Populus alba × P.glandulosa clone 84 K,derived from South Korea,is widely cultivated in China and used as a model in the molecular research of woody plants because of hi gh gene transformation efficiency.Here,we ...Populus alba × P.glandulosa clone 84 K,derived from South Korea,is widely cultivated in China and used as a model in the molecular research of woody plants because of hi gh gene transformation efficiency.Here,we combined63-fold coverage Illumina short reads and 126-fold coverage PacBio long reads to assemble the genome.Due to the hi gh heterozygosity level at 2.1% estimated by k-mer analysis,we exploited TrioCanu for genome assembly.The PacBio clean subreads of P.alba × P.glandulosa were separated into two parts according to the similarities,compared with the parental genomes of P.alba and P.glandulosa.The two parts of the subreads were assembled to two sets of subgenomes comprising subgenome A(405.31 Mb,from P.alba)and subgenome G(376.05 Mb,from P.glandulosa) with the contig N50 size of 5.43 Mb and 2.15 Mb,respectively.A high-quality P.alba × P.glandulosa genome assembly was obtained.The genome size was 781.36 Mb with the contig N50 size of 3.66 Mb and the longest contig was 19.47 Mb.In addition,a total of 176.95 Mb(43.7%),152.37 Mb(40.5%)of repetitive elements were identified and a total of 38,701 and 38,449 protein-coding genes were predicted in subgenomes A and G,respectively.For functional annotation,96.98% of subgenome A and 96.96% of subgenome G genes were annotated with public databases.This de novo assembled genome will facilitate systematic and comprehensive study,such as multi-omics analysis,in the model tree P.alba X P.glandulosa.展开更多
理解新疆杨(Populus alba var.pyramidalis)耗水特征对制定沙地人工林科学用水灌溉策略以及林场经营建设具有重要意义。采用包裹式树干茎流仪测定新疆杨液流,并对毛乌素沙地的环境因子进行长期监测。结果表明:新疆杨晴天液流速率最大,...理解新疆杨(Populus alba var.pyramidalis)耗水特征对制定沙地人工林科学用水灌溉策略以及林场经营建设具有重要意义。采用包裹式树干茎流仪测定新疆杨液流,并对毛乌素沙地的环境因子进行长期监测。结果表明:新疆杨晴天液流速率最大,阴天次之,雨天最小,日液流累计量分别为16.38、12.56、2.22 L,晴天和阴天的液流速率接近。5、6、7、8、9、10月的日平均液流量分别为12.12、14.07、14.08、11.60、8.73、3.92 L,5—8月是新疆杨主要的耗水期,累计耗水量为1722.53 L。新疆杨液流与净辐射、饱和水汽压差、气温、太阳辐射、土壤热通量、土壤温度显著正相关,相关系数分别为0.656、0.641、0.634、0.625、0.605、0.467;与土壤湿度、空气相对湿度、降水量显著负相关,相关系数分别为-0.340、-0.233、-0.178;与风速相关性不显著。净辐射对于新疆杨液流的影响最大。展开更多
Phytochrome-interacting factors(PIFs)have been established as negative regulators of vascular patterning and xylem differentiation in the herbaceous plant Arabidopsis thaliana,however,the regulatory role of PIFs in se...Phytochrome-interacting factors(PIFs)have been established as negative regulators of vascular patterning and xylem differentiation in the herbaceous plant Arabidopsis thaliana,however,the regulatory role of PIFs in secondary growth in woody species remains unclear.Here,we examines the expression patterns and involvement of PtoPIF3.1 and PtoPIF3.2 during stem growth and secondary xylem development in Populus tomentosa.Overexpression of either PtoPIF3.1 or PtoPIF3.2 significantly enhances both longitudinal stem growth and radial wood development.Conversely,Ptopif3.1 and Ptopif3.2 mutants generated by CRISPR-mediated genome editing exhibit reciprocal phenotypic defects.Exogenous auxin application partially restores the phenotypes of Ptopif3.1 and Ptopif3.2 mutants,and the auxin biosynthesis-deficient mutant Ptoyuc8 exhibits developmental abnormalities similar to those observed in Ptopif3 mutants.Further analysis reveal that PtoPIF3s directly bind to and activate expression of PtoYUC8 and cell expansion-related genes PtoEXPA1.1/1.2,while modulating cambial division and expression of secondary xylem development marker genes(PtoWOX4,PtoANT,PtoCYCD3s,and PtoHB7/8)through auxin-mediated signaling.Together,our findings establish PtoPIF3.1/3.2 as key regulators that coordinate stem elongation and secondary growth in Populus,highlighting the functional divergence of PIF homologs between herbaceous and woody species.展开更多
The ectomycorrhizal fungus Paxillus involutus was inoculated onto tissue-cultures of the hybrid poplar,Populus davidiana×P.bolleana,to evaluate the elemental defense effect to heavy metals copper and cadmium at d...The ectomycorrhizal fungus Paxillus involutus was inoculated onto tissue-cultures of the hybrid poplar,Populus davidiana×P.bolleana,to evaluate the elemental defense effect to heavy metals copper and cadmium at different concentrations by simulating Alternaria alternata fungus infection.The enrichment capacity of Populus davidiana×P.bolleana for Cu and Cd was closely associated with the degree of heavy metal stress.There was a significant positive interaction of applying Cu and Cd and the inoculation with P.involutus on A.alternata leaf blight disease index.The incidence rate and disease index of leaf blight underwent a significant reduction compared with the controls.Similarly,the ratio of the area of disease spot to leaf area,incidence rate,and disease index for Populus davidiana×P.bolleana leaves inoculated with Paxillus involutus(Batsch)Fr.were significantly lower than those of their nonmycorrhizal counterparts.With increasing the degree of Cu and Cd stress,a gradual increase in the average value of the membership function for the incidence rate and disease index was observed,indicating the weakened pathogen's ability to cause infection and the improved resistance of Populus davidiana×P.bolleana to leaf blight disease under Cu and Cd stress.Moreover,superoxide dismutase enzyme activity in Populus davidiana×P.bolleana increased significantly,reaching levels of 411.0 U/g FW and 421.6 U/g FW under Cu and Cd treatments,respectively.These changes in metabolic products and antioxidant enzyme activities suggest that P.involutus may enhance the resistance of Populus davidiana×P.bolleana to the fungus,Alternaria alternata Fr.Keissel under heavy metal stress by modulating these physiological indicators.展开更多
The pattern of codon usage in the chloroplast genome of Populus alba was investigated. Correspondence analysis （a commonly used multivariate statistical approach） and method of effective number of codons （ENc）-plo...The pattern of codon usage in the chloroplast genome of Populus alba was investigated. Correspondence analysis （a commonly used multivariate statistical approach） and method of effective number of codons （ENc）-plot were conducted to analyze synonymous codon usage. The results of correspondence analysis showed that the distribution of genes on the major axis was significantly correlated with the frequency of use of G＋C in synonymously variable third position of sense codon （GC3S）, （r=0.349）, and the positions of genes on the axis 2 and axis 3 were significantly correlated with CAI （r=-0.348, p〈0.01 and r=0.602, p〈0.01）. The ENc for most genes was similar to that for the expected ENc based on the GC3s, but several genes with low ENc values were lying below the expected curve. All of these data indicated that codon usage was dominated by a mutational bias in chloroplast gcnome ofP. alba. The selection in nature for translational efficiency only played a minor role in shaping codon usage in the chloroplast genome ofP alba.展开更多
