Based on the fact that soil microorganisms can enhance the adaptability of plants to global change， the effects of soil microorganisms on the ecological stoichiometric characteristics of rhizosphere soil microorganisms were studied under the background of nitrogen deposition， and then the regulation of changes in ecological stoichiometric characteristics on the soil microbial nutrient limitation was explored. Under the premise of soil sterilization treatment（sterilized soil（+S） and non-sterilized soil（-S））， one-year-old potted seedlings of Caragana korshinskii were inoculated in two ways（inoculation（+M） and without inoculation（-M））， and nitrogen addition treatments（no nitrogen application（CK）， low nitrogen（LN， 3 g·m^-2·a^-1）， high nitrogen（HN， 6 g·m^-2·a^-1）） were set up. Compared with the original microbial community composition in non-sterilized soil without fungus inoculation， the correlation between ecological stoichiometric characteristics of microhabitat and microbial nutrient limitation under different treatments was explored.Results were as follows： （1）In sterilized soil treatment， the relative abundance of fungi in the rhizosphere soil of C. korshinskii mycorrhizal seedlings was significantly increased by 82.20%， 25.00% and 59.84% under CK， LN and HN treatments than that of non-mycorrhizal seedlings， respectively. （2）In the treatment of non-sterilized soil， the microbial biomass carbon-to-phosphorus ratio in the rhizosphere soil of non-mycorrhizal C. korshinskii seedlings under LN treatment was lower by 46.28% compared to CK treatment（P<0.05）， while that of mycorrhizal seedlings was 56.76% higher compared to CK treatment（P<0.05）. （3）Under the nitrogen addition treatments， stoichiometry of carbon and nitrogen-related soil enzyme activity， stoichiometry of carbon and phosphorus-related soil enzyme activity， and vector length in the rhizosphere soil of C. korshinskii non-mycorrhizal seedlings under sterilized soil treatment were significantly lower than those of mycorrhizal seedlings（P<0.05）. （4）PLS-PM path analysis showed that the total effect coefficient of microbial regulation on microbial nutrient limitation was greater than that of nitrogen addition treatment. In summary， soil indigenous microorganisms and mycorrhizal fungi synergistically regulated the enzymatic stoichiometric ratio of rhizosphere soil， and enhanced the adaptation of soil microbial nutrient limitation to nitrogen addition.

When cytosolic Ca²⁺ concentration is increased under salt stress， cells would activate Ca²⁺-regulated target enzymes or induce Ca²⁺ bind to Ca²⁺ high-affinity receptor proteins. Among them， plant Ca²⁺-ATPases are P-type ATPases， including endoplasmic reticulum Ca²⁺-ATPase（ECAs） and plasma membrane Ca²⁺-ATPase（ACAs）； they are able to translocate Ca²⁺ from the cytosol to apoplast or compartmentalize Ca²⁺ in organelles. Numerous studies have shown that salt tolerance of plants is largely related to their ability to maintain the activities of calcium pump， namely Ca²⁺-ATPases. The activities of Ca²⁺-ATPases in various plant species were sensitive to salt stress； exogenous Ca²⁺ application can alleviate cell injury by salt stress， suggesting that exogenous calcium -mediated Ca²⁺-ATPase might play an important role in intracellular calcium homeostasis and signal transduction. Therefore， this review summarized the types， structures and properties of plant Ca²⁺-ATPase， and the involvement of Ca²⁺-ATPase of subcellular localization in plant response to salt tolerance and the research progress of exogenous calcium and Ca²⁺-ATPase in regulation on plant salt tolerance. It emphasized potential roles of Ca²⁺-ATPases of plant plasma membrane， tonoplast， nuclear membrane， endoplasmic reticulum and Golgi in regulation of salt tolerance in plants， and presented an outlook in the field. This work provided help for a better understanding of physiological and molecular mechanisms of plant salt tolerance and provided new ideas for crop salt-tolerance cultivation.

