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Secondary microbial gas accompanied by abnormally high CO2/N2 concentrations is widely developed in the southern Junggar Basin (SJB). However, the mechanism of nonhydrocarbon-enriched coalbed methane (CBM) remains unclear. Due to the close correlation between microbial gas and hydrogeology, the geochemical and microbial sequencing experiments were conducted to reveal hydrogeological controls on CBM geochemistry in this study. The results showed that CBM derives from thermogenic and biogenic genesis in SJB, and the biogenic genesis is mainly generated through CO2 reduction. CO2 is biogenic and N2 is of atmospheric and thermal genesis. CO2 concentration mainly depends on microbial production and consumption. The higher alkane-degrading bacterial abundance in As/V-enriched environments promotes CO2 generation, while high HCO3− contents inhibit CO2 dissolution in water and consumption by methanogens. Alkane-degrading bacteria enrichment and discontinuous CO2 consumption lead to the significantly high CO2 concentration. Atmospheric N2 concentration was negatively correlated with groundwater runoff intensity, while thermogenic N2 concentration showed a weak correlation with total dissolved solids (TDS). High atmospheric infiltration and thermogenic N2 replenishment lead to a N2 concentration exceeding 10%. Stable carbon isotopes are related to methanogens, and more methanogens in Li/Zn/Cu/Rb/Sn-enriched environments lead to decreasing δ13C–CH4. However, when TDS exceeds 15,000 mg/l, the inhibited methanogen production results in δ13C–CH4 higher than −55‰. Three CBM geochemistry distribution models were ultimately established: atmospheric mixed in the runoff–weak runoff area, reformation by shallow microbial gas migration in the weak runoff–stagnant area, and damping microbial gas generation with abundant alkane-degrading bacteria in the weak runoff–stagnant area. [ABSTRACT FROM AUTHOR]

Summary: Circular RNA (circRNA) is a kind of new regulatory RNA with diverse biological functions. Numerous circRNAs have been identified in many plant species; however, evolution of plant circRNAs remains largely unknown.In this study, we assembled full‐length sequences of 6519 rice (Oryza sativa) circRNAs and analyzed their conservation in another 46 plant species based on comparison of sequences and expression patterns.We found that, at the genomic level, 8.7% of the 6519 circRNAs were conserved in dicotyledonous plants and 49.1% in Oryza genus. Meanwhile, 57.8% of parental protein‐coding genes of the rice circRNAs originated recently after divergence of monocotyledonous plants, implying recent origin of the majority of rice circRNAs, a conclusion further supported by the results based on analysis of 4663 full‐length circRNAs in Arabidopsis thaliana. Accordingly, we proposed three models to address the origination of different types of circRNAs.Taken together, the results obtained in this study provide new insights for the evolutionary dynamics of plant circRNAs and candidate circRNAs for further functional exploration. [ABSTRACT FROM AUTHOR]

Abstract Background Rapeseed (Brassica napus L.) has spring and winter genotypes adapted to different growing seasons. Winter genotypes do not flower before the onset of winter, thus leading to a longer vegetative growth period that promotes the accumulation and allocation of more resources to seed production. The development of winter genotypes enabled the rapeseed to spread rapidly from southern to northern Europe and other temperate regions of the world. The molecular basis underlying the evolutionary transition from spring- to winter- type rapeseed is not known, however, and needs to be elucidated. Results We fine-mapped the spring environment specific quantitative trait locus (QTL) for flowering time, qFT10-4,in a doubled haploid (DH) mapping population of rapeseed derived from a cross between Tapidor (winter-type) and Ningyou7 (semi-winter) and delimited the qFT10-4 to an 80-kb region on chromosome A10 of B. napus. The BnFLC.A10 gene, an ortholog of FLOWERING LOCUS C (FLC) in Arabidopsis, was cloned from the QTL. We identified 12 polymorphic sites between BnFLC.A10 parental alleles of the TN-DH population in the upstream region and in intron 1. Expression of both BnFLC.A10 alleles decreased during vernalization, but decreased more slowly in the winter parent Tapidor. Haplotyping and association analysis showed that one of the polymorphic sites upstream of BnFLC.A10 is strongly associated with the vernalization requirement of rapeseed (r2 = 0.93, χ2 = 0.50). This polymorphic site is derived from a Tourist-like miniature inverted-repeat transposable element (MITE) insertion/deletion in the upstream region of BnFLC.A10. The MITE sequence was not present in the BnFLC.A10 gene in spring-type rapeseed, nor in ancestral ‘A’ genome species B. rapa genotypes. Our results suggest that the insertion may have occurred in winter rapeseed after B. napus speciation. Conclusions Our findings strongly suggest that (i) BnFLC.A10 is the gene underlying qFT10-4, the QTL for phenotypic diversity of flowering time in the TN-DH population, (ii) the allelic diversity caused by MITE insertion/deletion upstream of BnFLC.A10 is one of the major causes of differentiation of winter and spring genotypes in rapeseed and (iii) winter rapeseed has evolved from spring genotypes through selection pressure at the BnFLC.A10 locus, enabling expanded cultivation of rapeseed along the route of Brassica domestication.

Abstract Background MicroRNAs (miRNAs) and short interfering RNAs (siRNAs) are two major classes of small RNAs. They play important regulatory roles in plants and animals by regulating transcription, stability and/or translation of target genes in a sequence-complementary dependent manner. Over 4,000 miRNAs and several classes of siRNAs have been identified in plants, but in tobacco only computational prediction has been performed and no tobacco-specific miRNA has been experimentally identified. Wounding is believed to induce defensive response in tobacco, but the mechanism responsible for this response is yet to be uncovered. Results To get insight into the role of small RNAs in damage-induced responses, we sequenced and analysed small RNA populations in roots and leaves from wounding or topping treated tobacco plants. In addition to confirmation of expression of 27 known miRNA families, we identified 59 novel tobacco-specific miRNA members of 38 families and a large number of loci generating phased 21- or 24-nt small RNAs (including ta-siRNAs). A number of miRNAs and phased small RNAs were found to be responsive to wounding or topping treatment. Targets of small RNAs were further surveyed by degradome sequencing. Conclusions The expression changes of miRNAs and phased small RNAs responsive to wounding or topping and identification of defense related targets for these small RNAs suggest that the inducible defense response in tobacco might be controlled by pathways involving small RNAs.