Comprehensive Overview of Populus simonii Research in the Recent Years

As an important ecological tree species in northern China, Populus simonii plays a crucial role in maintaining ecological balance and promoting environmental sustainability. The academic community has conducted a series of in-depth studies on this species, covering key areas such as genomics, survival mechanisms, and genetic breeding. Through the analysis of the genomic structure and function of P. simonii, we have not only revealed the molecular basis for its adaptation to harsh environments but also identified key genes that promote its growth and resistance to pests and diseases. Furthermore, exploring the survival mechanisms of P. simonii has deepened our understanding of its stress resistance traits, including how it effectively copes with abiotic stresses such as drought, salinization, and heavy metal pollution. In genetic breeding, significant progress has been made through the application of modern biotechnology, improving the growth rate and wood quality of P. simonii and enhancing its environmental adaptability and disease resistance. These research findings have not only enriched our knowledge of the biological characteristics of P. simonii but also provided a solid scientific foundation for its application in ecological restoration, forestry production, and environmental management.

Assembly and analysis of the Populus deltoides mitochondrial genome:the first report of a multicircular mitochondrial conformation for the genus Populus

Genomics research of Populus deltoides,an important timber species that is widely planted worldwide,is an important part of poplar breeding.Currently,the nuclear and chloroplast genome of P.deltoides have been sequenced,but its mitochondrial genome(mitogenome)has not been reported.To further explore the evolution and phylogeny of P.deltoides,the mitogenome of P.deltoides I-69 was assembled using reads from Nanopore and Illumina sequencing platforms and found to consist of 802,637 bp and three circular chromosomes(336,205,280,841,and 185,591 bp)containing 58 genes(34 protein-coding genes,21 tRNA genes,and 3 rRNA genes).RNA analysis in combination with several species showed signifi cantly fewer RNA editingsites in the mitogenomes of poplar and other angiosperms than in gymnosperms.Sequence transfer analysis showed extensive mitogenome rearrangements in Populus species,and with evolution from lower to higher plants,tRNA transfer from chloroplasts to mitochondria became increasingly frequent.In a phylogenetic analysis,the evolutionary status of P.deltoides was determined,and the section Populus was supported.Our results based on the fi rst report of a multicircular conformation of the Populus mitogenome provide a basis for further study of the evolution and genetics of P.deltoides and other Populus species and for breeding programs.

Influences of the Populus deltoids seedlings treated with exogenous methyl jasmonate on the growth and development of Lymantria dispar larvae

Lyantria dispar larvae were fed with the leaves of Populus deltoids seedlings exposed to methyl jasmonate （MeJA） for 24 h. The growth and development of the larvae were investigated, and phenolics contents in treated leaves including pyrocatechol, caffeic acid, coumarin, fernlic acid and benzoic acid were also surveyed by high-pressure liquid chromatography （HPLC）. Results indicated that approximate digestibility, efficiency of conversion of ingested food, efficiency of conversion of digested food, and weight of the larvae were inhibited obviously, especially from the sixth day, which may result from the increase of total phenolics contents in treated leaves. This result provides strong supports for MeJA acting as the airborne signal molecule between woody plants.

公路绿化植物油松(Pinus tabulaeformis)和小叶杨(Populus simonii)对重金属元素的吸收与积累

对内蒙古西部公路绿化植物油松(Pinustabulaeformis)、小叶杨(Populussimonii)及其根际土壤中重金属元素(Cd、Hg、Pb、Cu、Zn、Ni、Cr)和类金属元素(As和Se)含量以及根际土壤重金属(Cu、Zn、Pb、Ni和Cr)形态、土壤pH值进行了测定。对比分析了公路沿线不同绿化植物及其不同器官对重金属元素的吸收与积累特征。结果表明:绿化植物根际土壤对重金属元素的吸附及污染程度以Cd为最高。随原子序数的递增,小叶杨和油松两种植物的根部和茎叶两种营养器官中重金属的含量均表现出“N”字形变动趋势。而且重金属元素在不同植物不同器官中的含量具有Zn>Cu>Ni,Cr,As,Pb>Cd>Hg的基本规律。小叶杨茎叶对重金属元素Cr、Ni和Pb的富集能力较根部为强,油松茎叶对重金属元素Cr、Ni、Cu和Pb的富集能力较根部为强。绿化植物根际土壤重金属元素有效态占总量百分比的大小序列为Zn>Pb>Ni、Cr>Cu,与重金属元素在不同植物不同器官中的含量大小序列Zn>Cu>Ni、Cr、As、Pb>Cd>Hg并非趋于一致。公路绿化植物对根际土壤中重金属元素的吸收和积累与重金属元素有效态所占的比例有关。