Establishing the somatic embryogenesis system of Isodon rubescens to give full play to its value in traditional Chinese medicine， and promote the stability and utilization of its resources. The leaves of I. rubescens were used as explants to dedifferentiate into embryonic callus and further proliferate to induce somatic embryo. The histological and cytological observation of embryonic callus and somatic embryo at each stage was made by paraffin section， and the effect of hormones on plant regeneration was tested. The results showed that in B5+1.0 mg·L^-1 2，4-D medium， leaves could dedifferentiate into light yellow and granular embryonic callus. In MS+1.0 mg·L^-1 2，4-D+0.2 mg·L^-1 6-BA medium， the embryogenic callus had the best proliferation effect， and the maximum net proliferation was 2.81 g. The optimal medium for somatic embryo induction was MS+1.5 mg·L^-1 TDZ+0.2 mg·L^-1 NAA， and the highest induction rate was 91.33%. In MS+0.5 mg·L^-1 6-BA+0.5 mg·L^-1 IBA medium， embryogenic callus containing somatic embryos could differentiate into small plants. In histological observation， the embryonic callus was yellowish or yellowish white granules with large and obvious nuclei. Two kinds of somatic embryogenesis were observed in the inner and outer origin of the callus， and the later developed into spherical， heart-shaped， torpedo-shaped， cotyledon-shaped embryo or cluster embryo structures containing starch granules. This study successfully established the indirect somatic embryogenesis system of I. rubescens， which laid a foundation for optimizing the “quality” and “quantity” of embryogenic callus， and also provided the theoretical basis for the research of molecular breeding and somatic embryo technology.

Pinus koraiensis is an important tree species used as fruit in northeast China， but due to its long growth cycle， its genetic improvement progress is slow. In order to evaluate and screen the elite P. koraiensis germplasm resources， 36 half-sib families of 20-year-old P. koraiensis from Xiyang forest seed orchard in Jilin Province were used as materials， and the growth traits and wood properties of different families were investigated. The results of variance analysis showed that the differences of each trait among families reached extremely significant level（P<0.01）， and the phenotypic variation coefficients of different investigated traits was 5.89%~45.21%. Except trait straightness（0.46）， the family heritabilities of other traits exceeded 0.5， which all belonged to high heritability. Correlation analysis results showed that the growth traits such as tree height and diameter at breast height had significantly positive correlations（r>0.663）. The contents of hemicellulose， cellulose and holocellulose were significantly correlated with each other among wood traits， while only cellulose and holocellulose were negatively correlated with some growth traits among growth traits and wood properties. The results of principal component analysis showed that 14 traits constituted five principal components， and the cumulative contribution rate was 79.24%. The comprehensive evaluation method was used to evaluate 36 half-sib families， with an admission rate of 10%， three elite families（PK61， PK29 and PK22） were selected according to their growth traits， and the genetic gain of each growth trait ranged from 6.41%- 33.91%. According to wood properties， three elite families（PK16， PK78 and PK10） were preliminarily screened， and the genetic gain of each wood trait ranged from 1.08%-6.72%. Combined with growth and wood properties， three excellent families（PK61， PK29 and PK44） were selected， and the genetic gain of each index ranged from 0.27%-37.28%. The elite families selected in this study can provide the basis for the selection of improved varieties of P. koraiensis.

Superoxide dismutase（SOD） widely presents in plants and can be mainly classified into three categories： Mn-SOD， Fe-SOD and Cu/Zn-SOD. They play different defense roles in cells and enhance plant tolerance. Additionally， Ni-SOD in blue cells and marine organisms remains to be explored. In this paper， the physicochemical properties and mechanisms of action of SOD were analyzed according to the different metal ions contained in SOD， and the role of SOD in plants under stress conditions such as drought， salinity and cold were elucidated， and the role of SOD in plant growth and development in future was prospected， and a reference for studying the mechanisms of plant growth and development under adverse environments was provided.

