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    20 November 2023, Volume 43 Issue 6
    Taxonomy
    Rediscovery and Supplementary Morphological Description of the Oreocharis parvifolia (Gesneriaceae)
    Huan LI, Yulu ZHOU, Quanyuan LI, Fang WEN, Xinxiang BAI
    2023, 43(6):  801-805.  doi:10.7525/j.issn.1673-5102.2023.06.001
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    Oreocharis parvifolia, a perennial herb in Gesneriaceae Rich. & Juss., was originally collected by French missionary J.P.Cavalerie in Guizhou in 1908, and published as a new species by Pan Kaiyu in 1988. However, there was no further related collections records and images for the next 100 years. Based on literature and type sample research, combined with field investigation, the type origin of this species was confirmed in August 2022, the supplementary morphological was described, and color photos and distribution point information were provided.

    Asplenium×akaishiense Otsuka (Aspleniaceae), a New Recorded Hybrid Species from China
    Yanfei YIN, Jianquan TANG, Huayuan Zhao, Jijian ZHAO, Yingying XIANG, Weixing SHEN
    2023, 43(6):  806-809.  doi:10.7525/j.issn.1673-5102.2023.06.002
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    Asplenium×akaishiense Otsuka, a new recorded species in China, was collected from Mount Taishan, Tai’an, Shandong Province, and the morphological characteristics of A.×akaishiense Otsuka was described. It was speculated that the plant might be a natural hybrid of A. ruprechtii Sa. Kurata and A. tenuicaule Hayata, for its morphology was between the two parents.

    Systematic and Evolutionary
    Taxonomy and Geographical Distribution of the Genus Eurhynchiastrum(Brachytheciaceae, Bryophyta) in China
    Yilin ZHAO, Yang SU, Hongzhu LIANG, Youfang WANG, Min LI
    2023, 43(6):  810-814.  doi:10.7525/j.issn.1673-5102.2023.06.003
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    Since its establishment in 2002, no taxonomic study on the genus Eurhynchiastrum Ignatov & Huttunen has been carried out in China. Based on the related specimens and literatures, the authors conducted an investigation on the genus in China. The results showed that the genus was distributed in China with a single species, E.pulchellum(Hedw.) Ignatov & Huttunen. The morphological characters, habitats and geographical distribution of the species were described. Additionally, a plate illustrating the main morphological features was provided, and a discussion on the comparison among allied genera and species was included. Furthermore, the potential geographic distribution of E.pulchellum in China was predicted.

    Genetic and Breeding
    Effects of Light Signal on Anthocyanin Biosynthesis and Gene Expression of AmRosea1 Overexpressed 84K Poplar
    Huiling YAN, Xinxin ZHANG, Xiyang ZHAO, Guanzheng QU, Zhaoning WANG, Rui HAN
    2023, 43(6):  815-825.  doi:10.7525/j.issn.1673-5102.2023.06.004
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    To explore the reasons of color change in AmRosea1 overexpressed 84K poplar(Populus alba× P. glandulosa ‘84K’) caused by light signal, the wild type and AmRosea1 overexpressed 84K poplar were used as the materials. The anthocyanin content, chlorophyll content, soluble sugar content and POD activity under LED light, natural light, LED red light, LED blue light, and LED red and blue light treatment were measured, and the changes of physiological indexes of wild type and transgenic lines under different optical signal were determined respectively. The results showed that under different light intensities, compared with the LED light treatment, the leaves of the transgenic lines turned red, and the anthocyanin content and soluble sugar content increased, and the chlorophyll content and POD activity decreased under natural light. After 30 days of different light treatments, the LED red-blue light treatment that the antho-cyanin content increased, the soluble sugar content and POD activity decreased, and the chlorophyll content decreased slightly under LED red and blue light induction compared with LED red and blue light. Based on the experimental results, it was speculated that strong light and red and blue light quality might activate the anthocyanin biosynthesis pathway and accumulate a large amount of anthocyanins in AmRosea1 overexpressed 84K poplar, which in turn the leaves turned red.

