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, Available online doi: 10.11833/j.issn.2095-0756.20240301
Abstract:
Objective The objective is to explore the effects of different concentrations of lead (Pb) stress on the root growth physiology, root exudates and rhizosphere soil nutrient environment of Hydrangea macrophylla, and analyze its adaptation mechanism, provide a scientific basis to repair lead-contaminated soil. Method The effects of Pb [0 (the control), 500, 1 500, 2 500 mg·kg−1] stress on the growth and uptake of Pb, root oxidative damage, root antioxidant system, root osmotic regulatory substances and root exudates, soil physical and chemical properties, soil enzymes and rhizosphere Pb chemical morphology were studied by a pot experiment. Result Pb stress inhibited the growth of H. macrophylla, especially under 2 500 mg·kg−1 Pb treatment, the biomass decreased significantly by 23.7% compared with the control, but H. macrophylla had a certain tolerance to high concentrations of Pb. The oxidative damage caused by Pb stress on H. macrophylla was alleviated by increasing SOD and POD activities in the root, increasing GSH content and enhancing the antioxidant capacity. H. macrophylla also increased the content of osmotic regulatory substances. The soluble sugar content reached the maximum under 2 500 mg·kg−1 Pb treatment, while the proline content was opposite. The root could secrete fatty acids and amines to maintain cell structure, eliminate reactive oxygen species, and the increase of glycolic acid secretion promoted Pb absorption. Soil microecological environment was improved under Pb stress. The activities of sucrase and catalase in rhizosphere soil reached the maximum under the treatment of 2500 mg·kg−1 Pb, which effectively improved soil nutrients. With the increase of Pb concentration, rhizosphere pH value decreased and EC value increased, and the exchangeable ionic state and carbonate binding state of soil Pb accounted for 2.03% and 8.09% respectively, which increased the available state composition of Pb and was conducive to the absorption of Pb by H. macrophylla. Conclusion H. macrophylla has good adaptability to Pb, and can grow normally in soil with high concentration of Pb and improve the physical and chemical properties of soil. [Ch, 2 fig. 4 tab. 40 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240358
Abstract:
Objective This study is to analyze the habitat quality and its influencing factors in Haikou, so as to provide data support and scientific reference for ecological environment protection and urban construction. Method Based on the land use data of 2000, 2010 and 2020, InVEST model and the methods of land use transfer, habitat quality change rate and spatial statistical analysis were used to analyze the spatial-temporal dynamic changes in habitat degradation and habitat quality in Haikou, and summarize the influencing factors. Result ① From 2000 to 2020, forestland was the main type of land use in Haikou, accounting for 47.22%, 55.03%, and 48.75% of the total area in each period, followed by cropland. During the research period, the increase of built land area was the largest, with an increase of 230.37 km2, mainly transformed from forestland, cropland, and grassland. ②The change rate of habitat degradation degree was −1.77% from 2000 to 2010, and 12.20% from 2010 to 2020. The level of habitat degradation showed a spatial distribution pattern centered around the urban area and decreasing in circles. ③The overall habitat quality in Haikou was good. The proportion of areas with excellent habitat quality grades was around 50.00% in all stages, while the proportion of areas with poor grades increased from 5.33% in 2000 to 16.83% in 2020. The habitat quality level changed significantly and frequently in areas such as the urban-rural fringe in the central urban area of Haikou. During the research period, the habitat quality index of Haikou firstly increased and then decreased, and showed an overall decrease from 0.6880 to 0.6588. Conclusion From 2000 to 2020, the overall habitat quality in Haikou firstly increased and then decreased, which is closely related to the intensity of urban construction. Haikou should maintain the ecological priority and pay attention to ecological restoration of the main urban area, ecological infrastructure construction, and strengthen the protection and comprehensive management of the ecological system of the peripheral natural environment of the main urban area. [Ch, 5 fig. 7 tab. 25 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240458
Abstract:
