Abstract:Regional droughts caused by global climate change pose a severe challenge to plant survival. Plant drought resistance and mechanical resistance are key factors determining their growth and survival. Tropical forests, as the terrestrial ecosystems with the highest biodiversity and productivity on Earth, however, the relationship between drought tolerance and mechanical resistance of their dominant tree species leaves remains unclear. This study took the dominant tree species in the tropical seasonal rainforest of Xishuangbanna as the research object. By measuring key morphological and hydraulic traits such as the pressure-volume curve of leaves, leaf mechanical resistance (LMR), leaf dry matter content (LDMC), and leaf mass per area (LMA), and combining phylogenetic analysis to explore evolutionary relationships, the relationship between leaf drought tolerance and mechanical resistance and its driving mechanism were further analyzed. The results showed that the morphological, hydraulic traits and mechanical resistance of leaves of tropical seasonal rainforest tree species varied greatly and were not significantly constrained by phylogeny; leaf drought resistance and mechanical resistance were significantly positively correlated with LMA and LDMC; leaf drought tolerance and mechanical resistance were also significantly positively correlated, and this co-variation relationship was regulated by leaf structural investment. This reveals a synergistic relationship between leaf drought resistance and mechanical resistance in dominant tree species of tropical seasonal rainforests, providing a scientific basis for understanding the ecological adaptation strategies of plants in this region and predicting the dynamics of forest communities under climate change.

Abstract:River corridors are important habitats for spontaneous plants in cities. Revealing the diversity characteristics and causes of spontaneous plants in different grades of rivers can help improve the urban vegetation research system and guide the low-maintenance and sustainable landscape creation of river corridors. This study adopted the typical plot sampling method to conduct a comprehensive investigation of 330 plots in the sample sections of the Ganjiang River (mainstream) and Wusha River (tributary) from March to November 2023. A total of 240 species of spontaneous plants were recorded, belonging to 49 families and 169 genera, with herbaceous plants being the majority. The results showed that there were differences in the number of high-frequency species and their life form composition between the two river sections, with more high-frequency plants in the tributary than in the mainstream. Seasonal dynamics dominated the community pattern, forming a continuous distribution of single dominant groups in spring and autumn and a fragmented distribution of double groups in summer. Among different riverbank gradients, except for the Margalef richness index of the tributary showing the characteristic of municipal road side>water side, the other α-diversity indices all presented a spatial difference feature of lower section>upper section>middle section>water side>municipal road side. The Shannon-Wiener diversity index and Pielou evenness index showed significant differences under extreme and mild disturbances. The diversity of spontaneous plants in urban riverbanks is the result of the combined effect of riverbank environmental heterogeneity and human disturbance gradients. Therefore, ecological protection and restoration should maintain the longitudinal riverbank gradient from water side to road side, respect the seasonal dynamics of communities, and implement management methods based on disturbance grading, that is, protect mild disturbances, utilize moderate disturbances, and guide intense disturbances. Therefore, applying the dominant native plants of each gradient as landscape resources can promote the coordinated development of ecological restoration, low-maintenance management, and characteristic landscape creation of river corridors.

Abstract:To reveal the stoichiometric characteristics and influencing factors of leaves and twigs of mangrove plants, the contents of carbon (C), nitrogen (N), and phosphorus (P) and the stoichiometric ratios of current-year leaves and twigs of three mangrove species (Kandelia obovata, Avicennia marina, and Aegiceras corniculatum) in Zhangjiang River estuary, Fujian Province, were determined, and their correlations with leaf phenotypic traits and basal diameter were analyzed. The results showed that the mean contents of C, N, and P in leaves of the three mangrove species were 421.91, 18.05 and 1.79 g/kg, respectively, and those in twigs were 439.28, 9.70 and 1.58 g/kg, respectively. There were significant differences in nutrient contents in organs among different species. The N:P ratio of the mangrove ecosystem in this area was lower than the threshold, indicating that the ecosystem was N-limited. There were significant correlations between the element allocation of organs and leaf phenotypic traits of each tree species, reflecting the nutrient acquisition strategies of mangrove plants. The C:N and C:P of leaves and twigs were significantly negatively correlated with basal diameter, while the N:P of twigs was significantly positively correlated with basal diameter, indicating that the resource allocation of different-sized individuals changed dynamically. There were certain correlations between organs, species, leaf phenotypic traits, basal diameter, and the stoichiometric characteristics of mangrove species. Therefore, it was suggested that the stoichiometric characteristics of the three mangrove species were jointly affected by species, organ type, leaf nutrient acquisition strategy, and individual growth status, and were reflected in the nutrient allocation patterns and phenotypic traits.