    Phenotypic Variation and Diversity Analysis of Tilia mandshurica Natural Populations Based on Leaf and Fruit Traits
    Huaizhi MU, Qingyu WANG, Yue ZHANG, Songtong LÜ, Xuhong JIN, Xiao ZHANG, Fucai XIA
    2023, 43(6):  826-834.  doi:10.7525/j.issn.1673-5102.2023.06.005
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    In order to explore phenotypic variation and diversity of Tilia mandshurica natural populations, and to provide reference for the selection, protection, and utilization of T.mandshurica germplasm resources. Leaves and fruits from eight T.mandshurica natural populations were measured for the determination of 11 phenotypic traits, and the phenotypic traits from different populations were compared by variance analysis, coefficient of variation and Shannon-Wiener index, and eight populations were conducted by principal component analysis and cluster analysis. Variance analysis showed extremely significant differences in leaf and fruit traits among different populations and within populations, and the percentage of variance component among populations for each trait was higher than that of within populations, and phenotypic differentiation coefficients ranged from 0.83-0.95, and the main source of phenotypic differences was from different populations. The coefficient of variation of different traits ranged from 20.0%-39.9%, indicating a large degree of variation. The Shannon-Wiener index of different traits from different populations ranged from 1.262-1.443, indicating rich phenotypic diversity populations. The 11 phenotypic traits were divided into four principal components, with a cumulative variance contribution rate of 88.46%. According to the principal component comprehensive model, the comprehensive ranking of the eight populations from high to low was Hunchun, Longtan, Huinan, Jiaohe, Dongfeng, Dunhua, Huadian and Luobei. According to leaf and fruit traits, the eight populations were clustered into three groups, among which Dongfeng and Luobei had relatively larger leaf, while Dunhua, Hunchun, Huadian, and Jiaohe belonged to the groups with larger fruit petiole and bract. The left populations, Longtan and Huinan belonged to the larger fruit group. The phenotypic traits of T.mandshurica natural populations exhibited significant variation and rich diversity, and the main source of phenotypic differences was from inter-population variation, and large gains might be achieved through selection.

    Effects of Different Vectors and Agrobacteriumtumefaciens on Transient Expression of Alfalfa
    Min SUN, Honghong YANG, Anqi WANG, Yuejing ZHANG, Xiaowei DA, Ji ZHANG, Kun SUN, Jianping WU, Hanqing FENG
    2023, 43(6):  835-845.  doi:10.7525/j.issn.1673-5102.2023.06.006
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    Alfalfa(Medicago sativa) is an important forage plants. In order to effectively express foreign genes in alfalfa, by using the green fluorescent protein(GFP) as report gene and Nicotiana benthamiana as a comparison, the effects of two different vectors(the non-replicating and the BeYDV(bean yellow dwarf virus)-based replicating vectors), and two different Agrobacterium tumefaciens strains(LBA4404 and EHA105) on the transient expression of alfalfa leaves were investigated. The results showed that the combination of LBA4404 with the replicating vector(re-vector/LBA4404) led to effective expression of GFP in alfalfa leaves. By using LBA4404 with the replicating vector, the effects of the concentration ofre-vector/LBA4404 and incubation time after infection on the transient expression were also evaluated. It was found that with the increase of concentration of bacterial suspension or time post-infection, the expression level of GFP increased first but then decreased. In the leaves of alfalfa, the highest expression level of GFP was observed when the concentration of LBA4404 strain was 1.0(OD600); and the expression level of GFP reached the peak at 5-7 d after infection. Compared with Nicotiana benthamiana, achieving the highest expression level of GFP in alfalfa might need higher concentration of Agrobacterium tumefaciens and longer incubation time after infection.

