Abstract:In order to reveal the plant resources and ecological environment changes in Guangzhou, the vascular plants and vegetation in hotspot areas were investigated from 2017 to 2019. A total of 3 508 species of vascular plants belonging to 1 362 genera and 230 families were recorded, of which 174 species in 78 genera and 25 families are lycophytes and ferns, 34 species in 20 genera and 8 families are gymnosperms, and 3 300 species in 1 264 genera and 197 families are angiosperms. There are 20 national and 5 provincial key protected plants, and 131 alien invasive plants. It also shows that the flora of seed plants has the transitional characteristics from tropical to subtropical and the typical families includes Lauraceae, Fagaceae, Pentaphylacaceae, Phyllanthaceae, Aquifoliaceae, Celastraceae and Theaceae. The vegetation investigation and evaluation indicated that the community composition and structure of different vegetation types had gone through a positive and healthy developmental tendency and the forest vegetation has been succeeding toward the zonal climax community types under the circumstance of strict ecological protection and sustainable utilization. These results present the comprehensive basic data on the current status of plant diversity and the dynamics of vegetation changes in the recent 10 years, which are important for making biodiversity conservation and development strategies and keeping the local biosecurity in Guangzhou.

Abstract:Nitrogen (N) deposition has been increasing during recent decades and may affect supply of soil nutrients and resources acquired by organism. Soil enzyme activity is an important indicator for reflecting the nutrient acquisition of plants and microorganisms. To explore the effects of long-term N and phosphorus (P) additions on activities of N and P cycling enzymes in subtropical forest soil, two plantations of Acacia auriculiformis and Eucalyptus urophylla in south China were applied N and P fertilizers for 8 years, each with 50 kg/(hm²·a), and then the activities of soil enzymes, including P-cycling enzymes[phosphomonolipase (PME) and phosphodiesterase (PDE)] and N-cycling enzymes[β-1,4-acetylglucosaminidase (NAG) and l-leucine aminopeptidase (LAP)] were measured. The results showed that N addition had no significant effect on activities of soil N and P cycling enzymes. P and N+P additions had significant negative effects on activities of PME and PDE, but which had no effect on activities of NAG and LAP. The growth of soil microorganisms and plants of subtropical plantations in south China may be limited by P rather than by N, and P fertilization could alleviate soil P limitation on plants and microorganisms. Therefore, these would provide an important insight for forest management in the future.

Abstract:In order to explore the ability to resist heavy metal pollution and potential of ecological restoration of three herbage, such as Thysanolaena latifolia, Neyraudia reynaudiana and Miscanthus sinensis, their physiological indexes and heavy metal contents grown in lead-cadmium contaminated soil were measured. The results showed that POD activity and Pro content of three plants were in the order of M. sinensis > N. reynaudiana > T. latifolia under the same pollution level, while MDA content was M. sinensis > T. latifolia > N. reynaudiana. Lead (Pb) and cadmium (Cd) contents in M. sinensis were the highest among three species with the biggest bio-accumulating coefficient. The resistant capability to heavy metals was in the order of M. sinensis > N. reynaudiana > T. latifolia. Therefore, Miscanthus sinensis could be used as an alternative plant for vegetation restoration in mining areas.

Abstract:To study the distribution and enrichment characteristics of metal elements in fruits of Camellia oleifera and planting soil, the assessment of eight heavy metals (Pb, Cr, Cd, As, Hg, Ni, Cu and Zn) and its enrichment capacity were studied in main production areas of Zhejiang province during the maturity period. The results showed that the contents of all measured metals in the soils were lower than the risk screening values of GB 15618-2018. The levels of As, Ni and Cu in soils of Changshan County, and the levels of Pb, Cr and Fe in soils of Jiangshan County were significantly higher than the values in other areas. The single-factor pollution index of Cd in Changshan and Jiande soils were 0.93 and 0.81 respectively, which were at the pollution cordon. Cr, Ni, Cu and Zn were mainly found in the seed, and Hg was mainly found in shell, and Pb, Cd, As, Fe and Mn were mainly found in the green peel. The enrichment coefficients of Cu, Fe and Mn in seed are greater than 0.4, indicating its high absorption capacity of these metals, while enrichment coefficients of Ni, Zn less than 0.4, and enrichment coefficients of Pb, Cr, Cd, As, Hg, Ni, and Zn less than 0.1. The enrichment coefficients of Cu and Mn in shell are greater than 0.4, indicating its high absorption capacity of these metals, while enrichment coefficients of Fe less than 0.4, and enrichment coefficients of Pb, Cr, Cd, As, Hg, Ni, and Zn less than 0.1. The enrichment coefficients of Cu, Fe and Mn in the green peel were greater than 0.4, indicating its strong absorption capacity, while the enrichment coefficients of Pb, Cr, Cd, As, Hg, Ni and Zn were less than 0.1. The camellia oleifera fruit have middle enrichment ability of some transition metal (Cu, Fe, and Mn), and have week enrichment ability of Pb, Cr, Cd, As and Hg.

