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    20 July 2025, Volume 45 Issue 4
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    Review Article
    Research Progress on the Biosynthesis and Functions of Plant Terpenoids
    Yongchang XUE, Hexian WANG, Di ZHAO, Jing GUO, Ao LI
    2025, 45(4):  479-490.  doi:10.7525/j.issn.1673-5102.2025.04.002
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    Terpenoids， as key secondary metabolites， are involved in physiological processes such as antioxidation， signaling， and stomatal movement in plants under adversity stress， and play an important role in plant adversity response. They can not only directly participate in plant defense mechanisms， but also act as signaling molecules to regulate plant-plant interactions and influence the adaptability and stability of plant communities. Due to their wide range of biological activities， terpenoids have been widely used in the food， pharmaceutical and cosmetic industries. With the development of synthetic biotechnology， the research field of terpenoids will become more diversified and challenging， and their applications will be more promising. This review comprehensively analyzed the biosynthetic pathways of terpenoids and their physiological and ecological functions in plants， aiming to deepen the understanding of the adaptive strategies of plants to adversity， to provide reference for the study of plant resistance， and to provide a new approach for the development of sustainable agriculture and pharmaceutical and health industries.

    Original Paper
    The Salicylic Acid Responsive UrSTR4 Gene is Involved in Rhynchophylline Biosynthesis in Uncaria rhynchophylla
    Guoju XU, Piaoxue GUO, Xunran ZHU, Zimei YANG, Huanyu CHENG, Wei QIANG
    2025, 45(4):  491-503.  doi:10.7525/j.issn.1673-5102.2025.04.003
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    Uncaria rhynchophylla is a traditional Chinese medicinal herb， whose active components rhynchophylline（RIN） and isorhynchophylline（IRN） exhibit remarkable pharmacological activities. Strictosidine synthase（STR） is the key enzyme for RIN and IRN biosynthesis， yet the functional divergence of STR gene family in U. rhynchophylla remains unclear. Utilizing transcriptome data of U. rhynchophylla seedlings under shading and ethylene treatments， 27 STR genes（UrSTR1-UrSTR27） were systematically identified in U. rhynchophylla. Evolutionary analysis revealed significant expansion of UrSTR gene family， suggesting functional diversification in response to environmental cues. Exogenous salicylic acid（SA） treatment（0.6 mmol⋅L-1） markedly increased RIN and IRN contents， while upregulating UrSTR4 expression level by 30.6-fold. Multiple sequence alignment showed UrSTR4 lacked the conserved Glu-309 residue but shared hydroxyl-containing residues with Camptotheca STR3. An efficient transient transformation system（8 kPa pressure， 1-min Agrobacterium infection） was established by using plant living transformation instrument. The transient overexpression of UrSTR4 enhanced RIN and IRN contents by 1.96- and 1.82-fold， respectively. This study identified new targets for metabolic regulation of bioactive compounds in U. rhynchophylla and the established transient transformation system provided technical support for functional research on UrSTR genes.