    Physiology and Ecology
    Effects of Different Pruning Treatments on Growth and Photosynthetic Characteristics of 10-year-old Triploid Populus tomentosa
    Tianmeng REN, Yu BAO, Yaxun SU, Qingbin CHEN, Liying WEI, Ruoxuan JI, Xiao YU, Xinli XIA, Weilun YIN, Chao LIU
    2023, 43(6):  846-856.  doi:10.7525/j.issn.1673-5102.2023.06.007
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    In order to explore the response of photosynthetic physiological characteristics to different pruning intensities in Populus of middle and high forest age, 10-year-old triploid Populustomentosa asexual lines B301 and S86 were used as materials, light pruning(pruning the lower 1/3 of the canopy) and heavy pruning(pruning the lower 1/2 of the canopy) and unpruned trees as the control were adopted respectively. The results showed that pruning had no significant effect on the growth rate of height, diameter at breast height and wood volume of 10-year-old Populus, but heavy pruning increased the net photosynthetic rate(Pn), transpiration rate(Tr), and stomatal conductance(Gs) of their remaining leaves and enhanced material synthesis at the single-leaf level, while pruning had no significant effect on instantaneous water use efficiency(WUE). From a comprehensive analysis of growth and physiology, pruning the lower 1/2 of the canopy could improve the physiological condition of 10-year-old Populus tomentosa, but had no significant effect on the growth of the stand.

    Effects of Stand Age on Functional Traits and Understory Soil Physicochemical Properties of Populus tomentosa and Their Coupling Relationships
    Yuwei YANG, Baohui HE, Xuejiao HAN, Haixiang SHI, Guimin ZHANG, Xinghui LU
    2023, 43(6):  857-867.  doi:10.7525/j.issn.1673-5102.2023.06.008
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    In order to reveal the adaptation strategy of Populus tomentosa to the environment, and to provide scientific basis for better forest management, the 10-, 20- and 35-year-old Populus tomentosa in the Yellow River floodplain of western Shandong Province were taken as the research objects, and 10 indicators of branch and leaf functional traits were measured, and the changes of community functional traits with the different stand ages were analyzed, and the main indicators affecting the changes of functional traits were clarified, and the relationships between functional traits and environmental factors were analyzed respectively. The results showed that (1)the coefficient of variation of branch density was the smallest, 10.431, and the coefficient of variation of leaf nitrogen-phosphorus ratio was 94.243, which indicated that leaf nitrogen-phosphorus ratio was greatly affected by the different stand ages, while branch density was more stable. leaf nitrogen-phosphorus ratios were significantly lower than 14 in three stand ages, indicated that the growth was manly limited by nitrogen. (2)As the age of the forest increased, the soil environment was improved, soil total nitrogen and soil available potassium showed an increasing trend, and the soil bulk density showed a decreasing trend, these changes were conducive to the better growth of P.tomentosa. (3)Among the environmental factors, stand density, soil available potassium content, soil bulk density and soil water content were the environmental factors that significantly affecting the growth of P.tomentosa. The results proved that the functional traits of the P.tomentosa showed strong adaptability in balancing growth and environmental changes at different stand ages, and that the growth of P.tomentosa in this region was mainly limited by nitrogen, so nitrogen fertilizer could be applied appropriately to facilitate its growth.