美洲黑杨(Populus deltoides Marsh)×青杨(P.cathayana Rehd.)分子连锁图谱的构建

利用随机扩增ＤＮＡ多态性ＲＡＰＤ方法，在美洲黑杨（Ｐ．ｄｅｌｔｏｉｄｅｓＭａｒｓｈ）×青杨（Ｐ．ｃａｔｈａｙａｎａＲｅｈｄ．）３代谱系中分析分子标记，构建出第１张美洲黑杨×青杨分子连锁图谱。共从３００个１０ｍｅｒ随机引物中筛选出７９个适合引物，检测出可供构图的分离标记１８０个。该图谱由２０个连锁群，１１０个ＲＡＰＤ标记组成。总图距为覆盖基因组总长度的７０３５％，标记间的平均间距为１７２７ｃＭ．连锁群长度在３７１～１８９８，相应标记分别在３～１０。本图谱为杨树抗病、虫和其它性状基因定位提供了框架结构，为实现杨树分子遗传育种迈进了最重要的一步。

Pb胁迫对欧美杂交杨(Populus deltoides×Populus nigra)生物量分配格局及其Pb富集特性的影响

采用速生树种修复重金属污染土壤的方法近年来受到越来越多关注,但已有结果存在很大不确定性。为了解杨树在不同Pb胁迫条件下生长响应和Pb富集效果,以长江上游两种典型土壤(酸性紫色土和钙质紫色土)为栽培介质,采用盆栽试验方法,研究了不同Pb浓度处理下(CK:0mg·kg-1;T1:200mg·kg-1;T2:450mg·kg-1;T3:2000mg·kg-1)欧美杂交杨(Populus deltoides×Populusnigra)生物量生产与分配格局以及Pb吸收、富集特性。两种土壤条件下杨树各器官生物量及总生物量均表现出随Pb胁迫程度的增加而降低的趋势,Pb胁迫条件下杨树生物量分配格局在钙质紫色土中表现为茎>粗根>叶>细根。相同浓度Pb处理条件下,单株杨树总生物量均表现为钙质紫色土大于酸性紫色土。随着Pb处理浓度的增大,杨树各器官Pb含量及积累量显著增加。Pb胁迫使杨树对Pb的富集系数逐渐增大而耐性系数逐渐减小。T3处理条件下杨树对Pb的富集系数在酸性紫色土中较大,且各处理条件下杨树对Pb的耐性系数均为酸性紫色土中较大。这些结果表明,高浓度Pb胁迫条件下酸性紫色土中的欧美杂交杨表现出较好的吸收和富集Pb的特性,这为Pb污染土壤的生物修复提供了一定的科学依据。

镉胁迫对欧美杂交杨(Populus deltoides×Populus nigra)光合作用与生物量生产的影响

采用盆栽实验研究了生长在四川盆地典型Cd污染冲积土和紫色土上的欧美杂交杨(Populus deltoides×Populus nigra)对国家土壤环境质量标准中Cd浓度梯度(0、0.3、1.0、2.0 mg/kg)的光合响应和生物生产量。Cd处理显著降低紫色土上生长的杨树叶绿素a和叶绿素总量,增加气孔导度与胞间CO2浓度,增加凋落叶生物量,降低茎生物量、根生物量和单株总生物量。但是,Cd处理对冲积土上生长的杨树叶绿素特征、光合生理指标和生物量生产并无明显差异。尽管同一生长基质上不同Cd处理间杨树光合生理指标与生物量生产均有一定程度的影响,但紫色土上生长的杨树生理和生长特征均显著低于冲积土上生长的杨树。这些结果表明,自然条件国家土壤环境质量标准内,Cd污染并不对杨树生长构成较大威胁,而生长土壤基质的选择可能对杨树的栽培更为重要。这为Cd污染土壤区域城市森林建设和速生丰产林建设提供了一定的科学依据。