Estimation of the transpiration rate for a tree is generally based on sap flow measurements within the hydro-active stem xylem. In this study, radial variation of sap flow velocity（Js） was investigated at five depth...Estimation of the transpiration rate for a tree is generally based on sap flow measurements within the hydro-active stem xylem. In this study, radial variation of sap flow velocity（Js） was investigated at five depths of the xylem（1, 2, 3, 5 and 8 cm under the cambium） in three mature Xinjiang poplar（Populus alba L. var. pyramidalis） trees grown at the Gansu Minqin National Studies Station for Desert Steppe Ecosystem from May to October 2011. Thermal dissipation probes of various lengths manufactured according to the Granier＇s design were installed into each tree for simultaneous observation of the radial patterns of Js through the xylem. The radial patterns were found to fit the four-parameter GaussAmp equation. The peak Js was about 27.02±0.95 kg/（dm2？d） at approximately 3 to 5 cm deep from the cambium of the three trees,and the lowest Js appeared at 1 cm deep in most of the time. Approximately 50% of the total sap flow in Xinjiang poplar occurred within one-third of the xylem from its outer radius, whereas 90% of the total sap flow occurred within two-fifth of the xylem. In addition, the innermost point of the xylem（at 8-cm depth）, which appeared as the penultimate sap flow in most cases during the study period, was hydro-active with Js,8 of 7.55±3.83 kg/（dm2？d）. The radial pattern of Js was found to be steeper in midday than in other time of the day, and steeper diurnal fluctuations were recorded in June, July and August（the mid-growing season）. Maximum differences between the lowest Js（Js,1 or Js,8） and the highest Js（Js,3 or Js,5） from May through October were 12.41, 17.35, 16.30, 18.52, 12.60 and 16.04 g/（cm2？h）, respectively. The time-dependent changes of Js along the radial profile（except at 1-cm depth） were strongly related to the reference evapotranspiration（ET0）. Due to significant radial variability of Js, the mean daily sap flow at the whole-tree level could be over-estimated by up to 29.69% when only a single probe at depth of 2 cm was used. However, the accuracy of the estimation of sap flow in Xinjiang poplar could be significantly improved using a correction coefficient of 0.885.展开更多
Although pruning is important to obtain highquality,large-diameter timber,the effects of pruning on nonstructural carbohydrates(NSC)in aboveground organs of many timber species are not well understood.Three intensitie...Although pruning is important to obtain highquality,large-diameter timber,the effects of pruning on nonstructural carbohydrates(NSC)in aboveground organs of many timber species are not well understood.Three intensities of pruning(none,moderate and severe)were tested on poplars(Populus alba×P.talassica)in the arid desert region of northwest China to compare the concentrations of soluble sugar(SS),starch(ST)and total nonstructural carbohydrate(TNC)in leaves,branches and trunks during the growing season.The concentration of NSC components after different pruning intensities varied similarly in seasonal patterns,increasing slowly at the beginning of the growing season,continuously declining in the middle,then gradually recovering by the end of the growing season.The monthly mean NSC concentration in poplar differed significantly among the three pruning intensities(p<0.05).The SS concentration in pruned trees was higher than in unpruned trees(p<0.05).For moderately pruned trees,the concentrations of ST and TNC in trunks and branches were higher than in unpruned and in severely pruned trees(p<0.05).Compared with no pruning,pruning changed the seasonal variation in NSC concentration.The orders of SS and TNC concentrations in aboveground organs were leaf>branch>trunk,while the order of ST concentration was trunk>leaf>branch,which was related to functional differences of plant organs.The annual average growth in height of unpruned,moderately pruned,and severely pruned poplars was 0.21±0.06,0.45±0.09 and 0.24±0.05 m,respectively,and the annual average growth in DBH were 0.92±0.04,1.27±0.06 and 1.02±0.05 cm,respectively.Our results demonstrate that moderate pruning may effectively increase the annual growth in tree height and DBH while avoiding damage caused by excessive pruning to the tree body.Therefore,moderate pruning may increase the NSC storage and improve the growth of timber species.展开更多
Static tests under cyclic loading were carried out on Populus alba var. pyramidalis to determine its characteristic curves of restoring forces. The results show that P alba var. pyramidalis had good elastic performanc...Static tests under cyclic loading were carried out on Populus alba var. pyramidalis to determine its characteristic curves of restoring forces. The results show that P alba var. pyramidalis had good elastic performance. There was degradation of strength and stiffness under cyclic loading and unloading, where characteristic curves of restoring forces ofP. alba var. pyrarnidalis assumed a ＂flat and contrary S-shape＂ form. Simultaneously, P alba vat. pyramidalis showed typical characteristics of brittle destruction under large high peak loading and unloading. Furthermore, dynamic tests were carried out under wind loads to obtain dynamic displacement curves and dynamic strain curves. P alba var. pyramidalis reflected its stochastic dynamic performance in building up its resistance to the stochastic wind loads and its dynamically hysteretic properties. The dynamic response of this species was random and fuzzy under stochastic wind loads. This study has theoretical significance and reference value to research on the static characteristics and wind-induced dynamic performance of forests.展开更多
