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    20 May 2023, Volume 43 Issue 3
    Review
    Research Progress on the Regulatory Mechanism of Plant Root Hair Development
    Yuping QIU, Yichuan WANG, Hongwei GUO
    2023, 43(3):  321-332.  doi:10.7525/j.issn.1673-5102.2023.03.001
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    Root hairs are tubular extensions of plant root epidermal cells that play vital roles in soil fixation, water and inorganic salts absorption, and information exchange between plant roots and outside world. The developmental processes of root hair are highly plastic and might easily be affected by various plant hormones and environmental factors. Due to the structural and functional characteristics of root hair, it is often used as model to study apical growth and fate determination of plant cells. Therefore, the regulatory mechanism of root hair development has been a hot topic in the field of botany. The review summarized the research progress in the field of root hair development in the past two decades.

    Genetic and Breeding
    Establishment of an Efficient Regeneration System in Iris lacteal var. chinensis with Immature Embryo
    Wenjie AN, Yinjie WANG, Qingquan LIU, Yongheng YANG, Ting ZHANG, Shaoru FAN, Yongxia ZHANG, Haiyan YUAN
    2023, 43(3):  333-339.  doi:10.7525/j.issn.1673-5102.2023.03.002
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    The effect of sampling time and plant growth regulators on the induction of callus, somatic embryo and adventitious bud were investigated with immature embryos of Iris lacteal var. chinensis as explants. The results showed that the most feasible sampling time for immature embryos was 35-45 d after pollination, the young embryos were fully developed, but the endosperm was not completely hardened, and the young embryo was easy to dissect. The optimum medium for callus induction was MS+1.0 mg·L-1 2,4-D+0.2 mg·L-1 6-BA with the induction rate of 83.33%. The appropriate medium for somatic cell induction was MS+0.25 mg·L-1 2,4-D+0.05 mg·L-1 6-BA with the induction rate of 71.67%. The most suitable medium for adventitious bud induction and proliferation was MS+0.2 mg·L-1 TDZ+0.05 mg·L-1 NAA with the induction rate of 78.33% and proliferation coefficient 3.65 in this experiment. The rooting rate was more than 95% after four weeks cultivation on MS medium supplemented with 0.1 mg·L-1 NAA. Then, the medium was washed off and explants were transplanted to sterilized vermiculite, and the survival rate was more than 95%. This study has established an efficient regeneration system of I. lacteal var. chinensis embryos, which can lay a foundation for genetic transformation and gene function analysis of I. lacteal var. chinensis.

    Genetic Transformation and Function Analysis of PsnHB13 and PsnHB15 of Populus simonii × Populus nigra
    Zhanmin ZHENG, Yubing SHANG, Guangbo ZHOU, Di XIAO, Yi LIU, Xiangling YOU
    2023, 43(3):  340-350.  doi:10.7525/j.issn.1673-5102.2023.03.003
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    Transcriptome analysis in Populus simonii × P. nigra overexpressing PsnCycD1;1showed PsnHB3 and PsnHB15 are differential genes. Analysis of PsnHB13 and PsnHB15 conservative domains through InterPro tool. The STRING software was utilized to explore PsnHB13 and PsnHB15 proteins interaction network analysis. Yeast two hybrid was used to verify the interaction proteins,calculate the ratio of leaf length to width,the ratio of dry weight to fresh weight of leaves and stems of transgenic plants,and analyze the transcriptome of PsnHB13 overexpression plants. Conserved domain analysis showed that PsnHB13 and PsnHB15 genes belonged two subfamilies,showing that PsnHB13 mainly contains the HDZip I domain,and PsnHB15 mainly contains the HDZip Ⅲ domain. ,Each gene is screened to 10 interacting genes. Moreover,PsnHB15 has a higher probability of interaction with family proteins. Yeast two-hybrid assays demonstrated that PsnHB15 interacts with PsnHB13 and PsnHB13 interacts with PsnCycD1;1. The aspect ratio of leaves in transgenic lines overexpressing PsnHB13 and PsnHB15 increased in the early seedling stage.The ratio of dry weight to fresh weight in stems of PsnHB13 overexpression lines increased significantly(P<0.05). The analysis of the transcriptome revealed that Gene Ontologies(GO) enrichment analysis identified 3 significantly enriched GO terms,including response to chemical,response to organic substance,regulation of RNA metabolic process. KEGG pathway enrichment analysis demonstrated that transcription factors,plant hormone signal transduction and Cytochrome P450 were significantly enriched. These differential genes,including MADS-box transcription factor,MYBP transcription factor,ERF1 transcription factor,GH3 auxin responsive genes,SAUR protein family. PsnHB13 and PsnHB15 play an important role in the growth and development of Populus simonii × P. nigra,and are key genes to explore the growth law of plants and reveal the relationship between cell cycle and growth regulation.