Objective The study is to explore the niche and interspecific association of dominant species of woody plants in the evergreen broad-leaved forest in Bailushan scenic area, Zhejiang Province and understand their relationship and succession characteristics, so as to provide reference for ecological restoration and biodiversity conservation of subtropical evergreen broad-leaved forests. Method Taking the dominant species of woody plants in the evergreen broad-leaved forest in the study area as the research object, a long-term fixed plot with an area of 1 hm² was established. Ecological niche analysis, variance ratio method (RV), χ2 test, Pearson correlation coefficient, and Spearman rank correlation coefficient were used to analyze the niche and interspecific relationship of dominant woody plant species with importance values greater than 1.00%. Result (1) Schima superba, Lithocarpus glaber, Quercu sphillyreoides, and Pinus massoniana were the constructive species of the community. Among them, S. superba had the highest importance value (VI=27.37%), Levins niche width (BL=20.95), and Shannon niche width (BS=3.11), while the other three species had importance values greater than 10%. The average BL and BS were 16.63 and 2.87, respectively. (2) The mean niche overlap index of dominant species was 0.39. Most species were relatively independent in resource utilization and interspecific competition was weak. S. superba, L. glaber, Q. sphillyreoides, and P. massoniana had high niche overlap (mean Oik=0.73), indicating a high degree of similarity in resource utilization. The niche overlap index of Castanopsis sclerophylla with these four species was relatively low (mean Oik=0.17), indicating the weakest competition. (3) The overall association of dominant species in the community showed a significant positive correlation (P＜0.05). According to χ2 test, among the 153 pairs out of 18 dominant woody plant species, only 12 pairs showed significant associations (P＜0.05), while 91.00% pairs were not significantly correlated. Similar results were observed in Pearson correlation and Spearman rank correlation tests, and 71.25% and 71.90% of species pairs were not significantly correlated. The positive and negative association ratio was greater than 1, indicating that species tended to distribute independently. Conclusion The community is in the middle to late stage of succession and has a relatively stable ecological state. In the management of evergreen broad-leaved forests in the early or middle stage of succession in central Zhejiang, it is recommended to moderately retain P. massoniana when regulating high-density stands and appropriately plant Q. sphillyreoides in forest gaps and edges to promote positive succession and enhance the stability of forest ecosystems. [Ch, 4 fig. 2 tab. 36 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240356
Abstract:
Objective Neotrichocolea bissetii, a vulnerable liverwort by International Union for Conservation of Nature (IUCN), is endemic to East Asia. This study aims to clarify the structure traits of chloroplast genome and phylogenetic status of N. bissetii, the results can provide theoretical reference for the species identification, resource conservation and systematic evolution of N. bissetii. Method DNA was extracted, sequenced and assembled from N. bissetii samples collected in the field. The chloroplast genome structure, repeat sequences and codon bias were analyzed. The phylogenetic relationship was constructed based on the chloroplast genome sequences of 19 bryophytes. Result The whole genome sequence of the chloroplast of N. bissetii was 118 423 bp, including a pair of reverse repeat regions (IR, 9 031 bp), a large single copy region (LSC, 80 837 bp) and a small single copy region (SSC, 19 524 bp). It contained 79 protein-coding genes, 8 rRNA and 36 tRNA. In addition, a total of 56 simple sequence repeats (SSR) were detected in the whole chloroplast genome, most of which were AT/AT dinucleotide sequences. Codon preference analysis showed that the codon preferred to ends in A/U. With the exception of a few variable regions, the IR boundary regions of the chloroplast genome of the N. bissetii were very conserved. Phylogenetic tree showed that this species was most closely related to Trichocoleopsis sacculata. Conclusion The chloroplast genome of N. bissetii is a typical tetrad structure and relatively conserved. Phylogenetic tree analysis indicates that N. bissetii and T. sacculata into a branch structure. [Ch, 5 fig. 3 tab. 32 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240244
