Critical effects on the photosynthetic efficiency and stem sap flow of poplar in the Yellow River Delta in response to soil water

To explore the critical relationships of photosynthetic efficiency and stem sap flow to soil moisture,two-year-old poplar saplings were selected and a packaged stem sap flow gauge,based on the stem-heat balance method,and a CIRAS-2 portable photosynthesis system were used.The results show that photosynthetic rates(P_(n)),transpiration rates(T_(r)),instantaneous water use efficiency(WUE)and the stem sap flow increased initially and then decreased with decreasing soil water,but their critical values were different.The turning point of relative soil water content(W_(r))from stomatal limitation to nonstomatal limitation of P_(n)was 42%,and the water compensation point of P_(n)was 13%.Water saturation points of P_(n)and T_(r)were 64%and 56%,respectively,and the WUE was 71%.With increasing soil water,the apparent quantum yield(AQY),light saturation point(LSP)and maximum net photosynthetic rate(P_(n)max)increased first and then decreased,while the light compensation point(LCP)decreased first and then increased.When W_(r)was 64%,LCP reached a lower value of 30.7µmol m^(-2)s^(-1),and AQY a higher value of 0.044,indicating that poplar had a strong ability to utilize weak light.When W_(r)was 74%,LSP reached its highest point at 1138.3µmol·m^(-2)s^(-1),indicating that poplar had the widest light ecological amplitude and the highest light utilization efficiency.Stem sap flow and daily sap flow reached the highest value(1679.7 g d^(-1))at W_(r)values of 56%and 64%,respectively,and then declined with increasing or decreasing W_(r),indicating that soil moisture significantly affected the transpiration water-consumption of poplar.Soil water was divided into six threshold grades by critical values to maintain photosynthetic efficiency at different levels,and a W_(r)of 64-71%was classified to be at the level of high productivity and high efficiency.In this range,poplar had high photosynthetic capacity and efficient physiological characteristics for water consumption.The saplings had characteristics of water tolerance and were not drought resistant.Full attention should be given to the soil water environment in the Yellow River Delta when planting Populus.

RAD-seq data reveals robust phylogeny and morphological evolutionary history of Rhododendron

Rhododendron is famous for its high ornamental value.However,the genus is taxonomically difficult and the relationships within Rhododendron remain unresolved.In addition,the origin of key morphological characters with high horticulture value need to be explored.Both problems largely hinder utilization of germplasm resources.Most studies attempted to disentangle the phylogeny of Rhododendron,but only used a few genomic markers and lacked large-scale sampling,resulting in low clade support and contradictory phylogenetic signals.Here,we used restriction-site associated DNA sequencing(RAD-seq)data and morphological traits for 144 species of Rhododendron,representing all subgenera and most sections and subsections of this species-rich genus,to decipher its intricate evolutionary history and reconstruct ancestral state.Our results revealed high resolutions at subgenera and section levels of Rhododendron based on RAD-seq data.Both optimal phylogenetic tree and split tree recovered five lineages among Rhododendron.Subg.Therorhodion(cladeⅠ)formed the basal lineage.Subg.Tsutsusi and Azaleastrum formed cladeⅡand had sister relationships.CladeⅢincluded all scaly rhododendron species.Subg.Pentanthera(cladeⅣ)formed a sister group to Subg.Hymenanthes(cladeⅤ).The results of ancestral state reconstruction showed that Rhododendron ancestor was a deciduous woody plant with terminal inflorescence,ten stamens,leaf blade without scales and broadly funnelform corolla with pink or purple color.This study shows significant distinguishability to resolve the evolutionary history of Rhododendron based on high clade support of phylogenetic tree constructed by RAD-seq data.It also provides an example to resolve discordant signals in phylogenetic trees and demonstrates the application feasibility of RAD-seq with large amounts of missing data in deciphering intricate evolutionary relationships.Additionally,the reconstructed ancestral state of six important characters provides insights into the innovation of key characters in Rhododendron.

Advances in Genomic,Transcriptomic,and Metabolomic Analyses of Fruit Quality in Fruit Crops

Fruit quality is the main factor determining market competitiveness;it represents the combination of fruit flavor,color,size,and the contents of aromatic and bioactive substances.Research on the genetic basis of fruit quality can provide new information about fruit biology,promote genomic-assisted breeding,and provide technological support for the regulation of fruit quality via habitat selection and/or the control of environmental conditions.High-throughput sequencing is a powerful research method for studying fruit quality traits,and reference genome sequences for many important fruit crops have provided vast amounts of genomic data.To study fruit quality,it is important to select appropriate omics strategies and to analyze omics data meaningfully.Here,we summarize genomic mechanisms of fruit quality formation:gene duplication,transposable element insertion,structural variations and genome methylation in functional genes.We review the genomic,transcriptomic,and metabolomic strategies that have been used to study the genetic basis of fruit quality traits.We also describe some of the genes associated with fruit traits;these genes are a valuable resource for genomics-assisted breeding and are useful models for deciphering the mechanisms of agronomic traits,such as fruit color,size,hardness,aroma components,sugar and acid content.Finally,to maximize the application of omics information,we propose some further directions for research using omics strategies.