Because overexpression of Vitreoscilla hemoglobin gene(Vgb)gene in plants can enhance tolerance to waterlogging,here Vgb was inserted into Populus alba×glandulosa to investigate its expression and effects on grow...Because overexpression of Vitreoscilla hemoglobin gene(Vgb)gene in plants can enhance tolerance to waterlogging,here Vgb was inserted into Populus alba×glandulosa to investigate its expression and effects on growth and physiological responses to waterlogging stress in the transgenic poplars.Southern blotting and RT-PCR analysis of Vgb-transgenic P.alba×glandulosa showed that the Vgb gene was integrated into the genome of the V13-81 and V13-85 transgenic lines and expressed.In greenhouse waterlogging stress tests,mortality of the transgenic poplar was significant lower than that of nontransgenic plants with increasing treatment time from 2 to 22 days.The transgenic plants had higher chlorophyll content and less chloroplast damage than in the control plants.Additionally,starch accumulation increased,and growth was enhanced in the transgenic plants,suggesting that the Vgb-expressing lines had improved energy reserves.Field trials of the transgenic poplar suggested that Vgb expression promotes growth and influences wood quality.Taken together,our results suggest that the expression of Vgb can increase the accumulation of chlorophyll and starch in the transgenic poplar,improve its ability to endure flooding,and improve growth and wood quality of the transgenic plants.展开更多
The effect of Thidiazuron （TDZ）, basal media and light quality on adventitious shoot regeneration from in vitro cultured stem of Populus albaxP berolinensis were determined to establish a high efficiency shoot regen...The effect of Thidiazuron （TDZ）, basal media and light quality on adventitious shoot regeneration from in vitro cultured stem of Populus albaxP berolinensis were determined to establish a high efficiency shoot regeneration system from stem explants of P. alba^P berolinensis. Stems ofPopulus alba^P berolinensis were collected from cultured shoots in vitro derived from dormancy buds of 3-year-old seedlings. The stem explants were cultured on MS medium containing 0.02-mg·L-1NAA （naphthaleneacetic acid）, and 0.1, 0.3, 0.5 and 1.0 mg·L-1 concentrations of TDZ to determine the effect of TDZ on shoot regeneration. Three basal media, i.e. MS, woody plant medium （WPM） and B5, were used to test their influences of different media on adventitious shoot regeneration. Green, red, blue and yellow plastic films in comparison with florescent light as control were used to observe their effects on shoot regeneration. The results showed that differ- ent concentrations of TDZ had an evident influence on shoot regeneration. Lower concentration of TDZ （0.1 mg·L-1） resulted in more ad- ventitious shoot regeneration and higher concentration of TDZ （〉0.1 mg·L-1） inhibited shoot regeneration. Among different media, MS medium exhibited a high efficiency for shoot regeneration, followed by WPM medium, while B5 medium inhibited shoot regeneration. Normal light and yellow light exhibited better effects on shoot regeneration, compared with other light.展开更多
Laboratory feeding experiments with the poplar aphid, Chaitophorus populeti （Panzer）, feeding on transgenic poplar （P. alba × P. glandulosa） varieties C13-5 and C013-5, were carried out to study the effect of...Laboratory feeding experiments with the poplar aphid, Chaitophorus populeti （Panzer）, feeding on transgenic poplar （P. alba × P. glandulosa） varieties C13-5 and C013-5, were carried out to study the effect of transgenic poplar on the ladybird Harmonia axyridis （Pallas）. The mortality and development time of the immature stages, the eclosion rate and body mass of H. axyridis were measured. The results indicated that C. populeti feeding on different varieties of transgenic plants had no statistically significant ef- fect on the mortality ofH. axyridis larvae. The development time of larval and pupal stages were not significantly different between the two transgenic poplars and a non-transgenic poplar. Furthermore, the body mass and eclosion rate did not show any difference between the H. axyridis feeding on aphids reared on transgenic plants and those from non-transgenic plants. It is suggested that transgenic plants have no deleterious effect on the predatory ladybird.展开更多
Populus alba is a foundation species in evolutionary and ecological studies in the northern hemisphere.In this study,the chloroplast genome and gene map of P.alba were constructed.The P.alba chloroplast genome is 156,...Populus alba is a foundation species in evolutionary and ecological studies in the northern hemisphere.In this study,the chloroplast genome and gene map of P.alba were constructed.The P.alba chloroplast genome is 156,505 bp in length comprising a large single-copy region,two inverted repeat regions and a small single-copy region.The genome contains 131 genes,including 86 protein-coding genes(77 PCG species),eight ribosomal RNA genes(four rRNA species)and 37 transfer RNA genes(30 tRNA species).Phylogenetic analysis indicates that all Populus chloroplast genome sequences are clustered together and divided into three large branches.Among reported Populus chloroplast genomes,the leuce section formed monophyletic,indicating that all Populus spp.have a common maternal ancestor.P.rotundifolia and P.tremula are closely related and are sisters to P.davidiana.P.alba is closely related to P.adenopoda.Population genetic research in ecology and evolution may be easily developed through chloroplast genomes as they are conserved.This research will benefit future studies related to Populus,one of the world’s most ecologically and economically important genera.展开更多
