Abstract:Timely assessment of species threatened status is an important basis for adjusting the endangered level of species and implementing effective protection measures. The endemic plants in the Jinsha River area, including Aristolochia delavayi, Hibiscus aridicola, Stemona mairei and Amorphophallus albus, were investigated and evaluated. According to the “IUCN Red List Categories and Criteria: Version 3.1” and “Guidelines for Using the IUCN Red List Categories and Criteria: Version 15.1”, the threatened category of the four species were re-analyzed and evaluated based on the data obtained through field surveys. The results showed that A. delavayi was assessed as Vulnerable (VU), H. aridicola and A. albus were listed as Endangered (EN), and S. mairei was listed as Near Threatened (NT) under the existing wild population resources. Compared with the current threatened category of the four species, the threatened status of A. delavayi was downgraded from Endangered to Vulnerable, H. aridicola was upgraded from Vulnerable to Endangered, A. albus was upgraded from Near Threatened to Endangered, and S. mairei remained unchanged. This study provides a scientific reference for understanding the current status of wild resources, updating threatened category, and timely adjusting effective protection strategies of the four endemic plants.

Abstract:In order to understand the response of plant leaf functional traits to soil characteristics in karst forest, the woody plant communities in Maolan National Reserve were investigated by using the methods of sample plot and transversal, the weighted average leaf traits of woody plants in different terrain were calculated, and the relationship between leaf functional traits and soil characteristics analyzed by One-Way ANOVA and redundancy. The results showed that there were significant differences in plant leaf functional traits between different terrains at the growth type (evergreen/defoliate) and community level (P<0.05), among which the leaf area was the most sensitive, its response to habitat was obvious. However, leaf thickness of evergreen plants was greater than that of deciduous plants, while specific leaf area was the opposite, and the difference in chlorophyll content is not significant (P>0.05). There were significant difference in soil characteristics among different terrains (P<0.05). The field water capacity, capillary porosity, contents of total nitrogen, total phosphorus and organic matter of soil on funnel terrain were higher, and the soil fertility was the best, followed by valley and shady slope, while the soil on sunny slope was relatively barren. There was a correlation between leaf functional traits and soil characteristics in different terrain, but the interpretation rate of leaf functional traits variation was different in different terrain soil characteristics. The main soil characteristics affecting leaf functional traits were organic matter content, total nitrogen content, total phosphorus content, field water capacity and soil bulk density. Therefore, leaf functional traits and soil characteristics differ greatly in different terrain of Maolan karst forest. With the change of soil characteristics, leaf functional traits have different response characteristics, which is conducive to species coexistence and biodiversity maintenance in forest area.

Abstract:Leaf morphological traits are the direct manifestation of plant environmental adaptability. Different canopy positions can form different microenvironments, which are direct places for plant leaves to interact with the external environment. In order to understand the influence of canopy position on leaf morphological traits, leaf morphological traits, including leaf length, leaf width, leaf thickness, petiole length, petiole diameter and leaf shape index, and allometry relationship among different crown positions of evergreen tree Cinnamomum camphora were analyzed. The results showed that there were significant differences in leaf morphological traits among different canopy orientations, but the change trends of the upper and lower layers of canopy was not completely consistent. In the upper layer of canopy, except leaf shape index and petiole length, the other 4 leaf morphological traits were the highest in the east side. In the lower layer of canopy, except leaf shape index, the other 5 leaf morphological traits were the smallest in the east side. In the same direction, there were some differences between the upper and lower layers of canopy, and the leaf shape index of lower layer was higher than that of upper layer, while the other morphological traits showed the opposite trend. In addition, the interaction of canopy layer and orientation had significant effects on leaf length, leaf thickness, petiole length, and petiole diameter. The leaf morphological traits in each canopy layer and canopy orientation mostly showed allometric relationship because allometric index was not equal to 1, and there were no significant differences in most of them. The leaf width vs. leaf thickness, leaf width vs. petiole length, leaf length vs. leaf thickness, and leaf length vs. petiole length showed allometric relationships for all canopy layers and directions. Therefore, canopy position had great influences on leaf morphological traits of C. camphora, but the allometric relationships between morphological traits were relatively stable, which was an important reflection of leaf phenotypic plasticity and the stability of internal relationships.