Abstract:Metal elements are essential for plant biological processes but may also cause stress. To explore the characteristics of metal element absorption and utilization by coastal halophytes under high-salt conditions, this study selected six common coastal halophytes in Hainan [Vitex trifolia, Volkameria inermis, Stachytarpheta jamaicensis, Eupatorium odoratum, Lantana camara, and Ipomoea pes-caprae] as research subjects. The contents of four metal elements, potassium (K), calcium (Ca), sodium (Na), and magnesium (Mg), in their leaves and soil were determined, and the enrichment coefficients, stoichiometric ratios, and their correlations were analyzed. The results showed that the metal element contents in the leaves of coastal halophytes were distributed as K>Na> Ca>Mg, with contents of 21.07, 1.49, 1.13, and 0.59 mg/g, respectively. There were significant interspecific and regional differences, reflecting the adaptive regulatory mechanisms of plants to different soil conditions and environmental stresses. The plants had the strongest absorption capacity for K and Na, while the absorption capacity for Ca and Mg was relatively weak. Coastal halophytes had the strongest enrichment effect on metal elements K and Na. Different coastal halophytes had different enrichment abilities for different metal elements. Among them, Vitex trifolia and Ipomoea pes-caprae had the best enrichment abilities for K, Na, and Mg, while Eupatorium odoratum had the best enrichment ability for Ca. The leaf K content was significantly positively correlated with soil Na and Mg, and significantly negatively correlated with soil K, K:Na, K:Mg, and Ca:Mg. Leaf Ca was significantly positively correlated with soil K, K:Ca, K:Na, and K:Mg. Leaf Na and Mg had no significant correlation with soil metal elements and their stoichiometric ratios, indicating that coastal halophytes have complex ion regulation mechanisms. This provides guidance for comprehensively and systematically revealing the nutrient status of the ecosystem in coastal sandy areas and the cultivation and management of coastal halophytes, and also supplements the content of metal elements in coastal halophytes.

Abstract:To explore the influence mechanisms of tree species, decay grades and distance on the content of soil humus during the decomposition process of common tree species in karst forests, and to understand the functional role of fallen trees in forest ecosystems, the contents of total carbon, humic acid, fulvic acid and humin in the surface soil at 10, 30 and 50 cm away from the fallen trees of Cyclobalanopsis glauca, Platycarya longipes, Liquidambar formosana and Machilus rehderi in the evergreen and deciduous broad-leaved mixed forest of Maolan karst were measured. The results showed that the tree species, decay grades and the interaction between tree species and decay grades of fallen trees in karst forests significantly affected the contents of various components of soil humus (total carbon, humic acid, fulvic acid and humin), while distance significantly affected the organic carbon and humin of soil humus. The contents of total carbon, humic acid, fulvic acid and humin in the soil adjacent to the fallen trees of M. rehderi were significantly lower than those of L. formosana, C. glauca and P. longipes. The contents of total carbon and humin in the soil adjacent to the heavily decayed fallen trees of L. formosana and P. longipes were significantly higher than those of the slightly decayed ones. With the increase of distance from the fallen trees, the contents of total carbon and humin of M. rehderi and L. formosana showed a significant downward trend. The correlations between the contents of organic carbon, total nitrogen, total phosphorus, hydrolyzable nitrogen and available phosphorus in the soil adjacent to the fallen trees and the contents of various components of soil humus significantly increased with the increase of decay grades. Therefore, the decomposition of fallen trees in karst forests had an important impact on soil carbon and nutrient cycling. There were differences in the accumulation patterns of soil humus among different tree species, and decay grades could regulate the relationship between fallen tree decomposition and nutrient cycling.