南洞庭湖杨树(Populus deltoides)清理迹地恢复初期涨水前后土壤种子库特征

本文研究了南洞庭湖杨树清理1 a、2 a后的迹地(简称1 a和2 a)和未清理杨树洲滩(ck)涨水前后土壤种子库特征变化及其与地上植被的关系.结果显示:杨树清理迹地土壤种子库共萌发物种23科59属65种,涨水前后土壤种子库密度和种类均表现出1 a>2 a>ck的趋势,且随着土层加深而递减.退水后ck、1 a、2 a不同土层物种数量和密度较涨水前均有所减少,其中一或二年生物种较涨水前有所减少,多年生物种占比增加;湿生物种与中生物种数目较涨水前均有所减少,而2 a土壤种子库中生物种比例较涨水前有所增加.涨水前后土壤种子库Shannon-Wiener和Simpson指数变化较小,退水后Margalef指数较涨水前有所下降.退水后地上植被物种Shannon-Wiener和Simpson指数高于涨水前地上植被,而Margalef指数有所下降.涨水前Srensen相似性系数表现为1 a>2 a>ck的趋势,退水后表现为2 a>1 a>ck的趋势,涨水前后不同恢复年份土壤种子库和地上植被优势物种所占比例有所差异.研究表明,南洞庭湖杨树清理迹地退水后土壤种子库密度和种类显著下降,随着恢复年份和水淹频次的增加,一或二年生物种迅速减少,多年生物种比例增加,地上植被物种均匀性有所增加,可见水文因子是影响南洞庭湖杨树清理迹地种子库恢复能力的重要因素.

Isolation and characterization of two genes encoding polygalacturonase-inhibiting protein from Populus deltoides

Polygalacturonase-inhibiting proteins （PGIPs） are extracellular proteins that belong to the leucine-rich repeat （LRR） protein superfamily. PGIPs inhibit fungal polygalacturonases （PGs） and promote accumulation of oligogalacturonides, which activate plant defense responses. PGIPs play important roles in resistance to infection of pathogens. In this study, reverse transcriptase-polymerase chain reaction （RT-PCR） and RNA ligase-mediated rapid amplification of cDNA ends （RLM-RACE） were used to isolate the full-length PGIP cDNA from Populus deltoides （GenBank accession no. of PdPGIP2 and PdPGIP4：EF684913 and EF684912）. Domain analysis revealed that the deduced amino acid sequences of PdPGIP2 and PdPGIP4 had a typical PGIP topology. Phylogenetic analysis of known PGIPs indicated that the two PdPGIPs were clustered to the defense-related PGIP clade. Using real-time RT-PCR, the expression patterns of the two PdPGIPs following treatment with a fungal pathogen and defense-related signaling molecules were studied. The expression levels of PdPGIP2 and PdPGIP4 were both up-regulated when inoculated with the phytopathogenic fungus Marssonina brunnea. Therefore, it was proposed that the two PGIPs might be involved in the resistance to Marssonina brunnea in P. deltoides.

Phenotypic variation among five provenances of Populus simonii in northern China

We investigated phenotypic variation ofPopulus simonii from five provenances in northern China. Our results show that significant differences exist between plants of different provenances in morphological and physiological traits, except for leaf-stalk length and the number of leaf margins. The coefficient of variation for all traits ranges from 14.77% to 81.49%. The mean phenotypic coefficient of differentiation （VST） is 47.1%, which means that the variation within provenances is the major source for phenotypic variation in P. simonii. Given our cluster analysis of provenances based on an average linkage computing method, the five provenances ofP. simonii investigated could be divided into three groups. Our results provide a theoretical basis for genetic resource conservation and provenance selection of natural P. simonii in northern China.

