Abstract:In order to explore the regulation mechanism of suberin biosynthesis in Brachypodium distachyon, we cloned the transcription factor gene BdMYB92 regulating suberin synthesis in the roots of B. distachyon by bioinformatics analysis using Bd21 as the experimental material (GenBank accession number OP497966). The expression pattern of BdMYB92 gene in different tissues of B. distachyon and its response to six abiotic stress treatments (drought in the air, simulated drought in the 20% PEG-6000, 4 ℃ cold treatment, 200 mmol/L NaCl, 100 μmol/L ABA and mechanical damage) were analyzed by quantitative PCR. The interaction between BdMYB92 protein and the promoter of BdFAR4 gene was verified by dual-luciferase report assays and yeast one-hybrid. The results showed: (1) the full-length cDNA of BdMYB92 was 1 343 bp, with an open reading frame was 990 bp, encoding 329 amino acids. The molecular weight of the protein was 36.4 kD, and the theoretical isoelectric point was 5.54. (2) The subcellular localization results confirmed that BdMYB92 was located in the nucleus. (3) Quantitative PCR analysis showed that the expression of BdMYB92 was significantly higher in the root than in other tissues such as sheats, nodes, spikelets and internodes. All six abiotic stress treatments could induce the up-regulated expression of BdMYB92, and the response to drought stress was the fastest, indicating that BdMYB92 was involved in the response to stresses in B. distachyon. (4) The results of dual-luciferase report assays and yeast one-hybrid showed that BdMYB92 interacted with the promoter region of the suberin synthesis gene BdFAR4 and could directly regulate the transcription expression of the suberin synthesis gene BdFAR4. It is speculated that BdMYB92 may interact with other suberin synthesis genes in B. distachyon, thereby regulating the deposition of suberin in roots.

Abstract:The CO family genes regulate flowering time by integrating circadian rhythms, light signals, and meristem-related genes through the photoperiod pathway, and play a crucial role in the process of plant flower formation. In this study, a CO family gene cloned from Chrysanthemum lavandulifolium by RT-PCR method, was named ClCOL16 (GenBank accession number: AOA52174.1). Arabidopsis thaliana was transformed by inflorescence immersion mediated by Agrobacterium tumefaciens, and T3 generation transgenic plants were selected by resistant screening and PCR detection of the heterologous COL gene. To analysis the function of ClCOL16 in plant photoperiod regulation of flowering and lay the foundation for the further study for flowering regulation mechanism in Chrysanthemum morifolium, we cultured six transgenic lines randomly selected and the wild type (WT) of A. thaliana in a long day environment (alternating light and dark at 16 h/ 8 h) to observe their phenotypes, and detected the expression of ClCOL16 in WT and transgenic A. thaliana leaves after the 37 days of planting. The results showed: (1) ClCOL16 gene of C. lavandulifolium ORF was 1 278 bp and encoding a protein of 425 amino acids; Structural analysis showed ClCOL16 protein contains a B-box and a CCT conserved domain, which is a typical characteristic of CO family Group Ⅲ. (2) NCBI blast analysis showed that ClCOL16 protein had the highest identity with COL16 (GenBank accession number: GEZ38716.1) from Tanacetum cinerariifolium, up to 94.38%, which further proved that it belongs to the CO family Group Ⅲ. (3) Expression analysis showed that ClCOL16 gene was constitutive expression in C. lavandulifolium, and the highest expression was in leaves； ClCOL16 gene was regulated by circadian clock, under short-day condition its expression showing obvious circadian rhythm. (4) Ectopic expression showed that compared to wild type A. thaliana, the flowering time of ClCOL16 transgenic lines was advanced by 7 days, the number of rosette leaves was reduced by 3 to 4, and the expression of ClCOL16 gene in leaves was significantly increased. All the results indicated that ClCOL16 gene ectopic expression lead to early flowering in A. thaliana. According to the experimental results, we speculated that ClCOL16 gene may be an important gene involved in responding to light signal, and participating in the regulation of photoperiodic flowering pathway in C. morifolium.