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Objective In order to reveal the diversity of ant species in different vertical zones in Tianshan Mountains, the ant community structure, relationship between species diversity and altitude and vegetation in the middle-western section of Tianshan Mountains were studied. Method Ant communities in four vertical zones were surveyed by plot sampling and searching methods. The sampling adequacy was tested by Estimate S 9.1.0, and the diversity indexes in different zones were calculated. The correlations between diversity indexes and altitude and vegetation characteristics were analyzed by SPSS 24.0, if the correlation between species diversity and elevation was significant, both linear and binomial models were used for fitting, the fitting was evaluated based on R2 value while the significance was tested. Result A total of 136 247 ants were collected, and 29 species belonging to 12 genera and 2 subfamilies were recognized. Tetramorium caespitum, Lasius niger and Formica fusca were the dominant species of the middle-western section of Tianshan Mountains in Xinjiang. Sampling adequacy analysis showed that the most of ant species were collected. The richness of ant species of the four vertical zones as follows: Dushanzi vertical zone (18 species) ＞ Narathi vertical zone (14 species)＞ Kuqa vertical zone (13 species) ＞ Ulastai vertical zone (10 species). Diversity analysis showed that the ant species diversity of the middle-western section of Tianshan Mountains generally decreased with the altitude increasing. The species number and diversity index of the four vertical zones were significantly negatively correlated with the altitude change. On the four vertical zones, the correlation significance between evenness index and altitude was not the same, the change trends of binomial and linear models also lacked regularity. There was no significant correlation between dominance index and elevation change, but the binomial model analysis of each vertical zone showed a trend of increasing firstly and then decreasing with the elevation increasing. Community similarity analysis found that the similarity coefficient of ant community was between 0.166 7 to 0.600 0 (average 0.289 0), which was at the medium dissimilarity level, and indicating significant differentiation among ant communities. Correlation analysis showed that the species number was significantly positively correlated with tree canopy density, while the correlation between other diversity indexes and vegetation characteristics was not significant. Conclusion Altitude significantly affected ant species diversity in this region, while slope, humidity and vegetation also play an important role. In the Tianshan area of Xinjiang,under the influence of multiple factors such as vegetation types mainly being grassland and shrubland, hot and dry climate, high altitude and large temperature difference, and the ecosystem in this region is relatively fragile, so the protection of biodiversity in this region should be strengthened. [Ch, 5 fig. 5 tab. 37 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240359
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Objective The objective is to analyze the dynamic variations in sap flow rate of Salix psammophila branches across various diameter classes and explore the water use control strategies of S. psammophila in response to soil water potential (Psw) and meteorological factors under the influence of rainfall during the growing season, so as to provide theoretical reference for understanding the water consumption characteristics of desert shrubs under seasonal drought. Method 12 branches from 3 sample trees (including 4 diameter levels: 6−8 mm, 8−10 mm, 10−12 mm, and greater than 12 mm) were selected from the national germplasm resource bank of S. psammophila in Hobq Desert. From May to October 2023, sap flow system for small stems or branches was used to continuously monitor changes of sap flow, Psw and meteorological factors such as precipitation, air temperature and relative humidity. Principal components analysis and stepwise linear regression were used to analyze the response of sap flow to major meteorological factors and Psw at different depths before and after rainfall. Result (1) During the growing season, the daily variation of sap flow rate at different diameter levels of S. psammophila showed a “single peak” or “double peak” curve from May to August, while a “U” shaped curve was easy to appear in September to October, and the onset time of sap flow rate was gradually delayed. (2) The sap flow rate of S. psammophila with smaller diameter was significantly positively correlated with Psw in 20 and 40 cm soil layers (P＜0.05), and was more directly influenced by Psw in 40 cm soil layer. There was a significant positive correlation between the flow rate of S. psammophila with larger diameter and Psw in 60 and 80 cm soil layer (P＜0.05), and was more directly affected by Psw in 80 cm soil layer. (3) When the precipitation exceeded 10 mm, the sap flow rate of S. psammophila at different diameter levels showed