Institutional Repository of Chengdu Institute of Biology, CAS
Not a member yet
6513 research outputs found
Sort by
Responses of nutrient capture and fine root morphology of subalpine coniferous tree Picea asperata to nutrient heterogeneity and competition
No full textInvestigating the responses of trees to the heterogeneous distribution of nutrients in soil and simultaneous presence of neighboring roots could strengthen the understanding of an influential mechanism on tree growth and provide a scientific basis for forest management. Here, we conducted two split-pot experiments to investigate the effects of nutrient heterogeneity and intraspecific competition on the fine root morphology and nutrient capture of Picea asperata. The results showed that P. asperata efficiently captured nutrients by increasing the specific root length (SRL) and specific root area (SRA) of first-and second-order roots and decreasing the tissue density of first-order roots to avoid competition for resources and space with neighboring roots. The nutrient heterogeneity and addition of fertilization did not affect the fine root morphology, but enhanced the P and K concentrations in the fine roots in the absence of a competitor. On the interaction between nutrient heterogeneity and competition, competition decreased the SRL and SRA but enhanced the capture of K under heterogeneous soil compared with under homogeneous soil. Additionally, the P concentration, but not the K concentration, was linearly correlated to root morphology in heterogeneous soil, even when competition was present. The results suggested that root morphological features were only stimulated when the soil nutrients were insufficient for plant growth and the nutrients accumulations by root were mainly affected by the soil nutrients more than the root morphology
Photoprotection regulated by phosphorus application can improve photosynthetic performance and alleviate oxidative damage in dwarf bamboo subjected to water stress
No full textWater and nutrients, particularly phosphorus (P), are the two most limiting factors for dwarf bamboo growth in tropical and subtropical areas. Dwarf bamboo is highly sensitive to water stress and often causes severe P deficiency in its growing soils due to the characteristics of shallower roots and expeditious growth. However, little is known about its photoprotective response to soil water deficit and the underlying mechanisms regulated by P application. In this study, a completely randomized design with two factors of two water regimes (well-watered and water-stressed) and two P levels (with and without P application) was arranged to investigate this issue in dwarf bamboo (Fargesia rufa) plants. Water stress not only decreased water status and photochemical activity but also increased lipid peroxidation due to reactive oxygen species, (ROS) accumulation irrespective of P application. In this case, thermal dissipation and antioxidative defense were promoted. Moreover, the role of the water water cycle under this stress still could not be ignored because it accounted for a large proportion of total energy (Jpsll). P application significantly enhanced photochemical activity accompanied by increased chlorophyll content in water stressed plants. Meanwhile, P application remarkably reduced thermal dissipation and hardly affected photorespiration and the water water cycle under water stress. Although P application only enhanced ascorbate (AsA) level, ROS, particularly hydrogen peroxide (H2O2), and lipid peroxidation were significantly reduced in water-stressed plants. Therefore, P application can improve the photosynthetic capacity by regulating the redistribution of energy absorbed by PSII antennae and independently activating of the H2O2-scavenging function of AsA to alleviate oxidative damage in F rufa plants, thereby improving their survival under water stress conditions. (C) 2017 Elsevier Masson SAS. All rights reserved
Aristolochia longeracemosa, a new synonym of A. chlamydophylla (Aristolochiaceae)
No full textAristolochia Linnaeus (1753: 960) (Aristolochiaceae) comprises about 500 species. The genus has worldwide distribution (Wanke et al. 2006). Recent findings of Aristolochia (Phuphathanaphong 2006, Xu et al. 2011, Huong et al. 2014, Do et al. 2015, Wu et al. 2015), together with the previous treatments for the Flora of Thailand (Phuphathanaphong 1987), the Flora of Vietnam (Pham 2000) and the Flora of China (Huang et al. 2003) confirmed the Thai & Indo-Chinese floristic region as a center of diversity for Aristolochia, with currently about 90 species. A high degree of endemism is found for specific countries (Huang et al. 2003, Phuphathanaphong 2006). However, the delimitation and taxonomic status of some species are still unclear due to limited access to specimen databases, especially for the type specimens in those countries. Notably, recent