Abstract:To explore the appropriate salinity and appropriate region of Sesuvium portulacastrum growth, the growth and chlorophyll fluorescence parameters were measured simulated artificial ecological floating bed for hydroponics in constant temperature incubator. The results showed that the growth of S. portulacastrum was well at 0-15‰ salinity conditions, and seawater with 10‰ salinity promoted its growth. The relative growth rate and fluorescence parameters were inhibited when the salinity was 5‰ and above 20‰. The light energy utilization and electron transfer efficiency of S. portulacastrum decreased under salt stress, and regulatory energy dissipation increased, thus affecting photosynthesis. When salinity reached 30‰, S. portulacastrum death finally. Therefore, S. portulacastrum had a good potential for ecological restoration and marine vegetables development at the appropriate temperature, the salinity of 0-15‰ water area could be the restoration application area, while 10‰ salinity could promote its growth and cultivation of marine vegetables.

Abstract:In order to understand the photosynthetic characteristics and response mechanism of nitrogen metabolism in Clematis, the growth, light response curve, A-Ci curve and nitrogen metabolism related enzyme activities of 1-year-old Clematis crassifolia and C. paten ssp. tientaiensis were studied under different ratios of NH₄⁺-N:NO₃^--N. The results showed that the ratio of NH₄⁺-N:NO₃^--N significantly affects the biomass and chlorophyll content of clematis, and the biomass, Chl a, Chl b, and Car contents of C. crassifolia reach the maximum under the ratio at 1:1, while the Chl a and Chl b contents of C. paten ssp. tientaiensis reach the maximum under the ratio at 1:3. Under the ratio of 1:1, the light saturation point (LSP) of C. crassifolia and the light compensation point (LCP) of C. paten ssp. tientaiensis were the maximum, and the V_cmax and J_max values of C. crassifolia leaves were significantly higher than those under other ratios. The glutamine synthetase (GS) activity of C. paten ssp. tientaiensis was the highest under the ratio of 3:1, while NR and nitrite reductase (NiR) activities under the ratio at 1:3 were significantly higher than those under other ratioes. Therefore, the mixed application of NH₄⁺-N and NO₃^--N could effectively promote the growth and photosynthesis, and enhance the nitrogen utilization efficiency of two Clematis. C. crassifolia was suitable for 1:1 of NH₄⁺-N to NO₃^--N, while C. paten ssp. tientaiensis was more suitable for 1:3.

Abstract:In order to reveal the effect of environment condition on seed germination of Sorghum halepense, its germination characters were studied in Hainan Island. The results showed that the germination rate of S. halepense seeds was high with more than 85%, and the germination time was the shortest (2.64 d) under day and night temperature at 35℃/25℃. The seeds treated with 98% concentrated sulfuric acid could improve germination rate. The seed germination time was shortened treated with concentrated sulfuric acid, gibberellin and grinding. The seeds on the soil surface had the highest germination rate, and germination rate decreased and germination time increased with burial depth. Among different treatments, such as temperature, dormancy breaking and burial depth, there were no significant differences in germination rate and germination time of S. halepense seeds between outbreaking and non-outbreaking regions. Therefore, environmental conditions could influence germination of S. halepense seeds, and the seeds under high temperature and on the soil surface had high germination rate and short germination time. Seeds of S. halepense in Hainan Island had high germination rate and wide ecological breadth of germination, which was one of important reasons for its sudden disaster in Hainan in recent years. So, the strengthen control before flowering of S. halepense, reduce seed maturation and dissemination.

Abstract:In order to understand the anti-elastase effect of white tea, the inhibitory effect of aqueous extract from six white tea samples (CB1-CB6) on porcine pancreatic elastase (PPE) were measured. The results showed that CB4 had the strongest inhibition on PPE among six white tea samples with inhibition rate of 69.73%. In addition, elastase inhibition activity of CB4 increased with the concentration, showing a dose-dependent manner. Among the four extraction layers, ethyl acetate (WEA) layer had the strongest inhibitory activity, reaching 82.58%. The total polyphenol (TPs) content in CB4 was high, and the contents of epigallocatechin gallate (EGCG), epicatechin gallate (ECG), and caffeine (CAF) were the highest among six samples. Among 4 extraction layers, the contents of EGCG, ECG, ECG, and total polyphenols in WEA layer were the highest and that of CAF was very low. There were significant positive correlation between elastase inhibition rate and the contents of TPs, EGCG and CAF with correlation coefficient above 0.90. However, neither 0.1-1.0 mg/mL EGCG nor 0.05-2.0 mg/mL CAF had inhibitory effects on PPE activity. Conversely, 0.05-2.0 mg/mL GA showed a promotion effect on PPE activity, and the promoting effect of GA was positively correlated with its concentration. Therefore, it was suggested that white tea exhibited potentially anti-aging activity, but the active ingredients that inhibited PPE were not EGCG, GA and CAF.