Psathyrostachys juncea was considered an important ancestral species of Leymus. The genomic Cot-1 DNA library with highly repeat sequences of Psa. juncea was constructed， and sequenced and characterized， and the results showed that the library could be classified into six types： retrotransposons， transposons， satellite DNA， LZ-NBS-LRR， uncharacterized sequences， and retrotransposon LTR mixed LTR/Copia， and the proportions were 49.5%， 1.0%， 28.7%， 5.9%， 13.9% and 1.0% of the Cot-1 DNA， respectively. Furthermore， two satellite DNAs and five retrotransposon sequences were used as probes， and chromosomes in Psa. juncea， Leymus secalinus and L. racemosus were detected by florescence in situ hybridization （FISH）. The results showed that the hybridization signals of satellite DNA sequences TaiI-family and pSc250-family were mainly distributed at the ends of chromosomes， and the number of TaiI-family hybridization signals were 20， 16， 7， and 18 in Psa. juncea， L. secalinus， L. racemosus （PI 531811） and L. racemosus （PI 531812）， respectively， and the number of pSc250-family hybridization signals were 17 and 24 in Psa. juncea and L. secalinus， respectively， but no signal was detected in two L. racemosus samples. The distribution of retrotransposon sequences on the chromosomes of three detected species was basically dispersed， and the distribution of chromosome sequences in Leymus species showed a tendency of homogenity. Especially， clone sequences pPj-44 and pPj-28 showed significant differences in signal distribution between Psa. juncea and Leymus species， suggesting sequence expansion and contraction， respectively， during allopolyploidization， and clone sequence pPj-77 only differentiated the hybridization intensity of 10 chromosomes from the rest of the chromosomes in one L. racemosus（PI 531812）. The results suggested the repeats of Psa. juncea evolved rapidly and had homogenous diffusion during the polypoid formation of Leymus species and the repeat composition might be significant different among different Leymus species.

To complement and improve the community composition and structural characteristics of the summit mossy dwarf forests in Southwest China， based on the community survey data of the 1 hm² forest dynamic plot（FDP）， the Center for Tropic Forest Sciences（CTFS） standard was used to investigate all woody trees with DBH ≥ 1 cm in the plot. Then， ten standard plots（a total of 0.6 hm²， 20 m×30 m each） were selected from the 1 hm² FDP， and all vascular plants within the 0.6 hm² plot were investigated and counted by plant community inventory. The species composition and community structure were analyzed by the aspects of species richness and quantitative characters， and the diameter class structure of the dominant tree species. The main results were as follows： （1）there were 3 614 woody individuals from 42 species， 32 genera， 20 families， with DBH≥1 cm within the 1 hm² FDP； in the 0.6 hm² plot， there were 103 species of vascular plants in 42 families， 67 genera and 1 536 individuals of 24 woody species with height≥3 m； （2）Rhododendron sinofalconeri was， absolutely dominant in the community， with important values 3-4 times higher than those of the secondary dominant species； （3）The age structure of the whole community showed a “L” shape； however， Rhododendron sinofalconeri was dominant in adult individuals， being different from other dominant species； （4）The community was composed of tree， shrub and herb layers as well as epiphytes and parasitic plants， and named as Rhododendron sinofalconeri， Clethra delavayi var. yuiana， Illicium tsaii summit mossy dwarf forests. In the Bozhu Mountain， Wenshan county， Yunnan， China， the mossy dwarf forest community was rich in species， stable in composition， prominent in dominant species and good in their regeneration. The canopy appearance of the community was flat， and the community succession was in a mature forest state.

