Divergent changes in particulate and mineral-associated organic carbon upon permafrost thaw

Acknowledgements This work was supported by the National Natural Science Foundation of China (31988102, 31825006, 91837312, and 32101332), the Second Tibetan Plateau Scientific Expedition and Research (STEP) program (2019QZKK0106 and 2019QZKK0302), and the Fundamental Research Foundation of Chinese Academy of Forestry (CAFYBB2020MA008).Peer reviewedPublisher PD

Effect of ε-Poly-L-lysine on Postharvest Diseases and Disease-Resistant Substance Metabolism in Passion Fruits

In order to investigate the inhibitory effect of ε-poly-L-lysine (ε-PL) on the occurrence of Lasiodiplodia theobromae-induced diseases and its correlation with disease resistance in postharvest passion fruits, harvested golden passion fruits (cv. Fujian Baixiangguo 3) were immersed in either sterile distilled water (as control group) or 100 mg/L ε-PL solution for 10 min, inoculated with L. theobromae, and stored at (28 ± 1) ℃ and 90% relative humidity for up to 7 days. The changes of fruit lesion diameter, cell membrane permeability, lignin content and disease resistance-related enzyme activities in the pericarp were assayed every day. The results showed that compared to the control group, ε-PL delayed the increase in cell membrane permeability and lesion diameter, and enhanced the content of lignin and the activities of disease resistance-related enzymes including cinnamate-4-hydroxylase (C4H), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), peroxidase (POD), β-1,3-glucanase (GLU), 4-coumarate CoA ligase (4-CL), chitinase (CHI) and cinnamyl alcohol dehydrogenase (CAD), thereby maintaining cell membrane integrity by delaying the increase of cell membrane permeability, enhancing disease resistance, and inhibiting the occurrence of L. theobromae-induced diseases in harvested passion fruits

Enhanced response of soil respiration to experimental warming upon thermokarst formation

As global temperatures continue to rise, a key uncertainty of terrestrial carbon (C)–climate feedback is the rate of C loss upon abrupt permafrost thaw. This type of thawing—termed thermokarst—may in turn accelerate or dampen the response of microbial degradation of soil organic matter and carbon dioxide (CO2) release to climate warming. However, such impacts have not yet been explored in experimental studies. Here, by experimentally warming three thermo-erosion gullies in an upland thermokarst site combined with incubating soils from five additional thermokarst-impacted sites on the Tibetan Plateau, we investigate how warming responses of soil CO2 release would change upon upland thermokarst formation. Our results show that warming-induced increase in soil CO2 release is ~5.5 times higher in thermokarst features than the adjacent non-thermokarst landforms. This larger warming response is associated with the lower substrate quality and higher abundance of microbial functional genes for recalcitrant C degradation in thermokarst-affected soils. Taken together, our study provides experimental evidence that warming-associated soil CO2 loss becomes stronger upon abrupt permafrost thaw, which could exacerbate the positive soil C–climate feedback in permafrost-affected regions

Decadal soil carbon accumulation across Tibetan permafrost regions

Acknowledgements We thank the members of Peking University Sampling Teams (2001–2004) and IBCAS Sampling Teams (2013–2014) for assistance in field data collection. We also thank the Forestry Bureau of Qinghai Province and the Forestry Bureau of Tibet Autonomous Region for their permission and assistance during the sampling process. This study was financially supported by the National Natural Science Foundation of China (31670482 and 31322011), National Basic Research Program of China on Global Change (2014CB954001 and 2015CB954201), Chinese Academy of Sciences-Peking University Pioneer Cooperation Team, and the Thousand Young Talents Program.Peer reviewedPostprintPostprin

Response to Comment on 'Soil carbon persistence governed by plant input and mineral protection at regional and global scales'

We demonstrated that ignoring the non-linear relationship between topsoil Delta C-14 and plant carbon (C) input in Wu et al.'s analysis was the fundamental reason for the discrepancy between their analysis and ours. By considering such a non-linear relationship, plant C input still predominantly governs the topsoil C turnover

Predicting alien herb invasion with machine learning models: biogeographical and life-history traits both matter