Abstract:In order to understand the effects of climate change on vegetation phenology in tropical and subtropical monsoon regions of China, vegetation phenology parameters in three provinces (regions) of south China were extracted using Double Logistic method and threshold method based on MODIS EVI time series data from 2001 to 2020, and the spatio-temporal variation characteristics of vegetation phenology were analyzed. The results showed that the start of growing season was mainly concentrated in the 90^th—105^th day, the end of growing season in the 320^th—335^th day, and the length of growing season in the 220^th—235^th day. In the past 20 years, the start of growing season was delayed, the end of growing season was basically unchanged, and the length of growing season was shortened. In terms of spatial distribution, the start of growing season gradually delayed from west to east and from north to south in Guangdong and Guangxi, and gradually delayed from northeast to southwest in Hainan. The distribution of wilting period was late in the center and early in the periphery of Guangdong Province, while it was early in the center but late in the periphery of Hainan Province. The length of growing season gradually shortened from west to east in Guangdong and Guangxi, while it gradually extended from southwest to northeast in Hainan. With the increase of altitude, the start of growing season of different regions and different vegetation varied and fluctuated greatly, while the end of growing season was first delayed and then advanced, and the length of growing season was first extended and then shortened. Therefore, these revealed the change characteristics of vegetation phenology in the three provinces (regions) of south China under the background of climate warming, and had guiding significance for more comprehensive understanding of the response of southern vegetation to climate warming.

Abstract:The phenological patterns of plants tend to fluctuate, with variations occurring in the timing and amount of leaf-out, flowering, and fruiting from year to year or event to event. However, the phenological patterns in tropical regions are still largely unknown. The phenology of 126 plant species located in the campus of Hainan University in Haikou, Hainan Island were observed and recorded over three years, including leaf-out, flowering, and fruiting time. The main climate factors affecting plant phenology in tropical areas were analyzed by multiple regression analysis of phenology and environmental variables. The results showed that plant phenological patterns in the tropics were distinctly seasonal, leaf-out, flowering, and fruiting phenology occurred in April—June, April—August, and May—November, respectively. The climatic factors affecting the phenological pattern of leaf spreading and flowering were the average sunshine duration per month, and the number of fruit bearing species per month was correlated with air temperature, especially the number of fruit ripening species per month was significantly correlated with the monthly minimum air temperature. There were differences in the phenological periods among different functional groups. The leaf-out of shrubs was earlier than that of herbs and trees, leaf-out of wind-borne plants was earlier than that of insect-borne plants, and the leaf-out and fruit ripening time of fleshy-fruited plants were earlier than those of non-fleshy fruited plants. Bloom of trees was earlier than that of herbs and shrubs, which non-fleshy-fruited plants was earlier than fleshy-fruited plants, and fruit mature of wind-borne plants was earlier than that of insect-borne plants. These would be of great significance for predicting tropical phenological events in the future.

Abstract:The interspecific relationship is one of the important quantitative and structural characteristics of plant communities, which directly affects the stability of communities, and it is of great significance to study the interspecific relationship and community stability for the protection and stability of plant population. Alsophila spinulosa community in Chishui National Nature Reserve of Guizhou Province was investigated by means of sample method, and the overall correlation and interspecific correlation of plants were analyzed and the stability coefficient of the community was calculated. The results showed that Phyllostachys edulis was dominant species in the community, and the interspecific relationship between P. edulis and A. spinulosa showed a significant positive correlation. Alsophila spinulosa was greatly affected by interspecies at the early development stage, but was relatively independent state at the late development stage, showing weak or no correlation with other species, and was less affected by interspecies. The contribution law analysis showed that the stability coefficient of P. edulis-A. spinulosa community was 21/79, indicating that the community was stable in Jinshagou area.

