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2017  Vol. 35  No. 5

Abstract:
Scanning electron microscope (SEM) and light microscope (LM) were used to examine the morphology and structure of stamens, staminodes, and pistils in Anaxagorea javanica Blume. The glandular morphology of staminodes and stigma were different, but the chemical compositions were very similar. The cross-section of the stamens and staminodes were also similar. We speculated that the staminodes might be transitional structures between the stamens and pistils. In the female stage, the mucilage released by the staminode apically glandular hairs is used by pollinating insects; in the male stage, the staminodes are S-shaped and cover the stigma to prevent self-pollination.Flaky stamens, staminodes and the large pores which scattered with the ventral side of themt are considered original characters in Annonaceae.
Abstract:
We investigated specimens and wild populations of Stemona mairei (H. Lév.) K. Krause, and combined field observations of individuals from the locations of the type specimens of S.jinshajiangensis X.D. Cong et G.J. Xu and S.jinshajiangensis var. dianbeiensis X.D. Cong et G.J. Xu. Results showed that the variation in morphological characteristics of S.jinshajiangensis and S.jinshajiangensis var. dianbeiensis were within the normal profile of S. mairei. Therefore, we suggest that S.jinshajiangensis and S.jinshajiangensis var. dianbeiensis should be defined as synonymies of S. mairei. A supplementary morphological description of S. mairei is provided according to the six wild populations. We also briefly evaluated the threatened status of S. mairei and its potential as a medicinal resource based on our preliminary study of its flowering, fruiting, and seed dispersal tactics.
Abstract:
Freshwater diatom samples were collected and identified from the North Region of Wuyi Mountain, China, in November 2015. According to light microscope (LM) and scanning electron microscope (SEM), a newly reported diatom, Gomphonema biceps Meister, was identified and described here in detail. The morphological differences between this geographic population of G. biceps were compared with previously reported foreign populations and similar species with asymmetrical valve shape. In addition, the geographical distribution and habitat characteristics of G. biceps were discussed in this paper.
Abstract:
The seedling stage is the most vulnerable stage of life for a plant, and analysis of the factors influencing seedling survival can help us understand species coexistence mechanisms. We examined the importance of biotic and abiotic factors using Generalized Linear Mixed Models with survival data from 3554 seedlings of 128 species in a 25 hm2 Badagongshan forest dynamic plot in central China. Results showed that:(1) At the community level, focal seedling survival was significantly negatively correlated with conspecific neighbor density, indicating negative density-dependence (NDD) effects in this plot, but was positively related to canopy openness. (2) At the age class, the survival of <4-year-old seedlings showed significant negative correlation with conspecific neighbor density; for seedlings ≥ 4 years old, the importance of NDD was exceeded by environmental factors. (3) Compared with the evergreen species, the survival rate of deciduous species was more susceptible to conspecific neighbor density, and significantly positively related to canopy openness. (4) The effects of biotic and abiotic factors on seedlings differed among species. For instance, Machilus ichangensis Rehd. et Wils. was positively related to canopy openness, whereas Symplocos anomala Brand seedling survival showed significant negative correlation with conspecific neighbor density, heterospecific adult basal area, and canopy openness, and significant positive correlation with heterospecific seedling neighbor density and elevation.
Abstract:
Glyptostrobus pensilis (Staunton ex D. Don) K. Koch, also called the Chinese swamp cypress or water pine, is a well-known relict plant and "living fossil". It is listed as a "Grade Ⅰ" wild plant under the state key protected list, and is only known from extremely small populations in South and South-East China, as well as Vietnam and Laos. It is also categorized as "Critically Endangered" with a decreasing trend according to the IUCN evaluation criteria. We investigated the community vegetation, health status, disturbance factors, and alien invasive plants of 42 wild populations of G. pensilis in China in 2016. Community phylogenetic diversity analysis indicated that the health status of the G. pensilis populations was related to the degree of threat of anthropogenic disturbance. In addition, populations with high phylogenetic diversity values were always in good condition. The presence of alien invasive species in the community will make the phylogenetic structure clustered and result in the decrease of the phylogenetic diversity value. It should be noted, therefore, that the exclusion of anthropogenic activities and elimination of alien invasive plants will improve the health status of populations and individuals, increase the phylogenetic diversity of the community, and enhance the resistance and recoverability of G. pensilis populations.