    Analysis on Leaf Color and Growth Variation of Transgenic BpGLK Betula pendula ‘Dalecarlica'
    Li CAO, Yunli YANG, Tianfang LI, Jing JIANG
    2023, 43(3):  351-360.  doi:10.7525/j.issn.1673-5102.2023.03.004
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    Physiology and Ecology
    Bryophyte Diversity of Underground Forests in Craters of Jingpohu Global Geopark
    Mingyang CONG, Yongkun LI, Wenjing YANG, Puqing CHEN
    2023, 43(3):  361-369.  doi:10.7525/j.issn.1673-5102.2023.03.005
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    To explore the bryophyte diversity of underground forests in craters of Jingpohu Global Geopark, the typical investigation method was used, and a total of 3 622 bryophyte specimens were collected, and morphological and anatomical methods were used to identify the specimens. The results showed that, 292 species(126 genera and 53 families) were recorded, 31 species (17 genera and 14 families) were liverworts, 261 species (109 genera and 39 families) were mosses. The number of bryophyte species of four craters was 192 species in Ⅳ, 126 species in Ⅰ, 113 species in Ⅲ, and 61 species in Ⅱ, respectively. The dominant families were Brachytheciaceae, Mniaceae, Pottiaceae, etc., accounting for 42.12% of the total species, and the dominant genera were BrachytheciumEntodonPlagiomnium, etc., accounting for 18.49% of the total species, and the dominant species were Pylaisia polyanthaPylaisiadelpha yokohamaeEntodon flavescens, respectively. There were 20 common species of bryophytes in four craters, and the unique species in the Ⅳ crater was the most(88 species). The diversity of the ‘moderate interference hypothesis’ was supported, and the similarity of bryophytes between Jingpo Lake crater and Wudalianchi volcanos was high(20.42%), which revealed that the terrain contributes greatly to the diversity. The alpha diversity of bryophytes in the crater I exhibited a mid-peak pattern, which was in line with the ‘Mid-elevation bulge’ theory, priority should be given to the central elevation where the bryophytes were the most abundant. The study showed that the underground forests in Jingpohu Global Geopark craters preserved high bryophyte diversity and played an important role in the volcanic ecosystem of China, and a key protection should be given to bryophytes in this volcanic geological wonder to preserve genetic resources, and the results provided first-hand basic information and important scientific significance.

    Effects of Exogenous Hormones Soaking and Osmotic Treatment on Thermal Dormancy of Seeds of Fraxinus mandshurica
    Chunjing JIAO, Mingyue LI, Peng ZHANG
    2023, 43(3):  370-378.  doi:10.7525/j.issn.1673-5102.2023.03.006
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    To explore the effects of exogenous hormones soaking combined with polyethylene glycol 6000 (PEG) osmotic treatment on the thermal dormancy and related physiological changes in seeds of Fraxinus mandshurica, non-dormant F. mandshurica seeds were used as materials and then soaked with 1 mmol·L-1 gibberellin(GA4+7), ethylene(ETH) and cytokinins(6-BA) for 24 h respectively, and the germination of seeds cultured in different mass fractions(0, 5%, 25%, 50%) PEG solution at the induction thermal dormancy temperature(25 ℃)for 7 d and then at 10 ℃ was assayed. On this basis, the treatments with significant results were selected to determine the changes in seeds endogenous hormones content and cell wall degrading enzyme activity. The results showed that: compared with hormone treatment alone, GA4+7 combined with different mass fraction PEG had no significant effect on germination ability. With the increase of PEG mass fraction, the germination ability of 6-BA combined with PEG treatment gradually increased and then tend to stabilized, when combined with 25% PEG, the germination percentage and germination index respectively increased 69.31% and 1.04, and the germination time was shortened by 7.8 d. The seeds germination ability treated ETH combined with PEG gradually increased with the increase of PEG mass fraction, when combined with 50% PEG, the germination percentage and germination index respectively increased 43.43% and 0.76. Hormone combined with osmotic treatment significantly increased endosperm cellulase activity, but the GA and ABA contents in embryo and endosperm were not significantly regularity. In conclusion, exogenous hormone combined with osmotic treatment could reduce the thermal dormancy of F. mandshurica seeds, and the effect was different depending on the hormone species.