Abstract:In order to understand the potential distribution of six subtropical evergreen Quercus species in south-west China under future climate scenarios, based on the distribution data, physiological and ecological characteristics of six Quercus trees in Southwest China, including Q. guyavaefolia, Q. aquifolioides, Q. rehderiana, Q. semecarpifolia, Q. senescens and Q. dolicholepis, environmental data and future the 2070s (2061—2080) climate scenario data (SSPs126, SSPs245, SSPs585), Maximum Entropy (MaxEnt) model and Geographic Information System (GIS) technology were used to analyze the impact of future climate change on the potential distribution of these tree species. The results showed that the AUC values of the MaxEnt model for all six Quercus species were more than 0.9, indicating high model simulation accuracy. The main environmental factors affecting the distribution of six Quercus speciesincludedtemperature seasonality, annual precipitation, altitude, minimum temperature of coldest month and slope. Consequently, these tree species were mostly suitable for distributing in warm and humid mountainous areas with minimal seasonality temperature changes. Compared to the other three tree species, Q. aquifolioide, Q. rehderiana and Q. semecarpifolia were more suitable for growing in middle and high mountain areas with lower temperatures and slightly greater seasonal temperature changes. The potential suitable areas for these six Quercus species were southwest China, as well as western of central China, western of south China and southern of northwest China. The high suitable areas were mainly located in southern Sichuan and northwestern Yunnan. Under the future climate scenarios, the suitable areas of main subtropical evergreen Quercus trees in southwest China would expand to the northwest as a whole.

Abstract:In order to explore the nutrient cycling characteristics of C, N and P in Tiankeng forest communities in Dashiwei, Leye, Guangxi, the contents and stoichiometric ratios of C, N and P in plant leaf, litter and soil of forest communities inside and outside Tiankeng were compared, and their internal relationship and interaction were studied by using correlation analysis and redundancy analysis. The results showed that the leaf and litter of the forest inside Tiankeng showed a pattern of low C, low N and high P, and the soil was low C, low N and high P compared with the forests outside the Tiankeng. The C:N and C:P in leaf were significantly positively correlated with the C and N:P in litter, and C in leaf showed significantly negative correlation with P in soil. The N and N:P in leaf outside Tiankeng were significantly negative correlated with N:P in soil, and C:N in leaf was significantly positive correlated with C and C:N in soil, indicating that the C and P in litter inside Tiankeng forest might came from leaves, while C and N in leaf outside Tiankeng forests were mainly from soil. The explanation rates of soil C:N:P for the change of C:N:P of leaves and litter were 90.7% and 50.6%, respectively. The P had the highest explanation for the change of C:N:P of leaves and litter. Plants inside Tiankeng were more sensitive to the change of P content, while plants outside Tiankeng were more sensitive to the change of N content, which indicating that the forest inside Tiankeng might be the P-limited site, while the forest outside Tiankeng might be the N-limited site. The differences and associations of C:N:P in leaf-litter-soil of the forests inside and outside karst Tiankeng reflected the characteristics of nutrient cycling and the adaptation of plant community.