Populus alba‘Berolinensis’is a fast-growing,high-yielding species with strong biotic and abiotic stress resistance,and widely planted for timber,shelter belts and aesthetic purposes.In this study,molecular developme...Populus alba‘Berolinensis’is a fast-growing,high-yielding species with strong biotic and abiotic stress resistance,and widely planted for timber,shelter belts and aesthetic purposes.In this study,molecular development is explored and the important genes regulating xylem forma-tion in P.alba‘Berolinensis’under artificial bending treat-ments was identified.Anatomical investigation indicated that tension wood(TW)was characterized by eccentric growth of xylem and was enriched in cellulose;the degree of ligni-fication was lower than for normal wood(NW)and oppo-site wood(OW).RNA-Seq-based transcriptome analysis was performed using developing xylem from three wood types(TW,OW and NW).A large number of differentially expressed genes(DEGs)were screened and 4889 counted.In GO and KEGG enrichment results,genes involved in plant hormone signal transduction,phenylpropanoid biosynthesis,and cell wall and secondary cell wall biogenesis play major roles in xylem development under artificial bending.Eight expansin(PalEXP)genes were identified from the RNA-seq data;four were differentially expressed during tension wood formation.Phylogenetic analysis indicated that PalEXLB1 belongs to the EXPB subfamily and that the other PalEXPs are members of the EXPA subfamily.A transcriptional regulatory network construction showed 10 transcription factors located in the first and second layers upstream of EXP,including WRKY,ERF and bHLH.RT‒qPCR analy-sis in leaves,stems and roots combined with transcriptome analysis suggests that PalEXPA2,PalEXPA4 and PalEXPA15 play significant regulatory roles in cell wall formation during tension wood development.The candidate genes involved in xylem cell wall development during tension wood formation marks an important step toward identifying the molecular regulatory mechanism of xylem development and wood property improvement in P.alba‘Berolinensis’.展开更多
Populus alba is a large woody deciduous plant.The plant has been introduced to shooting,then multiplication of rooting on Murashige and Skoog(MS)medium.This work was designed to estimate the effect of two factors(low ...Populus alba is a large woody deciduous plant.The plant has been introduced to shooting,then multiplication of rooting on Murashige and Skoog(MS)medium.This work was designed to estimate the effect of two factors(low levels of 1-Naphthaleneacetic acid NAA and sucrose)on P.alba response resulting in 6 treatments compared to the control,with twelve measured responses.There was a significant difference in some measurements in morphology,like plantlets fresh-weight,shoot-,root-length,and leaf number.In the physiological measurements,there were significant differences in all the measured parameters.The low concentrations of sucrose and media composition/power(MS grams/L)led to starvation in plants;however,these conditions led to enhancement in some morphological and physiological parameters to overcome the starvation effect,compared to the control.The RAPD-PCR molecular marker(four decamers)was used to evaluate the new individuals’genetic variation(instability),resulting in a total polymorphism percentage of 50.83%.It was formerly known that the plantlets were identical to each other and to the mother plant.In this study,however,the use of distinct media power,hormonal and sucrose levels resulted in molecular variation reflected in P.alba’s morphological and physiological responses.展开更多
Hybridization remains an important method for breeding new poplar varieties.It results in significant variation in leaf phenotype among parents and offspring,and among offspring themselves.This study aimed to investig...Hybridization remains an important method for breeding new poplar varieties.It results in significant variation in leaf phenotype among parents and offspring,and among offspring themselves.This study aimed to investigate whether leaf shape variations were similar in offspring produced from reciprocal crosses.Specifically,two hybrid combinations were produced:the direct cross with Populus ussuriensis as the maternal parent and P.simonii×P.nigra as the paternal parent(HY53),and the reciprocal cross with P.simonii×P.nigra as the maternal parent and P.ussuriensis as the paternal parent(HY268).Using 3-month-old rooted cuttings from 40 clones(36 F1 hybrids and their parents)growing in a greenhouse,we measured and analyzed 14 leaf morphological traits to assess genetic variation and heterosis.The results showed HY53 clones generally exhibited greater average height than HY268 clones.Leaf phenotypes differed between the two hybrid combinations,with significant differences observed among parents and offspring for almost all traits,as revealed by analysis of variance(ANOVA).The phenotypic coefficient of variation was higher in HY268 clones.Additionally,leaf traits demonstrated high repeatability.Notably,some hybrid offspring exhibited positive or negative mid-parent heterosis,as well as over-parent heterosis for certain leaf phenotypes.The systematic cluster analysis further indicated distinct separation among HY268 clones.This research provides valuable materials for poplar breeding and offers insights into hybrid vigor in wood plants.The findings highlight the importance of reciprocal crossing in influencing leaf phenotype variation and heterosis,offering practical insights for future breeding strategies.展开更多
[Objective] The research aimed to study the influence of different afforestation technology measures on soil nutrients of P. alba wood-land in arid valley region of Rikaze, Tibet. It aimed to improve afforestatio...[Objective] The research aimed to study the influence of different afforestation technology measures on soil nutrients of P. alba wood-land in arid valley region of Rikaze, Tibet. It aimed to improve afforestation technology measure in arid valley region of Rikaze, Tibet, and provide theoretic basis for restoring the degraded ecosystem at upper reaches of the Yarlung Zangbo River. [ Method] In arid valley region of Duojiao Vil-lage, Nanmulin County, Rikaze City, the planted land using rooting powder, egg shell, leaves, mud and water retention agent was taken as re-search object, while the land without any afforestation measures was taken as the control, to determine soil nutrients under different afforestation measures. [Result] Under different afforestation measures, the contents of various soil nutrients were all obviously higher than control, in which available potassium, available phosphorus, alkali hydrolysable nitrogen and organic matter in soil obviously increased than control, but there was no similar rule among different measures. [Conclusion] Vegetation restoration in dry valley belt of Rikaze by different afforestation measures is favorable for improving physical-chemical properties of soil and increasing soil fertility.展开更多