Abstract:To investigate the purification effect of native wetland plants on local urban sewage and clarify the possibility of using native plants instead of exotic introduced plants for water body restoration, eight native plants in Guangdong Province were selected: Ranunculus sceleratus, Commelina diffusa, Nephrolepis cordifolia, Monochoria vaginalis, Alocasia macrorrhiza, Kyllinga brevifolia, Ludwigia adscendens, and Acorus tatarinowii. Through a simulated hydroponic experiment, the removal effects of these plants on chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), and total phosphorus (TP), as well as their sewage adaptation capabilities, were explored. The results showed that wetland plants had a significant ability to remove nitrogen and phosphorus from water, and their removal effects varied with plant species and treatment time. Ranunculus sceleratus, Ludwigia adscendens, and Acorus tatarinowii could effectively remove phosphorus, achieving optimal removal rates of 92.40%, 95.33%, and 96.20% in high-concentration sewage, respectively. All eight tested plants had good ammonia nitrogen removal effects, and the treatment time should be selected based on plant species and sewage concentration to achieve better removal rates. Therefore, all eight native wetland plants could be used to restore low-concentration domestic sewage, and when the sewage concentration is high, Ranunculus sceleratus, Ludwigia adscendens, and Acorus tatarinowii are recommended as restoration materials. These would provide a reference for the selection of plant materials for domestic sewage restoration in the Pearl River Delta region.

Abstract:To explore the regulatory network of flavonoid biosynthesis in Lycium barbarum var. auranticarpum, we utilized broad-target metabolomics and transcriptomics to analyze the differential metabolites and differentially expressed genes between L. barbarum var. auranticarpum (yellow goji) and its hybrid (hybrid yellow goji). The results showed that 55 kinds of flavonoids were present in higher amounts in the fruits of hybrid yellow goji, among which flavonols (63) and dihydroflavones (13) were dominant (60.09%). By screening the differential metabolites in the flavonoid biosynthesis-related pathways, it was found that cinnamic acid, swertiamarin and dihydroquercetin were present in higher amounts in hybrid yellow goji, while quercetin and epicatechin were only present in hybrid yellow goji. A total of 23 244 differentially expressed genes were detected in yellow goji and hybrid yellow goji, with 14 129 genes upregulated and 9 115 genes downregulated in hybrid yellow goji. Eleven differentially expressed structural genes related to the flavonoid biosynthesis pathway were screened out. The expression of seven key structural genes (LbANS, LbF3′H, LbF3′5′H, Lb4CL, LbDFR, LbPAL and LbFLS) involved in flavonoid biosynthesis were all higher in hybrid yellow goji than in yellow goji. Meanwhile, four MYB transcription factors were upregulated in hybrid yellow goji. Therefore, these key structural genes and transcription factors may be the key genes regulating the differential accumulation of flavonoids in yellow goji and hybrid yellow goji.

Abstract:To reveal the impact of plant growth on soil N₂O and CO₂ emissions, a combined field and pot experiment was conducted to study the soil greenhouse gas emissions of Mikania micrantha and its competing plants, Pueraria lobata var. thomsonii and Ipomoea batatas. The results showed that the CO₂ equivalent emissions from the soil where M. micrantha grew were significantly lower than those from the soil where P. lobata var. thomsonii and I. batatas grew, indicating a lower greenhouse effect potential. The relative contribution of fungi to N₂O emissions (79.3%) was significantly higher than that of bacteria (58.1%). The random forest model revealed that total soil nitrogen (TN), nitrate nitrogen (NO₃^--N), and ammonium nitrogen (NH₄⁺-N) were the core driving factors of greenhouse gas emissions (explaining more than 11%), and were significantly positively correlated with CO₂ equivalent emissions (R²=0.49-0.82). The greenhouse gas emission effect of the soil where M. micrantha grows is closely related to the choice of control species. Compared with the local plants P. lobata var. thomsonii and I. batatas, the soil where M. micrantha grows shows a lower greenhouse effect potential, which may be related to the different nitrogen utilization strategies and nitrogen cycling microbial community regulation mechanisms of different plants. This provides an important reference for the assessment of the ecological effects of invasive plants, but further validation is needed by combining more species and long-term observations.

Abstract:To explore the effects of different water and fertilizer coupling conditions on the growth and physiological and biochemical indicators of Camellia huana in Guizhou, plants with similar growth vigor were selected, and three irrigation volumes and four levels of fertility were set. At the end of the growing season, the biomass, plant height, ground diameter and other growth indicators were measured, and the contents of total flavonoids, total phenols, total sugars, total amino acids, malondialdehyde, proline, catalase and acid phosphatase in leaves were determined. The results showed that among various water and fertilizer coupling patterns, the W₂F₂ combination [irrigation volume of 800 mL/ind., fertilizer application (N-P-K) 1.6-1.0-1.0 g/ind.] was more conducive to the growth and accumulation of active components of C. huana, and multiple indicators such as aboveground biomass, total biomass, total phenols and total flavonoids reached their peaks. Therefore, it was recommended that when promoting the cultivation of C. huana, the water and fertilizer management measures of the W₂F₂ combination be adopted, which can promote the growth and secondary metabolite synthesis of C. huana, and significantly improve the stress adaptability and quality of the plants.