Abstract:To clarify the expression characteristics of chrysanthemum miR156 and its target gene CmSPL13 in response to stress and growth and development, this study obtained the promoter sequence of MiR156 by high-fidelity PCR amplification and analyzed the sequence characteristics using chrysanthemum ‘Jinba’ as the plant material. Though hormone (methyl jasmonate, methyl salicylic acid, anxin NAA) and stress (drought, salt) treatments, the response and expression characteristics of chrysanthemum miR156 and the target gene CmSPL13 to hormone and stress were analyzed. The relationship between miR156 expression characteristics and flowering time under sucrose treatment was analyzed, which laid a foundation for the molecular mechanism of miR156 involved in the growth and development of chrysanthemum and response to stress. The results show that: (1) the MiR156 promoter was successfully cloned, which contains cis-acting elements in response to hormones including jasmonic acid, salicylic acid and auxin, anaerobic induction, drought induction and other stresses, light response and so on. (2) Under methyl jasmonate treatment, the expression level of miR156 was significantly up-regulated from 0 to 3 h, and the expression level gradually decreased after 3 h, showing a trend of first increasing and then decreasing. The expression of the target gene CmSPL13 showed a trend of first decreasing and then rising, reaching a peak at 12 h; under melhyl salicylic acid and auxin NAA treatments, the expression of miR156 decreased significantly at 3 h, then increased gradually, reached a peak at 6-12 h, and then gradually decreased, the expression of CmSPL13 has the opposite trend of miR156; under PEG treatment, the expression level of miR156 was lower than that before treatment, and gradually down-regulated from 6 to 24 h, the target gene CmSPL13 was significantly upregulated from 6 to 12 h treatment; under salt treatment, the expression level of miR156 was significantly up-regulated from 0 to 3 h, and then gradually decreased, the expression of CmSPL13 was gradually adjusted up from 6 to 12 h. (3) Quantitative real-time PCR analysis showed that the expression level of miR156 gradually decreased with the increase of chrysanthemum leaf maturity, however, the expression of CmSPL13 is gradually increasing. (4) Sucrose could inhibit the expression of miR156, significantly increase the expression of flowering-related genes CmFTL3, CmAP1L1 and CmSOC1, and promote the flowering of chrysanthemum, the flowering time in sucrose treated plants is 2.8 days earlier than non-treated control. It was suggested that miR156 and its target gene CmSPL13 were involved in the regulation from infancy to adulthood, and there is also a regulatory mechanism that sugar signals inhibit the expression of miR156 to promote chrysanthemum flowering; jasmonate and salicylic acid may antagonistically regulate the expression of miR156 and its target genes in chrysanthemum at the later stage of treatment, and may participate in the early response to salt stress.

Abstract:Based on the genome-wide expression profile of cotton seedlings under low phosphorus stress in the early stage of our research group and the genome database, we cloned a AP2/ERF gene (GhERF5) from upland cotton ‘Xinluzao 19’. Genomic DNA and cDNA sequence of the gene were cloned and analyzed by bioinformatics method. We used semi-quantitative RT-PCR and real-time PCR (qRT-PCR) to detect the gene expression changes in roots, stems, leaves, flowers and other tissues, as well as the relative expression of the gene at different time points under low phosphorus stress.The results showed that: (1) the AP2/ERF gene, named GhERF5, was successfully cloned. The length of open reading frame was 963 bp, encoding 320 amino acids. Analysis revealed that this gene sequence belonged to the AP2 family, with a conserved structure named AP2. (2) Sequence alignment analysis showed that the similarity of Gossypium arboreum L. (GaERF5) and Gossypium raimondii L. (GoraiERF5L) was 95%. Evolution analysis showed that the similarity between the GhERF5 protein sequence of G.hirsutum L. and the GhERF5L of G.hirsutum L. was the highest. It was speculated that the GhERF5 gene was located in the D sub-genome. (3) RT-PCR and qRT-PCR analysis showed that GhERF5 was expressed in all tested tissues including root, stem, leaf and flower, and the expression level was the highest in leaf, followed by root and stem, and the expression was the lowest in flower, and the change trend of low phosphorus treatment from 0-72 h was first decreasing, then rising and then decreasing, and at 72 h, low phosphorus treatment was about 33% that of suitable phosphorus treatment. This study demonstrated that GhERF5 gene belongs to low phosphorus stress response gene and may be involved in G. hirsutum L. response to low phosphorus stress.