Abstract:
The regional study of alien invasive plants and their categorization have important guiding significance for local governments in the management and control of such plants. We conducted a comprehensive survey of alien invasive plants in Anhui Province from 2013 to 2015 based on literature reports, specimen records, and taxonomic research. The species composition, life form, original locality, floristic composition, and horizontal distribution patterns of alien invasive plants in Anhui Province were analyzed, and their invasion levels were also rated. Results showed a total of 132 species of invasive plant species in Anhui Province. These plants showed diversified species, with a high proportion of American and Pan-tropical origin, high proportion of hazardous species, significant regional differentiation, and similar invasion pathways. We proposed that the prevention and control of alien invasive plants should pay considerable attention to plants originating from America and Pan-tropical genera and hotspots with frequent human activities. In addition, current deficiencies in the study of alien invasive plants in China are discussed, and several noteworthy and long overlooked issues about the cognition of alien invasive species are clarified.
Abstract:
Three different planting methods, that is, cutting, gauze wrapped, and covered soil in a bag, were used to investigate effects on the growth of Vallisneria natans (Lour.) Hara under static and constant water disturbance. Results showed that different planting methods had significantly different effects on the growth of V. natans. In terms of morphological characteristics, average plant height and average leaf width under the covered soil conditions were obviously higher than those under cutting and gauze wrapped conditions, but the number of ramets and average root length were lower. In addition, the biomasses of the aboveground and underground parts, as well as total biomass, under the covered soil conditions were obviously greater than those under cutting and gauze wrapped conditions, but the underground part to aboveground part ratio was lower. Leaf chlorophyll a content was obviously higher under the covered soil conditions than that under cutting and gauze wrapped conditions. The dynamic and static water environments had no significantly different effects on other indicators, except that the number of ramets in the static water environment was higher than that in the dynamic water environment. This study showed that dynamic and static water environments and different planting methods could have significant and different effects on the growth of V. natans. The growth of V. natans was greater under the covered soil treatment than that under the cutting and gauze wrapped treatment, and plant height, leaf width, and biomass were greater under the static than dynamic water environment.
Abstract:
Canopy spectral reflectance is directly related to inversion of Phyllostachys pubescens Mazel canopy parameters, which is of great significance in the indirect estimation of P. pubescens forest soil fertility. The effects of model parameters on leaf and canopy reflectance at the leaf and canopy scales were analyzed based on PROSPECT and PROSAIL models. PROSAIL canopy radiative transfer was used to establish the leaf area index (LAI) and a canopy reflectance lookup table for P. pubescens forest, with optimum canopy reflectance then determined by the cost function to achieve accurate simulation of P. pubescens forest canopy reflectance. Results showed that at the leaf scale, the sensitivity of the input parameters in the PROSPECT model decreased in the order of leaf structure parameters (N) > chlorophyll content (Cab) > equivalent water thickness (EWT) > dry matter content (Cm) > carotenoid content (Car). At the canopy scale, the sensitivity of the input parameters in the PROSAIL model decreased in the order of LAI > Cab > EWT > Cm > N > Car > ALA (average leaf angle). Leaf reflectance was greater than canopy reflectance. In the 400 to 900 wavelength range, canopy spectral reflectance of the PROSAIL model exhibited better fitting than the measured reflectance, with a relative error of 6.71%.
