige alpine wetland during August 2018, including undegraded wetland (UD), lightly degraded wetland (LD), moderately degraded wetland (MD), and severely degraded wetland (SD). The results showed that carbon sink strengths differ among the Zoige wetlands with different degradation stages during the growing season. From UD to LD, the rate of carbon sequestration (mean value of NEE) increased by 25.70%; however, from LD to SD, it decreased by 81.67%. Wetland degradation significantly reduced soil water content (SWC), soil organic carbon (SOC), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN). NEE was significantly correlated with MBC and MBN, while ER was positively correlated with ST but negatively correlated with SOC (P < 0.01). Among all measured environmental factors, GEP was positively correlated with pH (P < 0.01), while CH4 flux was most closely correlated with SOC, SWC, MBC, MBN, and ST (P < 0.001), and was also affected by pH and NO3- content (P < 0.01). These results suggest that the capacity of carbon sequestration in the Zoige wetlands reduced with intensification of the degradation. This study provides a reference for sustainably managing and utilizing degraded wetlands under climate change
Distinctive pattern and mechanism of precipitation changes affecting soil microbial assemblages in the Eurasian steppe
No full textPrecipitation may increase or decrease by different intensities, but the pattern and mechanism of soil microbial community assembly under various precipitation changes remain relatively underexplored. Here, although +/- 30% precipitation caused a small decrease (-19%) in the within-treatment taxonomic compositional dissimilarity through the deterministic competitive exclusion process in a steppe ecosystem, +/- 60% precipitation caused a large increase (similar to 35%) in the dissimilarity through the stochastic ecological drift process (random birth/death), which was in contrast with the traditional thought that increasing the magnitude of environmental changes (e.g., from +30% to +60%) would elevate the importance of deterministic relative to stochastic processes. The increased taxonomic dissimilarity/stochasticity under +/- 60% precipitation translated into functional dissimilarity/stochasticity at the gene, protein, and enzyme levels. Overall, our results revealed the distinctive pattern and mechanism of precipitation changes affecting soil microbial community assembly and demonstrated the need to integrate microbial taxonomic information to better predict their functional responses to precipitation changes
Effects of climate change on richness distribution patterns of threatened conifers endemic to China
No full textClimate change inevitably affects the geographical distribution of species on earth. Conifers, which are important components of forest tree species, are highly threatened and particularly sensitive to climate change. Approxi-mately 23.6% (145/615 species) of the world's conifers are native to China, among which 53 species are threatened. Thus, understanding the impact of climate change on the species richness and distribution of threatened conifers endemic to China (hereafter referred to as threatened conifers) is of great importance. Here, we investigated the habitat suitability under present climate conditions and predicted the impact of future climate change on these threatened conifers using species distribution modeling. Combined with the current natural reserve system, we evaluated the conservation effectiveness, determined the key conservation areas, and proposed suggestions for the future protection of these threatened conifers. Our results showed that the threatened conifers were mainly distributed in mountainous areas and climate variables played a major role in the distribution of these threatened conifers. We also found that the richness hotspots were predicted to shrink and move northward with a changing climate. The lowest elevation of threatened conifers predicted to contract their species range mainly occurred below 1000 m or above 2000 m, while most species whose lowest elevations ranged from 1000 to 2000 m were projected to expand their distribution areas under the future climate scenario. Therefore, different conservation measures should be taken for threatened conifers with different distribution patterns. The central Hengduan Mountains and the Western Sichuan Plateau were identified as areas needing attention and areas worth exploring, respectively, which should be given more attention in future field sur-veys and conservation efforts. This study highlighted the critical role of these threatened conifers as good in-dicators for measuring and proposing conservation strategies to minimize the impacts of climate change
A MADS-box transcription factor, SlMADS1, interacts with SlMACROCALYX to regulate tomato sepal growth