Abstract:Squalene synthase (SQS) is one of the key enzymes in the synthesis of phytosterols and terpenoids. In order to reveal the function of SQS gene in Dioscorea nipponica, we used the cDNA of D. nipponica as template to clone the DnSQS gene by PCR, and analyzed the obtained sequence by bioinformatics. Simultaneously, the content of diosgenin in different tissues was detected by HPLC, and the expression characteristics of DnSQS gene in different tissues, hormone induction and abiotic stress were analyzed by real-time fluorescence quantitative PCR. The results showed that: (1) two genes (DnSQS1 and DnSQS2) of D. nipponica were successfully cloned. They encode 409 and 433 amino acids, respectively. However, the secondary structures of the encoded proteins consist mostly of α-helix and random coil, both of which have a conserved catalytic core generated by α-helix folding, two functional structures rich in aspartic acid, two transmembrane helix structures and are localized in the endoplasmic reticulum. (2) DnSQS1 and DnSQS2 were closely related to DzSQS, and the evolution of the two DnSQS proteins was reasonably conserved. (3) The contents of diosgenin in different tissues were different, and the levels of the content were in the order of leaf > rhizome > aboveground stem > root; the expression levels of DnSQS1 and DnSQS2 genes in different tissues were also significantly different, with DnSQS1 being expressed at the highest level in aboveground stems and DnSQS2 being expressed at the highest level in leaves. (4) The expression of two DnSQS genes could be induced by MeJA, ABA, SA, Eth, H₂O₂, NaCl and PEG-6000, while GA₃ treatment inhibited the expression of two DnSQS genes. Studies have shown that the two DnSQS genes may be involved in the synthesis of diosgenin and play an important role in the mechanism of adversity stress.

Abstract:In order to investigate the growth of Citrullus lanatus seedlings under different concentrations of cadmium stress (0, 60, 120, 180 and 240 mg/L) and the changes of physiological characteristics and anatomical structure of leaves, and preliminary explore the physiological mechanism of watermelon tolerance to cadmium stress, we took the ‘Beikang No. 1’ as experimental material, and adopted pot experiments in laboratory. The results showed that: (1) under the condition of cadmium stress, the growth of C. lanatus seedlings was inhibited. With the increase of cadmium stress concentration, the yellowing phenomenon of C. lanatus seedlings leaf morphology gradually increased, the root morphology gradually weakened, and the plant height, stem diameter, stem node number and leaf number all showed a downward trend. (2) Under cadmium stress, the cells in the main veins of C. lanatus seedling leaves were damaged, the diameter of the main veins and the density of mesophyll tissue decreased significantly. (3) With the increase of cadmium stress concentration, the water content, net photosynthetic rate and SOD activity of C. lanatus seedlings were significantly decreased, while the malondialdehyde and free proline contents were significantly increased, the POD activity and soluble protein content were increased first and then decreased, resulting in significant effects on physiological characteristics. The results showed that the C. lanatus seedlings of ‘Beikang No.1’ had certain adaptability to cadmium. Under the low concentration (60 mg/L) cadmium stress, the morphological and physiological characteristics of C. lanatus seedlings did not change significantly, but under the high concentration (180 mg/L) cadmium stress, the growth of C. lanatus seedlings was severely inhibited, and osmotic adjustment system and biofilm protection system were seriously damaged.