    Nutrient Absorption Characteristics of Epimedium brevicornu and Its Relationship with Pharmacodynamic Components
    Ying DUAN, Xiaojuan XU, Jie MAO, Chenxia ZHAO, Huizhen WANG, Honggang CHEN, Jinjin MENG, Tao DU
    2025, 45(4):  504-517.  doi:10.7525/j.issn.1673-5102.2025.04.004
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    In order to explore the absorption and distribution characteristics of nutrient elements and the accumulation of pharmacodynamic components in E. brevicornu， and to clarify the characteristic elements affecting the accumulation of pharmacodynamic components， the dry matter accumulation， nutrient element content and flavonoid content in leaves of 3-year-old E. brevicornu were determined， and the correlation between flavonoid components and nutrient elements in leaves was analyzed. The results showed that （1）with the plant growth， the dry matter accumulation increased first and then decreased， and the dry matter accumulation was rapid and reached the maximum in the post-fruit growth period（T5）. （2）The contents of nitrogen（N） and phosphorus（P） in the upper part showed a decreasing trend at the growth stage， while the contents of potassium（K） in the underground part showed a decreasing-rising-decreasing trend， while the contents of K in the underground part had no obvious change， and the net accumulation of N， P and K was the largest in the fruiting period（T4）. （3）The accumulation of 11 nutrient elements during the growth period was listed in a decreasing order： N>Ca>K>Mg>P>S>Fe>Mn>Zn>Cu>B. （4）The accumulation of flavonoids in leaves increased first and then decreased. （5）The correlation analysis showed that the flavonoid content had synergistic effect with the contents of magnesium（Mg）， iron（Fe） and copper（Cu）， and had antagonistic effect with the contents of boron （B） and manganese（Mn）. Stepwise regression analysis showed that N， calcium（Ca）， Mn and Fe were the characteristic elements that affected the content of flavonoids in leaves. In conclusion， dry matter accumulation and nutrient accumulation of E. brevicornu were the most critical in the fruiting period. The macroelements should be applied before the fruiting period， mainly N and K fertilizers， ensuring the supply of Mg， Fe and Cu. The accumulation of pharmacodynamic components was the largest in the post-fruit growth period. Combined with the results of this experiment and local climatic conditions， it was recommended that the leaves of E. brevicornu in Linxia of Gansu Province and similar areas should be harvested in early September.

    Effect of Environmental Factors on the Active Ingredients of Codonopsis pilosula
    Hao GUO, Caixia CHEN, Xiaojing AN, Xian’en LI, Haiying WANG, Zhongting XIA
    2025, 45(4):  518-532.  doi:10.7525/j.issn.1673-5102.2025.04.005
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    To clarify the key factors affecting the content of active ingredients in Codonopsis pilosula， and to provide scientific basis for the selection of producing areas’ environmental factors for standardized cultivation， the effects of 32 environmental factors such as meteorology and soil conditions in different producing areas were explored. In this study， samples of cultivated C. pilosula and its root zone soil were collected from a total of 27 sampling sites in the main producing areas（Chongqing， Inner Mongolia， Gansu， and Shanxi）. The soil physicochemical indicators from different producing areas and the contents of lobetyolin and polysaccharides in C. pilosula weremeasured， and the correlations between various environmental factors and the active ingredients in C. pilosula were analyzed. The results indicated that there were regional differences in the content of active ingredients in C. pilosula. The highest polysaccharide content was 386 mg⋅g-1 in samples collected from Ar Horqin Banner in Chifeng city. The highest lobetyolin content was 2.128 mg⋅g-1 in samples collected from Wuxi in Chongqing city. Among the factors contributing to the variance in the content of active ingredients in C. pilosula from different producing areas， monthly extreme temperature had the highest contribution， followed by soil enzyme activity and organic matter factors， with soil nutrients contributing the least. The effects of different environmental factors on accumulation of polysaccharides and lobetyolin in C. pilosula varied in different producing areas. Polysaccharides contents in C. pilosula were mainly influenced by soil organic matter， precipitation in October， and soil alkaline phosphatase activity， while lobetyolin was primarily affected by soil available nitrogen， soil acid phosphatase activity， the minimum temperature in May and July-August， and soil pH. In summary， monthly extreme temperature was the main factor driving the variation in content of active ingredients in C. pilosula， and attention should be paid to the impacts of precipitation， soil nutrients， and phosphatase activity.