Abstract:In order to understand the function of transcription factor WOX in Dendrobium officinale, the WOX family members in D. officinale were identified by whole genome analysis techniques, the bioinformatics of WOXs and expression patterns of WOXs were analyzed. The results showed that there were nine WOX transcription factors in D. officinale genome, named DoWOX 1 to DoWOX 9, respectively. The most of DoWOXs contained 2-3 exons, while DoWOX9 had only one exon. The promoters of DoWOXs contained cis-regulatory elements related to hormone induction, stress responsive, plant growth and development. The expression of DoWOX1, DoWOX2, DoWOX3, DoWOX4 and DoWOX9 were the highest at protocorm-like body (PLB) stage by qPCR, which of DoWOX4 was the highest at small flower bud stage, and then decreased. In addition, the expressions of DoWOX3, DoWOX7 and DoWOX9 were the highest in columns, and that of DoWOX4 was the highest in lips. Therefore, DoWOXs might be involved in regulating the growth and development of D. officinale, and play an important role in maintenance of PLBs state and flower development.

Abstract:Based on morphological and molecular evidences, Aponogeton undulatus Roxb., discovered in Hainan Province, is reported as a newly recorded species of Aponogetonaceae from China. It is similar to A. lakhonensis A. Camus, but differs by its leaf blade undulate at margin and cuneate at base. Additionally, a detailed description and color photographs are provided herein.

Abstract:Phyllanthodendron petraeum P. T. Li and P. orbicularifolium P. T. Li are two species endemic to Guangxi, China. A series of morphological characters of leaves, disk glands and styles were considered to be important to distinguish them from each other in previous taxonomic literature. However, results from recent examination of herbarium specimens and filed investigations suggested that all the cited characters could not differentiate the two species. We believe that P. petraeum and P. orbicularifolium are conspecific. We therefore reduce P. orbicularifolium as the synonymy of P. petraeum.

Abstract:Yushania lipingensis (Poaceae:Bambusoideae), a new species from Guizhou, China, is described and illustrated. The new species is morphologically similar to Y. auctiaurita, but differs in its culm leaf sheath abaxially densely yellow-brown or purple antrorsely setose, both culm leaf auricles and foliage leaf auricles strongly curved falcate with well developed and usually radiating oral setae, culm leaf ligule with a truncate and densely ciliolate apex, culm leaf blades adaxially puberulent, and foliage leaf blades with 5-6 pairs of secondary veins.

Abstract:Alpinia calcicola Q. B. Nguyen & M. F. Newman, a newly recorded species of Alpinia (Zingiberaceae) from China is reported. Morphological characteristic description, geographical distribution and color photos are provided. The voucher specimens are deposited in Herbarium of South China Botanical Garden (IBSC).

Abstract:In order to understand the chemical constituents of Hibiscus syriacus stem, thirteen copounds were isolated from 85% ethanol extract of its stems by several column chromatographic techniques, such as MPLC- MCI-gel, silica gel, Sephadex LH-20 and preparative HPLC. Based on physicochemical properties and NMR spectral data, their structures were identified as methyl 4-[2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-(hydroxymethyl) ethyl] sinapate (1), 2,6,2ʹ,6ʹ-tetramethoxy-4,4ʹ-bis(2,3-epoxy-1-hydroxypropyl) biphenyl (2), 3,4,5- trimethoxycinnamic acid methyl ester (3), 3,4-dimethoxycinnamic acid methyl ester (4), trans-p-hydroxy- cinnamic acid methyl ester (5), methyl caffeate (6), methyl feruate (7), syringaresinol (8), clemaphenol A (9), (E)-2-methoxy-5-propenylphenyl β-d-glucopyranoside (10), orientin (11), luteolin (12), and apigenin (13). Among them, compounds 1-10 were lignans and compounds 11-13 were flavonoids. Compound 1 was a new natural product, compound 1-12 were isolated from this plant for the first time. Compounds 1-10 at 40 μmol/L did not exhibit good cytotoxic activities to in vitro growth of human leukemia HL-60 cells and human lung cancer A-549 cells.