Tyrosine decarboxylase(TyDC)converts tyrosine to tyramine and plays a crucial role in secondary metabolite reactions,development,and stress responses in plants.Currently,the biological role of TyDC proteins from trees...Tyrosine decarboxylase(TyDC)converts tyrosine to tyramine and plays a crucial role in secondary metabolite reactions,development,and stress responses in plants.Currently,the biological role of TyDC proteins from trees is unknown.This study provided evidence showing that poplar PaTyDC4 functions in wood development and drought stress response.PaTyDC4 is preferentially expressed in wood-forming cells in stems.Overexpression of PaTyDC4 in poplars under the control of a xylem-specific promoter resulted in an increase in the ratio of xylem to phloem width,vessel cell area,and lignin accumulation in the stems.Biochemical assays revealed that PaTyDC4 was a component of the PaC3H17-PaMYB199 module-mediated pathway.In poplar stems,Pa TyDC4 expression was directly suppressed by PaMYB199,which was attenuated by the interaction between PaC3H17 and PaMYB199.In addition,Pa TyDC4 overexpression lines showed stronger drought tolerance than the wild-type lines,with higher photosynthetic capacity and lower levels of H_(2)O_(2).These results indicate that PaTyDC4 promotes xylem differentiation and lignin deposition during secondary growth and confers drought tolerance.Our findings may be useful for the genetic modification of biomass and drought resistance in trees.展开更多
基金supported by grants CAFYBB2017ZY001 and TGB2016001 from Fundamental Research Funds of the Chinese Academy of Forestry。
文摘Populus alba × P.glandulosa clone 84 K,derived from South Korea,is widely cultivated in China and used as a model in the molecular research of woody plants because of hi gh gene transformation efficiency.Here,we combined63-fold coverage Illumina short reads and 126-fold coverage PacBio long reads to assemble the genome.Due to the hi gh heterozygosity level at 2.1% estimated by k-mer analysis,we exploited TrioCanu for genome assembly.The PacBio clean subreads of P.alba × P.glandulosa were separated into two parts according to the similarities,compared with the parental genomes of P.alba and P.glandulosa.The two parts of the subreads were assembled to two sets of subgenomes comprising subgenome A(405.31 Mb,from P.alba)and subgenome G(376.05 Mb,from P.glandulosa) with the contig N50 size of 5.43 Mb and 2.15 Mb,respectively.A high-quality P.alba × P.glandulosa genome assembly was obtained.The genome size was 781.36 Mb with the contig N50 size of 3.66 Mb and the longest contig was 19.47 Mb.In addition,a total of 176.95 Mb(43.7%),152.37 Mb(40.5%)of repetitive elements were identified and a total of 38,701 and 38,449 protein-coding genes were predicted in subgenomes A and G,respectively.For functional annotation,96.98% of subgenome A and 96.96% of subgenome G genes were annotated with public databases.This de novo assembled genome will facilitate systematic and comprehensive study,such as multi-omics analysis,in the model tree P.alba X P.glandulosa.
基金upported by grants from the National Key Research and Development Program of China(2022YFD1201600)the National Natural Science Foundation of China(32371903).
文摘Phytochrome-interacting factors(PIFs)have been established as negative regulators of vascular patterning and xylem differentiation in the herbaceous plant Arabidopsis thaliana,however,the regulatory role of PIFs in secondary growth in woody species remains unclear.Here,we examines the expression patterns and involvement of PtoPIF3.1 and PtoPIF3.2 during stem growth and secondary xylem development in Populus tomentosa.Overexpression of either PtoPIF3.1 or PtoPIF3.2 significantly enhances both longitudinal stem growth and radial wood development.Conversely,Ptopif3.1 and Ptopif3.2 mutants generated by CRISPR-mediated genome editing exhibit reciprocal phenotypic defects.Exogenous auxin application partially restores the phenotypes of Ptopif3.1 and Ptopif3.2 mutants,and the auxin biosynthesis-deficient mutant Ptoyuc8 exhibits developmental abnormalities similar to those observed in Ptopif3 mutants.Further analysis reveal that PtoPIF3s directly bind to and activate expression of PtoYUC8 and cell expansion-related genes PtoEXPA1.1/1.2,while modulating cambial division and expression of secondary xylem development marker genes(PtoWOX4,PtoANT,PtoCYCD3s,and PtoHB7/8)through auxin-mediated signaling.Together,our findings establish PtoPIF3.1/3.2 as key regulators that coordinate stem elongation and secondary growth in Populus,highlighting the functional divergence of PIF homologs between herbaceous and woody species.
基金supported by the National Natural Science Foundation of China(31800542)Natural Science Foundation of Heilongjiang Province(LH2023C105)Heilongjiang Research Institutes Basic Research Funding Project(LKSB2024-9)。
文摘The ectomycorrhizal fungus Paxillus involutus was inoculated onto tissue-cultures of the hybrid poplar,Populus davidiana×P.bolleana,to evaluate the elemental defense effect to heavy metals copper and cadmium at different concentrations by simulating Alternaria alternata fungus infection.The enrichment capacity of Populus davidiana×P.bolleana for Cu and Cd was closely associated with the degree of heavy metal stress.There was a significant positive interaction of applying Cu and Cd and the inoculation with P.involutus on A.alternata leaf blight disease index.The incidence rate and disease index of leaf blight underwent a significant reduction compared with the controls.Similarly,the ratio of the area of disease spot to leaf area,incidence rate,and disease index for Populus davidiana×P.bolleana leaves inoculated with Paxillus involutus(Batsch)Fr.were significantly lower than those of their nonmycorrhizal counterparts.With increasing the degree of Cu and Cd stress,a gradual increase in the average value of the membership function for the incidence rate and disease index was observed,indicating the weakened pathogen's ability to cause infection and the improved resistance of Populus davidiana×P.bolleana to leaf blight disease under Cu and Cd stress.Moreover,superoxide dismutase enzyme activity in Populus davidiana×P.bolleana increased significantly,reaching levels of 411.0 U/g FW and 421.6 U/g FW under Cu and Cd treatments,respectively.These changes in metabolic products and antioxidant enzyme activities suggest that P.involutus may enhance the resistance of Populus davidiana×P.bolleana to the fungus,Alternaria alternata Fr.Keissel under heavy metal stress by modulating these physiological indicators.
基金supported by the National High Tech Development Project of Chinathe 863 Program (Grant Nos.2007AA02Z329)the National Natural Science Foundation of China (Grant Nos.20060213024).