    Regulation of Salicylic Acid on Tolerance to Saline Alkali Stress at Seedling Stages of Betula platyphylla
    Jingzhe WANG, Chaokui NIU, Xinyuan LIANG, Chenjing SHEN, Jing YIN
    2023, 43(3):  379-387.  doi:10.7525/j.issn.1673-5102.2023.03.007
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    To investigate the effects of salicylic acid(SA) on growth and secondary production synthesis of Betula platyphylla seedling under saline alkali stress, three treatments were applied to birch seedlings: water treatment(control), 200 mmol·L-1 NaHCO3, 200 mmol·L-1 NaHCO3+360 μmol·L-1 SA. The relative conductivity, chlorophyll fluorescence parameters, osmotic content, anti-stress enzyme activity, the relative expression of key genes of triterpene synthesis pathway in the middle leaves of birch seedlings in response to different treatments were detected respectively, and the total triterpenoids, flavonoids and polyphenols of birch seedlings were analyzed. The results showed that: ①under the 200 mmol·L-1 NaHCO3 treatment, then 360 μmol·L-1 SA treatment significantly reduced the relative conductivity of the leaves of birch seedlings, improved the Fv/Fm value of chlorophyll fluorescence parameters of birch seedlings, increased the content of the osmotic regulator proline and soluble protein, and enhanced the activities of antioxidant enzymes(SOD, POD, CAT, APX) in birch seedlings to a certain extent. ②200 mmol·L-1 NaHCO3 saline alkali stress promoted the upregulation of the expression of key genes of triterpene synthesis pathway FPSSSSEBPX and BPW in birch seedlings, and significantly promoted the synthesis of polyphenols in birch seedlings in the early stage, and significantly promoted the accumulation of total triterpenoids and flavonoids in the late stage of saline-alkali stress(P<0.05). The application of SA under saline-alkali stress promoted the upregulation of HMGRFPSSE, and BPX gene expression in birch seedlings, and promoted the synthesis of flavonoids in the early stage of stress, and significantly promoted the accumulation of total triterpenes in the late stage of stress, which was 34% higher than that of the saline-alkali stress group and 47% higher than that of the water treatment on 7th day. Overall, under saline-alkali stress, SA with suitable concentration improves the tolerance to saline-alkali of birch seedlings by adjusting osmotic equilibrium, alleviating light inhibition, enhancing the antioxidant defense system of birch seedlings, and regulating substance metabolism.

    Regulatory Effects of Salicylic Acid,Nano-zinc Oxide and Growth-promoting Fungi YZ13-1 on the Resistance to Drought Stress of Fraxinus mandshurica
    Chenjing SHEN, Wenbo WU, Luran GENG, Fulong WANG, Pengzhou ZHAO, Jinhui SONG, Yaguang ZHAN, Jing YIN
    2023, 43(3):  388-395.  doi:10.7525/j.issn.1673-5102.2023.03.008
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    To investigate the effects of salicylic acid(SA), nano-zinc oxide(ZnO NPs) and growth-promoting endophytic fungus YZ13-1(Fusarium graminearum) on drought tolerance of Fraxinus mandshurica seedlings. Two years old potted F. mandshurica seedlings were used as materials and 5 groups of treatments were set in this experiment:T1,drought stress treatment (soil water content was 20%-25%); T2, T3 and T4 groups were additionally treated with 50 mg·L-1 SA,100 mg·L-1 ZnO NPs, growth-promoting fungus YZ13-1 suspension on the basis of T1 group; CK, control group(soil water content was 50%-55%). The results showed that compared with T1 group, the activities of peroxidase(POD), ascorbate peroxidase(APX), catalase(CAT) were increased by 2 times, soluble sugar(SS), proline(PRO) and phenolic substances increased by 44%, 60%, 16%, and relative electrical conductivity(RWC) of leaves decreased by 14% in T2 group. Compared with endophytic fungi and ZnO NPs, SA could significantly increase the anti-stress enzyme activity, increase the contents of osmotic substances and phenolic substances, and thus improve the drought resistance ability of F. mandshurica under drought stress. The study clarified that three induction treatments could improve the drought resistance of F. mandshurica, and SA treatment was the best, providing a theoretical basis for screening drought resistance agents of F. mandshurica.