    Callus Induction and Secondary Metabolites Accumulation of Diploid Cyclocarya paliurus
    Zhuosui LI, Yilin GAO, Han LIU, Xulan SHANG
    2025, 45(4):  533-545.  doi:10.7525/j.issn.1673-5102.2025.04.006
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    This study aimed to explore the effects of hormone combination on callus induction and proliferation of diploid Cyclocarya paliurus and the accumulation of main secondary metabolites during subculture. The effects of different hormone combinations on accumulation of secondary metabolites during callus induction and subproliferation were investigated using diploid C. paliurus leaves as explants by orthogonal experiment design. An optimal treatment for the maximum yields of total triterpenoids， total polyphenols， total flavonoid and crude polysaccharides were selected by entropy weight method. The highest callus induction rate was 100% in treatment 2（0.5 mg⋅L-1 6-BA+1 mg⋅L-1 2，4-D+0.2 mg⋅L-1 NAA）， followed by treatment 9 （2.5 mg⋅L-1 6-BA+1.5 mg⋅L-1 2，4-D+0.2 mg⋅L-1 NAA） and treatment 5（1.5 mg⋅L-1 6-BA+1 mg⋅L-1 2，4-D+0.4 mg⋅L-1 NAA）， with an induction rate of 96.67% and 93.64%， respectively. The order of factors affecting callus induction rate was 2，4-D， NAA， 6-BA. An optimal concentration of 2，4-D and NAA was 1.0 mg⋅L-1 and 0.2 mg⋅L-1， with no significant effect of 6-BA. The colors of induced callus were light green and yellowish green； the morphology of the callus was characterized by loose texture. There were differences in the callus growth and accumulation of secondary metabolites among treatments when different combinations of hormones were used for subculture； the growth characteristics of calli in the same treatment changed greatly during continuous subculture. The first ranked formula was treatment 4 （0.2 mg⋅L-1 KT+0.5 mg⋅L-1 6-BA+0.75 mg⋅L-1 NAA+0.4 mg⋅L-1 2，4-D） with a score of 0.44，followed by treatment 2（0.75 mg⋅L-1 6-BA+0.75 mg⋅L-1 NAA+0.2 mg⋅L-1 2，4-D） and treatment 6（0.2 mg⋅L-1 KT+1.0 mg⋅L-1 6-BA+0.5 mg⋅L-1 NAA+0.2 mg⋅L-1 2，4-D） with a score of 0.31 and 0.26， respectively. The yield of secondary metabolites in treatment 4 generally reached a high level from the 8th generation， with total triterpenoid yield of 28.91 mg⋅bottle-1， total polyphenol yield of 6.89 mg⋅bottle-1， total flavonoid yield of 1.77 mg⋅bottle-1，and crude polysaccharide yield of 57.45 mg⋅bottle-1. In summary， the optimal formula for callus induction of diploid C. paliurus was MS+0.5 mg⋅L-1 6-BA+1.0 mg⋅L-1 2，4-D+0.2 mg⋅L-1 NAA. The subculture proliferation formula was MS+0.2 mg⋅L-1 KT+0.5 mg⋅L-1 6-BA+0.75 mg⋅L-1 NAA+0.4 mg⋅L-1 2，4-D. This study provided a reference for production of secondary metabolites by callus culture and further cell suspension culture.

    Light Requirements for Germination of Emmenopterys henryi Oliv. Seeds and Transcriptome Response Analysis
    Xinyu CHENG, Mengqiao GUO, Haiyun GUAN, Jian RU, Yan BAI, Lianjin GUO
    2025, 45(4):  546-557.  doi:10.7525/j.issn.1673-5102.2025.04.007
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    This study aimed to investigate the light duration required for seed germination of Emmenopterys henryi Oliv.， an endangered species endemic to China， and to explore the correlation between morphological traits and germination rate of seeds under different light durations. Using E. henryi seeds as material， this study compared the differences in germination rates under light treatments of 0， 1， 2（8 h/1st day+4 h/2nd day）， 2， 4， 6， 8 d. The correlation between seed morphology and germination time was also analyzed. In addition， transcriptome sequencing and analysis using high-throughput technology were perfomed on E. henryi seeds subjected to dark treatment （2 d） and basic light exposure （the shortest light duration required for a germination rate of ≥50%， 2 d）. Results showed that， under light treatment conditions， the germination rates increased with extension of light duration. For the seeds subjected to the 8 d light treatment， the germination rate reached 98.89% after 10 d of cultivation. The analysis of correlation between seed morphological characteristics and germination time showed that the length of seed kernel and length-to-width ratio of seed kernel were significantly negatively correlated with germination time（P<0.05）. Transcriptomic responses of the seeds following dark treatment（2 d） and basic light treatments（2 d） indicated 4 657 differentially expressed genes（DEGs）， including 2 950 upregulated and 1 707 downregulated genes. Among the 185 transcription factors identified， all members of the HSF family were downregulated in the light treatment group. GO terms related to protein metabolism were significantly enriched. DEGs were significantly enriched in KEGG pathways（P-adjust<0.05） related to embryo development and seedling stress resistance， including diterpenoid biosynthesis （ko00904）， cysteine and methionine metabolism（ko00270）， and plant-pathogen interaction（ko04626）. In summary， E. henryi seeds with larger kernels germinated earlier， and light supplied for two days was sufficient to meet the basic germination requirements of the seeds. This study provided a theoretical basis for elucidating the mechanisms underlying the abnormal population structure of wild E. henryi populations and for promoting its population restoration in natural conditions.