Research Progress of Soybean Protein Adhesive:A Review

Traditional formaldehyde-based adhesives rely excessively on petrochemical resources,release toxic gases,and pollute the environment.Plant-derived soybean protein adhesives are eco-friendly materials that have the potential to replace the formaldehyde-based adhesives used to fabricate wood-based panels.However,the poor water resistance,high brittleness,and poor mildew resistance of soybean protein adhesives limit their industrial applications.This article reviews recent research progress in the modification of soybean protein adhesives for improving the bonding performance of adhesives used for wood-based panel fabrication.Modification methods were summarized in terms of water resistance,solid content,and mildew resistance.The modification mechanisms and remaining problems were also discussed.Finally,the current industrial applications and the future research direction of soybean protein adhesives are discussed.

Transcription factor PagLBD21 functions as a repressor of secondary xylem development in Populus

During secondary growth in trees,xylem cells differentiated from cambium cells begin to synthesize secondary cell walls that are primarily composed of cellulose,hemicellulose and lignin,and are deposited between primary cell walls and plasma membranes,leading to wood formation.Identification of regulatory genes functioning during this developmental process is valuable for increasing wood production.In this study,we functionally characterized an LBD(LATERAL ORGAN BOUNDARIES DOMAIN)transcription factor PagLBD21 as a repressor of secondary xylem development in Populus.Compared to wild type plants,transgenic plants overexpressing PagLBD21(PagLBD21OE)exhibited decreased xylem widths in cross-sections.Consistent with the functional analysis,RNA sequencing(RNA-seq)analysis revealed that genes functioning in xylem development and secondary cell wall biosynthesis pathways were significantly down-regulated in PagLBD21OE plants.We also performed DNA affinity purification followed by sequencing(DAP-seq)to identify genome-wide target genes of PagLBD21.Furthermore,we compared the RNA-seq and DAP-seq datasets of PagLBD21 and PagLBD3,and the results showed that there was a significant overlap between their target genes,suggesting these two LBD transcription factors are functionally redundant during secondary growth.

N-glucosyltransferase GbNGT1 from ginkgo complements the auxin metabolic pathway

As auxins are among the most important phytohormones,the regulation of auxin homeostasis is complex.Generally,auxin conjugates,especially IAA glucosides,are predominant at high auxin levels.Previous research on terminal glucosylation focused mainly on the O-position,while IAA-N-glucoside and IAA-Asp-N-glucoside have been neglected since their discovery in 2001.In our study,IAA-Asp-N-glucoside was found to be specifically abundant(as high as 4.13 mg/g)in the seeds of 58 ginkgo cultivars.Furthermore,a novel N-glucosyltransferase,termed GbNGT1,was identified via differential transcriptome analysis and in vitro enzymatic testing.It was found that GbNGT1 could catalyze IAA-Asp and IAA to form their corresponding N-glucosides.The enzyme was demonstrated to possess a specific catalytic capacity toward the N-position of the IAA-amino acid or IAA from 52 substrates.Docking and site-directed mutagenesis of this enzyme confirmed that the E15G mutant could almost completely abolish its N-glucosylation ability toward IAA-Asp and IAA in vitro and in vivo.The IAA modification of GbNGT1 and GbGH3.5 was verified by transient expression assay in Nicotiana benthamiana.The effect of GbNGT1 on IAA distribution promotes root growth in Arabidopsis thaliana.

An integrated approach to configure rGO/VS_(4)/S composites with improved catalysis of polysulfides for advanced lithium-sulfur batteries

Lithium-sulfur(Li-S)battery is labeled as a promising high-energy-density battery system,but some inherent drawbacks of sulfur cathode materials using relatively complicated techniques impair the practical applications.Herein,an integrated approach is proposed to fabricate the high-performance rGO/VS_(4)/S cathode composites through a simple one-step solvothermal method,where nano sulfur and VS_(4) particles are uniformly distributed on the conductive rGO matrix.rGO and sulfiphilic VS_(4)provide electron transfer skeleton and physical/chemical anchor for soluble lithium polysulfides(LiPS).Meanwhile,VS_(4) could also act as an electrochemical mediator to efficiently enhance the utilization and reversible conversion of LiPS.Correspondingly,the rGO/VS_(4)/S composites maintain a high reversible capacity of 969 mAh/g at 0.2 C after 100 cycles,with a capacity retention rate of 82.3%.The capacity fade rate could lower to 0.0374%per cycle at 1 C.Moreover,capacity still sustains 795 m Ah/g after 100 cycles in the relatively high-sulfurloading battery(6.5 mg/cm^(2)).Thus,the suggested method in configuring the sulfur-based composites is demonstrated a simple and efficient strategy to construct the high-performance Li-S batteries.

Towards safe lithium-sulfur batteries from liquid-state electrolyte to solid-state electrolyte

Lithium-sulfur(Li-S)battery has been considered as one of the most promising future batteries owing to the high theoretical energy density(2600 W-h-kg-1)and the usage of the inexpensive active materials(elemental sulfur).The recent progress in fundamental research and engineering of the Li-S battery,involved in electrode,electrolyte,membrane,binder,and current collector,has greatly promoted the performance of Li s batteries from the laboratory level to the approaching practical level.However,the safety concerns still deserve attention in the following application stage.This review focuses on the development of the electrolyte for Li S batteries from liquid state to solid state.Some problems and the corresponding solutions are emphasized,such as the soluble lithium polysulfides migration,ionic conductivity of electrolyte,the interface contact between electrolyte and electrode,and the reaction kinetics.Moreover,future perspectives of the safe and high-performance Li S batteries arealso introduced.