文摘The pattern of codon usage in the chloroplast genome of Populus alba was investigated. Correspondence analysis （a commonly used multivariate statistical approach） and method of effective number of codons （ENc）-plot were conducted to analyze synonymous codon usage. The results of correspondence analysis showed that the distribution of genes on the major axis was significantly correlated with the frequency of use of G＋C in synonymously variable third position of sense codon （GC3S）, （r=0.349）, and the positions of genes on the axis 2 and axis 3 were significantly correlated with CAI （r=-0.348, p〈0.01 and r=0.602, p〈0.01）. The ENc for most genes was similar to that for the expected ENc based on the GC3s, but several genes with low ENc values were lying below the expected curve. All of these data indicated that codon usage was dominated by a mutational bias in chloroplast gcnome ofP. alba. The selection in nature for translational efficiency only played a minor role in shaping codon usage in the chloroplast genome ofP alba.
基金supported by the National Natural Science Foundation of China (31070628)Field support for this research was provided by Gansu Minqin National Studies Station for Desert Steppe Ecosystem
文摘Estimation of the transpiration rate for a tree is generally based on sap flow measurements within the hydro-active stem xylem. In this study, radial variation of sap flow velocity（Js） was investigated at five depths of the xylem（1, 2, 3, 5 and 8 cm under the cambium） in three mature Xinjiang poplar（Populus alba L. var. pyramidalis） trees grown at the Gansu Minqin National Studies Station for Desert Steppe Ecosystem from May to October 2011. Thermal dissipation probes of various lengths manufactured according to the Granier＇s design were installed into each tree for simultaneous observation of the radial patterns of Js through the xylem. The radial patterns were found to fit the four-parameter GaussAmp equation. The peak Js was about 27.02±0.95 kg/（dm2？d） at approximately 3 to 5 cm deep from the cambium of the three trees,and the lowest Js appeared at 1 cm deep in most of the time. Approximately 50% of the total sap flow in Xinjiang poplar occurred within one-third of the xylem from its outer radius, whereas 90% of the total sap flow occurred within two-fifth of the xylem. In addition, the innermost point of the xylem（at 8-cm depth）, which appeared as the penultimate sap flow in most cases during the study period, was hydro-active with Js,8 of 7.55±3.83 kg/（dm2？d）. The radial pattern of Js was found to be steeper in midday than in other time of the day, and steeper diurnal fluctuations were recorded in June, July and August（the mid-growing season）. Maximum differences between the lowest Js（Js,1 or Js,8） and the highest Js（Js,3 or Js,5） from May through October were 12.41, 17.35, 16.30, 18.52, 12.60 and 16.04 g/（cm2？h）, respectively. The time-dependent changes of Js along the radial profile（except at 1-cm depth） were strongly related to the reference evapotranspiration（ET0）. Due to significant radial variability of Js, the mean daily sap flow at the whole-tree level could be over-estimated by up to 29.69% when only a single probe at depth of 2 cm was used. However, the accuracy of the estimation of sap flow in Xinjiang poplar could be significantly improved using a correction coefficient of 0.885.
基金supported by Key Projects of Universities for Foreign Cultural and Educational Experts Employment Plan in 2018(T2018013)granted from Special Funds for Sustainable Development of Science and Technology Platform for Fundamental Research Business Expenses of Central Universities(2572018CP05).
文摘Although pruning is important to obtain highquality,large-diameter timber,the effects of pruning on nonstructural carbohydrates(NSC)in aboveground organs of many timber species are not well understood.Three intensities of pruning(none,moderate and severe)were tested on poplars(Populus alba×P.talassica)in the arid desert region of northwest China to compare the concentrations of soluble sugar(SS),starch(ST)and total nonstructural carbohydrate(TNC)in leaves,branches and trunks during the growing season.The concentration of NSC components after different pruning intensities varied similarly in seasonal patterns,increasing slowly at the beginning of the growing season,continuously declining in the middle,then gradually recovering by the end of the growing season.The monthly mean NSC concentration in poplar differed significantly among the three pruning intensities(p<0.05).The SS concentration in pruned trees was higher than in unpruned trees(p<0.05).For moderately pruned trees,the concentrations of ST and TNC in trunks and branches were higher than in unpruned and in severely pruned trees(p<0.05).Compared with no pruning,pruning changed the seasonal variation in NSC concentration.The orders of SS and TNC concentrations in aboveground organs were leaf>branch>trunk,while the order of ST concentration was trunk>leaf>branch,which was related to functional differences of plant organs.The annual average growth in height of unpruned,moderately pruned,and severely pruned poplars was 0.21±0.06,0.45±0.09 and 0.24±0.05 m,respectively,and the annual average growth in DBH were 0.92±0.04,1.27±0.06 and 1.02±0.05 cm,respectively.Our results demonstrate that moderate pruning may effectively increase the annual growth in tree height and DBH while avoiding damage caused by excessive pruning to the tree body.Therefore,moderate pruning may increase the NSC storage and improve the growth of timber species.
基金supported by the National Natural Science Foundation of China (Grant No. 30872071)
文摘Static tests under cyclic loading were carried out on Populus alba var. pyramidalis to determine its characteristic curves of restoring forces. The results show that P alba var. pyramidalis had good elastic performance. There was degradation of strength and stiffness under cyclic loading and unloading, where characteristic curves of restoring forces ofP. alba var. pyrarnidalis assumed a ＂flat and contrary S-shape＂ form. Simultaneously, P alba vat. pyramidalis showed typical characteristics of brittle destruction under large high peak loading and unloading. Furthermore, dynamic tests were carried out under wind loads to obtain dynamic displacement curves and dynamic strain curves. P alba var. pyramidalis reflected its stochastic dynamic performance in building up its resistance to the stochastic wind loads and its dynamically hysteretic properties. The dynamic response of this species was random and fuzzy under stochastic wind loads. This study has theoretical significance and reference value to research on the static characteristics and wind-induced dynamic performance of forests.
基金supported by the Basic Research Fund of RIF(Grant No.CAFYBB2017ZA001-3)the National Natural Science Foundation of China(Grant No.31700589)the Forestry Genetic Breeding National Key Laboratory(Chinese Academy of Forestry Sciences)Open Project(Grant No.TGB 2013005).