Abstract:
We identified a mutant with extra leaves at the nodes of the panicle from a T-DNA insertion population constructed in our lab, and morphologically named it as a flag leaf mutant (J4 mutant). Analysis revealed that the extra leaves were abnormally developed, with short leaf blades, shortened epidemical cell lengths, and decreased numbers of vascular bundles in the leaf blade. Using TAIL-PCR and inverse-PCR analysis, we cloned the T-DNA flanking sequence in this mutant and accurately located the inserted T-DNA onto chromosome 2. Gene expression analysis revealed that AK100376, a T-DNA flanking gene, was obviously downregulated in both the J4 mutant and similar phenotype mutant neck leaf 1. Thus, AK100376 might be a candidate gene related to the phenotype in the J4 mutant. Here, we identified a flag leaf mutant and determined the phenotype-related candidate gene through expression analysis of the T-DNA flanking genes.
Abstract:
We investigated aspects of epigenetic regulation to reveal the genetic variation of Pinus elliottii×P. caribaea var. hondurensis. We analyzed the cytosine methylation patterns in P. elliottii×P. caribaea var. hondurensis hybrids and their parents using the MSAP method, and comparatively examined the methylation types and differences between the hybrids and their parents. Our results showed that the relative levels of methylation in the parent and hybrid CCGG were 77.74%-81.75%. The relative level of CG methylation was lower than the relative level of CNG methylation. The relative level of CG/CNG methylation was higher than that in the parents. There was a 1:1 ratio between heredity in hybrid. CG and CNG methylation sites inherited from parents were equal, as were the methylation sites inherited from the female and male parents. The ratio of new methylation to complete demethylation sites was close to 7:1 in the hybrids. This study infers that methylation mutation promoted the growth and development of the heterozygotes.
Abstract:
A population of interspecific ‘Jiangshanjiao’ (Actinidia chinensis Planch×A. eriantha Benth) and male A. chinensis Planch hybrids was used in this study. Sex ratio and flowering traits were investigated in the spring of 2012, 2013, and 2016, respectively. The sex ratio of female to male progeny was lower than 1:1, which means there are more male than female plants in the hybrid population. The basic petal color of the progeny was red, but a subtle segregation of color distribution, color depth, and red color types were observed in the population. Clustering analysis using extracted parameters with CMYK mode showed four sub-clusters, among which two groups of hybrids were consistent with scarlet and violet petal phenotypes, respectively. The early flowering season, flowering duration, flower diameter, flower number, and petal number per flower were found to have wide variations, and changed with investigation year. The average time span between the first and the last early flowering season of the hybrids was 14 d. Average proportion of the hybrids in the early flowering season reached a maximum of 25.5% in the population. Flowering duration of the population in 2016 was the longest, with 47.4% of hybrids blooming for 10-13 d, but was the shortest in 2013, with 55.2% of hybrids blooming for 3-5 d. A few progenies had larger flowers and more petals per flower or more flowers per inflorescence. There were 21 combination types of petal-flower-inflorescence number in the hybrid population.
Abstract:
Plant hairy roots are an important platform for the synthesis of valuable secondary metabolites and for the functional analysis of natural product biosynthetic pathways. Diosgenin is a precursor of more than three hundred sterol drugs, but knowledge regarding how it is biosynthesized in plants remains limited. Fenugreek (Trigonella foenum-graecum L.) is a plant with high diosgenin content. In this study, we used a fenugreek variety from Shanxi Province in China to investigate the effects of two key factors on fenugreek hairy root formation. The two key factors were the density of Agrobacterium rhizogenes and co-incubation supplemented with ultrasonic treatment. Hairy root number and its transformation frequency were improved under increasing A. rhizogenes density, with OD600 values from 1.1 to 4.4. Compared with that measured at the OD600 value of 1.1, the incubation at 2.2 and 4.4 led to better performance, with hairy root numbers increasing 2.58 and 7.33 times, respectively, and root transformation frequency improving 3.90 and 4.32 times, respectively. During the co-incubation of A. rhizogenes with fenugreek explants, 30 s ultrasonic treatment (operating frequency 40 KHz, ultrasonic power 180 W) slightly decreased the efficiency of hairy root induction, whereas 60 s treatment increased the efficiency by 2.48 times compared with incubation without ultrasonic treatment. The established fenugreek hairy root system provides a platform for the synthesis of diosgenin and a strong basis for the analysis of diosgenin biosynthesis pathways in the future.