a “multi peak” curve, and the daily cumulative flow decreased. The cumulative contribution rate of soil temperature, saturated vapor pressure deficit, relative air humidity, and air temperature to changes in sap flow rate before rainfall was 71%, and the cumulative contribution rate of Psw in 10 and 20 cm soil layers to changes in sap flow rate after rainfall was 63%. Conclusion The instantaneous variation and overall level of S. psammophila sap flow rate are affected by meteorological factors and soil water supply, respectively, indicating that the short-term and long-term flow characteristics of S. psammophila under seasonal drought have different responses to environmental factors. [Ch, 7 fig. 5 tab. 30 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240416
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Objective Taking the forest communities of Yandang and Kuocang Mountains in Taizhou as the research objects, this study focuses on the differences of forest community structure and species composition of 2 mountain systems and their causes, which provides technical support for understanding the changes of evergreen broad-leaved forests in Taizhou. Method Based on the survey of 11 plots in Yandang Mountain and 15 plots in Kuocang Mountain (20 m×20 m), species composition, diameter structure and their relationships with the environmental factors were analyzed using methods such as Redundancy Analysis (RDA). Result Forest communities of Yandang Mountain recorded 67 species of trees, belonging to 31 families and 46 genera while those of Kuocang Mountain recorded 89 species of trees, belonging to 38 families and 62 genera. Species having important values ≥1% in the forest communities of Yandang and Kuocang Mountains were Schima superba, Liquidambar formosana, Cinnamomum camphora, Cunninghamia lanceolata, Loropetalum chinense, Eurya rubiginosa, Cyclobalanopsis glauca, Castanopsis sclerophylla, Adina pilulifera, Eurya muricata, Styrax faberi. The important value of Schima superba in the forest communities of Kuocang Mountain was 27.37%, which was 16.80% higher than that in Yandang Mountain. Shannon-Wiener index and Pielou evenness index of the forest communities of Yandang Mountain were significantly higher than those of Kuocang Mountain (P＜0.05). The total individual diameter distribution of species in 2 forest communities showed inverted J shapes. Total nitrogen, rock exposure rate, pH, soil total carbon and electrical conductivity were the main factors affecting the diversity indexes of forest communities of 2 mountains. Conclusion Shannon-Wiener index and Pielou evenness index of Yandang Mountain forest community were significantly higher than those of Kuocang Mountain forest communities. The main difference between 2 mountain forest communities is that the important value of Schima superba in Kuocang Mountain forest community is significantly higher than that in Yandang Mountain. [Ch, 3 fig. 3 tab. 42 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240401
Abstract:
Objective The objective of this study is to interpret the carbon accumulation characteristics during the growth process of typical Pinus massoniana forests, and investigate the mechanism and potential of carbon sequestration in P. massoniana forests. Method Four different afforestation years (8, 12, 22, 38 years) of P. massoniana plantations with similar slopes and altitudes were selected in Laoshan Forest Farm, Qiandaohu Town, Chun’an County, Zhejiang Province. Multiple statistical methods combined with redundancy analysis and structural equation modeling were employed to analyze the carbon density characteristics of P. massoniana forests with different afforestation years and the main factors affecting their carbon density. Result The total biomass reached its maximum value at 38 years (mature forest), which was significantly higher than that of young and middle-aged forests (P＜0.05). The biomass of the herb layer and litter layer reached their maximum values at 22 years of afforestation, with values of 13.74 and 5.24 t·hm−2, respectively. Carbon density of the tree layer increased with the increase of afforestation years, reaching a maximum value of 176.36 t·hm−2 at 38 years (mature forest). There were significant differences in soil carbon density among different ages of P. massoniana forests (P＜0.05). The carbon density in the soil layers of 0−10 and 10−30 cm reached their maximum values at 38 years (mature forest), which were 38.60 and 57.13 t·hm−2, respectively. Redundancy analysis revealed that total potassium, available potassium, and slope direction were the main contributing factors to carbon density of P. massoniana forests, accounting for approximately 28.70%, 27.00%, and 9.90% of the carbon density of each component, respectively, and were crucial to overall carbon sequestration of soil and vegetation. The structural equation model demonstrated that bulk density, vegetation density, and total potassium content had significant effects on carbon density in P. massoniana forests. Conclusion The carbon density of P. massoniana forests is closely related to the years of afforestation, with mature P. massoniana forests exhibiting the highest capacity for carbon sequestration. Environmental factors and soil nutrient status are crucial for enhancing the carbon sequestration potential of P. massoniana forests. [Ch, 4 fig. 5 tab. 44 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240381