Abstract:To analyze the effects of flooding stress (control, mild waterflooding, waterflooding and waterlogging) on physiology, biochemistry and leaf structure of Chionanthus virginicus seedlings, and to explore their waterlogging tolerance and physiological mechanism, so as to provide theoretical basis for the introduction and cultivation application of C. virginicus, we used two years old seedlings of C. virginicus as materials to determine the changes of physiological indexes and leaf structure characteristic of C. virginicus seedlings under different degrees of flooding and different stress time points. The results showed that: (1) the POD activity of C. virginicus leaves showed a “decline-rise-decline” trend under mild waterflooding and waterlogging, and showed a first decrease and then increase trend under waterlogging. Under each waterlogging treatment, SOD activity increased first and then decreased, while relative conductivity increased, and MDA accumulated in different degrees. Under mild waterlogging, the contents of SS and SP increased first and then decreased. Under waterflooding and waterlogging, the content of SS increased, and the content of SP decreased first and then increased. (2) With the increase of stress degree, the thickness of leaves increased, the thickness of top and lower epidermis decreased, palisade tissue thickness, spongy tissue thickness, CTR and P/S decreased first and then increased, and SR increased first and then decreased. (3) Under waterlogging stress, the chloroplasts were enlarged and rounded, most of them did not stick to the cell wall, the margins degraded, osmophilic grains and starch grains expanded and increased, and the grana lamellae were vacuolized. The intensification of stress resulted in the degradation of nuclei and chloroplasts, the accumulation of starch granules and cell death. (4) Leaf top epidermis thickness had very significantly positive correlation with SOD activity and significantly positive correlation with POD activity. The Palisade tissue thickness had very significantly positive correlation with the contents of MDA and SS, and significantly positive correlation with the content of SP. Leaf thickness had very significantly positive correlation with relative conductivity, MDA, SS and SP contents. The spongy tissue thickness had significantly positive correlation with the relative conductivity and SS content. In conclusion, mild waterflooding and waterflooding had little effect on C. virginicus seedlings. The seedlings could adapt to stress by adjusting physiological indexes and leaf structure, and had certain waterlogging tolerance. Under waterlogging treatment, the physiological indexes and leaf structure of seedlings changed obviously, and the plants died a lot.

Abstract:Rudbeckia hirta not only had the ability of cold，drought and saline-alkali resistance, but also was the most commonly used ground cover plant in urban landscaping. In this study, Funneliformis mosseae was selected as the inoculant substrate in pot experiments. 70 days after the colonization, NaCl and NaHCO₃ solutions at different concentrations (0, 65, 135, 195 and 260 mmol·L^-1) were subjected to salt or alkali stress. After 10 days of treatment, we determined AM fungal colonization, chlorophyll content, malondialdehyde (MDA) content, antioxidant enzymatic activity and osmotic regulation substance, so as to clarify the effects of AM fungus on the root colonization status and salinity tolerance of R. hirta and to provide a theoretical basis for the use of R. hirta to repair saline-alkali soil and the application of AM fungi in practical production. The results showed that: (1) compared to control, colonization rate and colonization intensity of AM fungi under salt stress were significantly reduced, while the trend of rising and then decreasing under alkali stress was shown. (2) Under saline-alkali stress, AM fungi could increase chlorophyll content and decrease MDA content in leaves of R. hirta to a certain extent compared with uncolonized plants. As the concentration of saline-alkali solution increases, AM fungi could not only improve the R. hirta proline, soluble sugar and soluble protein contents of osmotic regulation substances, also could enhance plant activities of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX), which indicated that inoculation of AM fungi could improve the saline-alkali tolerance of R. hirta. (3) PCA analysis showed that the resistance mechanisms between salt stress and alkali stress were not the same，with chlorophyll, MDA, POD, SOD, proline and soluble sugar as the main factors in salt stress, and SOD, CAT and proline as the dominant factors in alkali stress. In addition, VPA analysis also showed that AM fungi had a greater effect on the overall physiological characteristics of R. hirta than saline-alkali stress. The results showed that low alkali stress could promote the colonization of R. hirta by AM fungi, and inoculation of AM fungi could significantly reduce the MDA content of R. hirta under saline-alkali stress, improved antioxidant enzyme activity and osmoregulatory substance accumulation, so as to improve the salinity tolerance of R. hirta.