studies have significantly revised the taxonomic status of several previously described Aristolochia species when herbarium materials from multiple countries in the region were consulted (Do et al. 2014, Do 2016, Zu et al. 2016). On the basis of the examination of the protologue, the type specimens, and recent collections from the herbaria BKF, C, GXMI, HITBC, IBSC, KUN, PE and PEM, we conclude that Aristolochia longeracemosa B. Hansen & Leena Phuphathanaphong (1999: 557), described from collections made in northern Thailand, is conspecific with A. chlamydophylla C. Y. Wu ex S. M. Hwang (1981: 223) from southern China. Hence, we here propose the former as a new synonym of the latter. A detailed comparison of the morphological characters and habitat of these two species is provided
Polystichum hastipinnum (subg. Haplopolystichum; Dryopteridaceae), a new cave fern from Guangdong, China
No full textA new species of Polystichum (subg. Haplopolystichum; Dryopteridaceae), P. hastipinnum, is described from a limestone cave in northern Guangdong, China. Polystichum hastipinnum is most similar to P. kwangtungense in having oblong pinnae, but the former has stipe and rachis scales denser, basalmost pair of pinnae hastate and with bases somewhat cordate, while the latter has stipe and rachis scales much sparser, basalmost pair of pinnae oblong and with bases cuneate
Large-scale patterns of distribution and diversity of terrestrial nematodes
No full textLatitude, climate and vegetation type are key factors in the distribution of soil nematodes. The diversity of most aboveground organisms increases with decreasing latitude, but the macro-ecological diversity and geographic distribution patterns of belowground animals have been poorly studied. The large-scale geographic distribution patterns of soil nematodes were examined in terms of their abundance and their driving forces, with a view towards ascertaining whether the large-scale patterns (LSP) of distribution and diversity of soil nematodes were driven by latitude, climate and vegetation type. A literature review representing multiple vegetation types across latitudinal gradients was conducted, and information was gathered pertaining to soil nematodes throughout the globe. Different databases, such as Google Scholar, Web of Sciences, Scopus and PubMed, were searched to collect data published in English-language journals. A correlational analysis between soil nematode diversity and latitude, mean annual precipitation and mean annual temperature was performed. The present review also compared the abundance and genus of soil nematodes among different vegetation types. The LSP of the soil nematodes was unimodal, and a higher nematode abundance was recorded at latitudes between 30 and 55 degrees. A significant correlation was observed between the latitude and species richness index, whereas latitude explained 65.9% of the variation in the species richness index across plots. Nematode abundance showed a distinct peak at a mean annual temperature of approximately 8 degrees C, but no significant correlation was found between the nematode abundance and mean annual precipitation. The highest mean value of soil nematode abundance was recorded in temperate coniferous forests, followed by tropical forest, grassland, temperate broadleaf forest, crop field and garden, desert and polar vegetation types. The mature index of soil nematodes was negatively correlated with latitude. A redundancy analysis (RDA) showed that the composition of the trophic group of the soil was greatly influenced by latitude (LA) and mean annual precipitation (MAP). The number of the soil nematode genera was found to be highest in temperate broadleaf forests, followed by tropical forest, grassland, temperate coniferous forest, crop field and garden, desert and polar vegetation types. Soil nematodes exhibited large-scale distribution patterns along latitudes on a global scale as a result of hydrothermal conditions, plant growth and human activities. (C) 2017 Elsevier B.V. All rights reserved
N addition suppresses the performance of grassland caterpillars (Gynaephora alpherakjj) by decreasing ground temperature