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Objective Analyze the effects of different microorganisms on the weathering and elemental release of basalt, to explore the role of microorganisms in the weathering process of basalt, and to provide a theoretical basis for microorganisms promoting basalt weathering. Method Different microbial strains (Bacillus mucilaginosus and Trichoderma asperellum) were selected to carry out simulation experiments on biological weathering of basalt. By means of elemental geochemical methods (elemental dissolution amount and rate) and mineral analytical methods (material composition), the effects of microorganisms on the release amount, release rate, and release capacity of Si, Ca, Al, Fe, and Mg elements from basalt were investigated, and preliminarily explored the release mechanisms. Result Microorganisms contributed to the weathering of basalt and the dissolution of elements, compared to the control group, the pH of the fungal and bacterial system solutions decreased by 1.46 and 0.88 units, respectively. Compared to the control group, the release amounts of Si, Ca, Al, Fe and Mg elements in basalt was significantly increased by 10.2, 2.6, 8.2, 92.9 and 9.9 times under the action of fungi, and it was significantly increased by 2.7, 1.2, 1.7, 19.7 and 3.2 times under bacterial action. The order of element release from basalt under the action of fungi and bacteria was same: Ca＞Mg＞Fe＞Si＞Al. Microorganisms create an acidic environment mainly by secreting organic acids or by complexing to promote the weathering of basalt and increase the rate of elemental dissolution. Conclusion Microorganisms can effectively increase the release and rate of elements during the weathering process of basalt, there are also differences among different strains. The release and rate of elements during the weathering process of basalt under the treatment of T. asperellum are higher than those under the treatment of B. mucilaginosus, indicating that fungi have a more significant role in accelerating the weathering process of basalt. [Ch, 6 fig. 41 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240415
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Objective The objective is to investigate the effects of leaf microstructure of garden plants on particle retention capacity, and provide theoretical basis for the selection of urbangarden tree species. Method 13 evergreen shrubs, including Pyracantha fortuneana, Fatsia japonica and Nerium oleander were studied in Zhengzhou City, Henan Province. The retention of particles of different sizes [total suspended particulate matter (TSP), large particulate matter (PM>10), inhalable particulate matter (PM10) and fine particulate matter (PM2.5)] per unit leaf area was measured by graded membrane filtration method. The microstructure of leaf surface was observed by scanning electron microscopy and ultra depth microscope, and the relationship between particle retention capacity and leaf surface microstructure features was analyzed. Result (1) There were significant differences in the retention capacity of 13 evergreen shrubs with different particle sizes (P＜0.05), and the strongest comprehensive dust-retention ability was found in P. fortuneana, F. japonica, and N. oleander, with a dust retention capacity per unit area of 2.59, 2.23 and 1.97 g·m−2, respectively, 3.58−4.70 times that of Mahonia fortunei and Nandina domestica, which had a weak dust retention capacity. (2) Particles tended to be distributed near the midrib and leaf tip. Observation of leaf surface microstructure revealed that there were various structures such as grooves, fuzz, and protrusions on the upper surface. Most of the stomata were located on the lower surface of the leaf. These structures synergistically affected the retention of particles in plants, and concurrently enhanced the roughness of leaf surfaces. The surface roughness in N. oleander leaves was the highest (4.53 μm), with regular semi-circular protrusions on the upper surface and large concave stomata on the lower surface, surrounded by hairy tissue to attach dust particles. (3) Correlation analysis indicated that leaf area, roughness, stomatal length were significantly positively correlated with the content of TSP, PM10 and PM2.5 retention per unit leaf area (P＜0.05, P＜0.01), and stomatal width and stomatal area were significantly positively correlated with PM10 and PM2.5 retention (P＜0.05). Conclusion P. fortuneana, F. japonica, and N. oleander are recommended as excellent garden dust-retaining species in controlling air pollution in Zhengzhou City. [Ch, 5 fig. 3 tab. 35 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240354