Viviparous reproduction is a beneficial supplement to spore reproduction of pteridophytes， which enriches the reproduction and regeneration system and affects the population genetic diversity and environmental adaptability. In this study， Cystopteris chinensis， a national key protected wild plant， was selected as materials， and morphological and anatomical methods were used， the morphological and anatomical characteristics of the gemmae with the unknown process behind the pinna were examined， and the reproductive structure and development process were revealed， and the viviparous origin and ecological adaptation mechanism of the gemmae were traced. The results showed that： （1）The gemmae and sporangium groups appeared in the middle of the last veins on the abaxial leaf pinna， but the gemmae were located in the apical pinnate lobes. The gemmae formation included three stages： initiation， expansion and maturation， the gemmae gradually grew from yellow-green globule to dark green spindle-shaped， and matured when the base turned black to form a separate layer. （2）The gemmae originated from the parenchyma cells in the extension area of the vascular bundle sheath， which continuously divided and grew to form the gemmae primordium， and gradually broke through the lower epidermis of the leaf to form spherical gemmae. With the gemmae expansion， the middle and lower cells differentiated into storage cells and vascular bundles， and the apex differentiated into growth points to form buds. （3）Few gemmae could directly sprout on the leaves to form new autotrophs. After falling to the soil for 1 week， the mature gemmae began to germinate， which grew cylindrical roots at the base， and the fist bud germinated at the top. The residual gemmae still germinated into new leaves in the second year， which were different from those produced by stem buds.

In order to explore the metabolic mechanism of Lanzhou lily（Lilium davidii var. unicolor） in response to autotoxicity stress， one-year-old（Lily1）， two-year-old（Lily2） and three-year-old（Lily3） Lanzhou lilies were used as materials， and gas chromatography-mass spectrometry（GC-MS） was used to analyze the metabolomic changes of Lanzhou lily under continuous cropping years， and a total of 124 metabolites were detected and identified. R software was used to normalize the samples， and orthogonal partial least squares discriminant analysis（OPLS-DA） was used to find differential metabolites， and related metabolite pathways were screened for joint analysis. The results showed that there were 16 differential metabolites（lipids， flavonoids， saccharides and phenols） between Lily1 and Lily2， and all of them were up-regulated； and it was significantly enriched in tyrosine metabolism， propionic acid metabolism and flavonoid biosynthetic metabolic pathways. The contents of lipids， flavonoids and saccharides increased， indicating that in the second year of continuous cropping， Lanzhou lily responded to autotoxicity stress by actively synthesizing lipids， flavonoids and saccharides. There were 21 differential metabolites between the metabolomes of Lily1 and Lily3， including one up-regulated metabolite（3-α-mannobiose） and 20 down-regulated metabolite packages （amines， acids， and lipids）； and five metabolic pathways were significantly enriched， including biosynthesis of tropane， piperidine and pyridine alkaloids， phosphate and hypophosphite metabolism， lysine degradation， glutathione metabolism and D-amino acid metabolism. There were 21 differential metabolites between Lily2 and Lily3 groups， and the only up-regulated metabolite was 3-α-mannobiose. The results showed that in the third year of continuous cropping of Lanzhou lily， saccharides， as carbohydrates， were directly involved in cell membrane stability， actively responded to autotoxicity stress. The 20 down-regulated metabolites were amines， acids and lipids； only the propionic acid metabolism and flavonoid biosynthetic metabolism pathways were significantly enriched.

To reveal the reproductive characteristics and pollination mechanisms of Bulbophyllum andersonii， the pollination biology including flowering phenology， breeding system， pollinator， flower morphological characteristics， and flower volatile components were investigated in a wild population in Xishuangbanna， Yunnan in 2023. The results were as follows： the blooming period of B. andersonii was in mid-July， and the individual flowering period was five days. The breeding system was outcrossing and dependent on pollinators， and the natural seed setting rate was 26.06%. Bagging experiments indicated self-incompatibility， no apomixis and no spontaneous autogamy. Floral features such as the hinge structure of the labellum， pollination channels， and broad lateral sepals played important roles in pollination. Gampsocera sp.（Chloropidae） was the only effective pollinator and exhibited lip-licking behavior during the flower visit. Using Scanning Electron Microscopy， a large number of special particles were observed on the lips of B. andersonii， which might be the food rewards for the flower visitors. Flower volatile odors primarily contained monoterpenoids and aromatics， among which 1，2-Dimethoxybenzene and N， N-diethyl-m-toluamide might be related to the flower visiting behavior of insects. The results indicated that the flower morphology and flower scent of B. andersonii were adaptable to pollination by Gampsocera sp.， which seemed to be apt to a specialized pollination system.