    Tissue Culture and Rapid Propagation of Endangered Salvia petrophila
    Yingying WANG, Dengli YU, Fengjin QIU, Rongrong YAN, Guoxiong HU
    2025, 45(4):  558-568.  doi:10.7525/j.issn.1673-5102.2025.04.008
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    To establish the rapid propagation system of tissue culture of an endangered plant Salvia petrophila， the disinfectant concentration and duration in the sterilization process， as well as the regulation of hormone types and concentrations on seed germination， the subculture and preliferation of stem segments with axillary buds at the base， induction and differentiation of callus from stem segments， rooting， hardening off and transplanting were investigated respectively. The results showed that （1） the appropriate sterilization method for S. petrophila seeds was 75% alcohol treatment for 30 s， followed by 5% sodium hypochlorite solution for 8 min， achieving a germination rate of 40.83%. （2） The appropriate medium for seed germination was MS supplemented with 1.0 mg⋅L-1 6-BA and 0.1 mg⋅L-1 NAA， resulting in a germination rate of 71.12%. （3） For subculture proliferation， the appropriate medium was MS with 1.0 mg⋅L-1 6-BA and 0.1 mg⋅L-1 NAA， yielding a proliferation coefficient of 5.5. （4） For stem segments， the appropriate callus induction medium was MS+1.0 mg⋅L-1 6-BA+1.0 mg⋅L-1 2，4-D， with an induction rate of 97.10%. The appropriate differentiation medium for callus induced from stem segments was MS+1.5 mg⋅L-1 6-BA+0.1 mg⋅L-1 NAA. （5） The appropriate basic medium for adventitious bud rooting was 1/2MS with 1.0 mg⋅L-1 NAA， achieving a rooting coefficient of 99.11%. （6） After hardening off， the rooted seedlings of S. petrophila were transplanted into a mixed substrate of peat， perlite， and vermiculite in a volume ratio of 1∶1∶1， resulting in a survival rate of 85.5%. The results might lay a technical foundation for the species conservation and resource utilization of S. petrophila， and also provided valuable ideas for the rapid propagation techniques of other Salvia species.