Abstract:5-aminolevulinic acid (ALA), a key biosynthetic precursor of tetrapyrroles, is vital for plants adaptation to abiotic stress. To verify the effects of different concentrations of ALA, we applied exogenous ALA with different concentrations (0, 5, 10, 15, 20, 25 mg·L^-1) to the leaves of Lycium ruthenicum seedlings subjected to 300 mmol·L^-1 NaCl. Then, the physiological and growth indexes of L. ruthenicum seedlings were determined, and comprehensively evaluated the salt tolerance of the seedlings under each treatments. Results revealed that: (1) compared with the control, the plant biomass, the contents of chlorophyll, carotenoid and soluble protein, the activity of POD were significantly decreased by 33.39%, 19.06%, 24.38%, 39.57% and 47.91% (P<0.05) in L. ruthenicum leaves under the salt stress, but the contents of proline (Pro) and malondialdehyde (MDA) were significantly increased by 165.74% and 49.16%, respectively. (2) When exogenous ALA and NaCl were treated at the same time, the contents of carotenoid and malondialdehyde (MDA), the activities of CAT, POD, the plant height and total biomass were restored to the control level, and the contents of chlorophyll and proline (Pro) were significantly increased compared with the control in L. ruthenicum seedlings. (3) The contents of carotenoid and proline, the activities of antioxidant enzymes and biomass of the leaves of L. ruthenicum seedlings performed a trend that first increased and then decreased with the add of ALA concentration. The evaluation by membership function analysis indicated that 15 mg·L^-1 ALA had the best effects on alleviating salt stress in L. ruthenicum seedlings under 300 mmol·L^-1 NaCl stress. These findings suggested that ALA of appropriate concentration can regulate photosynthesis and antioxidant enzyme activities of L. ruthenicum seedlings by promoting the accumulation of chlorophyll and heme, and increase the accumulation of proline in vivo, thus effectively alleviating the toxic effect of salt stress on plants and promoting plant growth.

Abstract:In this study, the responses of CaCl₂ addition to seedlings of Cornus hongkongensis subsp. tonkinensis, which were subjected to 3‰ salt stress, were evaluated by physiological indexes, including seedling growth, phytosynthetic pigment content, photosynthetic gas exchange parameters and osmotic regulation substance content, etc. The main results were: (1) 3‰ sea salt stress significantly inhibited seedling growth, increased the contents of malondialdehyde (MDA), soluble sugar, soluble protein, proline and activity of superoxide dismutase (SOD), increased photosynthetic pigment synthesis, photosynthetic parameters including intercellular carbon dioxide concentration (C_i), net photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r). (2) For alleviating treatments with CaCl₂ to stressed seedlings by 3‰ salt, application of CaCl₂ with low concentration (10-20 mmol·L^-1) to stressed seedlings reduced the salt damage rate and mortality rate, decreased SP content and further promoted leaf and plant biomass of seedlings. Correspondingly, MDA content in alleviated seedlings was significantly decreased at medium and low concentrations of CaCl₂. Alleviator with medium concentration (30 mmol·L^-1) promoted the synthesis of chlorophyll B and total photosynthetic pigment. C_i, P_n, G_s and T_r in stressed seedlings were effectively enhanced in all alleviating treatments. Comparatively, the effects at low concentration of CaCl₂ on alleviating stress were significantly superior to that at medium and high concentrations. CaCl₂ application with high concentration (40 mmol·L^-1) did not relieve all measured physiological indexes stressed by 3‰ sea salt. In conclusion, the application of low concentration of CaCl₂ (10-20 mmol·L^-1) could reduce the damage of salt stress by reducing the decomposition of photosynthetic pigments, improving the photosynthetic rate, inhibiting the accumulation of reactive oxygen species, and maintaining the stability of plasma membrane, thus reduce salt damage rate and mortality of seedlings, and effectively alleviate the inhibition effect of salt stress on C. hongkongensis subsp. tonkinensis.