No full textNitrogen deposition may stimulate plant biomass production and improve the quality of plant tissue, with both effects potentially facilitating herbivore growth and development. We hypothesized that simulated N deposition (N addition) would facilitate the growth and development of the grassland caterpillar Gynaephora alpherakjj, a notorious pest species in the alpine Tibetan meadow. We tested this hypothesis in two complementary experiments. The first field experiment tested N (ambient N levels vs. N addition) and caterpillar effects (caterpillar absence vs. presence) on plant community and sedge (major food plant species for caterpillars) biomass, growth, and development rate of the caterpillars, and microhabitat temperature. The second chamber experiment tested N addition effects through plant tissue quality on caterpillar performance. Results show that N addition increased the biomass and leaf N concentration of the sedge species, but decreased the feeding time, growth, and development rate of the caterpillars in the field experiment. The independent chamber experiment showed that increased leaf N facilitated the caterpillar growth and development. These results suggest that the reduced performance of caterpillars was not caused by an N addition-induced change in food quality. By contrast, N addition significantly reduced the ground surface temperature presumably because of canopy shading, as indicated by increased plant height and biomass in the N addition treatment. A significant quadratic relationship between ground surface temperature and the number of feeding caterpillars in the field experiment explained the difference in feeding time between the N addition and ambient N treatments. It can thus be concluded that N addition reduced caterpillar performance by stimulating plant growth leading to reduced ground surface temperatures, which decreased caterpillar feeding activity. Our results suggest that the effect of N deposition on abiotic factors could be critical to the growth, development, and survival of immobile herbivore species or the individuals at immobile stages that cannot quickly respond to changing microclimatic environments
UV-Blocking Coating with Self-Healing Capacity
No full textUV-blocking coatings are necessary to protect materials from photochemical degradation, especially for organic polymers. And self-healing capacity is necessary to ensure the service time of UV-blocking coatings. Here, an UV-blocking coating (denoted as beta CD-TiO2/P(HEMA-co-BA)) with self-healing capacity is prepared successfully by copolymerizing 2-hydroxyethyl methacrylate (HEMA), butyl acrylate (BA) and functional monomers, inclusion complexes of beta-cyclodextrin (beta CD)-modified TiO2 nanoparticles, and hydroxyethyl methacrylate-adamantine (HEMA-Ad). The beta CD-TiO2/P(HEMA-co-BA) coating not only shows excellent UV-blocking property but also enhances mechanical properties and good self-healing properties. After being damaged, beta CD-TiO2/P(HEMA-co-BA) can repair scratches by adding a little water, and the UV-blocking capacity can be restored completely along with the self-healing process. Furthermore, the self-healing process is repeatable at a given place
Synthesis of 5-subsituted flavonols via the Algar-Flynn-Oyamada (AFO) reaction: The mechanistic implication
No full textHerein, we report a synthetic method with improved selectivity for 5-substituted flavonols via the Algar-Flynn-Oyamada reaction (AFO), by using of sodium carbonate/hydrogen peroxide A series of 5 substituted flavonols was obtained with moderate to high yields. The mechanism of the AFO reaction was elucidated. LCMS analysis and in situ H-1 NMR analysis indicated that the epoxide was involved in the transformation from chalcone to flavonol and/or aurone under alkaline base/peroxide conditions. (C) 2017 Elsevier Ltd. All rights reserved
Astragalosidic Acid: A New Water-Soluble Derivative of Astragaloside IV Prepared Using Remarkably Simple TEMPO-Mediated Oxidation
No full textThere is an urgent need for a water-soluble derivative of astragaloside IV for drug R&D. In the present study, a remarkably simple method for the preparation of such a water-soluble derivative of astragaloside IV has been developed. This protocol involves oxidative 2,2,6,6-tetramethylpiperidine-1-oxyl free radical (TEMPO)-mediated transformation of astragaloside IV to its carboxylic acid derivative, which is a new compound named astragalosidic acid. The structure of astragalosidic acid was elucidated by means of spectroscopic analysis. Its cardioprotective activity was investigated using an in vitro model of cardiomyocyte damage induced by hypoxia/reoxygenation in H9c2 cells. The oxidative TEMPO-mediated transformation proposed in the present study could be applied to other natural saponins, offering an effective and convenient way to develop a new compound with greatly improved structure-based druggability
Metal- and Acid-Free Methyl Triflate Catalyzed Meyer-Schuster Rearrangement
No full textA novel metal-and acid-free preparation of synthetically useful alpha,beta-unsaturated carbonyl compounds from propargyl alcohols has been realized. This Meyer-Schuster rearrangement process is effectively catalyzed by methyl triflate (20 mol%) to prepare a broad scope of conjugated E-enals and E-enones generally in good to excellent yields (up to 90%). This reaction procedure operates under mild conditions (70 degrees C), in air, with short reaction times (1 h). Moreover, a carbocation intermediate trapped by the solvent 2,2,2-trifluoroethanol was isolated during this transformation