    Optimal Germination Temperature of Tree Seeds with Different Primary Dormancy Types and Their Responses to Thermal Dormancy Induction
    Zhe WANG, Mingyue LI, Meiru ZHU, Peng ZHANG
    2025, 45(4):  569-579.  doi:10.7525/j.issn.1673-5102.2025.04.009
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    In order to clarify the optimal germination temperature conditions of tree seeds with different primary dormancy types and their responses to thermal dormancy induction， the seeds of nine different tree species with three primary dormancy types （non-dormancy， physical dormancy and physiological dormancy） were used as materials for germination tests at 5， 10， 15， 20， 25， 30 and 35 ℃， respectively， and an appropriate germination temperature was determined according to seed germination performance. On this basis， the seeds were cultured at 25， 30 and 35 ℃ and transferred to the appropriate germination temperature for 14 days. The response of different primary dormancy types of seeds to thermal dormancy induction was compared according to seed germination performance. The results showed certain differences in an optimal germination temperature of seeds with different primary dormancy types. The optimal germination temperature for non-dormant seeds （Picea koraiensis， Larix principis-rupprechtii， and Pinus thunbergii） was in a range of 10-25 ℃， for physically dormant seeds （Gleditsia japonica， Robinia pseudoacacia， and Amorpha fruticosa） was in a range of 10-35 ℃， for physiologically dormant seeds （Pinus tabuliformis， Fraxinus rhynchophylla， and Pyrus ussuriensis） was in a range of 5-30 ℃. High temperatures inhibited germination in most seeds. Only the physiologically dormant P. ussuriensis seeds entered thermal dormancy under high temperatures （with dormancy rates of 80%-86%）， while the other physiologically dormant seeds （P. tabuliformis and F. rhynchophylla） had higher mortality rates （46%-69%）. Non-dormant seeds had higher mortality rates （56%-100%）， while physically dormant seeds had lower mortality rates （24%-64%）. Physically dormant seeds had germination rates of 36%-76% at high temperatures of 25-35 ℃. Non-dormant and physically dormant seeds did not enter thermal dormancy under high temperatures， while the response of physiologically dormant seeds to thermal dormancy under high temperatures was inconsistent.

    Response of Arabidopsis thaliana Histone Chaperone HIRA to Enhanced UV-B Radiation
    Qianwen MAO, Guohua WANG, Rong HAN
    2025, 45(4):  580-591.  doi:10.7525/j.issn.1673-5102.2025.04.010
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    UV-B radiation significantly inhibits plant growth， leading to short roots and DNA damage. Research has shown that the histone chaperone HIRA（HISTONE REGULATOR A） plays a role in chromatin-related DNA damage repair. In this study， using the Columbia ecotype of Arabidopsis thaliana and the hira mutant as materials， the comparison of phenotypic and physiological indicators between the control group （-UV-B） and the UV-B treatment group（+UV-B） revealed that the absence of the HIRA gene led to shorter roots and smaller plants in A. thaliana. After UV-B treatment， the roots of hira mutant were significantly shorter than those of the wild type， with increased levels of reactive oxygen species and malondialdehyde， and decreased levels of soluble protein and chlorophyll. Subcellular localization of A. thaliana transformation showed that HIRA was located in the nucleus. UV-B radiation caused chromosome bridges and abnormal mitosis in the root tip meristematic zone cells of the mutant. Further research results indicated that UV-B radiation significantly upregulated the expression of DNA damage repair related genes. In conclusion， HIRA was involved in the process of cell mitosis and damage repair under UV-B radiation.

    Alleviative Effects of Foliar TiO2-NPs Pretreatment on Wheat Seedling Growth under UV-B Stress
    Jianhua WANG, Huize CHEN, Rong HAN
    2025, 45(4):  592-602.  doi:10.7525/j.issn.1673-5102.2025.04.011
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    The aim of this study was to reveal the alleviating effect of foliar pretreatment with TiO2-NPs （titanium dioxide nanoparticles） on the growth of wheat seedlings under UV-B stress. Using T.aestivum as material， the effects of leaf TiO2-NPs pretreatment on mitosis， DNA damage， antioxidant enzyme system， and antioxidant-related genes in the alleviation of UV-B stress were comprehensively studied at the cellular， physiological， biochemical， and genetic levels. The results showed that 10 mg⋅L-1 TiO2-NPs foliar pretreatment significantly alleviated the inhibition of wheat seedling growth under low-（5.04 kJ⋅m-2） and high-dose（10.08 kJ⋅m-2） UV-B stress conditions. After UV-B stress， plant height of TiO2-NPs-treated wheat seedlings increased by 44.71% and 127.43%， root length increased by 38.92% and 159.10%， fresh weight increased by 50.03% and 78.67%， and dry weight increased by 37.33% and 126.84%， respectively. The proportion of mitotic abnormalities in root tip cells of TiO2-NPs pre-treated wheat seedlings was only 39.57% and 28.63% under low and high doses of UV-B stress， respectively， and the CPDs content in cells decreased by 60.43% and 48.81%， respectively， compared with the control group. TiO2-NPs foliar pretreatment increased the flavonol content by 1.44 times and 1.53 times under low- and high-dose UV-B stress， respectively， significantly increased the expression of flavonol synthesis genes（CHS and CHI） and SOD， and improved the ROS scavenging ability of wheat seedlings. In conclusion， foliar pretreatment with 10 mg⋅L-1 TiO2-NPs significantly improved the activity of plant antioxidant system， reduced the ROS-caused damage on wheat plants， and improved the tolerance of plants to UV-B stress.