    Effects of Cryopreservation on Physiological and Biochemical Characteristics of Fraxinus mandshurica Embryos
    Yue REN, Cheng WEI, Tiantian XU, Hailong SHEN, Ling YANG
    2023, 43(3):  396-403.  doi:10.7525/j.issn.1673-5102.2023.03.009
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    In this paper, the zygotic embryos were used as storage materials to further analyze the changes of physiological and biochemical indexes of the zygotic embryos before and after cryopreservation, and the effects of freezing method and dewatering time on physiological and biochemical indexes were clarified, which provided physiological data support for the establishment of long-term storage methods of fine genetic materials of Fraxinus mandshurica. Under the condition of dehydration for 120 min, the activity of dehydrogenase in zygote embryos was the highest, and the activity of catalase, peroxidase and mass fraction of proline reached the maximum. They were 1 168.85 U·g-1·min-1, 338.33 U·g-1·min-1 and 394.99 μg·g-1, respectively. Dehydrogenase activity, proline content, peroxidase activity and catalase activity in zygotic embryo cells were all the minimum values after vitrification. The soluble protein fraction and superoxide dismutase activity in zygote embryos reached the maximum values after storage by slow freezing method, which were 18.82 mg·g-1 and 361.97 U·g-1, respectively, which were significantly higher than those by other freezing methods. The activity of zygotic embryos reached the highest value under the conditions of drying and dewatering for 120 min and fast freezing. The results showed that the survival rate and physiological indexes of the zygotic embryos of F. mandshurica were affected by different freezing methods, dehydration time and their interaction. In addition to the decrease of malondialdehyde content, the dehydrogenase activity, antioxidant enzyme activity, proline content and soluble protein content in the zygotic embryo cells of F. mandshurica increased with the increase of dehydration time after being stored in different freezing methods. The survival rates of zygotic embryos and somatic embryos after cryopreservation were 62.26% and 51.68%. Therefore, the method of drying and dewatering for 120 min combined with fast freezing is suitable for cryopreservation of F. mandshurica embryos.

    Selection of Cryopreservation Conditions of Sinopodophyllum hexandrum Seeds Based on Entropy Weight TOPSIS Model
    Xijia JIU, Yuhui WANG, Honggang CHEN, Huizhen WANG, Cuiyun ZENG, Tao DU
    2023, 43(3):  404-411.  doi:10.7525/j.issn.1673-5102.2023.03.010
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    To explore the optimal cryopreservation conditions for Sinopodophyllum hexandrum seeds, and to provide technical support for the long-term preservation of S. hexandrum seeds, four kinds of seeds with different moisture contents(1.6%, 9.6%, 20.9% and 30.5%) were obtained by silica gel drying, natural shade drying and soaking methods, and cryopreserved by direct freezing, slow freezing and vitrification respectively, and the seed viability and the activity of superoxide dismutase(SOD), peroxidase(POD), and the contents of malondialdehyde(MDA), total protein(TP), soluble starch and soluble sugar in seeds were measured before and after cryopreservation respectively. The results showed that the seed viability of S. hexandrum seeds with different water content declined in varying degrees after three cryopreservation methods, but the seeds with water content of 1.6%, 9.6% and 20.9% had no significant difference compared with the control group(P>0.05). After cryopreservation, the contents of soluble sugar and total protein in S. hexandrum seeds with four kinds of water content increased, and the content of soluble sugar was the biggest, while the content of starch in seeds showed a downward trend as a whole, and the activities of superoxide dismutase and peroxidase declined slightly when the water content was 1.6% and 9.6%. The content of MDA increased when the water content was 1.6% and 30.5%, but decreased when the water content was 9.6% and 20.9%, indicating that the seeds with different water content were damaged to different degrees after freezing in liquid nitrogen. The activities of antioxidant enzymes decreased, while the increase of protein content and the accumulation of soluble sugar content caused by starch degradation improved the low temperature tolerance of seeds. As a result, the content of malondialdehyde(MDA) in chilling injury products showed different trends. The seeds of vitrification freezing group with 1.6% water content and seeds of direct freezing group and slow freezing group with 9.6% water content were the top three places by entropy weight TOPSIS. The results showed that the liquid nitrogen cryopreservation technology of S. hexandrum seeds could be feasible, and the seeds with 9.6% water content would be the best cryopreservation conditions by direct freezing or slow freezing.

