A New Micropropagation Technology of Tilia amurensis:In VitroMicropropagation of Mature Zygotic Embryos and the Establishment of a PlantRegeneration System

Tilia amurensis is an economically valuable broadleaf tree species in Northeast China.The production of highqualityT.amurensis varieties at commercial scales has been greatly limited by the low germination rates.Thereis thus a pressing need to develop an organogenesis protocol for in vitro propagation of T.amurensis to alleviate ashortage of high-quality T.amurensis seedlings.Here,we established a rapid in vitro propagation system forT.amurensis from mature zygotic embryos and analyzed the effects of plant growth regulators and culture mediain different stages.We found that Woody plant medium(WPM)was the optimal primary culture medium formature zygotic embryos.The highest callus induction percentage(68.76%)and number of axillary buds induced(3.2)were obtained in WPM+0.89μmol/L 6-benzyladenine(6-BA)+0.46μmol/L kinetin(KT)+0.25μmol/Lindole-3-butryic acid(IBA)+1.44μmol/L gibberellin A_(3)(GA_(3)).The multiple shoot bud development achievedthe highest percentage(83.32%)in the Murashige and Skoog(MS)+2.22μmol/L 6-BA+0.25μmol/L IBA+1.44μmol/L GA_(3).The rooting percentage(96.70%)was highest in 1/2 MS medium+1.48μmol/L IBA.Thesurvival percentage of transplanting plantlets was 82.22%in soil:vermiculite:perlite(5:3:1).Our study is the firstto establish an effective organogenesis protocol for T.amurensis using mature zygotic embryos.

Estimating the productive potential of five natural forest types in northeastern China

Background: There is a serious lack of experience regarding the productive potential of the natural forests in northeastern China, which severely limits the development of sustainable forest management strategies for this most important forest region in China. Accordingly, the objective of this study is to develop a first comprehensive system for estimating the wood production for the five dominant forest types.Methods: Based on a network of 384 field plots and using the state-space approach, we develop a system of dynamic stand models, for each of the five main forest types. Four models were developed and evaluated, including a base model and three extended models which include the effects of dominant height and climate variables. The four models were fitted, and their predictive strengths were tested, using the "seemingly unrelated regression"(SUR) technique.Results: All three of the extended models increased the accuracy of the predictions at varying degrees for the five major natural forest types of northeastern China. The inclusion of dominant height and two climate factors(precipitation and temperature) in the base model resulted in the best performance for all the forest types. On average, the root mean square values were reduced by 13.0% when compared with the base model.Conclusion: Both dominant height and climate factors were important variables in estimating forest production. This study not only presents a new method for estimating forest production for a large region, but also explains regional differences in the effect of site productivity and climate.

Core Competitiveness as the Fundamental Guarantee for Sustainable Development of Geo-parks

With the booming development over the past years,geo-parks have achieved impressive progress together with a series of problems.Most importantly,geological tourism is not in prosperity.How to prosper geological tourism and achieve the sustainable development of geoparks is the top concern of workers engaged in tourism geology in China.This article discusses the problem from the perspective of core competitiveness of geo-parks,particularly from three aspects of subject,object and medium,and puts forward methods to form the core competitiveness.

Two gene clusters and their positive regulator SlMYB13 that have undergone domestication-associated negative selection control phenolamide accumulation and drought tolerance in tomato

Among plant metabolites,phenolamides,which are conjugates of hydroxycinnamic acid derivatives and polyamines,play important roles in plant adaptation to abiotic and biotic stresses.However,the molecular mechanisms underlying phenolamide metabolism and regulation as well as the effects of domestication and breeding on phenolamide diversity in tomato remain largely unclear.In this study,we performed a metabolite-based genome-wide association study and identified two biosynthetic gene clusters(BGC7 and BGC11)containing 12 genes involved in phenolamide metabolism,including four biosynthesis genes(two 4CL genes,one C3H gene,and one CPA gene),seven decoration genes(five AT genes and two UGT genes),and one transport protein gene(DTX29).Using gene co-expression network analysis we further discovered that SlMYB13 positively regulates the expression of two gene clusters,thereby promoting phenolamide accumulation.Genetic and physiological analyses showed that BGC7,BGC11 and SlMYB13 enhance drought tolerance by enhancing scavenging of reactive oxygen species and increasing abscisic acid content in tomato.Natural variation analysis suggested that BGC7,BGC11 and SlMYB13 were negatively selected during tomato domestication and improvement,leading to reduced phenolamide content and drought tolerance of cultivated tomato.Collectively,our study discovers a key mechanism of phenolamide biosynthesis and regulation in tomato and reveals that crop domestication and improvement shapes metabolic diversity to affect plant environmental adaptation.

