An ethylene-induced NAC transcription factor acts as a multiple abiotic stress responsor in conifer

The proper response to various abiotic stresses is essential for plants’survival to overcome their sessile nature,especially for perennial trees with very long-life cycles.However,in conifers,the molecular mechanisms that coordinate multiple abiotic stress responses remain elusive.Here,the transcriptome response to various abiotic stresses like salt,cold,drought,heat shock and osmotic were systematically detected in Pinus tabuliformis(P.tabuliformis)seedlings.We found that four transcription factors were commonly induced by all tested stress treatments,while PtNAC3 and PtZFP30 were highly up-regulated and co-expressed.Unexpectedly,the exogenous hormone treatment assays and the content of the endogenous hormone indicates that the upregulation of PtNAC3 and PtZFP30 are mediated by ethylene.Time-course assay showed that the treatment by ethylene immediate precursor,1-aminocyclopropane-1-carboxylic acid(ACC),activated the expression of PtNAC3 and PtZFP30 within 8 hours.We further confirm that the PtNAC3 can directly bind to the PtZFP30 promoter region and form a cascade.Overexpression of PtNAC3 enhanced unified abiotic stress tolerance without growth penalty in transgenic Arabidopsis and promoted reproductive success under abiotic stress by shortening the lifespan,suggesting it has great potential as a biological tool applied to plant breeding for abiotic stress tolerance.This study provides novel insights into the hub nodes of the abiotic stresses response network as well as the environmental adaptation mechanism in conifers,and provides a potential biofortification tool to enhance plant unified abiotic stress tolerance.

Phylogenetic relationship of Picea mongolica with other Picea species in the same area based on chloroplast gene variations

Picea mongolica is a conifer with a limited distribution in China and its taxonomic status is controversial.In order to explore genetic diff erences between P.mongolica and other nearby Picea species and to investigate its taxonomic status,phylogenetic relationships were analyzed between P.mongolica and Picea koraiensis,Picea meyeri and Picea wilsonii by three chloroplast gene sequences matK,chlB and atpA.The length of joint chloroplast sequence is 2379 bp.The fi fteen haplotypes were identifi ed by haplotype network analysis,among which two were major haplotypes and nine were unique.In addition,the genetic diversity of the sample collection species was inferred.Based on the haplotype network and Neighbor Joining phylogenetic tree analysis,P.mongolica was located on the basal clade of the phylogenetic tree which had more primitive taxa,and the genetic diversity of P.mongolica was highest.The signifi cant diff erences between P.mongolica and these other Picea species were identifi ed by this research.

Effects of DC Magnetic Bias on the Magnetic and Sound Fields of Transformer

DC bias current flowing into the neutral point of power transformer will seriously affect the normal operation of AC power system. In this paper, exciting current, harmonic component of the excitation current, magnetic flux density and noise of transformer were analyzed when the transformer is in the no-load operation state based on field-circuit coupled method. Through the calculation and analysis, some reference bases are provided for design of transformer.

Research on Numerical Simulation of 3D Leakage Magnetic Field and Short-circuit Impedance of Axial Dual-low-voltage Split-winding Transformer

It is difficult to accurately calculate the short-circuit impedance, due to the complexity of axial dual-low-voltage split-winding transformer winding structure. In this paper, firstly, the leakage magnetic field and short-circuit impedance model of axial dual-low-voltage split-winding transformer is established, and then the 2D and 3D leakage magnetic field are analyzed. Secondly, the short-circuit impedance and split parallel branch current distribution in different working conditions are calculated, which is based on field-circuit coupled method. At last, effectiveness and feasibility of the proposed model is verified by comparison between experiment, analysis and simulation. The results showed that the 3D analysis method is a better approach to calculate the short-circuit impedance, since its analytical value is more closer to the experimental value compared with the 2D analysis results, the finite element method calculation error is less than 2%, while the leakage flux method maximum error is 7.2%.

The long road to bloom in conifers

More than 600 species of conifers(phylum Pinophyta)serve as the backbone of the Earth’s terrestrial plant community and play key roles in global carbon and water cycles.Although coniferous forests account for a large fraction of global wood production,their productivity relies largely on the use of genetically improved seeds.However,acquisition of such seeds requires recurrent selection and testing of genetically superior parent trees,eventually followed by the establishment of a seed orchard to produce the improved seeds.The breeding cycle for obtaining the next generation of genetically improved seeds can be significantly lengthened when a target species has a long juvenile period.Therefore,development of methods for diminishing the juvenile phase is a cost-effective strategy for shortening breeding cycle in conifers.The molecular regulatory programs associated with the reproductive transition and annual reproductive cycle of conifers are modulated by environmental cues and endogenous developmental signals.Mounting evidence indicates that an increase in global average temperature seriously threatens plant productivity,but how conifers respond to the ever-changing natural environment has yet to be fully characterized.With the breakthrough of assembling and annotating the giant genome of conifers,identification of key components in the regulatory cascades that control the vegetative to reproductive transition is imminent.However,comparison of the signaling pathways that control the reproductive transition in conifers and the floral transition in Arabidopsis has revealed many differences.Therefore,a more complete understanding of the underlying regulatory mechanisms that control the conifer reproductive transition is of paramount importance.Here,we review our current understanding of the molecular basis for reproductive regulation,highlight recent discoveries,and review new approaches for molecular research on conifers.

Determination of conifer age biomarker DAL1 interactome using Y2H-seq

Age is a sophisticated physiological signal that ensures the sequence of different developmental stages in organisms.The regulation of ageing pathways appears to differ between gymnosperms and angiosperms.We previously identified DAL1 as a conserved conifer age biomarker that plays a crucial role in the transition from vegetative to reproductive life-history phases in pines.Therefore,elucidating the specific interaction events related to DAL1 is key to understanding how age drives conifer development.Large-scale yeast two-hybrid(Y2H)analysis followed by next-generation high-throughput sequencing(Y2H-seq)allowed us to identify 135 PtDAL1 interacting proteins in Pinus tabuliformis.Our study found that PtDAL1 interacting proteins showed an ageing-related module,with sophisticated interacting networks composed of transcription factors(TFs),transcriptional regulators(TRs),and kinases.These interacting proteins are produced in response to a variety of phytohormones and environmental signals,and are likely involved in wood formation,needle development,oleoresin terpenoids biosynthesis,and reproductive development.In this study,we propose a novel regulation model of conifer ageing pathways whereby PtDAL1 coordinates different environmental stimuli and interacts with corresponding proteins to regulate appropriate development.