Abstract:
Macrophytes and their epiphyton are the main primary producers in shallow lakes. Freshwater snails are the main primary consumers in freshwater ecosystems, but it is still debatable whether snail densities are an important factor that determine the growth of macrophytes and their epiphyton. We established four snail densities (0, 40, 80, and 240 ind·m-2) to investigate the grazing impact of snails (Radix swinhoei H. Adams) on the submerged macrophyte Vallisneria spinulosa Yan and its epiphyton, and determine the dynamics of the snail populations from the interaction. Results indicated that R. swinhoei strongly reduced the biomass of the epiphyton, but promoted the biomass of the macrophytes, and at the highest initial snail density even induced higher ramet number of macrophytes. The direct grazing effects of snails on macrophytes were observed but were not significant at the moderate eutrophic level, probably because submerged macrophytes alone could not support the high densities of snails. The size structure of the snail population could quickly respond to nutrient levels of the water-bodies and food resources in the environment.
Abstract:
This study aimed to explore how carbon limitation affects the carbon allocation and hydraulic characteristics of trees. It was conducted on three-year-old Robinia pseudoacacia Linn. seedlings by three-time artificial defoliation. Biomass allocation, leaf morphology, nonstructural carbohydrate (NSC) concentration in different tissues, root pressure, root hydraulic conductivity, branch water potential, branch percentage loss of conductivity (PLC), and xylem vulnerability to embolism were measured after defoliation. The biomasses of all organs, especially that of fine roots, were significantly reduced. Defoliation-induced carbon limitation significantly reduced NSC concentration in all tissues. NSC in the branch phloem, branch xylem, root phloem, and root xylem accounted for 29.6%, 20.2%, 10.2%, and 8.7% of the control, respectively. The reduction in NSC concentration in the roots was more severe than that in the branches. Root pressure and root hydraulic conductivity were also significantly reduced. Predawn and midday branch PLC was significantly increased, and xylem cavitation resistance was significantly decreased compared with that of the control. Results indicated that defoliation-induced carbon limitation reduced the ability of water uptake in the roots due to decreased biomass in the fine roots and decreased NSC. The reduced capacity of root water uptake further deteriorated hydraulic function of the roots and stems, which impeded long-distance water transport. Carbon limitation also reduced the safety of water transport by damaging cavitation resistance.
Abstract:
Plumbago auriculata Lam. is native to South Africa. Due to its self-incompatibility, the natural seed setting rate is extremely low, and thus seeds often rely on imports. To date, however, no research has been conducted on the biological characteristics, collection, or storage technologies of P. auriculata seeds. Here, the morphological structure, water absorption characteristics, and optimum germination temperature of the seeds were studied. According to morphological observation and germination rate, we screened high-quality seeds, which were then used to investigate optimum drying methods and storage temperature. Results showed that the P. auriculata seeds were long and oval in shape and 8.00-13.80 mm in length, with a5.3:1 aspect ratio. The seed coat was thin and soft, with reticular folds. The testa surface had numerous attachments, and a large distribution area of glands, conducive to seed propagation. Germ near the chalaza, encouraged higher germination rate. Optimum seed soaking time was longer than 11 h and optimal germination temperature was 25-30℃. When the seed coat appeared dark brown and the seed length was greater than 11 mm, the seed germination rate was greater than 75%, thus indicating high-quality seeds. The suitable seed drying temperature was 30℃ for 1 d. The optimum storage temperature of the dry seeds was -86℃. The shorter the storage time, the higher the germination rate. Fresh seeds should not be stored for more than 15 d at ultra-low temperature.