To evaluate the taxonomic significance of leaf epidermal micromorphological characteristics， 11 species and one variety of simple-leaved Sorbus from sect. Aria and sect. Micromeles native to China were investigated using light microscopy（LM）and scanning electron microscopy（SEM）. The results showed that the shapes of epidermal cells wereirregular or polygonal-irregular. Anticlinal wall of polygonal cells was straight or arched， and anticlinal wall of irregular cells was arched or wavy. The area of epidermal cells varied significantly among taxa， and the size of the upper epidermal cells was larger than the lower epidermal cells. Cuticular ornaments such as ridges， striations， wrinkles， secondary thickening， thickened areas， and epicuticular waxy ornamented with crusts， granules， threads， and platelets were observed by scanning electron microscopy. Leaves were glabrous or with trichomes， and the position， color， density， and type of trichomes were important characters for the segregation of the taxa. Stomatal apparatuses were anomocytic and distributed in areole of abaxial epidermis. Guard cells had annular outer edges， with or without T-piece at stomatal pole. The cell size， length， width， area， density， and index of stomata varied significantly among taxa. Therefore， foliar epidermal micromorphology proved to be valuable for simple-leaved Sorbus taxa definition and identification.

Primula lithophila was an early species published on plant specimens， and curremt literature of its phenological period and many biological characteristics were incorrectly described， which made it difficult to define the species. This study adopted methods such as field investigation， literature review， specimen collection， and morphological feature comparison in the type locality， the supplementary description of its phenological period and biological characteristics was provided. The results indicated that： the petioles of P. lithophila did not have wings， and color was pink with few white， scape 10-25 cm length， pedicel 15-30 mm length， corolla tube about 16 mm and limb diameter 10-15 mm respectively. Capsule tubular， about 3 mm long， approximately half long of the persistent calyx. The flowering period was from September to February， and the fruiting period was from March to June. In addition， two new recorded species： P. pelargoniifolia G.Hao， C.M.Hu & Z.Y.Liu and P. tardiflora（C.M.Hu） C.M.Hu， were reported.

To address the problem of the rooting ability of Fraxinus mandshurica cuttings significantly decreasing after three years due to age effect， four-year-old F. mandshurica seedlings were used to investigate the role of cycle rejuvenation through cuttings in overcoming age effect in this study. The impact of the number of cycles and topping treatment on the sprouting， growth， and rooting of F. mandshurica cuttings， as well as the physiological changes during its rejuvenation process were examined. The results showed that the measurement of increasing the number of rejuvenation cycles and topping treatment both enhanced the degree of rejuvenation in F. mandshurica， which were characterized by an increased number of sprouted branches， finer branches， and shorter internodes， while significantly improved the regeneration ability of the cuttings. When the number of rejuvenation cycles reached three and was combined with topping treatment， the number of sprouted branches increased by 6.56 times， and the rooting rate increased by 7.44 times compared to non-rejuvenated treatment. During one to three rejuvenation cycles， the indole acetic acid（IAA） and cytokinin（CTK） levels in the plants increased， the gibberellin（GA₃） levels significantly increased only at the third cycle， and the abscisic acid （ABA） levels decreased gradually. After rejuvenation， the activities of catalase（CAT）， peroxidase（POD）， and superoxide dismutase（SOD） and the contents of malondialdehyde（MDA） and soluble sugars decreased in the regenerated plants. These physiological changes were consistent with the juvenile state of the plants. Cycle rejuvenation can effectively restore the juvenile state， induce the formation of sprouts with higher IAA and GA₃ levels and lower ABA levels， and simultaneously reduce the oxidative state and soluble sugar content in F. mandshurica. These changes are beneficial for achieving rejuvenation of F. mandshurica， thereby increasing the rooting rate of F. mandshurica cuttings and enabling rapid and efficient clonal propagation of superior F. mandshurica varieties.