Two novel eukaryotic translation initiation factor 5A genes from Populus simonii×P.nigra confer tolerance to abiotic stresses in Saccharomyces cerevisiae

The role of plant eIF5A proteins in multiple biological processes, such as protein synthesis regulation, translation elongation, mRNA turnover, programmed cell death and stress tolerance is well known. Toward using these powerful proteins to increase stress tolerance in agricultural plants, in the present study, we cloned and characterized PsneIFSA2 and PsneIFSA4 from young poplar （P. simonii × P. nigra） leaves. The deduced amino acid sequences of PsneIF5A2 and PsneIF5A4 were 98 % similar to each other, and they are orthologs of eIF5A 1 in Arabidopsis. In a subcellular localization analysis, PsneIF5A2 and PsneIF5A4 proteins were localized in the nucleus and cytoplasm, qRT-PCR analysis showed that PsneIF5A2 and PsneIF5A4 were transcribed in poplar flowers, stem, leaves, and roots. In addition, they were also induced by abiotic stresses. Transgenic yeast expressing PsneIF5A2 and PsneIF5A4 had increased salt, heavy metal, osmotic, oxidative tolerance. Our results suggest that PsneIF5A2 and PsneIF5A4 are excellent candidates for genetic engineering to improve salt and heavy metal tolerance in agricultural plants.

Emissions of saturated C6-C10 aldehydes from poplar (Populus simonii×P. pyramidalis ‘Opera 8277’) cuttings at different levels of light intensity

Aldehydes play an important role in atmospheric chemistry and plant direct and indirect defense against environmental stresses.In this study,the emissions of saturated C6-C10 aldehydes from Populus simonii × P.pyramidalis ＇Opera 8277＇ cuttings were examined by using a gas chromatography/mass spectrometry（GC/MS） technique at three levels of light intensity（400,800 and 1 200 μmol·m-2·s-1）.A positive correlation between the emissions of these aldehydes and light intensity was found.Moreover,nordi-hydroguaiaretic acid（NDGA）,a special inhibitor of lipoxygenase（LOX）,significantly inhibited the emissions of C6-C9 aldehydes at three levels of light intensity,but did not influence the emission of decanal（C10）.The emissions of C6-C10 aldehydes in NDGA treated poplar cuttings,exhibited the same positive correlation with light intensity.The results indicated that LOX pathway contributes to the emissions of C6-C9 aldehydes,whereas some pathways regulated by light intensity might be a universal mechanism for emissions of C6-C10 aldehydes.

Morphological and physiological plasticity response to low nitrogen stress in black cottonwood(Populus deltoides Marsh.)

It is important to evaluate nitrogen use efficiency and nitrogen tolerance of trees in order to improve their productivity.In this study,both were evaluated for 338 Populus deltoides genotypes from six provenances.The plants were cultured under normal nitrogen(750μM NH_4 NO_3)and low nitrogen(5μM NH_4 NO_3)conditions for 3 months.Growth,chlorophyll content and glutamine synthetase activity of each genotype were measured.Under low nitrogen,heights,ground diameter,leaf area,leaf and root biomass,and chlorophyll contents were significantly lower than those under normal nitrogen level.Correlation analysis showed that nutrient distribution changed under different nitrogen treatments.There was a negative correlation between leaf traits and root biomass under normal nitrogen level,however,the correlation became positive in low nitrogen treatment.Moreover,with the decrease of nitrogen level,the negative correlation between leaf morphology and chlorophyll levels became weakened.The growth of the genotypes under the two treatments was evaluated by combining principal component analysis with a fuzzy mathematical membership function;the results showed that leaf traits accounted for a large proportion of the variation in the evaluation model.According to the results of comprehensive evaluation of plants under the two treatments,the 338 P.deltoides genotypes could be divided into nine categories,with wide genotypic diversity in nitrogen use efficiency and low nitrogen tolerance.As a result,26 N-efficient genotypes and 24 N-inefficient genotypes were selected.By comparative analysis of their morphological and physiological traits under the two treatments,leaf traits could be significant indicators for nitrogen use efficiency and nitrogen tolerance,which is of considerable significance for breeding poplar varieties with high nitrogen use efficiencies.