    Effects of “Fertilizer Island” Effect of Desert Plants on Spatial Distribution of Soil Nutrients
    Galip NARGIZA, Yuxin XIAO, Boyi SONG, Weiwei ZHUANG
    2023, 43(6):  868-880.  doi:10.7525/j.issn.1673-5102.2023.06.009
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    In order to explore the the “fertilizer island” effect in different spatial positions of two shrubs in the Gurbantunggut Desert, the dominant shrubs in the desert-Eremosparton songoricum and Calligonum mongolicum were used as research objects. Sampling points were set up by extending outward at 20(A), 60(B), 100(C), and 140 cm(D) with the shrub root as the center, each sampling point was sampled at three soil depths (0<h≤5 cm, 5 cm<h≤10 cm, 10 cm<h≤20 cm, and the soil nutrient content and enrichment at different spatial locations were analyzed respectively. The results indicated that: (1)Both E. songoricum and C. mongolicum had a “fertilizer island” effect, and there were significant differences in soil nutrient content among different species and spatial locations(P<0.05). The variation trend of the two plant soil nutrients in different spatial distributions was the same, that was, in the horizontal direction, they gradually decreased as the distance from the center of the shrub increased. Among them, the soil SOM, AK, and TN contents of E. songoricum at location D were decreased by an average of 58.16%, 52.94%, and 68.18% compared to A, respectively. The content of SOM, AK, TN, and EC in the soil at location D were decreased by an average of 61.38%, 13.33%, 69.23%, and 21.81%, respectively, compared to location A. In the vertical direction, the content of SOM, AK, and TN in the soil of the two types of plants showed the highest nutrient content in the surface soil, and showed a decreasing trend with the increase of soil depth. The content of AK, pH, and N-NO3- in the rhizosphere soil of C. mongolicum was significantly higher than that of E. songoricumP<0.05). (2)The enrichment rates of SOM, AK, TN, and total phosphorus(TP) in the soil of the two shrubs showed consistent trends, that was, the enrichment rate of soil nutrients gradually decreased with the increase of soil depth, and the enrichment rate of soil nutrients gradually decreased with the increase of shrub center. (3)There was a significant correlation(P<0.05) between soil enrichment rates at different spatial locations and plant height and crown width. The plant height and crown width of E. songoricum and C. mongolicum showed a significant positive correlation with soil SOM, TN, N-NO3- enrichment rates. In general, both plants showed a “fertilizer island effect”, with obvious spatial heterogeneity in different spatial distributions, different plants had different enrichment capacities for soil nutrients, and their “fertilizer island” effects were also different, with obvious species effects.

    Physiological Adaptation of Six Mangrove Seedlings to Different Salinity
    Fazhi FANG, Huiying GUI, Zhaojia LI, Xiaofeng ZHANG
    2023, 43(6):  881-889.  doi:10.7525/j.issn.1673-5102.2023.06.010
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    To investigate the physiological adaptability of mangrove plants under different salinity, the influences of different salinity(0, 5%, 10%, 15%, 20%, 25%, 30%, 35%) on the growth of six mangrove species(Bruguiera gymnorhizaCeriops tagalRhizophora stylosaBruguiera sexangulaAegiceras corniculatumKandelia obovata) were assayed, and the morphological and physiological characteristics of six species were determined respectively, including the biomass, plant height increment, base diameter increment, net photosynthetic rate, chlorophyll a content, chlorophyll b content, total chlorophyll content, superoxide dismutase(SOD) activity, proline(Pro) content and malondialdehyde(MDA) content. The results showed that the 5%-20% was suitable salinity for the growth of six mangrove seedlings, and the Parmentiera cerifera had high salt tolerance. The SOD activity, Pro content and MDA content and chlorophyll content of six mangrove seedlings increased, but net photosynthetic rate and growth rate decreased under salt stress. The results showed that the photosynthesis of the six species seedlings decreased under salt stress, the photosynthetic rate increased by increasing the chlorophyll content, and the plant stress resistance might be improved by increasing the SOD activity, Pro content and MDA content in the leaves.