No full textIn flowering plants, sepals play important roles in the development of flowers and fruit, and both processes are regulated by MADS-box (MADS) transcription factors (TFs). SlMADS1 was previously reported to act as a negative regulator of fruit ripening. In this study, expression analysis shown that its transcripts were very highly expressed during the development of sepals. To test the role of SlMADS1, we generated KO-SlMADS1 (knock-out) tomato mutants by CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9) technology and over-expression of SlMADS1 (OE-SlMADS1). The sepals and individual cells of KO-SlMADS1 mutants were significantly elongated, compared with the wild type (WT), whereas the sepals of OE-SlMADS1 tomatoes were significantly shorter and their cells were wider. RNA-seq (RNA-sequencing) of sepal samples showed that ethylene-, gibberellin-, auxin-, cytokinin-and cell wall metabolism-related genes were significantly affected in both KO-SlMADS1 and OE-SlMADS1 plants with altered sepal size. Since SlMA-CROCALYX (MC) is known to regulate the development of tomato sepals, we also studied the relationship be-tween SlMC and SlMADS1 and the result showed that SlMADS1 interacts directly with SlMC. In addition, we also found that manipulating SlMADS1 expression alters the development of tomato plant leaves, roots and plant height. These results enrich our understanding of sepal development and the function of SlMADS1 throughout the plant
Phylotranscriptomics reveals the evolutionary history of subtropical East Asian white pines: further insights into gymnosperm diversification
No full textFloristic composition within a geographic area is driven by a wide array of factors from local biotic interactions to biogeographical processes. Subtropical East Asia is a key biodiversity hotspot of the world, and harbors the most families of extant gymnosperms and a large number of endemic genera with ancient origins, but rare phylogenetic studies explored whether it served as a diversification center for gymnosperms. Here, we investigated the evolutionary and biogeographical history of subtropical East Asian white pines using an integrative approach that combines phylotranscriptomic and ecological analyses. Using 2,606 orthologous nuclear genes, we reconstructed a fully resolved and dated phylogeny of these species. Two main clades first diverged in the early Miocene, and by the late Miocene, all species appeared. Two white pines endemic to Taiwan Island experienced independent colonization events and regional extinction, which resulted in the present disjunctive distribution from mainland China. Ecological and biogeographical analyses indicate that the monsoon-driven assembly of evergreen broadleaved forests (EBLFs) might have significantly affected the diversification of subtropical East Asian white pines. Our study highlights the interactions of biotic and abiotic forces in the diversification and speciation of subtropical East Asian white pines. These findings indicate that subtropical East Asia is not only a floristic museum, but also a diversification center for gymnosperms. Our study also demonstrates the importance of phylotranscriptomics on species delimitation and biodiversity conservation, particularly for closely related species
α-Linolenic acid induces apoptosis, inhibits the invasion and metastasis, and arrests cell cycle in human breast cancer cells by inhibiting fatty acid synthase
No full textFatty acid synthase (FASN) is an enzyme that synthesizes endogenous fatty acids. FASN overexpressed in various cancers, which indicates the involvement of FASN in cancer progression. alpha-Linolenic acid (ALA) is an omega-3 fatty acid with many biological activities, including anti-cancer effects. The aim of the present study was to investigate the inhibitory effect of ALA on fatty acid synthesis pathway and breast cancer cells apoptosis. We found FASN expression decreased significantly in ALA treated breast cancer cells. Compared with palmitic acid (PA), ALA reduced cell viability in a dose-dependent manner. ALA showed a higher affinity with the TE domain than PA. ALA induced breast cancer cells apoptosis, which effects were similar with the knockdown of FASN. In addition, ALA inhibited the invasion and metastasis, and arrested cell cycle in breast cancer cells. We propose a hypothesis that ALA could contribute to the treatment of human breast cancer by inhibiting FASN
A new species of Prunus subgen. Cerasus from Central China
No full textA new species, Prunus wangii Q.L.Gan, Z.Y.Li & S.Z.Xu from western Hubei, Central China is described and illustrated. It is morphologically similar to P. clarofolia Schneid. and P. pseudocerasus Lindl., but differs in larger height, nearly erect branches, densely and horizontally arranged lenticels, straight lateral veins of leaves, persistent brownish bracts, reflexed and entire calyx lobes, 2-lobed petals with narrowly triangular sinus, earlier flowering and broadly ellipsoid fruits. Furthermore, P. wangii blooms in late February and the colour of flower changes with time, which makes it possible to be a new breeding material for ornamental cherry with early spring blooms