Characterization and identification of leaf morphology of Populus deltoides Bartr. clones

Leaves are of fundamental importance to plants, representing their facility to generate power and are the sensing units of plants towards the environment. An attempt was made to characterize and compare the variations of leaf morphology of various Populus deltoides Bartr. clones by studying the winter buds and other leaf parameters of fully developed leaves. To achieve these objectives, forty-three exotic and indigenous clones ofP. deltoides Bartr. were evaluated for different parameters. On the basis of various morphological characteristics the results reveal that each clone has a distinct color pattern of leaves. Different colors observed in these clones varied from light green through green to dark green. Two distinct lengths of the leaf apex were found, i.e., short and long; as well both acuminate and acute apex types were found. Erratic distribution of serration of leaves was also found. In this study, the morphological traits of leaves provided discriminatory grounds for separating various populations of P. deltoides Bartr. clones. Winter bud studies indicate that different clones vary considerably with regard to shape, color, shape of leaf scars and exudation.

Transformation of Tobacco with Two AP1 Genes Isolated from Poplar( Populus simonii × Populus nigra)

[ Objective ] This study aimed to analyze the functions of AP1 gene from Populus simonii × Populus nigra and to lay the theoretical foundation for shortening the breeding cycle of forest trees and investigating the flowering mechanism in poplar. [ Method] Plant expression vectors of AP1 genes were constructed and transformed into tobacco leaf disks with Agrobacterium-mediated method. Transgenic tobacco plants were identified by PCR. [ Result] AP1 genes were integrated into the genome of tobacco. Transgenic tobacco plants all presented an early flowering phenotype compared with wild-type tobacco. [ Conclusion] AP1 genes could promote early flowering in transgenic tobacco plants, which provided theoretical basis for molecular regulation of flowering in poplar.

Control Mechanisms and Simulation of <i>Populus simonii</i>Leaf Unfolding

Populus simonii Carr., one of the main poplar tree species, is cultivated widely in Northeast and Northwest China in protection and timber forests. Plant phenology plays an important role in timber production by controlling the growing period (i.e., the period between the leaf unfolding and the leaf turning yellow). It is important to understand this control mechanism and to improve the accuracy of the simulation of leaf unfolding phenology for P. simonii in order to determine accurately the timber production of P. simonii plantations. In this study, based on phenological observation data from 10 agricultural meteorological stations in Heilongjiang Province, China, model simulation was employed to determine the control mechanism of leaf unfolding of P. simonii. Furthermore, the predicting effects of nine phenology-simulating models for P. simonii leaf unfolding were evaluated and the distribution characteristics of P. simonii leaf unfolding in China in 2015 were simulated. The results show that P. simonii leaf unfolding is sensitive to air temperature;consequently, climate warming could advance the P. simonii leaf unfolding process. The phenological model based on air temperature could be better suited for simulating P. simonii leaf unfolding, with 76.7% of the calibration data of absolute error being less than three days. The performance of the models based solely on forcing requirements was found superior to that of the models incorporating chilling. If it was imperative that the chilling threshold is reached, the south of the Yunnan, Guangdong, and Guangxi provinces would be unsuitable for planting P. simonii. In this regard, the phenology model based on the chilling threshold as necessary condition was indicated a more reasonable model for the distribution characteristics of P. simonii leaf unfolding.

Compressive Strength Parallel to Grain Variation of Different Clones of Populus deltoides Marsh.