A widely targeted metabolite modificomics strategy for modified metabolites identification in tomato

The structural and functional diversity of plant metabolites is largely created via chemical modification of a basic backbone.However,metabolite modifications in plants have still not been thoroughly investigated by metabolomics approaches.In this study,a widely targeted metabolite modificomics(WTMM)strategy was developed based on ultra-high performance liquid chromatography-quadrupole-linear ion trap(UHPLC-Q-Trap)and UHPLC-Q-Exactive-Orbitrap(UHPLC-QE-Orbitrap),which greatly improved the detection sensitivity and the efficiency of identification of modified metabolites.A metabolite modificomics study was carried out using tomato as a model,and over 34,000 signals with MS2 information were obtained from approximately 232 neutral loss transitions.Unbiased metabolite profiling was also performed by utilizing high-resolution mass spectrometry data to annotate a total of 2,118 metabolites with 125 modification types;of these,165 modified metabolites were identified in this study.Next,the WTMM database was used to assess diseased tomato tissues and 29 biomarkers were analyzed.In summary,the WTMM strategy is not only capable of large-scale detection and quantitative analysis of plant-modified metabolites in plants,but also can be used for plant biomarker development.

OGG1 inhibition suppresses African swine fever virus replication

African swine fever virus(ASFV)is an important pathogen that causes a highly contagious and lethal disease in swine,for which neither a vaccine nor treatment is available.The DNA repair enzyme 8-oxoguanine DNA glycosylase 1(OGG1),which excises the oxidative base lesion 8-oxo-7,8-dihydroguanine(8-oxoG),has been linked to the pathogenesis of different diseases associated with viral infections.However,the role of OGG1-base excision repair(BER)in ASFV infection has been poorly investigated.Our study aimed to characterize the alteration of host reactive oxygen species(ROS)and OGG1 and to analyse the role of OGG1 in ASFV infection.We found that ASFV infection induced high levels and dynamic changes in ROS and 8-oxoG and consistently increased the expression of OGG1.Viral yield,transcription level,and protein synthesis were reduced in ASFV-infected primary alveolar macrophages(PAMs)treated by TH5487 or SU0268 inhibiting OGG1.The expression of BER pathway associated proteins of ASFV was also suppressed in OGG1-inhibited PAMs.Furthermore,OGG1 was found to negatively regulate interferonβ(IFN-β)production during ASFV infection and IFN-βcould be activated by OGG1 inhibition with TH5487 and SU0268,which blocked OGG1 binding to 8-oxoG.Additionally,the interaction of OGG1 with viral MGF360-14-L protein could disturb IFN-βproduction to further affect ASFV replication.These results suggest that OGG1 plays the crucial role in successful viral infection and OGG1 inhibitors SU0268 or TH5487 could be used as antiviral agents for ASFV infection.

Abundance of antibiotic resistance genes and their association with bacterial communities in activated sludge of wastewater treatment plants: Geographical distribution and network analysis