    Interannual Changes in the Effects of Soil Gravel Content on the Growth and Physiology of Handeliodendron bodinieri Seedlings
    Chaoyang MA, Tianfeng LIU, Xiaoxue LI, Cancan HUO, Lingling FU, Zailiu LI
    2023, 43(6):  890-899.  doi:10.7525/j.issn.1673-5102.2023.06.011
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    Handeliodendron bodinieri is an endangered species endemic in karst areas of southwest China. In order to explore the influence of soil gravel content on the growth and physiological characteristics of H. bodinieri seedlings in three consecutives growing seasons, annual H. bodinieri seedlings were used as experimental materials, different soil gravel content(0(control), 20%, 40%, 60%, 80%) were set, and the growth, photosynthesis and physiological indicators of each group of seedlings were determined and evaluated in three consecutive growth seasons. The results showed that in the first growing season, when the soil gravel content was 60%, the net photosynthetic rate of the seedlings was significantly higher than that of the control group; When the soil gravel content was 40%, the growth rate of seedling diameter, leaf biomass, transpiration rate, stomatal conductance, soluble protein mass fraction, and superoxide dismutase(SOD) activity were significantly higher than those of the control group; The intercellular CO2 molar fraction and soluble sugar mass fraction of seedlings were significantly higher than those of the control group when the gravel content was greater than 20%; There was no significant difference in plant height growth rate, leaf area, root, stem, and total biomass between the control group and the control group. In the second growing season, when the soil gravel content was 60%, the transpiration rate and soluble protein mass fraction of H. bodinieri seedlings were significantly higher than those of the control group; When the soil gravel content was 40%, the SOD activity of the seedlings was significantly higher than the control group, and the stem biomass was significantly higher than the control group when the soil gravel content was 20%. The other indicators showed similar trends to the first growth season. With the extension of the growing season, in the third growing season, the growth rate of plant height and ground diameter, stem biomass, leaf area, stomatal conductance, SOD and POD activities of H. bodinieri seedlings reached the maximum when the soil gravel content was 60%, which was significantly higher than that of the control group; The net photosynthetic rate and intercellular CO2 concentration of seedlings reached the maximum when the soil gravel content was 40%, which was significantly higher than that of the control group. The comprehensive analysis showed that in the three consecutive growth seasons, the soil gravel content with the highest score of H. bodinieri seedlings was 40%, 40% and 60% respectively. For three consecutive growth seasons, seedlings grew best at 60% soil gravel content.

    Effect of Current Twig Stem Structure on Leaf Spreading Efficiency of Different Oriental Cherry Cultivars
    Zihong HUANG, Shujun YAN, Qiang YU, Yongxin GUAN, Ling LING, Yuting SUN
    2023, 43(6):  900-909.  doi:10.7525/j.issn.1673-5102.2023.06.012
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    In order to clarify the differences in the adaptability of branches and leaves of different oriental cherry cultivars in resource utilization, biomass allocation, and leaf display strategies, and the effect of current twig stem structure on leaf spreading efficiency were discussed. 15 oriental cherry cultivars in Fuzhou National Forest Park were used as materials, and the stem length and stem slender ratio were used as the proxy of stem structure traits, and the leaf density, leaf/stem mass ratio and leaf area ratio were used to characterize the leaf spreading efficiency, and oriental cherry cultivars with greater leaf display efficiency were screened, the standardized major axis estimation (SMA) was employed to identify whether there was a significant difference on the link between stem structure and leaf display efficiency among different cultivars. The results showed that: (1)In 15 oriental cherry cultivars, there was a substantial negative relationship between stem structure and leaf display efficiency, with stem length and stem slender ratio increased, leaf density, leaf/stem mass ratio and leaf area ratio all steadily decreased respectively. (2)The leaf/stem mass ratio, leaf area ratio and leaf density of 15 cherry cultivars differed with stem structure increased. ‘Hejin’(HJ), ‘Taiwan mudan’(TWMD) and ‘Yunnan’(YNDY) performed better in terms of leaf density. In terms of leaf area ratio, ‘Danhong’(DH), YNDY and HJ performed better; that was, YNDY and HJ had higher leaf density and leaf area ratio under a specific stem structure. (3)Under specific stem structures, ‘Xishi’(XS), ‘Chumeiren’(CMR), ‘Jingweng’(JW) and HJ showed greater leaf/stem mass ratios. Combined with florescence, ‘Hejin’(HJ) had relatively higher leaf spreading efficiency and longer flowering period, which could be widely planted.