Abstract:We used Corylus heterophylla Fisch., C. mandshurica Maxim. et Rupr. and 25 C. heterophylla Fisch. × C. avellana L. strains with good growth, resistance and yield as materials to analyze the appearance quality. 17 appearance quality indexes such as nut length, nut width, nut weight, kernel weight, shell thickness, kernel percent, shell weight, shape index, elongation, arithmetic mean diameter, geometric mean diameter, sphericity, aspect ratio, surface area, volume, filling index were measured and analyzed. The appearance quality characteristics of the hazelnut strains were comprehensively evaluated by means of analysis of variance, correlation analysis, cluster analysis and principal component analysis. The analysis of nut quality is of great significance for the cultivation and screening of hazelnut strains, and which provides a scientific basis for the variety selection, development, processing and utilization of domestic strains of hazelnut. The results showed that: (1) the differences in 17 appearance quality indexes of different hazelnut strains showed significant levels. There were obvious differences in shell weight, volume and nut weight, variability coefficient of which were 31.49%, 30.44%, 27.50%, respectively. The variability coefficients of aspect ratio, shape index, elongation, sphericity were below 10%. (2) The nut length, width, thickness, nut weight, kernel weight, kernel percent of C. heterophylla Fisch. × C. avellana L. strains were better than that of C. heterophylla Fisch., C. mandshurica Maxim. et Rupr. The kernel weight and kernel percent of C. heterophylla Fisch. × C. avellana L. strains were 0.70-1.46 g, 31.48%-56.12%, respectively, which were significantly higher than that of C. heterophylla Fisch. (0.51 g and 35.13%), C. mandshurica Maxim. et Rupr. (0.37 g and 38.12%). (3) Results of correlation analysis showed that the larger the volume of nut, the greater its nut weight and the kernel weight. The thinner the shell, the higher the kernel percent. (4) Principal component analysis showed that the main indexes affecting the comprehensive score of nuts were length, width, thickness, nut weight, kernel weight, followed by shape index, aspect ratio, percent kernel and filling index. According to the comprehensive scores, the comprehensive characters of nuts of 81-7, U3, 85-28, Liaozhen 9, U2, Dawei, Liaozhen 2 and Liaozhen 3 were better.

Abstract:This study took 3 mountain ranges (Wumeng mountain, Miaoling mountain and Wuling mountain), 19 walnut and iron walnut populations,and 245 individual plants in Guizhou Province as the research materials,and analyzed the diversity, correlation, clustering and variation of 29 nut phenotypic traits, in order to reveal the phenotypic genetic diversity level of walnut resources in Guizhou, and provide a basis for the conservation and utilization of walnut resources in Guizhou and the construction of core germplasm. The results showed that: (1) the Simpson index of 18 phenotypic quality traits of 245 germplasm resources of walnut and iron walnut were 0.26-0.82, and the Shannon-Wiener index was 0.12-1.79. The shape of walnut leaflet was diverse, and parietal leaf degeneration was prone to occur, Nut shell surface characteristics, nut shape and Walnut skin color were rich in diversity. (2) The coefficient of variation of nut phenotype is 3.32%-47.67%, the average is 21.28% and the difference is significant (P<0.05), the coefficient of variation between populations is 9.42%-31.61% and the difference is significant (P<0.05). Intra-population and inter-population variation is the source of walnut phenotypic diversity. However, the differences in nut traits between populations were significantly higher than those within population, indicating that inter-population variation was the main source of nut phenotypic variation in this region. (3) The phenotypes of walnuts in the three mountain regions have different degrees of variation, among which, the Miaoling Mountain had a low degree of walnut phenotype variation, while the Wumeng mountain had a high degree of walnut phenotypic variation. UPGMA clustering results showed that the 19 walnut populations were divided into three categories according to the Guizhou Mountain range, indicating that the square European distance of the nut phenotypic traits of Guizhou walnut resources showed a positive correlation with the geographical region or climatic conditions. It is believed that Guizhou is rich in walnut germplasm resources and has high phenotypic diversity, and its phenotypic variation mainly comes from inter-population variation.