In order to explore the differences in the compressive strength parallel to grain （CSPG） between different clones and individual woods of Populus deltoides Marsh., the CSPGs of 5 15-year-old P. deltoides clones were determined and analyzed. The results showed that there were significant differences in CSPG of wood between different clones of P. deltoides . The CSPG of the tested clones reached more than 41 MPa, which was higher than the average compressive strength of P. deltoides （32.94 MPa）. Similar to the changes of stem height, the CSPG of the clones gradually increased with the increase of stem height. However, there were significant differences in CSPG of an individual plant at different tree heights. The CSPG of P. deltoides clones was related with their growth traits, but not significantly. Therefore, it is expected to achieve simultaneous and independent improvement on CSPG and the growth of P. deltoides , so as to get excellent individuals with fast growth and high CSPG.

Pollen development and floral morphology of Populus pseudo-simonii

Pollen development and floral morphology of Populus pseudo-simonii were investigated by stain-squashing and anatomical techniques. It took approximately 16 days for the pollen to develop from pollen mother cells to mature pollen in the green-house. Meiosis of pollen mother cells was regularly applied and completed by a process of simultaneous cytokinesis. Pollen development was considerably asynchronous. The meiotic division was initiated at the bulgy middle position of the flower bud and proceeded towards the tip and base of the bud. The number and size of the nucleoli varied during pollen development and at most eight nucleoli formed in each daughter nucleus at the meiotic telophase, suggesting a paleopolyploid origin of the genus Populus. An association between floral morphology and pollen development was found and the ratio of width to length of flower buds or catkins presented an S-shaped curve related to pollen development as a function of time. The investigation on the pollen development and floral morphology ofP. pseudo-simonii is important for further cross breeding programs of the section Tacamahaca.

小青杨（populuspseud－simoni）生理生态特性的研究

在野外条件下，测定了小青杨树冠不同方向净光合速率和呼吸速率日进程呈双峰曲线形式，双峰出现在上午９时及下午１５时，低谷出现在１３时，即“午睡现象”，这与光照强度关系不大，而与环境因子有密切关系。小青杨树冠四个方向的光照强度都呈单峰曲线形式、温度也呈单峰曲线形式，但二者的峰值不同。树冠不同方向水分状况不同，饱和亏缺大者，水势较小，蒸腾强度也小。树冠不同方向，叶绿素含量不一，东面和北面叶绿含量较其他两面高，ａ／ｂ比值小于１。

东北地区不同间伐强度青山杨人工林生长及木材性状变异

探究不同间伐强度对青山杨人工林生长及木材性状的影响,为东北地区培育杨树优质工业资源材提供理论基础。以18年生青山杨为试验材料,以初植株行距2 m×3 m为对照,设置3种强度的间伐处理(4 m×3 m、6 m×3 m、4 m×6 m)。间伐后第5年对试验林的生长性状(树高、胸径、2米径、冠幅)及木材性状(基本密度、纤维长、纤维宽、半纤维素含量、纤维素含量、综纤维素含量、木质素含量)进行了测定,并利用树高、胸径计算出单株材积及单位面积蓄积。方差分析结果表明,除基本密度外,各指标差异均达到极显著水平(P<0.01)。均值分析结果表明,林木各生长指标与木质素含量的均值在株行距为6 m×3 m时达到最大,其余各木材指标均在株行距为4 m×3 m或6 m×4 m时达到最大;各测定指标表型变异系数变化范围为3.35%~29.87%;除基本密度外,各指标重复力均超过0.590。相关性分析结果表明,各生长指标间均达显著正相关水平(0.690<r<0.993),而木材性状间及生长性状与木材性状间的相关性较弱。分别以生长性状、木材性状及联合生长与木材性状为评价指标对各处理进行综合评价后发现,Qi分别在株行距为6 m×3 m、4 m×6 m及4 m×6 m时达到最大。间伐能够促进林分生长,改良林木材性,且保留株行距为4 m×6 m时,林木材性及生长与木材综合改良效果较为优良;保留株行距为6 m×3 m时,林木生长效果最好。因此,今后可根据培育目标的不同选择适宜的间伐强度进行东北地区杨树优质工业资源材的培育。