Identifying the variables associated with invasiveness is a core task for developing risk assessment models to predict invasion potential. However, quantitative models with both biogeographical and life-history variables for invasion risk assessment in China are limited. We hypothesized that (1) compared to statistical algorithms, some machine learning models could offer a promising quantitative approach with high accuracy for potential invader prediction; (2) native range distribution size, origins and life-history traits co-determine an alien plant's performance in the latter invasion stage. In this study, we used four machine learning models [classification and regression tree (CART), multivariate adaptive regression spline (MARS), random forest (RF) and multiple additive regression tree (MART)] and two traditional statistical algorithms [logistic regression (LR) and linear discriminant analysis (LDA)] to assess the relative importance of biogeographical and trait variables in the naturalized-invasion stage of 150 invasive and 87 non-invasive herb plants in China. Our results showed that good performance was the case for all predictive models (AUROC ranges from 0.68 to 0.87), which had overall mean performance value ranging from 0.66 to 0.82. Compared with traditional statistical algorithms, MART and RF models have a consistently higher accuracy, indicating that these two models could be used as alternative quantitative approaches for risk assessment. Additionally, both biogeographical (native range distribution size) and life-history traits (seed weight) were screened out by the models, suggesting their high correlation with plant invasiveness and important roles in risk assessment

Conspecific plasticity and invasion: invasive populations of Chinese tallow (Triadica sebifera) have performance advantage over native populations only in low soil salinity.

Global climate change may increase biological invasions in part because invasive species may have greater phenotypic plasticity than native species. This may be especially important for abiotic stresses such as salt inundation related to increased hurricane activity or sea level rise. If invasive species indeed have greater plasticity, this may reflect genetic differences between populations in the native and introduced ranges. Here, we examined plasticity of functional and fitness-related traits of Chinese tallow (Triadica sebifera) populations from the introduced and native ranges that were grown along a gradient of soil salinity (control: 0 ppt; Low: 5 ppt; Medium: 10 ppt; High: 15 ppt) in a greenhouse. We used both norm reaction and plasticity index (PIv) to estimate the conspecific phenotypic plasticity variation between invasive and native populations. Overall, invasive populations had higher phenotypic plasticity of height growth rate (HGR), aboveground biomass, stem biomass and specific leaf area (SLA). The plasticity Index (PIv) of height growth rate (HGR) and SLA each were higher for plants from invasive populations. Absolute performance was always comparable or greater for plants from invasive populations versus native populations with the greatest differences at low stress levels. Our results were consistent with the "Master-of-some" pattern for invasive plants in which the fitness of introduced populations was greater in more benign conditions. This suggests that the greater conspecific phenotypic plasticity of invasive populations compared to native populations may increase invasion success in benign conditions but would not provide a potential interspecific competitive advantage in higher salinity soils that may occur with global climate change in coastal areas

A novel method for colposcopic shunting in HPV-positive women: Quantitative detection of HPV E7 oncoprotein

The objective of the study was to evaluate the clinical application potential of quantitatively detecting human papillomavirus (HPV) E7 oncoprotein in HPV-positive women, with the goal of detecting potential high-grade cervical squamous intraepithelial lesions (HSIL) and cervical cancer improving the accuracy of colposcopic shunting in these patients.HPV-positive women (N = 611) were selected for quantitatively detecting HPV E7 protein levels by magnetic particle-based chemiluminescence immunoassay before colposcopy. Receiver operating characteristic (ROC) curve analysis was performed (n = 400) to determine diagnostic detection thresholds for HPV E7 oncoprotein. ThinPrep cytology test (TCT) and Aptima HPV E6/E7 mRNA analysis were also performed (n = 211). The diagnostic performance of these three diagnostic methods in detecting HSIL and cervical cancer was compared with the gold standard of pathological diagnosis. The area under the ROC curve was 0.724. The diagnostic detection threshold of HPV E7 oncoprotein was ≥10.88 ng/mL. The sensitivity (SEN), specificity (SPE), positive predictive value (PPV), negative predictive value (NPV), and Youden index of HPV E7 oncoprotein for the identification of HSIL and cervical cancer were 78.7 %, 77.9 %, 72.2 %, 83.3 %, and 56.6 %, respectively, which were higher than those of TCT and HPV E6/E7 mRNA.The results indicate that quantitative detection of HPV E7 oncoprotein can effectively shunt HPV-positive women and reduce unnecessary colposcopy and biopsy. It can detect potential HSIL and cervical cancer in a timely manner and prevent high-risk patients from missing diagnosis