Abstract:In order to explore the effects of vibration on the shedding of bougainvillea glabra bracts and ethylene production in potted bougainvillea glabra, using the ‘Miss Manila’(Bougainvillea × buttiana ‘Miss Manila’)potted bougainvillea glabra as the test material, the bract shedding rate after treatments was measured under vibration , airtight environment and vibration and airtight environment treatments. The ethylene release, the content of 1-aminocyclopropane-1-carboxylic acid (ACC), the activity of ACC synthesis (ACS), the activity of ACC oxidase (ACO), relative expression of ethylene synthesis related genes were measured within 4 to 24h after treatment. The results showed that the shedding of bracts of potted bougainvillea glabra was significantly higher than that of the control (without treatment) within 7 days after vibration and airtight environment treatment and vibration treatment, and the ethylene release, ACC content, ACS activity and ACO activity of bracts (S1) with bract diameter of 0.5-1.4 cm and bract (S2) with bract diameter of 1.5-2.4 cm are all significantly higher than that of the control. With the change of time after treatment, it showed a trend of first increasing and then decreasing. The relative expression of BsSAMS, BsACS, BsACO genes in bracts S1 and S2 increased significantly, and its change trend was consistent with the change of ACS activity and ACO activity, which showed a trend of first increasing and then decreasing. The shedding of bracts, ethylene production, key enzyme activities of ethylene biosynthesis, the expression of ethylene synthesis genes BsSAMS, BsACS, BsACO all increase significantly after vibration in potted bougainvillea glabra. On the basis of vibration, a closed environment can promote bract shedding, ethylene biosynthesis, ethylene synthesis gene expression.

Abstract:By understanding the causes of seed dormancy of Phoebe sheareri, mechanical, acid-alkali corrosion and lamination treatment (5 ℃-25 ℃) were used to study the best methods to relieve seed dormancy. The results showed that the low permeability of seed coat was the main reason for inhibiting seed germination, and the seed dormancy type was physical dormancy. Acid and alkali corrosion treatments could not effectively break seed dormancy. After the seeds were treated with concentrated sulfuric acid and sodium hydroxide for different time (1-25 min), the germination rate was increased by 33%-55%, but the seeds were seriously damaged, and the decay rate was as high as 30%-97%. Both mechanical treatment and stratification treatments could effectively break seed dormancy, and removing whole seed coat by mechanical treatment had the best effect, and seed germination rate and germination potential increased by 99.33% and 76.00%, respectively. But this method was time-consuming and laborious. The seeds under 25 ℃ warm stratification for 45 d, 25 ℃/15 ℃ and 5 ℃/25 ℃/5 ℃ variable temperature stratification for 60 d could effectively promote germination, with the germination rate and germination potential increased by 89%-93% and 79%-83%, respectively, and there were no obvious differences in germination rate and germination potential among these types of stratification. However, compared with warm stratification, variable temperature stratification requires longer stratification time and higher seed decay rate. Therefore, 25 ℃ warm stratification for 45 d was the optimal way for breaking seed dormancy of P. sheareri.

Abstract:The roots of plants have the function of water absorption and transport, and some of them also have important medical value. The anatomical characteristics of coarse roots of 40 medicinal herbs were observed, the differences among functional groups were compared, the correlations of traits were analyzed, and the interspecific variability of root traits was explained in combination with phylogenetic and natural climate factors. The results showed that the root anatomical characteristics of herbaceous plants were significantly different among species. Compared with dicotyledonous plants, the proportion of root cortex in monocotyledonous plants was higher, while the proportion of median column was smaller, which revealed the differences in root absorption and transport strategies between the two plants. Traits network analysis showed that xylem area ratio (XAR) was the central trait with the highest degree and tightness. XAR was positively correlated with phloem area ratio but negatively correlated with cortex fraction (CF). Except for vessel frequency and CF, other traits showed no significant phylogenetic signals, indicating that root characters were less affected by phylogeny. In monocotyledon herbaceous species, mean annual precipitation was positively correlated with CF, while in dicotyledon herbaceous species, mean annual temperature was positively correlated with average vessel diameter. These would further reveal the diversity and adaptability of the root structure of medicinal herbs.