    The Influence of Cadmium, Microplastics, and Their Combination on the Growth and Photosynthetic Characteristics of Kandelia obovata
    Minwei CHAI, Yifan WU, Ruili LI, Lin ZHOU, Xiaoxue SHEN
    2025, 45(4):  603-613.  doi:10.7525/j.issn.1673-5102.2025.04.012
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    Urban mangroves are faced with the environmental problem of combined pollution of heavy metals and microplastics（MPs）. Cadmium（Cd） has a relatively high ecological risk， with polyethylene（PE） and polyvinyl chloride（PVC） to be common microplastic pollutants in mangroves. A combined stress experiment of Cd（0， 5， 50 mg⋅kg-1） and microplastics （small particle size PE-S（13 μm）， large particle size PE-L（830 μm）， small particle size PVC-S（13 μm）， large particle size PVC-L（830 μm）） was carried out for mangrove plant Kandelia obovata. The aims were to explore the influence of Cd， MPs， and their combination on the growth and photosynthetic characteristics of K. obovata. The results showed that （1）the impact of PE-MPs on the growth of K. obovata was not significant. Under high Cd stress（50 mg⋅kg-1）， PVC-L significantly restricted the growth of roots and leaves（P<0.05）. （2）The contents of nutrient elements Na，K，Ca，and Mg in leaves were affected by Cd stress， the types and sizes of MPs. （3）MPs and Cd had synergistic effect on the inhibition of chlorophyll content. The contents of chlorophyll a and carotenoids were the lowest under Cd5PVC-S stress， with the lowest content of chlorophyll b under Cd50PVC-S stress. Under Cd50 stress， PVC-S significantly improved net photosynthetic rate Pn， stomatal conductance Gs， transpiration rate Tr， actual photochemical quantum yield（Y（Ⅱ））， electron transfer rate（ETR）， photochemical quenching coefficient（qP） and the proportion used for photochemical dissipation（P） of K. obovata leaves（P<0.05）， indicating that PVC-S can alleviate the toxic effects of Cd stress on the photosynthesis of K. obovata. Compared to Cd stress alone， the combined stress of Cd and PE showed no significant effects on chlorophyll fluorescence parameters of K. obovata. Overall， PE and its combined stress with Cd showed no significant effects on the growth and photosynthesis of K. obovata； PVC had a stronger synergistic effect on Cd stress， with PVC-S alleviating the negative effects of Cd on the photosynthesis， and PVC-L having stronger toxic effect.