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Objective This study aims to employ bioinformatics methods to perform a comprehensive genome-wide identification of the soybean IGT gene family and explore the potential functions of IGT gene family in soybean. Method Soybean cultivar Glycine max‘Tianlong 1’ was selected and GmIGTs were identified by BLASTP search of IGT protein domain. The evolutionary relationships, gene structure, conserved motifs, cis-acting elements, and collinearity relationships were analyzed by bioinformatics methods. The expression patterns of GmIGTs in different tissue parts were analyzed. Result A total of 17 GmIGT genes were identified and classified into 4 branches based on their phylogenetic relationships: TAC, IGT-like, DRO, and LAZY. Protein conserved motif analysis revealed that all IGT proteins contained Motif2. Chromosomal localization and collinearity analysis showed that GmIGT genes were unevenly distributed on 11 chromosomes, and segmental duplication might have played a significant role in the expansion of GmIGT gene. Cis-acting element analysis indicated that GmIGT expression might be associated with light response, physiological response, plant hormone response and stress. RT-qPCR analysis demonstrated that GmIGT gene had obvious tissue-specific expression characteristics. Among them, GmIGT5 exhibited relatively high expression levels in all tissues, while GmIGT4 and GmIGT10 were highly expressed in stems and petioles. Conclusion GmIGT gene may play a potential role in shaping soybean plant architecture, and GmIGT4 and GmIGT10 may be the core genes involved in this process. [Ch, 9 fig. 2 tab. 23 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240383
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Objective This study is to explore the dominant factors in stand structure and soil nutrients that affect the understory herbaceous diversity of natural secondary Betula platyphylla forest, so as to provide theoretical basis for optimizing the stand structure and improving herbaceous diversity of natural secondary B. platyphylla forest in Qinghai Province. Method Taking the natural secondary B. platyphylla forest in Baoku Forest Farm of Datong County, Qinghai Province as the research object, 20 standard plots (24 m×24 m) were selected by typical sampling method. The effects of multiple factors (stand spatial structure, stand non-spatial structure, and soil nutrient) on herbaceous diversity were investigated by correlation analysis and redundancy analysis. Result (1) A total of 47 species of herbaceous plants belonging to 41 genera and 24 families were found under the B. platyphylla forest, among which Lolium perenne, Fragaria vesca, Polygonum viviparum, Galium bungei and Geranium wilfordii were the dominant species, with mean important values of 19.52%, 18.91%, 10.53%, 6.95% and 5.27%, respectively. (2) Redundancy analysis showed that openness, mean DBH, and size ratio could explain 44.1%, 16.8% and 8.2% of the variation patterns in herbaceous diversity, respectively, and were the main stand factors affecting herbaceous diversity. Alkali-hydrolyzed nitrogen and available potassium could explain 7.9% and 7.6% of herbaceous diversity pattern, respectively, and were the main soil nutrient factors. Conclusion Both stand structure and soil nutrients significantly affect understory herbaceous diversity. The overall level of understory herbaceous diversity can be improved by adjusting stand spatial structure, optimizing stand competition and improving soil fertility. [Ch, 2 fig. 4 tab. 37 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240307