Abstract:The study was conducted in May, July and September 2020 in the grazing exclusion plots (5 a) and grazing plots of the experimental area in the middle part of the northern slope of Tianshan Mountains. The quantitative characteristics (height, cover, density and biomass) and component (stem, leaf and root) biomass of Seriphidium transiliense in the grazing exclusion plots and grazing plots in different months were measured and analyzed to reveal the characteristics of plant populations and component biomass in response to the grazing exclusion, and to provide a basis for the restoration and rational use of degraded grassland. The results showed that: (1) compared with the grazing plots, the height, coverage and biomass of S. transiliense in the grazing exclusion plots increased significantly (P<0.05) in May, July and September, with the increase in height ranging from 69.90% to 95.53%, the coverage ranging from 186.53% to 297.82% and biomass ranging from 86.24% to 631.83%, respectively. (2) As the months progressed, the single plant biomass, stem biomass and leaf biomass of S. transiliense showed decreasing and then increasing trend in both the grazing exclusion plots and grazing plots, while root biomass showed an increasing trend. The grazing exclusion changed the proportion of plant components, with the proportion of stem and leaf biomass to plant biomass increasing significantly in July and September, while the proportion of root biomass decreased significantly in the grazing exclusion plots compared to the grazing plots. The study concluded that grazing exclusion facilitates the recovery of above-ground vegetation, which changes its building block structure, and is an effective measure to restore vegetation in degraded desert grasslands.

Abstract:Cupressus funebris plantation is the main forest type in central Sichuan Basin, and understory plants are important part of forest ecosystems. This study used the typical sampling method, investigated and analyzed the existing density of C. funebris plantation ［1 100 tree·hm^-2 (A), 950 tree·hm^-2 (B), 800 tree·hm^-2 (C), 650 tree·hm^-2 (D) and 500 tree·hm^-2 (E)］ on Shannon Niche width (B_sw), Levins niche overlap (O_ik), the correlation between niche width and mean overlap and environmental factors in understory plants with shrub and herb dominant populations of Yunding Mountain. We explored the response of different densities with dominant population in understory plants from niche characteristics, and determined the relatively appropriate stand densities. We analyzed of the relationship between populations, community and environment in understory plants under different densities of C. funebris plantation, then screened out the optimal stand densities, which were useful for C. funebris plantation understory plants diversity conservation and forest management measures. The results showed: (1) in the study area, there were 94 species of herbs in 38 families, 72 genera, and 99 species of shrubs in 42 families, 65 genera. The number of species increased first and then decreased with the stand density decrease of C. funebris, then reached a peak at 650 tree·hm^-2 density of the C. funebris. (2) With the stand density of the C. funebris increased, the B_sw values of dominant populations in herb layer were 28.07, 28.45, 26.34, 25.48 and 30.77, the mean niche overlap were 4.34, 5.75, 4.12, 2.14, 5.08, the B_sw values of dominant populations in shrub layer were 26.64, 28.05, 24.24, 23.72 and 25.65, and the mean values of niche overlap were 6.68, 6.44, 4.28, 5.54 and 6.19, respectively. Both the shrubs and herbs niche widths and the mean overlaps were larger at density D, indicated that at density D, the dominant populations of shrubs and herbs had high resource utilization capacity, this capacity was more conducive to ecological adaptability of community. (3) RDA results showed that stand density, canopy density and soil organic matter were the main environmental factors affected the niche width and niche overlap mean value on dominant populations of shrubs and herbs, soil water content and pH had little effect on them. Therefore, this study shows that the relative optimal density of C. funebris plantation in Yunding Mountain is 650 tree·hm^-2, which is also the most conducive to the resource utilization and ecological benefits of dominant population of understory plants in C. funebris plantation of Yunding Mountain.