The fixed monitoring plot was conducted in the Xilinhe National Nature Reserve to analyze tree species diversity， dominant species niche， interspecific associations and community stability in the Piceakoraiensis-Abies nephrolepis-Pinus koraiensis forest community by using a series of analysis methods including the α diversity index， the niche determination， the variance ratio（V_R）， the Chi-square test（χ² test）， the Spearman’s rank correlation coefficient test and the M. Godron stability. The results showed that： （1）the plot encompassed 20 tree species， 14 families and 14 genera， with a balanced distribution of trees， and the α diversity index was high； （2）the community niche overlap index was relatively high， but the cases with large （>0.7） or small（<0.4） niche overlap index were rare with a moderate degree of niche differentiation； （3）the overall correlation of the community was nonsignificant positive， and the interspecific correlations among the main tree species were mainly positive and nonsignificant correlation with strong interspecific independence； （4）the stability of M. Godron analysis fell to the point（32.79， 67.21） and was far from the stable point （20， 80）， indicating poor community stability； （5）P. koraiensis had the highest importance value and niche width in the sample plot， the average niche overlap index with other tree species was higher than the average value of the sample plot； the species was dominated by large-diameter individuals， and the relative frequency among tree species was low. Therefore， during the restoration process of Piceakoraiensis-Abies nephrolepis-Pinus koraiensis forest， the appropriate artificial intervention should be carried out to promote the recovery of Pinus koraiensis population， to regulate interspecies relationships， to enhance interspecies association strength， and to strengthen monitoring and protection of rare plant populations when community stability declined.

To explore whether there were any endangered links in sporogenesis and development of male and female gametophyte of endangered Berchemiella wilsonii， the reproductive biology of B. wilsonii was observed using paraffin section technique. The results showed that the flower of B. wilsonii had five stamens， four anthers， and the mature anther wall was composed of one inner layer， two middle layers and one tapetal layer. The tapetum developed normally with regularly arranged cells closely connected with the middle layer cells containing multiple nuclei in each cell. The cytoplasmic division of microspore mother cells was synchronous during meiosis， and mainly formed tetrahedral tetrads， the mature pollen grains were bicellular， round or oval in shape， which most of them had three germinating tubes. There were a few abnormal tapetum development and a few abortive pollen during anther development. B. wilsonii had two locule in ovary， only one chamber developed. The ovule was anatropous double integuments and crassinucellate. The chalazal end megaspore developed into functional megaspores，which underwent three times consecutive mitosis and further developed into polygonum embryo sac with seven cells and eight nucleus. Ovary ovule development was basically synchronized. The process of the mega-microsporogenesis and development of female and male gametophyte of B. wilsonii were normal， which was not the reason for the low seed setting rate.