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Objective This study explore the ecological niche and interspecific association of the dominant species of woody plants in evergreen broad-leaved forest in Jinzifeng National Forest Park, Zhejiang Province, in order to provide a reference for ecological restoration and biodiversity conservation of subtropical evergreen broad-leaved forest. Method Niche composition, niche width, niche overlap index, niche similarity coefficient, variance ratio method, \begin{document}$ {X}^{2} $\end{document} Result (1) There were 113 species of woody plants belonging to 31 families and 62 genera in the evergreen broad-leaved forest community in Jinzifeng National Forest Park, including Fagaceae, Rosaceae, Lauraceae, and Ericaceae. (2) The importance values and niche widths of Schima superba, Castanopsis eyrei and Pinus taiwanensis were larger. They were established species in this community, and had higher niche overlap values and niche similarity coefficients with other dominant species of woody plants. The niche overlap values and niche similarity coefficients of 21 dominant species of woody plants were mainly concentrated in the range of 0.10 − 0.50. (3) The dominant species of evergreen broad-leaved forest woody plants in Jinzifeng National Forest Park showed a significant positive association. Among 210 species pairs, 112 species pairs showed no significant positive association, 49 species pairs showed no significant negative association, only 2 species pairs showed extremely significant positive association (P＜0.01) , 8 species pairs showed significant positive association (P＜0.05) , 39 species pairs showed no association. Spearman rank correlation test and Pearson correlation test showed no significant association. Species pairs accounted for 81.4% and 80.0%, respectively. The interspecific association was weak, with positive and negative association ratios greater than 1. (4) The regression analysis of Pearson correlation coefficient and niche overlap values of dominant tree species showed a extremely significant positive correlation (P＜0.01). Conclusion The evergreen broad-leaved forest community in Jinzifeng National Forest Park is in the middle stage of succession, and the competition among species is gradually balanced. [Ch, 3 fig. 5 fig. 34 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240327
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Objective The objective is to study the gibberellin oxidase JrGA3ox gene, which is of great significance for improvement, growth and development, and drought resistance of Juglans regia varieties. Method J. regia wild-type (WT), JrGA3ox overexpression (OE) and interference (RNAi) plants were used as experimental materials. Drought treatment with 5% PEG 8000 volume fraction was simulated to investigate the plant phenotype, physiological and biochemical indexes and expression level of drought resistance gene under drought stress, and clarify the drought resistance mechanism of JrGA3ox gene. Result (1) Real-time fluorescent quantitative PCR verification showed that the expression level of JrGA3ox gene in OE plants and RNAi plants were 120 and 0.3 times that of WT plants, respectively. (2) Plant growth phenotype analysis showed that plant height and internode length of OE plants were significantly higher than those of WT plants, while those of RNAi plants were significantly lower than those of WT plants (P＜0.05). (3) Compared with WT plants, under drought stress for 0−28 days, RNAi plants showed better growth, while OE plants showed weaker growth. (4) Stomatal opening and chlorophyll mass fraction decreased gradually with the extension of drought stress time. Stomatal opening of RNAi plants were significantly lower than that of WT plants (P＜0.05), while stomatal opening of OE plants were significantly higher than that of WT plants. The chlorophyll mass fraction of RNAi plants were always significantly higher than that of OE plants and WT plants (P＜0.05). (5) After drought stress, the mass molar concentration of reactive oxygen species and malondialdehyde in OE plants were significantly higher than that in WT plants, while that in RNAi plants were significantly lower than that in WT plants (P＜0.05). (6) The activity of antioxidant enzymes and expression level of related resistance genes firstly increased and then decreased during the stress process, reaching their maximum value at 14 days of drought stress, and those in RNAi plants were significantly higher than those in WT plants, while those in OE plants were significantly lower than those in WT plants (P＜0.05). Conclusion JrGA3ox gene in J. regia can positively regulate plant height and internode length, and negatively regulate stomatal opening, photosynthesis, antioxidant enzyme activity of plants, thus improving plant drought resistance. [Ch.10 fig. 1 tab. 28 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240316