    Molecular biology
    Cloning of WRKY40 Gene from Leymus chinensis and Analysis of Disease Resistance in Transgenic Tobacco
    Danni LI, Jiali LIU, Jitao ZHANG, Baoxiang GU, Fengjin ZHU, Qingjie GUAN
    2023, 43(3):  412-420.  doi:10.7525/j.issn.1673-5102.2023.03.011
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    In order to cultivate rice varieties resistant to Xanthomonas oryzae pv. oryzaeRhizoctonia solaniMagnaporthe oryzae and Fusarium fujikuroi, the method of mining resistance genes is an important way to select resistant varieties. RT-PCR method was used to clone the LcWRKY40 gene (MN187915) from the leaves of Leymus chinensis. The result showed that the CDS was 1 053 bp in length and encoded 350 amino acids with a molecular weight of 38.1 kDa. The results of bioinformatics analysis showed that the primary structure of LcWRKY40 contained WRKY domain, zinc finger protein domain and nuclear localization sequence. Phylogenetic tree construction and motif analysis showed that the phylogenetic relationship between LcWRKY40 and HvWRKY38 was closed. The results of subcellular localization in tobacco showed that the LcWRKY40 protein was located in the nucleus, verified by the software prediction. qRT-PCR tissue specific expression analysis showed that LcWRKY40 gene was expressed in root, stem, leaf, leaf sheath, Lemma and anther of Leymus chinensis respectively, but the expression level was the highest in leaf but the lowest in Lemma. Transgenic LcWRKY40 tobacco plants and wild-type tobacco plants were inoculated with X. oryzae pv. Oryzae, R. solani, M. oryzae and F. fujikuroi, respectively, which showed that transgenic LcWRKY40 tobacco plants could alleviate the four pathogens in different degrees, and showed high resistance to M. oryzae and F. fujikuroi. Therefore, it was speculated that LcWRKY40 protein played a key regulatory role in signal pathways such as resisting disease stress and improved the resistance of plant pathogens, which layed a molecular foundation for the study of LcWRKY40 function and abiotic stress.

    Detailed Phenotypical Analysis on the Mutant ssr1-2 Encoding a Mitochondrial Protein of Arabidopsis thaliana
    Yuanyuan CAI, Jibenben XIA, Wenhan YING, Jieyao WANG, Tao XIE, Kongya XING, Xuanjun FENG, Xuejun HUA
    2023, 43(3):  421-431.  doi:10.7525/j.issn.1673-5102.2023.03.012
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    To explore the role of SSR1 gene encoding a functionally unknown mitochondrial protein of Arabidopsis thaliana in plant growth and stress response, ssr1-2 and its suppressor mutants EMS143 and EMS145 were used to track the growth of their roots and aboveground parts, as well as their proline sensitivity and iron homeostasis, and the effects of ssr1-2 short root phenotype on aboveground growth of seedlings were analyzed by micrografting. The results showed that the primary root length of ssr1-2 was shorter and the root architecture was similar to the fibrous root system. The growth of their shoots was also retarded, but appeared considerably later than the short-root phenotype. The results of micrografting revealed that the roots of ssr1-2 could restrict the growth of the wild-type shoots and, and conversely, the shoot of ssr1-2 could also affect the growth of the wild-type roots, but the former had a bigger effect. ssr1-2 showed a hypersensitive phenotype to proline in seed germination, root length and leaf chlorophyll content. In addition, ssr1-2 appeared insensitive to Fe nutrition, that was, the stimulating effect of Fe salt on seedling growth was significantly less than that of wild-type WS, indicating a significant decrease in its ability to utilize Fe. The results suggested that SSR1 might be involved in the regulation of A. thaliana root growth by affecting the utilization of iron nutrient, implying that the impairment of the mitochondrial iron utilization machinery might contribute significantly to the enhanced inhibitory effect of proline on plant growth and development.