To investigate the dormancy type and physiological and metabolic characteristics of Acanthopanax senticosus seeds during germination， the seeds from northeast China were treated with sand accumulation for 140 days under different temperature conditions（20 ℃， 4 ℃， 20 ℃/4 ℃） respectively. Five distinct stages were identified based on embryo phenotypic changes，and the dynamic changes in endogenous hormones， main nutrient substances and their hydrolases， antioxidant system， and metabolomics during these five stages were examined respectively. The results revealed that： （1）A. senticosus seeds exhibited good water absorption； while the constant temperature of 20 ℃ only promoted embryo elongation， but not germination. There was no increase in embryo rate at 4 ℃， and the embryo rate increased and the seeds germinated only when the temperature was maintained at 20 ℃ for 0-110 d and 4 ℃ for 110-140 d. （2）As the embryo growth rate increased， gibberellic acid content increased while abscisic acid content decreased. The levels of indoleacetic acid， indolebutyric acid， and naphthenic acetic acid all decreased. Fat content decreased while soluble sugar content increased. Fat content showed a significant negative correlation with lipohydrolase activity as well as a highly significant negative correlation with soluble sugar content. （3）A total of 92 differential metabolites were screened， and the carbon metabolism， energy metabolism， and antioxidant metabolism were the major differential metabolic pathways. Additionally， there were difference in sesquiterpene and triterpene biosynthesis， fatty acid biosynthesis and glyceride metabolism. In conclusion， seeds of A. senticosus were morphological and physiological dormancy， and variable temperature stratification was a necessary condition to break seed dormancy， and endogenous hormones might regulate seed dormancy and germination. Macromolecular nutrients such as fat were decomposed by hydrolases to provide material and energy for seed germination， which was also one of the necessary conditions for seed germination. This study provided theoretical guidance for identifying seed dormancy types and artificial propagation of A. senticosus.

In order to reveal the mechanism of selenium alleviating the cadmium stress in Astragalus membranaceus， the traditional medicinal plant A. membranaceus was used as materials， and the roles of ion antagonism， antioxidant enzyme system， heavy metal chelates and isoflavones in alleviating the Cd stress by Se were clarified comprehensively using hydroponic cultivation method. The results showed that 10 μmol·L^-1 Se significantly improved the growth of A. membranaceus seedlings under 50 μmol·L^-1 Cd stress， and reduced the accumulation of reactive oxygen species and membrane lipid peroxidation levels. The addition of Se significantly reduced the Cd content in all parts of A. membranaceus under Cd treatment. Meanwhile， the addition of Cd also reduced the Se content， indicating that it has a significant antagonistic effect on the absorption of Se and Cd. Se reduced the activities of POD， SOD， APX， CAT and GR in all parts of A. membranaceus under Cd stress. Correlation analysis showed that various antioxidant enzymes activities were significantly positively correlated with {\mathrm{O}}_{\mathrm{2}}^{•-} content， suggesting that the changes of antioxidant enzyme activity were more adapted to the level of reactive oxygen species in the plants. In addition， the addition of Se also reduced the content of non-protein sulfhydryl groups and metallothionein in all parts of A. membranaceus exposed to Cd treatment， and the contents showed a good positive correlation with the Cd content in corresponding part， indicating that the content of heavy metal chelates was regulated by the Cd content in various parts. Unlike antioxidant enzymes and metallothionein， the contents of three isoflavone components were significantly increased by Se addition in the roots of A. membranaceus seedlings under Cd stress. Furthermore， the expression levels of key enzyme genes in the isoflavone synthesis pathway， including CHS， IFS， I3'H， IOMT and UCGT， were significantly upregulated by Se under Cd stress. In summary， Se decreased the content of Cd in A. membranaceus seedlings under Cd treatment by antagonizing Cd during the absorption process， and reduced the degree of plant stress. At the same time， Se improved the tolerance of plant to Cd stress by upregulating the synthesis of secondary metabolites such as isoflavones.

In order to explore the genetic background of tulip germplasm resources， accurately evaluate and screen excellent germplasm for genetic improvement of tulips， the genetic background of 40 tulip varieties was analyzed by SRAP molecular markers， and their genetic diversity and relationships were clarified， respectively. The results showed that out of 43 pairs of SRAP primers， 21 pairs of polymorphic primers were available for genetic diversity analysis of tulips， and 249 clear and stable bands were amplified in the 40 tulip varieties， of which 245 were polymorphic bands with a polymorphism rate of 98.39%. The genetic similarity index of the 40 tested varieties ranged from 0.502 0 to 0.867 5， and the genetic diversity parameters including the number of alleles（N_{\mathrm{a}}^{\mathrm{*}}）， number of effective alleles（N_{\mathrm{e}}^{\mathrm{*}}）， Nei’s gene diversity index（H^*）， Shannon’s information index（I^*）， and polymorphic information content were 1.981 0， 1.514 9， 0.304 2， 0.460 3， and 0.321 2， resp-ectively， indicating rich genetic diversity in the tested materials. Cluster analysis and principal coordinate analysis showed that the 40 tulip varieties were classified into two major groups， among which ‘Christmas Magical’， ‘Banja Luka’， and ‘Madame Lefeber’ were relatively distant genetic relationships from other varieties and had certain differences in their genetic backgrounds.