Abstract:In order to elucidate the mutation mechanism of leaf color mutation ofAristaloe aristata, the phenotypic characteristics, leaf ultrastructure, photosynthetic pigment content, chlorophyll fluorescence parameters and metabolomics between leaf color mutant ‘MT-1’ and normal leaf color germplasm ‘WT-18’ were compared. The results showed that compared with ‘WT-18’, the mutant ‘MT-1’ exhibited yellow strips from young leaves, and the plant type became smaller and the growth was slower. The number of stomata became less and small, and the shape changed from rectangle to square. The number of chloroplasts and internal lamella decreased, and the volume decreased obviously. The contents of photosynthetic pigments, including chlorophyll a, chlorophyll b and carotenoids, and chlorophyll fluorescence dynamic parameters (F_o, F_m, F_v/F_m, Ф_PSⅡ, qP, qN and ETR) decreased significantly. The metabolites of ‘MT-1’ and ‘WT-18’ were significantly different. The KEGG metabolic pathway analysis showed that most of the different metabolites were enriched in amino acid metabolism, glucose metabolism, lipid metabolism, nucleic acid metabolism, secondary metabolite biosynthesis, and other pathways. Therefore, the changes in chloroplast related genes might be an important cause of leaf chlorosis mutation.

Abstract:Euchresta japonica is a Class II key protected wild plant in China. The response of photosynthetic characteristics to light intensity and drought was studied by setting different layers of shade nets and watering with different concentrations of polyethylene glycol solution. The results showed that the saturated light intensity of E. japonica leaves was 683.06~907.07 mmol/(m²·s). The maximum electron transfer rates (ETR_max) and the maximum net photosynthetic rate (P_nmax) under single layer shading were higher than those under double layer shading. The ETR_max and P_nmax under single layer shading without drought were the highest of 55.36 and 6.73 mmol/(m²·s), respectively. Under the same shading condition, the P_nmax and the corresponding saturated light intensity of E. japonica decreased with the increase of drought degree. The transpiration rate and water use efficiency under single layer shading were higher than those under double layer shading. The actual photochemical efficiency, photochemical quenching coefficient and non-photochemical quenching coefficient of photosystem II of E. japonica leaves showed no significant difference among different treatments (P>0.05). Euchresta japonica is a semi-sunny plant, whose leaves whose leaves can take advantage of weak light and its plants have strong drought tolerance. Therefore, it is suggested that proper shading and adequate soil water content should be maintained during field return, ex situ conservation and artificial cultivation.

Abstract:Plant ferritin (FER) can store iron and respond to various abiotic stresses. The FER gene family of cassava (Manihot esculenta) was analyzed based on a genome-wide level. The results showed that four FER genes had been identified from cassava, named MeFERs, encoded MeFERs could be divided into two clades based on phylogenetic tree analysis. All members contained Euk_Ferritin functional domain, and located in the chloroplast. The MeFERs genes located in chromosome LG7-LG10, respectively. Gene collinearity analysis showed that there were three potential duplicate gene pairs without tandem duplication events. The Ka/Ks value indicated that the homologous gene of MeFER was purified and selected. The family contained cis-acting elements in response to hormones and stress induction. Moreover, qRT-PCR analysis showed that the expression of MeFERs gene was tissue-specific, and MeFER4 gene responded to various stresses, with the most significant response under drought stress. Therefore, these would provide a foundation for future functional studies of the cassava FER gene family.

Abstract:In order to study the chemical constituents in butanol fraction of ethanol extract of Dendrobium nobile, column chromatographic techniques including silica gel, Sephadex LH-20, revised silica gel and HPLC were used to separate the compounds, and spectroscopic techniques including NMR and MS were implied to determine the structures. Totally 3 compounds were isolated, and their structures were identified as 2,11-epoxy-11,13-dihydro-xypicrotoxano-3(15)-lactone (1), 2,4,6-trimethoxyphenol-1-O-β-d-glycoside (2), 3-methylbutan-1-ol β-d-gluco-pyranoside (3). Compound 1 was a new picrotoxane-type sesquiterpene, which is one of the representative components in D. nobile. However, none of the compounds showedα-glucosidase and tyrosinase inhibitory activity, none of them showed activity, and compound 1 show no neuroprotective activity either.