    Pollination biology
    The Pollination Biology of Begonia Guangxiensis, a Narrowly Distributed Species
    Qiongyue LIANG, Changqiu LIU, Qifeng LU, Tao DENG, Bo CAI
    2023, 43(3):  432-438.  doi:10.7525/j.issn.1673-5102.2023.03.013
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    To examine the mating system of Begonia guangxiensis and whether the species relies on particular pollinators in its native habitat for pollination and whether it can achieve sexual reproduction in artificial habitats, the experiment of floral longevity observation, floral traits determination, pollination, flower visitor observation and seed germination determination of B. guangxiensis were carried out in this study. The result showed that B. guangxiensis had a long floral longevity, and the corolla sizes varied in different habitats; there was no significant difference in the proportion fruit set and seed germination rate between self-pollination and cross-pollination treatments and natural control between the two habitats; flower visitors included bees(Apis ceranaBombus eximius) and hoverflies(Episyrphus balteatusIschiodon scutellaris), and the visitor composition varied with habitats and years. All the results consistently indicated that the self-compatible B. guangxiensis relied on pollinators for sexual reproduction, but did not rely on a particular type of pollinator, but had a more generalized pollination system, and therefore could reproduce successfully in unnatural habitats.

    Plant Physiology
    Analysis of Metabolic Characteristics of Different Organs of Acanthopanax senticosus and Acanthopanax sessiliflorus Based on GC-MS
    Yanjun REN, Yu SUN, Xiaorui GUO, Mingyuan XU, Wenda SHAO, Kexin WU
    2023, 43(3):  439-446.  doi:10.7525/j.issn.1673-5102.2023.03.014
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    To clarify the differences of primary metabolism between Acanthopanax senticosus and A. sessiliflorus in different organs, and to explore their pharmacodynamic differences, medicinal value, and resource utilization structure, the metabolomics research strategy and GC-MS technology were used as methods. The results showed that 186 primary metabolites were identified in different parts of the two medicinal plants, and there were differences in primary metabolism between the two species. Further analysis showed that 52 differential metabolites in roots, 34 differential metabolites in stems, 39 differential metabolites in leaves, and 48 differential metabolites in petioles, were obtained respectively. The main metabolic pathways involved in differential metabolites were the aminoacyl tRNA biosynthesis pathway; biosynthetic pathways of valine, leucine, and isoleucine; glycine, serine, and threonine metabolic pathways; biosynthetic pathway of arginine; alanine, aspartate, and glutamate metabolic pathways; pyruvate metabolic pathway, respectively. In addition, there were differences in the levels of four key metabolites connecting primary metabolism and secondary metabolism in different organs respectively. A. senticosus and A. sessiliflorus were significantly different in the primary metabolism of different organs, which might be one of the reasons for the differences in pharmacological effects and secondary metabolism of different organs between the two species.

