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.

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.