Abstract:
The survival rate of cryopreservation based on vegetative cells and akinetes of Haematococcus pluvialis Flotow FACHB-712 were compared. Results showed that in most cases the survival rate of the vegetative cells was lower than 5% in liquid nitrogen with two-step cryopreservation, but the rate increased to 13.3% if the protocol was modified as follows:cell suspensions were added with glycerol as a cryoprotectant (10%), cooled at a rate of 0.5℃/min until -40℃, and then maintained for 30 min before being placed to liquid nitrogen. The survival rate of the akinetes reached 66.13% in liquid nitrogen with the two-step protocol. There were no obvious differences (P > 0.05) in the growth characteristics and the astaxanthin content of akinetes before and after preservation in liquid nitrogen. Comparatively, the ultrastructure of the vegetative cells was seriously damaged, whereas that of the akinetes was much less damaged after two-step cryopreservation treatment. If directly placed in -20℃, -80℃, or liquid nitrogen, respectively, the highest survival rate of the samples was about 27% in the treatment under -80℃. In conclusion, the two-step cryopreservation protocol in liquid nitrogen using akinete-stage cells was preferable for the long-term preservation of H. pluvialis FACHB-712, with the one-step protocol at -80℃ also applicable as an alternative approach.
Abstract:
Podophyllotoxin (PPT) is a frequently used clinical natural drug. In this study, we aimed to optimize the extraction process of PPT from Diphylleia sinensis H. L. Li by response surface methodology (RSM). Based on single factor experiments, three important factors, that is, ethanol concentration, extraction temperature, and extraction time, were selected for further optimization with three-factor/three-level Box-Behnken design. Based on the extraction rate of PPT, the optimal conditions were:ethanol concentration of 48.18%, extraction temperature of 62.66℃, and extraction time of 16.15 h. Under these optimal conditions, PPT yield could reach 7.636%, with the confirmatory experiment reaching 7.54%. Thus, there was no significant difference compared with the theoretical value, verifying the optimized method with RSM in this study.
Abstract:
To investigate the changes in the active ingredients and antioxidant capacity of fresh peony roots in the post-harvest drying process, the contents of paeoniflorin, albiflorin, and benzoylpaeoniflorin in the root during natural drying were determined by high performance liquid chromatography, and antioxidant activities of the materials were detected. Results showed that the content of paeoniflorin and benzoylpaeoniflorin increased at first and then degraded gradually, whereas albiflorin first decreased and then increased. Free radical scavenging ability, including that of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion, as well as inhibition of lipid peroxidation, were significantly increased in the roots during the early phase of the drying process, and there was a significant positive correlation with the content of paeoniflorin. Therefore, the mechanism of resistance to drought stress in the early stage of peony growth might be related to the increase in antioxidant activity and induction of the content of related active ingredients (such as paeoniflorin).
Abstract:
At present, atmospheric particulate matter (PM) is the main source of urban air pollution in China, in which fine particulate matter (PM2.5, ≤ 2.5 microns in aerodynamic diameter)seriously pollutes the environment due to their small size and inertia of sedimentation. Plants can significantly remove air particulate matter and effectively improve urban environmental quality. Here, we summarize the processes and methods of the removal of particulate matter by vegetation, and discuss the relationship between atmospheric particulate matter and forest vegetation. The effects of vegetation on the removal of atmospheric particulate matter are discussed with consideration of meteorological factors, and analysis of the resuspension processes and negative effects of plants on the retention abilities of atmospheric PM are also examined. Lastly, we propose key points and trends on plant adsorption of PM, especially PM2.5, based on the measurement and evaluation of PM adsorption abilities of plants, selection of local plants with high PM adsorption ability, and comprehensive measurement and systematic study on PM removal capability, especially of PM2.5, of different kinds of disposition model of plants.