Abstract:In order to clarify the impact of island spatial characteristics on plant species diversity, this study applied the sample line method and sampling method to conduct vegetation survey on 19 uninhabited islands around the main island of Pingtan, Fujian Province, and statistically analyzed the species richness of each island and the Margalef richness index, Shannon-Wiener diversity index, Simpson diversity index and Pielou evenness index of typical plant communities. We used multiple functions to fit the species-area relationship, and used Redundancy analysis to explore the spatial factors that affect the species diversity of typical plant communities on the island, so as to explore the formation and maintenance mechanism of plant species diversity on the islands. The results show that: (1) among the 19 uninhabited islands around the main island of Pingtan, 12 islands are dominated by typical island forest communities, 2 islands are dominated by shrub and grass layers and lack of tree layer, and 5 islands are only covered by grass. (2) The plant species richness of the 19 islands increased with the increase of the island area. When the island area increased to 7.184 hm², the rate of species increase slowed down. (3) The area, perimeter, perimeter area ratio and inshore distance of the island are the main spatial characteristics that affect species diversity. The larger the area and perimeter of the island, the smaller the perimeter area ratio and inshore distance, the higher the species richness of the island. (4) In the typical plant communities of the island, the species diversity of the tree layer is mainly affected by the island area, perimeter and perimeter area ratio, while the species diversity of the shrub and grass layers is mainly affected by the inshore distance. According to the research, the island area of 7.184 hm² can guarantee the survival space of most common plant species. The closer the island is to the mainland, the more conducive it is to the spread of species, and the higher its species immigration rate, thus improving the islands species diversity.

Abstract:In this study, more than 300 samples of the lichen family Physciaceae collected from Guancen Mountain and Wulu Mountain in Shanxi were identified and analyzed. Lichens of Physciaceae were studied in terms of species diversity, spatial distribution characteristics, habitat types and floristic composition in conjunction with existing reports. The species composition and floristic characteristics of the lichen family Physciaceae in China were clarified. The results showed that: (1) there were 197 species and 54 varieties, belonging to 7 genera. Rinodina was the dominant genus, accounting for about 30.5% of total species. (2) Lichens of Physciaceae are mostly distributed in Xinjiang, and Physcia is the most widely distributed genus in the family. However, 26.4% of these species are distributed in only a single area. (3) The lichen habitat types of Physciaceae are diverse, including tree, stone, moss, native and multi habitat, and the multi habitat lichen is the main one (48.5%). (4) The geographical composition of the lichen family Physciaceae in China is complex. There are a variety of floristic elements, but the temperate nature (43.1%) is the most prominent, with obvious East Asian characteristics. (5) There are four genera and ten species of the lichen Family Physciaceae distributed only in China, and they are mainly distributed in northeast, northwest and southwest China.

Abstract:Schizoiridoid glycosides are secondary metabolites produced in plants with multiple biological activities such as liver protection, anti-inflammatory, hypoglycemic and blood lipids, and are widely used in clinical practice. Based on the research progress on the biosynthesis pathway of schizoiridoid glycosides and the mining and regulation mechanism of key enzyme genes at home and abroad in recent years, this paper mainly reviews the research progress of the biosynthesis pathway of schizoiridoid glycosides in medicinal plants, key enzymes (GPPS, GES, G10H, 8HGO, IS, IO, 7DLGT, DL7H, LAMT, SLS) and coding genes. It provides a basis for further elucidating the mechanism of its biosynthesis pathway and the regulation of key enzymes, improving the accumulation of effective active ingredients, and easing the tension of wild resources of medicinal plants.