    Relationship Between Leaf Force-to-punch and Leaf Functional Traits under Different Measurement Methods
    Meijing OU, Hongyan LI, Qiuju ZHAO, Jiawei LI
    2023, 43(6):  910-922.  doi:10.7525/j.issn.1673-5102.2023.06.013
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    In order to investigate whether there were differences in the results of leaf force-to-punch under different calibration methods and different puncture needle diameters, and the relationship between the results and leaf functional traits, 30 dicotyledonous species were selected to determine the punching force and the tearing force of the leaves and the functional traits of leaves under three puncture needle diameters of 2.0, 1.0 and 0.5 mm, respectively. The results showed that: (1)the leaf force-to-punch differed significantly(P<0.05) among the three different puncture needle diameters, for the same species when the method calibrated by perimeter, the difference between 0.5 mm and 1.0 mm was 76%, between 0.5 mm and 2.0 mm was 76%, and between 1.0 mm and 2.0 mm was 33%(P<0.05); however, when calibrated by cross-sectional area, the difference was 66%, 56% and 30%(P<0.05) respectively. (2)There was no significant difference in leaf force to punch between the three puncture needle diameters under different calibration methods in the same life form, but there was significant differences(P<0.05) between herbs and different life form such as shrubs and trees, respectively, while the leaf force-to-punch of 0.5 mm diameter needles was greater than that of 1 and 2 mm needles. (3)Leaf force to punch was significantly positively correlated with leaf cuticle thickness, leaf thickness, and leaf tearing force(P<0.05), and negatively correlated with specific leaf area(P<0.05), and the correlation between punching force calibrated by needle circumference and leaf functional traits was stronger than that calibrated by cross-sectional area, whereas there was no significant difference in the correlation between leaf force to punch and leaf traits under the action of different diameters of puncture needles. Therefore, differences in both needle diameter and calibration methods produced differences in the results of leaf force to punch measurements. Differences in needle diameters did not affect the correlation between mechanical punching force and leaf functional traits, whereas differences in calibration methods affected the strength of the correlation between mechanical punching force and leaf functional traits. In conclusion, in the leaf force to punch research, selecting the appropriate calibration method and puncture needle diameter was conducive to improving the standardization and accuracy of the data, it was recommended that the two calibration methods based on the needle perimeter should be selected first, and among the three types of puncture needle diameter, 0.5 mm was selected to measure with small leaf area and dense and thin veins, and 2.0 mm was selected to measure with large leaf area and, dense and stiff veins.