    Plant reproductive biology
    Morph-anatomy of Leaf and Taxonomic Insights of Eight Viola species from Yunnan,China
    Qin TIAN, Chengyan SHAO, Hanning DUAN, Chenxuan YANG, Lu LI
    2023, 43(3):  447-460.  doi:10.7525/j.issn.1673-5102.2023.03.015
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    The taxonomy of Viola L. has been problematic due to its varied morphology in a large number of species with a wide distribution. To solve its taxonomic problem, leaf morphology and anatomy in eight Viola species from Yunnan, China were investigated using the microscope and paraffine section. The results showed that: (1)There were four leaf shapes grouped into the reniform, the hastate, the ovate, and the three-lobed types. (2)There were three types of uniseriately single-celled trichome, including the short-column, the medium-column, and the long-column, growing along the margins and veins of leaves. (3)The anticlinal wall of epidermal cells was the straight-arched, the sinuolate, and the sinuous patterns respectively. Most of the stomata were orbicular while some wereelliptical, which comprised the paracytic, the diacytic, and the anomocytic patterns. (4)The outlines of mid-rib transverse section were divided into the equal and the unequal types based on the different sizes between the adaxial and the abaxial epidermis. (5)The shapes of cross section of the petiole were grouped into the elliptical, the sub-orbicular, and the circle patterns, with obvious adaxially lateral wings and ridges. The number of vascular bundles was one or three, with varied three outlines containing the round, the shallowly U-type, and the deeply U-type. It was showed that some selected features of morpho-anatomy of leaf were much valuable for problematic species delimitation, including the leaf shape, the trichome, the epidermal cell, the outline of vascular bundle, and the shape of cross section of leaf and petiole. Additionally, it was supported that V. inconspicuaV. prionantha, and V. philippica should be treated as three independent species.

    Anatomical Structure and Ecological Adaptability of Stems and Leaves of Rhamnus ussuriensis
    Qingsong WU, Yinghui LIU, Shuo LI, Panpan LI, Youmin ZHANG
    2023, 43(3):  461-469.  doi:10.7525/j.issn.1673-5102.2023.03.016
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    To investigate the adaptability mechanism of the anatomical structure of the Rhamnus ussuriensis stems and leaves to the environment, the stems and leaves of Rh. ussuriensisis were studied by paraffin sections and scanning electron microscopy. The results showed that: leaf blade of Rh. ussuriensisis was bifacial; trichomes and stomata were distributed in lower epidermis; stomatal index was 39.04 %; the palisade tissue was composed of two layers of parenchyma cells; the palisade tissue had a compact structure, however, the spongy tissue was loosely arranged. The main veins of the leaves were developed, the vascular bundles were arranged in the ring-shape, the number of xylem vessels and the diameter was large respectively, and the parenchyma cells around the vascular bundle contained abundant ergastic substance. In the primary structure of stem, the cuticle of epidermal cells was thick, and the cells of cortex parenchyma contained crystal clusters. The vascular bundle was open collateral vascular bundle; the medulla was developed; the secondary structure of the stem had obvious annual rings, which was a typical ring-porous wood, with concave lenticels and developed secondary xylem; most of the vessels were spiral vessels and pitted vessels, and the vessel member were mostly compound pores. The rays were mainly single rays, with a small number of double rays. The anatomical structure of the R. ussuriensishas leaves and stems had obvious characteristics of drought resistance and cold resistance, it might adapt to arid and cold environments.

    Pollen Morphological Characters of 20 Species from Camellia Sect. Theopsis and Sect. Eriandria
    Yali ZHANG, Naiying YANG, Yao SONG, Xiangpeng LI, Weizhen GUO, Youming CAI
    2023, 43(3):  470-480.  doi:10.7525/j.issn.1673-5102.2023.03.017
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    To provide references for the phylogenetic evolution, classification and identification of plants in Camellia Sect. Theopsis and Camellia Sect. Eriandria were studied by pollen morphology. 20 species of the two sections, pollen shape and exine sculpture were used as materials and observed by scanning electron microscopy(SEM). Results indicated: (1)Pollen size of 20 species mainly belonged to medium(25-50 μm) and large(50-100 μm) pollen. The pollens were all single-grain pollen with three grooves, three-cracked in the polar view and long spherical in the equatorial view. (2)There were three types of pollen exine sculpture, including foveolate, granulate and verrucate. C. elongata was foveolate type, C. forrestii, and C. forrestii var. acutisepala were verrucate type, and the other 17 species were granulate type. We considered that the evolution trend of pollen exine sculpture of the two sections was foveolate→granulate→verrucate. The results of pollen exine sculpture types supported the view that Sect. Theopsis and Sect. Eriandria were a monophyletic clade, while the taxonomic status of C. tsofuii and C. lipoensis should be further studied.