文摘Because overexpression of Vitreoscilla hemoglobin gene(Vgb)gene in plants can enhance tolerance to waterlogging,here Vgb was inserted into Populus alba×glandulosa to investigate its expression and effects on growth and physiological responses to waterlogging stress in the transgenic poplars.Southern blotting and RT-PCR analysis of Vgb-transgenic P.alba×glandulosa showed that the Vgb gene was integrated into the genome of the V13-81 and V13-85 transgenic lines and expressed.In greenhouse waterlogging stress tests,mortality of the transgenic poplar was significant lower than that of nontransgenic plants with increasing treatment time from 2 to 22 days.The transgenic plants had higher chlorophyll content and less chloroplast damage than in the control plants.Additionally,starch accumulation increased,and growth was enhanced in the transgenic plants,suggesting that the Vgb-expressing lines had improved energy reserves.Field trials of the transgenic poplar suggested that Vgb expression promotes growth and influences wood quality.Taken together,our results suggest that the expression of Vgb can increase the accumulation of chlorophyll and starch in the transgenic poplar,improve its ability to endure flooding,and improve growth and wood quality of the transgenic plants.
文摘The effect of Thidiazuron （TDZ）, basal media and light quality on adventitious shoot regeneration from in vitro cultured stem of Populus albaxP berolinensis were determined to establish a high efficiency shoot regeneration system from stem explants of P. alba^P berolinensis. Stems ofPopulus alba^P berolinensis were collected from cultured shoots in vitro derived from dormancy buds of 3-year-old seedlings. The stem explants were cultured on MS medium containing 0.02-mg·L-1NAA （naphthaleneacetic acid）, and 0.1, 0.3, 0.5 and 1.0 mg·L-1 concentrations of TDZ to determine the effect of TDZ on shoot regeneration. Three basal media, i.e. MS, woody plant medium （WPM） and B5, were used to test their influences of different media on adventitious shoot regeneration. Green, red, blue and yellow plastic films in comparison with florescent light as control were used to observe their effects on shoot regeneration. The results showed that differ- ent concentrations of TDZ had an evident influence on shoot regeneration. Lower concentration of TDZ （0.1 mg·L-1） resulted in more ad- ventitious shoot regeneration and higher concentration of TDZ （〉0.1 mg·L-1） inhibited shoot regeneration. Among different media, MS medium exhibited a high efficiency for shoot regeneration, followed by WPM medium, while B5 medium inhibited shoot regeneration. Normal light and yellow light exhibited better effects on shoot regeneration, compared with other light.
基金supported by the National Premier Special Funds for Study and Industrialization of Transgenic Plants (J2002-B-004)the National Natural Science and Technology Support Plan of China "the technology researchdemonstration of forestry-paper integrate project" (Grant No. 2006BAD32B)
文摘Laboratory feeding experiments with the poplar aphid, Chaitophorus populeti （Panzer）, feeding on transgenic poplar （P. alba × P. glandulosa） varieties C13-5 and C013-5, were carried out to study the effect of transgenic poplar on the ladybird Harmonia axyridis （Pallas）. The mortality and development time of the immature stages, the eclosion rate and body mass of H. axyridis were measured. The results indicated that C. populeti feeding on different varieties of transgenic plants had no statistically significant ef- fect on the mortality ofH. axyridis larvae. The development time of larval and pupal stages were not significantly different between the two transgenic poplars and a non-transgenic poplar. Furthermore, the body mass and eclosion rate did not show any difference between the H. axyridis feeding on aphids reared on transgenic plants and those from non-transgenic plants. It is suggested that transgenic plants have no deleterious effect on the predatory ladybird.
基金The work was supported by the Fundamental Research Funds of the Chinese Academy of Forestry(No.CAFYBB2017ZX001-1)the National Natural Science Foundation of China(No.31470665).
文摘Populus alba is a foundation species in evolutionary and ecological studies in the northern hemisphere.In this study,the chloroplast genome and gene map of P.alba were constructed.The P.alba chloroplast genome is 156,505 bp in length comprising a large single-copy region,two inverted repeat regions and a small single-copy region.The genome contains 131 genes,including 86 protein-coding genes(77 PCG species),eight ribosomal RNA genes(four rRNA species)and 37 transfer RNA genes(30 tRNA species).Phylogenetic analysis indicates that all Populus chloroplast genome sequences are clustered together and divided into three large branches.Among reported Populus chloroplast genomes,the leuce section formed monophyletic,indicating that all Populus spp.have a common maternal ancestor.P.rotundifolia and P.tremula are closely related and are sisters to P.davidiana.P.alba is closely related to P.adenopoda.Population genetic research in ecology and evolution may be easily developed through chloroplast genomes as they are conserved.This research will benefit future studies related to Populus,one of the world’s most ecologically and economically important genera.
基金funded by the Fundamental Research Funds for the Central Universities(2572019CT02)Heilongjiang Touyan Innovation Team Program(Tree Genetics and Breeding Innovation Team)The Overseas Expertise Introduction Project for Discipline Innovation(B16010).
文摘Populus alba‘Berolinensis’is a fast-growing,high-yielding species with strong biotic and abiotic stress resistance,and widely planted for timber,shelter belts and aesthetic purposes.In this study,molecular development is explored and the important genes regulating xylem forma-tion in P.alba‘Berolinensis’under artificial bending treat-ments was identified.Anatomical investigation indicated that tension wood(TW)was characterized by eccentric growth of xylem and was enriched in cellulose;the degree of ligni-fication was lower than for normal wood(NW)and oppo-site wood(OW).RNA-Seq-based transcriptome analysis was performed using developing xylem from three wood types(TW,OW and NW).A large number of differentially expressed genes(DEGs)were screened and 4889 counted.In GO and KEGG enrichment results,genes involved in plant hormone signal transduction,phenylpropanoid biosynthesis,and cell wall and secondary cell wall biogenesis play major roles in xylem development under artificial bending.Eight expansin(PalEXP)genes were identified from the RNA-seq data;four were differentially expressed during tension wood formation.Phylogenetic analysis indicated that PalEXLB1 belongs to the EXPB subfamily and that the other PalEXPs are members of the EXPA subfamily.A transcriptional regulatory network construction showed 10 transcription factors located in the first and second layers upstream of EXP,including WRKY,ERF and bHLH.RT‒qPCR analy-sis in leaves,stems and roots combined with transcriptome analysis suggests that PalEXPA2,PalEXPA4 and PalEXPA15 play significant regulatory roles in cell wall formation during tension wood development.The candidate genes involved in xylem cell wall development during tension wood formation marks an important step toward identifying the molecular regulatory mechanism of xylem development and wood property improvement in P.alba‘Berolinensis’.