Abstract:To investigate the chemical constituents of the roots of Dendrobium hercoglossum and evaluate their biological activities, the ethyl acetate fraction of an ethanol extract from its roots was isolated and purified by using chromatographic techniques, including silica gel column chromatography and semi-preparative HPLC. The structures of the isolated compounds were elucidated through mass spectrometry and nuclear magnetic resonance spectroscopy (NMR), and then they were subsequently evaluated for anti-inflammatory and other biological activities. The results showed that eight compounds were isolated, such as (Z)-dimethomorph (1), (E)-dimethomorph (2), dengibsin (3), 4-O-demethyl-nobilone (4), dendroflorin (5), p-hydroxyphenylpropionic acid (6), syringic acid (7), 1H-indole-3-carbaldehyde (8). Compound 4 significantly inhibited LPS-induced NO production in RAW264.7 mouse macrophages, with an IC₅₀ value of (14.69±1.16) μmol/L. Compounds 1 and 2 were isolated as natural products for the first time, as well as their NMR data. Compounds 1-8 were isolated from D. hercoglossum for the first time. Compound 4 showed significant anti-inflammatory activity.

Abstract:To clarify the chemical constituents of endophytic fungus Neofusicoccum parvum QCZ-8 isolated from twig of Gannan navel orange, nine compounds were obtained from the rice fermentation of this fungus by multiple chromatographic techniques. Based on spectral data, they were identified as 5,7-dihydroxy-6-methoxyl-3-methyl-isocoumarin (1), (+)-orthosporin (2), 22Z-ergosta-4,6,8(14),22-tetraen-3-one (3), stigmast-4-en-3-one (4), ergosterol peroxide (5), 9,11-dehydroergosterol peroxide (6), 7-hydroxy-2,5-dimethyl-4H-1-benzopyran-4-one (7), (S)-mevalonolactone (8), and 2,3-dihydroxypropyl acetate (9). Among them, compound 1 was a new compound, compound 5 was isolated from this fungus for the first time, and the remaining seven compounds were obtained from the genus Neofusicoccum for the first time.

Abstract:Photoperiod is the most stable and reliable environmental signal perceived by plants, playing a core role in regulating flowering time and life cycle. During evolution, diverse plant species have established photoperiodic regulatory networks centered on the CO-FT module, which have further diversified into lineage-specific pathways adapted to different ecological environments. Due to the solar radiation rhythm caused by the tilt of the Earth’s axis of rotation, geographical latitude determines the interannual stability of day length in a given region, that is, the photoperiod remains relatively constant at the same time each year. Therefore, latitude defines the photoperiodic environment experienced by plants. Conversely, plant responses to changes in photoperiod are often used as biological indicators of latitude adaptation. Flowering, as one of the most sensitive phenotypes to photoperiod changes, has become an important entry point for studying the latitudinal adaptability of plants. Current research mainly focuses on the flowering regulation mechanisms of the photo-period pathways in typical long-day and short-day plants such as Arabidopsis thaliana, Glycine max, and Oryza sativa. This article will mainly review the photoperiod pathways and latitudinal adaptability of these three plants: Arabidopsis thaliana has formed a classic long-day flowering promotion model centered on the positive regulation of FT (flowering locus T) by CO (constans); Glycine max has evolved a short-day regulatory mechanism centered on E1 that inhibits the expression of FT and has developed diverse adaptation strategies at different latitudes; Oryza sativa retains both the conserved OsGI-Hd1-Hd3a pathway and the unique Ghd7-Ehd1-Hd3a/RFT1 pathway, enhancing its adaptability to photoperiod environments. Through comparative analysis, the conservation, diversity, and latitudinal adaptability of the main plant photoperiod flowering regulation pathways are demonstrated, providing a reference for in-depth research on this pathway and crop breeding.

Abstract:Tropical and subtropical fruits, due to their high water content, vigorous metabolism and susceptibility to pathogen infection, are prone to quality deterioration after harvest. This paper systematically reviews the physiological characteristics of bananas, lychees and figs, which are mainly cultivated in Guangdong Province, during storage, including the patterns of respiration, ethylene release, antioxidant systems and microbial infection. It elaborates in detail on the research progress of various preservation technologies such as physical, chemical and biological methods, and explores the application prospects of emerging technologies such as nanotechnology and genetic engineering in this field, with the aim of providing theoretical references for the development of new technologies in related areas.