    Ecological Stoichiometry and Homeostasis of Alpine Quercus semicarpifolia Leaves in Subalpine Zone of Hengduan Mountains
    Hongbo LI, Shi CHEN, Yaohua HUANG, Dingxu KANG, Jianrong WU, Huancheng MA
    2023, 43(6):  923-931.  doi:10.7525/j.issn.1673-5102.2023.06.014
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    To reveal the ecological adaptation mechanism of Quercus semicarpifolia in the subalpine zone of the Hengduan Mountains, the leaves and growing soil of eight plots were selected, and the C, N and P contents and their stoichiometric characteristics of leaves and growing substrate soil were measured, and the growth-limiting elements were determined. The ecological stoichiometry homeostasis model was used to determine the state of the alpine Quercus leaves. The soil C, N and P contents of the selected eight plots ranged from 38.86-70.19, 3.54-9.46 and 0.61-2.05 g?kg-1, with soil ω(C)∶ω(N) 5.65-16.07, ω(C)∶ω(P) 36.98-74.42 and ω(N)∶ω(P) 4.41-12.90, mean values were 9.48, 51.79 and 6.54, respectively. Leaf C, N and P contents ranged from 428.31-473.86, 21.22-31.68 and 2.21-3.68 g?kg-1, leaf ω(C)∶ω(N), ω(C)∶ω(P), and ω(N)∶ω(P) were 14.16-22.46, 121.41-215.86 and 6.99-12.84, with mean values of 17.36, 164.39 and 9.68, respectively. The alpine Quercus leaf N and P contents were higher than the global average. Leaf N and soil P, leaf N and soil ω(C)∶ω(N), leaf ω(C)∶ω(P) and soil ω(N)∶ω(P), leaf ω(C)∶ω(N) and soil ω(N)∶ω(P), and leaf ω(C)∶ω(P) and leaf ω(N)∶ω(P) were highly significantly and positively correlated in each plot (P<0.01). In addition,the leaf stoichiometric homeostasis index of alpine Quercus were probed in terms of 1/H absolute values, while 1/Hω(N) was -0.181-0.141, 1/Hω(P) was -1.255-1.206, and 1/Hω(N)∶ω(P)] was 0.391-0.960. The results indicated that each alpine Quercus 1/Hω(N) was in the homeostasis state, 1/H ω(P) and 1/Hω(N)∶ω(P)] were mostly in the weakly homeostasis state, weakly sensitive and sensitive state. Leaf ω(N)∶ω(P) ratio was less than or close to 16, illustrating that alpine Quercus in this region tended to be not deficient in both N and P elements. Alpine Quercus might overstore N and P elements to adapt to the changing external habitat, but still had a more conservative strategy for the use of external P elements. The alpine Quercus forests in this region had formed a good nutrient supply and return relationship with the soil in the long-term succession process, which had formed a relatively complete and stable subalpine forest ecosystem.

    Molecular biology
    Expression Pattern Analysis of PdbHMGs Genes in Populus davidiana×P. bolleana under Abiotic Stress
    Chunyao WANG, Xiaojin LEI, Zhongyuan LIU
    2023, 43(6):  932-942.  doi:10.7525/j.issn.1673-5102.2023.06.015
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    In order to investigate the function of HMG(High mobility group proteins) genes under abiotic stresses in Populus davidiana×P. bolleana, the HMG genes were cloned and the stress tolerant function of HMGs was identified, and the theoretical foundation for using the gene in tree breeding through genetic engineering was laid. Seven homologous genes of ArabidopsisHMGs(named PdbHMG1-7) were found by homologous sequence alignment, and sequence analysis of PdbHMG1-7 was performed using bioinformatics tools respectively, the expression patterns of PdbHMG1-7 gene in leaves and roots of Populus davidiana×P.bolleana under different stresses were investigated by qRT-PCR.Results The ORF length of PdbHMG1-7 were 456-2 004 bp respectively, the amino acid residues encoded by PdbHMG1-7 genes were 151-667 aa, and the molecular weight of the encoded protein were 16.72-75.54 kDa, and the theoretical isoelectric point were 5.35-9.36, and the seven PdbHMG were hydrophilic proteins. The results of multiple sequence alignment and phylogenetic tree analysis showed that all 7 PdbHMG genes contained HMG-box conserved domains and belonged to HMGB subfamily. The analysis results of cis-acting elements contained in the promoter showed that the promoter sequence of PdbHMG genes contained a variety of elements in response to hormones and stress. The expression pattern analysis showed that the expression levels of seven PdbHMGs in roots and leaves under NaCl, PEG6000, ABA and CdCl2 stress treatment changed in at least one stress treatment time point respectively. In leaves, PdbHMG2 were induced under the stress of NaCl, PEG6000, ABA and CdCl2, and almost all of them were significantly up-regulated respectively, but PdbHMG7 was down-regulated. Under NaCl and CdCl2 stress, PdbHMG1PdbHMG3 and PdbHMG6 were almost significantly up-regulated during the whole stress process respectively. The expressions of PdbHMG3 in leaves were also significantly up-regulated at most time points under NaCl and CdCl2 stress. In roots, the expression of PdbHMG3 and PdbHMG5 was significantly up-regulated in the whole process of NaCl treatment. However, PdbHMG6 was not significantly expressed during NaCl stress except for 9-12 h, the expression of PdbHMG6 was significantly down-regulated at other stress time points. During ABA treatment, PdbHMG6 was down-regulated in roots. Conclusion The results showed that seven PdbHMG genes could respond to at least one stress treatment in one organ, but the types and mechanisms of involved stress response might be different. This study provided a reference for further studying the function of PdbHMGs family genes in Populus davidiana×P. bolleana.