    Tolerance and Enrichment Characteristics of Agapanthus praecox ssp. orientalis ‘Big Blue’ under Cadmium Stress
    Ying WANG, Maojin ZHAO, Xiuming LIU, Yixuan WU, Jiahao ZHU, Chengzhong WANG
    2025, 45(4):  614-626.  doi:10.7525/j.issn.1673-5102.2025.04.013
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    To provide plant remediation materials with landscape properties for cadmium（Cd） contaminated soil， the experiment used a potted method to study the effects of different concentrations of exogenous cadmium（0， 200， 500 mg⋅kg-1） on the tolerance and enrichment characteristics of Agapanthus praecox ssp. orientalis ‘Big Blue’.The results showed that with the increase of cadmium stress concentration， the biomass of leaves and roots decreased， and when the cadmium concentration was 200 mg⋅kg-1， the leaf biomass didn’t decrease significantly compared with the control， while the root biomass decreased significantly compared with the control. The activities of catalase（CAT）， peroxidase（POD）， and superoxide dismutase（SOD） and contents of malondialdehyde（MDA）， soluble protein， proline in leaves significantly increased compared with the control at cadmium concentration of 500 mg⋅kg-1， and the corresponding indexes in roots significantly increased at cadmium concentration of 200 mg⋅kg-1 compared with the control. The soluble sugar content of leaves and roots significantly increased at a concentration of 500 mg⋅kg-1 compared with the control. The results indicated that Agapanthus praecox ssp. orientalis ‘Big Blue’had a certain tolerance to heavy metal cadmium， and the biomass decreased， the malondialdehyde contents increased， and the antioxidant enzyme activities and osmotic regulator contents increased to alleviate the toxicity of cadmium to Agapanthus praecox ssp.orientalis ‘Big Blue’ under high cadmium stress， and the roots were more sensitive to cadmium than the leaves.Chla， Chlb， Chla+b， Chla/b， and carotenoid content showed a downward trend， and the above five indicators were significantly lower than the control when the cadmium concentration was 500 mg⋅kg-1. Except for intercellular CO2 concentration， transpiration rate， photosynthetic rate， and stomatal conductance significantly decreased compared to the control at cadmium concentration of 500 mg⋅kg-1. Except for non-photochemical quenching coefficient（NPQ）， the maximum photochemistry efficiency（Fv/Fm）， PSⅡ potential activity（Fv/Fo）， the actual photochemical quantum efficiency（ΦPSⅡ）， photochemical quenching coefficient（qP） were reduced at the cadmium concentration of 500 mg⋅kg-1， which were significantly lower than those of the control. The enrichment coefficients of the leaves and roots of Agapanthus praecox ssp. orientalis ‘Big Blue’ were both less than 1， and the transport coefficients were both greater than 1. Although it didn’t fully meet the standards for cadmium hyperaccumulation plants， it had a strong enrichment effect on cadmium. Overall， it can be used as a plant remediation material with landscape effects，and the biomass and cadmium content of leaves and roots can be used as important indicators of the ability of the tolerance of Agapanthus praecox ssp. orientalis ‘Big Blue’ to cadmium stress.

    The Megasporogenesis, Microsporogenesis and Development of Female and Male Gametophyte in Rhus chinensis
    Xia ZHANG, Cai ZHOU, Yanyue BIAN, Yanzeqian ZHANG, Faju CHEN
    2025, 45(4):  627-635.  doi:10.7525/j.issn.1673-5102.2025.04.014
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    In order to reveal the functional differentiation of sex and to provide the embryological evidence in Rhus chinensis， the micro- and mega-sporogenesis and development of male and female gametophytes were investigated by paraffin section. Results showed that （1） the flowers of R. chinensis were complete flowers， but selective degeneration of pistils or stamen resulted in functional female or male flowers. （2） During the anther development of functional male flowers， the microspore tetrads were regular tetrahedral and the mature pollen grains were 2-cell type. The ovules in functional male flowers developed normally to the uninucleate embryo sacs， but abnormalities were observed during the transition from the binucleate to octa-nucleate embryo sac stage， and the nucleus of embryo sac disappeared， and eventually the fertile female gametophytes could not be formed. （3） During the ovule development of functional female flowers， the megaspore tetrads were straight， and the functional megaspore at the chalazal end developed into octa-nucleate embryo sac， which developed into the polygonum type. During the anther development of functional female flowers， tapetum disintegrated at the stage of sporogenous cells， being apoptotic for the sporogenous cells， and eventually atrophy and abortion for anther chambers. The development of functional male and female gametophytes in R. chinensis was similar to that of other plants in Anacardiaceae family， and abnormal development of the ovule from binucleate to octa-nucleate embryo sacs led to pistil abortion to form functional male flowers， and abnormal disintegration of the tapetum and sporogenous cells led to abortion of stamens to form functional female flowers.

