BackgroundThe plant tolerance mechanisms to low temperature have been studied extensively in the model plant Arabidopsis at the transcriptional level. However, few studies were carried out in plants with strong inherited cold tolerance. Chorispora bungeana is a subnival alpine plant possessing strong cold tolerance mechanisms. To get a deeper insight into its cold tolerance mechanisms, the transcriptome profiles of chilling-treated C. bungeana seedlings were analyzed by Illumina deep-sequencing and compared with Arabidopsis.ResultsTwo cDNA libraries constructed from mRNAs of control and chilling-treated seedlings were sequenced by Illumina technology. A total of 54,870 unigenes were obtained by de novo assembly, and 3,484 chilling up-regulated and 4,571 down-regulated unigenes were identified. The expressions of 18 out of top 20 up-regulated unigenes were confirmed by qPCR analysis. Functional network analysis of the up-regulated genes revealed some common biological processes, including cold responses, and molecular functions in C. bungeana and Arabidopsis responding to chilling. Karrikins were found as new plant growth regulators involved in chilling responses of C. bungeana and Arabidopsis. However, genes involved in cold acclimation were enriched in chilling up-regulated genes in Arabidopsis but not in C. bungeana. In addition, although transcription activations were stimulated in both C. bungeana and Arabidopsis, no CBF putative ortholog was up-regulated in C. bungeana while CBF2 and CBF3 were chilling up-regulated in Arabidopsis. On the other hand, up-regulated genes related to protein phosphorylation and auto-ubiquitination processes were over-represented in C. bungeana but not in Arabidopsis.ConclusionsWe conducted the first deep-sequencing transcriptome profiling and chilling stress regulatory network analysis of C. bungeana, a subnival alpine plant with inherited cold tolerance. Comparative transcriptome analysis suggests that cold acclimation is not a major chilling tolerance mechanism of C. bungeana. Activation of protein phosphorylation and ubiquitination may confer chilling tolerance to C. bungeana in a more rapid and flexible way than cold acclimation. Such differences may have contributed to the differences in cold tolerance between C. bungeana and Arabidopsis. The results presented in this paper will be informative for gene discovery and the molecular mechanisms related to plant cold tolerance.

Thermokarst lakes are potentially important sources of methane (CH4) and carbon dioxide (CO2). However, considerable uncertainty exists regarding carbon emissions from thermokarst lakes owing to a limited understanding of their patterns and motivators. In this study, we measured CH4 and CO2 diffusive fluxes in 163 thermokarst lakes in the Qinghai–Tibet Plateau (QTP) over 3 years from May to October. The median carbon emissions from the QTP thermokarst lakes were 1440 mg CO2 m−2 day−1 and 60 mg CH4 m−2 day−1, respectively. The diffusive rates of CO2 and CH4 are related to the catchment land cover type. Sediment microbial abundance and hydrochemistry explain 51.9% and 38.3% of the total variance in CH4 diffusive emissions, respectively, while CO2 emissions show no significant relationship with environmental factors. When upscaling carbon emissions from the QTP thermokarst lakes, the annual average CH4 release per lake area is equal to that of the pan‐Arctic region. Our findings highlight the importance of incorporating in situ observation data with different emission pathways for different land cover types in predicting carbon emissions from thermokarst lakes in the future.

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The calcineurin B-like protein (CBL)-interacting protein kinase (CIPK) complex is an essential calcium sensor and contributes to biotic and abiotic stress responses. However, citrus CBL and CIPK gene family members and their underlying roles during drought and arbuscular mycorrhizal fungi (AMF) colonization remain relatively unknown. In the present study, CBLs and CIPKs were characterized in Citrus sinensis by analyzing the presence of specific domains such as the elongation factor (EF)-hand motif in CBLs, and a protein kinase and an Asn-Ala-Phe domain in CIPKs. After mining the C. sinensis genome, we identified 8 CsCBLs and 17 CsCIPKs. Among these genes, three CsCBLs and nine CsCIPKs showed syntenic relationships with the Arabidopsis thaliana homologs AtCBLs and AtCIPKs, respectively. According to gene expression and cis-acting element analysis, all 8 CsCBLs and 16 CsCIPKs were expressed in the roots, where the regulation of expression was not consistent with their promoter cis-elements. Drought treatment remarkably downregulated the expression of CsCBL8 and upregulated CsCBL7, CsCIPK4, and CsCIPK7 expressions. The AMF colonization induced

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A novel nanocomposite ] was constructed by combining ferrocene (Fc) with the porous structural metal−organic framework ]. The proposed composite material could simultaneously and efficiently remove hexavalent chromium [Cr(VI)] and imidacloprid and reduced strongly noxious Cr(VI) to weakly noxious trivalent chromium [Cr(III)]. The removal efficiencies of the composite material for Cr(VI) and imidacloprid could reach 95% after 15 h. The adsorption process was determined by kinetics, isotherms, and thermodynamics. The results demonstrated that the adsorption kinetics of Cr(VI) followed the pseudosecond-order model mainly by chemisorption; meanwhile, the adsorption of imidacloprid by the material conformed to the pseudo-first-order kinetics, which indicated that physical adsorption was the main process. Additionally, the intraparticle diffusion model revealed that the uptake of imidacloprid and Cr(VI) occurred via intraparticle diffusion at the composite material. The adsorption procedure for Cr(VI) was fitted to the Langmuir model (R 2 = 0.995) via monolayer adsorption, and that for imidacloprid was fitted to the Freundlich model (R 2 = 0.995) due to multilayer or heterogeneous adsorption. The thermodynamic research confirmed that the adsorption procedure was exothermic and spontaneous. Infrared spectroscopy, X-ray photoelectron spectra, and the pH effect implied that intermolecular hydrogen bonding and electrostatic interaction played a crucial role during the removal process. Fc-MIL-100(Fe) also exhibited long-term stability and satisfactory regeneration and reusability. Therefore, this method may enhance an environmentally friendly and prospective approach for concurrently removing imidacloprid and Cr(VI) from wastewater.