    Plant synecology
    Effects of Eucalyptus Introduction on Species Composition and Diversity of Understory Plant Functional Groups
    Yuanyuan TANG, Fuying DENG, Xiaoqing ZHAO, Pei HUANG, Junyi TAO, Shijie ZHOU, Bocheng CHU
    2023, 43(6):  943-952.  doi:10.7525/j.issn.1673-5102.2023.06.016
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    In order to answer the controversial question of the effects of Eucalyptus introduction on plant diversity, the Eucalyptus forest in Lancang County, a large-scale introduction area of Eucalyptus in Yunnan Province, was taken as the research object, and the secondary evergreen broad-leaved forest and artificial Pinus kesiya forest were used as reference forests, and six groups of comparative plots were set up, and the plants were divided into different functional groups. The species composition characteristics and species diversity index of each functional group under Eucalyptus forest and reference forest were compared and analyzed, and the effects of Eucalyptus introduction on the species composition and diversity of understory plant functional groups were examined. The results showed that: (1)the replacement of the secondary evergreen broad-leaved forest by Eucalyptus plantation would increase the number of species in the warm-sun-medium functional group and decrease the number of species in the warm-shade-wet functional group. The replacement of artificial Simao pine forest by Eucalyptus forest would increase the number of species in warm-shade-wet functional group and reduce the number of species in warm-sun-medium functional group. (2)the species composition and important value of understory plants changed after Eucalyptus forest replaced the two reference forests, Eupatorium adenophorum occupied the absolute dominant position of warm-sun-medium functional group, and Arthraxon hispidus occupied the absolute dominant position of warm-shade-wet functional group. (3)after Eucalyptus forest replaced the two reference forests, the Shannon-Wiener diversity index and Pielou uniformity index of the warm-sun-medium functional group under the forest were significantly decreased(P<0.05), but there was no significant effect on the species diversity index of the warm-shade-wet functional group(P>0.05). In conclusion, Eucalyptus introduction changed the species composition of understory plant functional groups, and had different effects on the species diversity of different plant functional groups.

    Plant reproductive biology
    Embryo Development and Features of Seed and Fruit of Endangered Plant Cymbidium goeringii var. longibracteatum
    Renrui WANG, Xin LIU, Jie LI
    2023, 43(6):  953-960.  doi:10.7525/j.issn.1673-5102.2023.06.017
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    The embryo development, seed formation and fruit anatomical characteristics of Cymbidium goeringii var. longibracteatum were investigated by microscopic and ultrastructure obsevation on the capsules at various developmental stages obtained by artificial self-pollination. The results showed that: megasporocyte and mature embryo sac were observed at 60 d and 80 d after pollination resepectively, and the female gametophyte was of polygonum type. Spherical embryo and suspensor structures formed after 120 d, and the suspensor degenerated and embryo body was at the globular stage after 180 d, and development of the embryo was of the solanad type. The seeds were extremely tiny, consisting of endopleura, episperm and undifferentiated globular embryo, accounting for about 24% of the seed embryo volume, and with little content of nutrients, and an air cavity between the seed coats.The ovary was composed of six carpel valves, three of which were fertile with a ‘V’ shaped placenta, and the others were infertile carpel valves without placenta. The average weight of a single seed was (3.92 ±0.40) μg, and the number of seeds in a capsule was(37.98±3.71)×104.