文摘Populus alba is a large woody deciduous plant.The plant has been introduced to shooting,then multiplication of rooting on Murashige and Skoog(MS)medium.This work was designed to estimate the effect of two factors(low levels of 1-Naphthaleneacetic acid NAA and sucrose)on P.alba response resulting in 6 treatments compared to the control,with twelve measured responses.There was a significant difference in some measurements in morphology,like plantlets fresh-weight,shoot-,root-length,and leaf number.In the physiological measurements,there were significant differences in all the measured parameters.The low concentrations of sucrose and media composition/power(MS grams/L)led to starvation in plants;however,these conditions led to enhancement in some morphological and physiological parameters to overcome the starvation effect,compared to the control.The RAPD-PCR molecular marker(four decamers)was used to evaluate the new individuals’genetic variation(instability),resulting in a total polymorphism percentage of 50.83%.It was formerly known that the plantlets were identical to each other and to the mother plant.In this study,however,the use of distinct media power,hormonal and sucrose levels resulted in molecular variation reflected in P.alba’s morphological and physiological responses.
基金supported by“National Key R&D Program of China(2021YFD2200203)”“the Fundamental Research Funds for the Central Universities(No.2572022AW02 and No.2572023CT19)”。
文摘Hybridization remains an important method for breeding new poplar varieties.It results in significant variation in leaf phenotype among parents and offspring,and among offspring themselves.This study aimed to investigate whether leaf shape variations were similar in offspring produced from reciprocal crosses.Specifically,two hybrid combinations were produced:the direct cross with Populus ussuriensis as the maternal parent and P.simonii×P.nigra as the paternal parent(HY53),and the reciprocal cross with P.simonii×P.nigra as the maternal parent and P.ussuriensis as the paternal parent(HY268).Using 3-month-old rooted cuttings from 40 clones(36 F1 hybrids and their parents)growing in a greenhouse,we measured and analyzed 14 leaf morphological traits to assess genetic variation and heterosis.The results showed HY53 clones generally exhibited greater average height than HY268 clones.Leaf phenotypes differed between the two hybrid combinations,with significant differences observed among parents and offspring for almost all traits,as revealed by analysis of variance(ANOVA).The phenotypic coefficient of variation was higher in HY268 clones.Additionally,leaf traits demonstrated high repeatability.Notably,some hybrid offspring exhibited positive or negative mid-parent heterosis,as well as over-parent heterosis for certain leaf phenotypes.The systematic cluster analysis further indicated distinct separation among HY268 clones.This research provides valuable materials for poplar breeding and offers insights into hybrid vigor in wood plants.The findings highlight the importance of reciprocal crossing in influencing leaf phenotype variation and heterosis,offering practical insights for future breeding strategies.
基金Supported by the Natural Science Foundation of Tibet Autonomous Region(2016ZR-NY-02)Undergraduate Innovative Experimental Project of Tibet Agriculture and Animal Husbandry University+1 种基金Pilot Project of Education and Training Program Reform of Outstanding Agricultural and Forestry Talentsthe Program of Key Laboratory of Forestry Ecological Engineering in Tibet Plateau
文摘[Objective] The research aimed to study the influence of different afforestation technology measures on soil nutrients of P. alba wood-land in arid valley region of Rikaze, Tibet. It aimed to improve afforestation technology measure in arid valley region of Rikaze, Tibet, and provide theoretic basis for restoring the degraded ecosystem at upper reaches of the Yarlung Zangbo River. [ Method] In arid valley region of Duojiao Vil-lage, Nanmulin County, Rikaze City, the planted land using rooting powder, egg shell, leaves, mud and water retention agent was taken as re-search object, while the land without any afforestation measures was taken as the control, to determine soil nutrients under different afforestation measures. [Result] Under different afforestation measures, the contents of various soil nutrients were all obviously higher than control, in which available potassium, available phosphorus, alkali hydrolysable nitrogen and organic matter in soil obviously increased than control, but there was no similar rule among different measures. [Conclusion] Vegetation restoration in dry valley belt of Rikaze by different afforestation measures is favorable for improving physical-chemical properties of soil and increasing soil fertility.
基金Financial support was obtained from National Natural Science Foundation of China(Grant Nos.32101549 and 32201585)Natural Science Foundation of Shandong Province,China(Grant No.ZR202112010288)+2 种基金Science&Technology Specific Projects in Agricultural High-tech Industrial Demonstration Area of the Yellow River Delta(Grant No.2022SZX39)Technical Innovation and Application Development Special Project of Chongqing(Grant No.CSTB2022TIAD-LDX0013)the Taishan Scholar Program of Shandong(Grant No.tsqn202103092)。
文摘Tyrosine decarboxylase(TyDC)converts tyrosine to tyramine and plays a crucial role in secondary metabolite reactions,development,and stress responses in plants.Currently,the biological role of TyDC proteins from trees is unknown.This study provided evidence showing that poplar PaTyDC4 functions in wood development and drought stress response.PaTyDC4 is preferentially expressed in wood-forming cells in stems.Overexpression of PaTyDC4 in poplars under the control of a xylem-specific promoter resulted in an increase in the ratio of xylem to phloem width,vessel cell area,and lignin accumulation in the stems.Biochemical assays revealed that PaTyDC4 was a component of the PaC3H17-PaMYB199 module-mediated pathway.In poplar stems,Pa TyDC4 expression was directly suppressed by PaMYB199,which was attenuated by the interaction between PaC3H17 and PaMYB199.In addition,Pa TyDC4 overexpression lines showed stronger drought tolerance than the wild-type lines,with higher photosynthetic capacity and lower levels of H_(2)O_(2).These results indicate that PaTyDC4 promotes xylem differentiation and lignin deposition during secondary growth and confers drought tolerance.Our findings may be useful for the genetic modification of biomass and drought resistance in trees.