    Rhythms of Nectar Secretion, Morphological Characteristics of Developmental Floral Nectary in Rubus setchuenensis
    Yan SHEN, Xiaoyu TANG, Xiujun TANG, Lilin LUO, Zhenxing HUANG, Man LIU
    2025, 45(4):  636-647.  doi:10.7525/j.issn.1673-5102.2025.04.015
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    Rubus setchuenensis（Rosaceae） is a high-quality nectariferous plant. In order to clarify the nectar secretion rhythm and morphological characteristics of developmental floral nectary， the floral nectar secretion characteristics were observed and recorded， and morphological and anatomical characteristics and ultrastructure of floral nectary at five developmental stages（young bud stage， flower bud stage， initial flowering stage， full blooming stage and post anthesis stage） were investigated by paraffin section and scanning electronic microscope. The flowering period of R.setchuenensis was from June to November in Meitan County， Guizhou Province， and the vigorous nectar secretion period was from July to September. The flowering period and the nectar secretion period of a single flower were three days and two days， and the average total nectar secretion and total sugar content were （30.58±3.60） μL and （7.14±2.33） mg， respectively. The floral nectary of R.setchuenensis was located on the inner wall of the plate-like receptacle between the stamen base and the ovary， which was composed of epidermis， nectary parenchyma cells and vascular bundle. According to the position and anatomical structure of nectary， and the change of starch granules， floral nectary of R.setchuenensis would be divided into receptacle nectary， structural nectary and starch nectary， respectively. The nectary and epidermal stomata developed from the young bud stage and the budding stage， respectively. The original nectar was provided by the vascular bundle and stored in the nectary cells in the form of starch. The starch granules began to accumulate from the young bud stage， and the starch granule content， size and aperture area of stomata， and thickness of nectary reached the maximum at the initial flowering stage. The nectar was secreted from the cuticles and stomata on nectary epidermis， and the starch granules nearly disappeared at the full blooming stage and the post anthesis stage.

    Comparison of the Interspecific Difference of Primary Structure of Aerial Roots among Three Epiphytic Orchids
    Yin REN, Wenna WANG
    2025, 45(4):  648-658.  doi:10.7525/j.issn.1673-5102.2025.04.016
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    To understand the correlation between structure and function of aerial roots of epiphytic Orchidaceae plants， the paraffin embedding technique was used to obtain cross-sectional slices of the primary structures of aerial roots of Dendrobium loddigesii， Oncidium flexuosum and Dendrobium nobile. By measuring the cross-sectional areas of cortical tissue， vascular tissue and other structures of the primary roots， as well as the characteristics such as the number and size of cortical cells and vessels， the anatomical reasons for cross-sectional area changes of the aerial roots were analyzed. The results indicated that： （1）there were significant differences in the cross-sectional area of aerial roots among three species（P<0.05）， the cross-sectional area of the aerial root of D. nobile was the largest， followed by O. flexuosum and D. loddigesii. For each species， the proportions of velamen and cortex areas to the root cross-sectional area were relatively high（37.46%-57.03%）， thus the velamen and cortex had high correlations with the root cross-sectional area（r=0.91-0.98，P<0.05）. （2）Significant correlations existed between cortex area and cortical cell traits， vascular tissue area and conduit traits（P<0.05）. The correlation of cortex area with the mean cortical cell diameter（r=0.68-0.90） was stronger than that with cortical cell layers（r=0.56-0.66）. In addition， the correlation of vascular tissue area with conduit quantity（r=0.64-0.77） was closer than that with mean conduit diameter（r=0.58-0.71）. （3）D. nobile had significantly lower proportions of cortical and vascular tissue area but a significantly higher proportion of velamen area to the root cross-sectional area， when compared to the other two species. Besides， D. nobile also had thicker and more conduits and larger total conduit area， but lower conduit density， which reflected the diversity of different epiphytic orchid species in resource acquisition and strategies for drought stress tolerance. In summary， this study clarified the anatomical mechanisms underlying the cross-sectional area changes of aerial roots of three epiphytic orchids as well as the interspecific differences in resource acquisition strategies， and provided a new scientific perspective for understanding the relationship between plant root structure and function.