Ribulose-1，5-diphosphate carboxylase/oxygenase（Rubisco） is a key enzyme in photosynthesis， in which small subunits（rbcS） are encoded by nuclear genes and mainly expressed in leaves. In this study， the Rubisco small subunit genes PxrbcS1 and PxrbcS2， which are highly expressed in Populus × xiaohei’s leaves， were determined by RT-qPCR technology， and their upstream promoters of 2 240 and 2 174 bp were cloned respectively. The results of promoter element analysis showed that the promoters of PxrbcS1 and PxrbcS2 had multiple elements related to light induced expression， including G-box， MRE and Box4 elements. Plant expression vectors of pBI-121-pPxrbcS1：：GUS and pBI-121-pPxrbcS2：：GUS were constructed and genetically transformed into 84K poplar（P. alba×P. glandulosa）. GUS histochemical staining and qPCR expression analysis showed that the promoters of PxrbcS1 and PxrbcS2 could drive the GUS gene to express in 84K poplar leaves with high specificity. In conclusion， the above results showed that PxrbcS1 and PxrbcS2 promoters with high leaf expression activity were successfully cloned from P.×xiaohei， and the promoters might be applied to the study of gene functions related to plant photosynthesis and genetic operations to improve photosynthesis in plants， including poplars.

The establishment of shelter forests in the northeastern region of Ulan Buh Desert is a crucial ecological barrier to protect agricultural productivity within the eastern Hetao Plain. However， the lack of attention towards scientific research on artificial afforestation has resulted in a decline tendency in many shelter forest systems. The investigation of ecological adaptability of indigenous tree species after artificial cultivation was a crucial approach to guide the establishment and sustainable management of plantations. In order to further investigate the ecological adaptability of native tree species in Ulan Buh Desert after artificial cultivation， three native tree species： Ammopiptathus mongolicus， Zygophyllum xanthoxylon and Prunus mongolica were used as materials. By measuring the epidermal morphology， anatomical structure， and physiological indices of functional leaves， in conjunction with local meteorological data， the adaptive mechanisms of these plants to arid desert environments were clarified. The results showed that each of three plants exhibited distinct adaptations to arid desert environment in different ways. A. mongolicus enhanced light exposure and photosynthetic efficiency by augmenting leaf area， strengthened leaf mechanical defenses through dense epidermal hairs and well-developed cuticle， reduced light-induced damage and water transpiration， and maintained cellular water balance to minimize lipid peroxidation. The leaves of P. mongolica were clustered， by increasing number of leaves， the light receiving area was increased and the photosynthetic efficiency was improved， and by curling the leaves to avoid strong light burns， the water transpiration was reduced and the cell water balance was maintained by specializing the stomatal position（all the stomata were distributed on the lower surface of the leaves）， developed vascular bundles and rich mucous cells and crystal structures， and reduced cell membrane lipid peroxidation. The leaves of Z. xanthoxylon showed a cylindrical strip structure. By reducing the wind resistance， the probability of wind-sand flow damage to the leaves was reduced. The antioxidant enzyme activity and osmotic adjustment substance content in leaves was enhanced by physiological metabolic regulation， and the balance of cell water and reactive oxygen species metabolism was maintained. These findings suggested the different adaptation strategies adopted by the three plants in response to the desert environment， and provided the new ideas for introduction and domestication of native tree species in the northeastern Ulan Buh Desert.