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Objective This study aims to screen and identify ERF transcription factors of B2 subgroup involved in regulating lycopene β-cyclase OfLCYB gene of Osmanthus fragrans. Method ‘Yanhong Gui’, a cultivar of O. fragrans, was used as the material to screen OfERF genes of B2 subgroup from the O. fragrans transcriptome database. Bioinformatic analysis, real-time quantitative PCR (RT-qPCR) and yeast one-hybridization were used to analyze the sequence and expression characteristics of the OfERF gene and its binding to the OfLCYB gene promoter. Result The promoter of the OfLCYB gene contained two ATCTA cis-acting elements. Four OfERF genes of B2 subgroup were screened based on the O. fragrans transcriptome database, all of which contained an AP2 conserved structural domain. The RT-qPCR results showed that the expression levels of OfERF72a and OfERF72b genes gradually decreased with the flowering process, and were significantly negatively correlated with the expression of OfLCYB gene, with P values of 0.0338 and 0.0296 , respectively. The results of yeast one-hybridization proved that there was a physical binding between OfERF72b and the OfLCYB promoter. Conclusion OfERF72b may participate in the metabolism of carotenoid in O. fragrans by regulating the transcription of OfLCYB. [Ch, 7 fig. 3 tab. 25 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240266
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Objective Flower fragrance is an important characteristic of ornamental plants, which is very crucial for plants reproduction. This study aims to reveal the biosynthesis and release mechanism of floral substances in Chimonanthus, and to provide a solid theoretical basis for the utilization and development of Chimonanthus resources. Method Headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were used to identify and analyze floral substances of 3 Chimonanthus species, including C. praecox, C. salicifolius and C. nitens. Result A total of 44 floral substances were identified in 3 Chimonanthus species, among which 19, 23 and 18 substances were identified in C. praecox, C. salicifolius and C. nitens respectively. The floral substances of alcohols and esters were the highest in C. praecox, while the content of alkenes was the highest in the floral substances of C. salicifolius and C. nitens. The daytime release rhythms of floral substances in 3 Chimonanthus species were different. The floral substances of C. salicifolius and C. nitens in the morning, noon and afternoon were different, but the floral substances of C. praecox changed little. Phylogenetic analysis showed that C. salicifolius and C. nitens were more closely related than C. praecox. Conclusion The floral substances of C. salicifolius and C. nitens are similar, which caters to the phylogenetic relationship between them. In view of the special low-temperature flowering environment of C. praecox, the interaction between pollination insects and floral fragrance may be the reason for the uniqueness of floral substances. [Ch, 3 fig. 3 tab. 35 ref.]
, Available online doi: 10.11833/j.issn.2095-0756.20240254
Abstract:
Objective This study is to investigate the seed traits of female Torreya grandis, analyze the genetic variation of the population based on SSR primers, and compare the differences in seed phenotype, quality, and genetic diversity between and within populations of T. grandis. Method Female T. grandis from Fuyang, Shengzhou, Lin’an, Jiande in Zhejiang Province and Mount Huangshan in Anhui Province were used as materials to compare the phenotypic traits of T. grandis leaves and seeds through variance analysis and principal component analysis. The genetic diversity of T. grandis was compared by SSR molecular markers using female T. grandis from Fuyang, Shengzhou, Lin’an, Chun’an and Mount Huangshan as raw materials. Result Analysis of seed traits revealed that there were significant individual differences (P＜0.01) in 8 indicators: leaf quality, leaf shape index, seed mass, seed shape index, seed weight, kernel shape index, seed coat thickness, and shell thickness between and within populations. The relative fat content and soluble sugar content also showed extremely significant differences among populations (P＜0.01), with fat content ranging from 29.36% to 42.35%, indicating rich variation in T. grandis seed appearance and kernel quality. SSR primer analysis showed that the mean Nei’s genetic diversity index (H) was 0.400, the mean Shannon’s information index (I) was 0.650, and the mean polymorphic information content (PIC) was 0.400. Chun’an population exhibited the highest genetic diversity (H=0.410, I=0.658), while Shengzhou population showed the lowest (H=0.369, I=0.565). 92% of the total genetic variation existed within the population. Conclusion There are genetic variations in the phenotype and quality of T. grandis between and within populations. The genetic diversity of Chun’an population is the highest, and the genetic variation within the population is greater than that between populations. [Ch, 2 fig. 11 tab. 26 ref.]