Dryland mechanisms could widely control ecosystem functioning in a drier and warmer world
No full textResponses of terrestrial ecosystems to climate change have been explored in many regions worldwide. While continued drying and warming may alter process rates and deteriorate the state and performance of ecosystems, it could also lead to more fundamental changes in the mechanisms governing ecosystem functioning. Here we argue that climate change will induce unprecedented shifts in these mechanisms in historically wetter climatic zones, towards mechanisms currently prevalent in dry regions, which we refer to as 'dryland mechanisms'. We discuss 12 dryland mechanisms affecting multiple processes of ecosystem functioning, including vegetation development, water flow, energy budget, carbon and nutrient cycling, plant production and organic matter decomposition. We then examine mostly rare examples of the operation of these mechanisms in non-dryland regions where they have been considered irrelevant at present. Current and future climate trends could force microclimatic conditions across thresholds and lead to the emergence of dryland mechanisms and their increasing control over ecosystem functioning in many biomes on Earth. In drylands, there are unique mechanisms that influence multiple ecosystem processes. In this Perspective, the authors identify these dryland mechanisms and show that they could become more important in non-dryland regions or areas that will become drier in the future
Grassland soil organic carbon and the effects of irrigated cropping in Alberta, Canada
No full textHigh heterogeneity in the spatial distribution of soil organic carbon (SOC) in grasslands causes uncertainty in estimating its content and storage. In this study, we investigated the spatial distribution of SOC content and storage in the prairies of southern Alberta, Canada, and how it is affected by land use such as irrigated cropping and other environmental conditions such as cattle grazing, slope landscape position and dominant plant species. The mean SOC content was determined to be 11.5 g kg(-1) (range: 8.9 to 22.4 g kg(-1)) in the 0-10 cm layer and 6.8 g kg(-1) (range: 4.0 to 13.3 g kg(-1)) in the 10-30 cm layer; mean SOC storage was 1.59 kg C m(-2) (range: 1.23 to 2.78 kg C m(-2)) in the 0-10 cm layer and 2.07 kg C m(-2) (range: 1.21 to 3.62 kg C m(-2)) in the 10-30 cm layer. The SOC content was significantly affected by slope position in both the 0-10 and 10-30 cm layers, in the following order: bottom >middle > top position. Moreover, SOC storage was higher in sites dominated by shrubs than graminoid/forb communities. Thus, SOC content and storage had distinctly clustered spatial patterns throughout the study area and were significant differences between the 0-10 and 10-30 cm soil layers. Prior land-use change from arid grassland to irrigated cropland increased SOC content and storage in bulk soils
Disturbance-level-dependent post-disturbance succession in a Eurasian steppe
No full textAnthropogenic disturbances may decrease as we take measures to control them. However, the patterns and mechanisms of post-disturbance ecosystem succession have rarely been studied. Here we reported that disturbance level determined the importance of stochastic relative to deterministic changes in ecosystem components (plant community composition, soil microbial community composition, and soil physicochemical indices), and thus predefined the pattern of post-disturbance ecosystem succession. We proposed a theoretical framework with five disturbance levels corresponding to distinct succession patterns. We conducted a nitrogen addition experiment in a temperate steppe, monitored these ecosystem components during disturbance treatment (2010-2014) and post-treatment succession (2014-2018). The disturbance level experienced by each component in each treatment was inferred by fitting the observed succession patterns into the theoretical framework. The mean disturbance level of these components was found to increase quadratically with nitrogen addition rate. This was because increasing nitrogen addition reduced the importance of stochastic relative to deterministic changes in these components, and these changes had a quadratic relationship with disturbance level. Overall, our results suggested that by monitoring the importance of stochastic relative to deterministic changes in an ecosystem, we can estimate disturbance levels and predict succession patterns, as well as propose disturbance-level-dependent strategies for post-disturbance restoration