Wastewater treatment plants(WWTPs) are deemed reservoirs of antibiotic resistance genes(ARGs). Bacterial phylogeny can shape the resistome in activated sludge. However, the co-occurrence and interaction of ARGs abundance and bacterial communities in different WWTPs located at continental scales are still not comprehensively understood. Here, we applied quantitative PCR and Miseq sequence approaches to unveil the changing profiles of ARGs(sul1, sul2, tet W, tet Q, tet X), int I1 gene, and bacterial communities in 18 geographically distributed WWTPs. The results showed that the average relative abundance of sul1 and sul2 genes were 2.08 × 10^(-1) and 1.32 × 10^(-1) copies/16 S rRNA copies, respectively. The abundance of tet W gene was positively correlated with the Shannon diversity index(H′), while both studied sul genes had significant positive relationship with the int I1 gene. The highest average relative abundances of sul1, sul2, tet X, and int I1 genes were found in south region and oxidation ditch system. Network analysis found that 16 bacterial genera co-occurred with tet W gene. Co-occurrence patterns were revealed distinct community interactions between aerobic/anoxic/aerobic and oxidation ditch systems. The redundancy analysis model plot of the bacterial community composition clearly demonstrated that the sludge samples were significant differences among those from the different geographical areas,and the shifts in bacterial community composition were correlated with ARGs. Together,these findings from the present study will highlight the potential risks of ARGs and bacterial populations carrying these ARGs, and enable the development of suitable technique to control the dissemination of ARGs from WWTPs into aquatic environments.

A Highly Stable Two-Photon Ratiometric Fluorescence Probe for Real-Time Biosensing and Imaging of Nitric Oxide in Brain Tissues and Larval Zebrafish

Because nitric oxide(NO)plays important roles in nerve conduction,signal regulation,and immune protection,analysis of NO is of great significance for understanding the physiological and pathological processes related to neurological diseases.Herein,a highly stable and selective two-photon ratiometric fluorescent probe was developed for real-time sensing and imaging of NO in neurons,brain tissues,and larval zebrafish,in which a Rhodamine B derivative(RBD)was designed for specific recognition of NO and gold nanoclusters(AuNCs)were synthesized as reference element.The developed organic-inorganic nanoprobe exhibited high stability against biological thiol compounds and high selectivity against other reactive oxygen and nitrogen species,metal ions,and acids.In addition,the response time of the present nanoprobe was less than∼55 s.By using the developed nanoprobe,we proved that hypoxia-induced neuronal death was regulated by NO.Moreover,it was found that the hypoxia-induced NO increase in different brain regions was various and that the NO burst contributed to hypoxia-induced death of zebrafish.

Neural grafts containing exosomes derived from Schwann cell-like cells promote peripheral nerve regeneration in rats

Background:Schwann cell-like cells(SCLCs),differentiated from mesenchymal stem cells,have shown promising outcomes in the treatment of peripheral nerve injuries in preclinical studies.However,certain clinical obstacles limit their application.Hence,the primary aim of this study was to investigate the role of exosomes derived from SCLCs(SCLCs-exo)in peripheral nerve regeneration.Methods:SCLCs were differentiated from human amniotic mesenchymal stem cells(hAMSCs)in vitro and validated by immunofluorescence,real-time quantitative PCR and western blot analysis.Exosomes derived from hAMSCs(hAMSCs-exo)and SCLCs were isolated by ultracentrifugation and validated by nanoparticle tracking analysis,WB analysis and electron microscopy.A prefab-ricated nerve graft was used to deliver hAMSCs-exo or SCLCs-exo in an injured sciatic nerve rat model.The effects of hAMSCs-exo or SCLCs-exo on rat peripheral nerve injury(PNI)regeneration were determined based on the recovery of neurological function and histomorphometric variation.The effects of hAMSCs-exo or SCLCs-exo on Schwann cells were also determined via cell prolifer-ation and migration assessment.Results:SCLCs significantly expressed the Schwann cell markers glial fibrillary acidic protein and S100.Compared to hAMSCs-exo,SCLCs-exo significantly enhanced motor function recov-ery,attenuated gastrocnemius muscle atrophy and facilitated axonal regrowth,myelin forma-tion and angiogenesis in the rat model.Furthermore,hAMSCs-exo and SCLCs-exo were effi-ciently absorbed by Schwann cells.However,compared to hAMSCs-exo,SCLCs-exo signifi-cantly promoted the proliferation and migration of Schwann cells.SCLCs-exo also significantly upregulated the expression of a glial cell-derived neurotrophic factor,myelin positive regulators(SRY-box transcription factor 10,early growth response protein 2 and organic cation/carnitine transporter 6)and myelin proteins(myelin basic protein and myelin protein zero)in Schwann cells.Conclusions:These findings suggest that SCLCs-exo can more efficiently promote PNI regeneration than hAMSCs-exo and are a potentially novel therapeutic approach for treating PNI.