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2018  Vol. 36  No. 1

Abstract:
Spore development of Dryopteris erythrosora(Eaton) O. Ktze. was studied by transmission electron microscopy and cytochemical technology. Based on ultrastructural and cytochemical features, spore development was divided into three stages. (1) Spore mother cell and meiosis stage:sporocyte coat is formed at the late stage of the archesporial cells. The sporocyte coat covers the spore mother cells and the outer surface of the tetrads. The PAS reaction shows that this coat is polysaccharide in nature. It is an analogous structure with callose. During meiosis, spore coats are formed between the tetrad spores. The spore coats resemble the callose wall in function, formation site, and formation time. However, Sudan Black B staining shows that the spore coats may contain lipid material, which does not exist in the callose wall. (2) Exospore formation stage:exospore formation is Blechnoidal-type. The exospore consists of two layers, i.e. thin inner exospore and thick outer exospore. The former is composed of polysaccharides and the latter is composed of sporopollenin with a smooth outer surface. Globules participate in the formation of the outer exospore. Cytochemical staining shows that the center of the globules and inner part of the outer layer of the exospore are yellow, but the outer part of the globules and outer layer of the exospore became black when stained (probably containing lipids). It can be inferred that the globules and exospore develop simultaneously. (3) Perispore formation stage:perispore formation is Cavete-type. The perispore consists of an inner perispore and outer perispore. The thin inner perispore appresses the exospore closely. The outer perispore projects outwards and forms the outline of the ridge ornamentation of the spore. The development of the perispore is centripetal. Sudan Black and PAS reaction stain the perispore orange, indicating that the perispore may be composed of several polysaccharides. Spore wall cells participate in formation of the perispore. The present investigation provides new data for sporogenesis and spore wall development, which will contribute to revealing the cytological mechanism of sporogenesis.
Abstract:
Myrialepis, a rattan genus of Palmae, is widely distributed in Myanmar, Laos, Vietnam, Cambodia, Thailand, Malaysia, Singapore, and Indonesia. It grows in lowland to montane rainforest and is commonly found along forest margins and in disturbed forest, such as clearings, landslips, road cuts, and river banks. Here we report on a new distribution record of Myrialepis in Yunnan, China. The morphological and habitat characteristics of the genus are described, and a key to rattan genera in China has been compiled.
Abstract:
Five newly recorded species of Gomphonema (Bacillariophyta) are reported from Hainan Island, including Gomphonema jadwigiae Lange-Bertalot & Reichardt, G. pseudoclavatum Lange-Bertalot & Reichardt, G. pseudosphaerophorum Ehrenberg, G. salae Lange-Bertalot & Reichardt, and G. uruguayense Metzeltin, Lange-Bertalot & García-Rodríguez. The morphological characteristics of the five species are described in detail and compared to similar species. This investigation provides basic information for continued algal research in China.
Abstract:
In this paper, four newly recorded diatom species are reported from Maolan National Nature Reserve in China, including Lindavia tenuistriata (Hustedt) Nakov, Caloneis densema Kulikovskiy, Pinnularia latarea Krammer, and Surirella uninodes Skvortzov. Morphological taxonomic characters, habitat information, and geographical distribution are described in detail.
Abstract:
Yunnan is an extremely biodiverse area in southwestern China. It includes more than half of all Chinese plant species and the main vegetation types of Eurasia. However, the origin and evolution of its intricate biota are less known to science. Based on geological events in Yunnan since the Tertiary, we investigated the possible origin and evolution of Yunnan flora from the view of floristic biogeography. It was revealed that the flora of Yunnan might be derived from tropical-subtropical Tertiary flora of East Asia, with later divergence. The northwestern Yunnan flora likely evolved through rapid speciation from families and genera of cosmopolitan and north temperate distribution with uplift of the Himalayas and climatic oscillations after the late Tertiary, while southern Yunnan flora evolved tropical Asian flora by permeation of tropical Asian elements with southeastward extrusion of the Indochina block, with central Yunnan inheriting more elements of Tertiary flora from East Asia. The phylogenetic relationships (phylogenetic structure and β-diversity patterns) of the flora of northern, central, and southern Yunnan supported the deduction suggested from biogeography. The oblique abundance patterns of Yunnan seed plants corresponded well to the clockwise rotation and southeastward extrusion of the Langping-Simao (Indochina) Geoblock caused by the collision of India with Asia. The divergence of the flora of southern and southeastern Yunnan, in which the former was more closely related to Indo-Malaysian flora and the latter was more closely related to Eastern Asian flora, was well supported by the geological history of these regions; that is, the flora of tropical southeastern Yunnan derived from the South China Geoblock, whereas the southern Yunnan flora derived from the Shan-Thai Geoblock.
Abstract:
We examined the phytoplankton community structure in the Hulin area in the Sanjiang Plain wetland in July of 2014 with 10 sampling sites. We identified 133 taxa belonging to 8 divisions, 10 classes, 16 orders, 27 families, and 48 genera. They were predominantly Bacillariophyta and Chlorophyta. The phytoplankton species composition and abundance was significantly different at each sampling site. Most of the algae were found in the site Ⅸ. While the biomass in sites Ⅱ was greater than that of other sites. We found a large proportion of β-mesosaprobic-zone indicators. Meanwhile, cluster analysis and non-metric multi-dimensional scaling analysis showed that the water in Hulin wetland was of certain degrees of pollution, and the water was at the mesotrophic level.
Abstract:
The spatial distribution of fine roots can well reflect the utilization degree and adaptability of plants to the environment, which is essential for the evaluation of adaptation to adverse circumstances. We investigated the spatial distribution of Populus euphratica Oliv. fine roots (D ≤ 2 mm) and the relationship with groundwater depth and soil water content. Fine roots and soil samples were collected by the artificial trench profile method. Results showed that:(1) In the horizontal direction (range of 550 cm), fine root length density (RLD), fine root surface area density (SAD), and fine root mass density (RMD) of< P. euphratica changed insignificantly with distance from the tree trunk. (2) In the vertical direction, there were almost no fine roots in the top layer of the soil profile. With the increase in soil depth, both RLD and RMD exhibited increasing trends at first, and then showed decreasing trends. We found high fine specific root length (SRL) and specific root area (SRA) of< P. euphratica at the 280 cm soil depth. (3) RLD and RMD showed positive correlations with soil moisture content of the upper soil (0-180 cm), but exhibited spatial heterogeneities with soil moisture at deeper layers. These results revealed that P. euphratica roots were restricted by soil water conditions in the upper soil, and the fine roots in deeper soil were mainly affected by groundwater. The P. euphratica root system not only demonstrated the ability to develop into the deep moist soil, but also showed a strong horizontal expansion capability to cope with drought environments. This study provides a reference for understanding the adaptation mechanism of P. euphratica to extremely arid environments.
Abstract:
We investigated variability of vegetation coverage across different grassland types in key years (2000-2010) of major ecological construction projects in northern Shaanxi Province. Products of ecosystem classification and ecological parameter data were utilized to systematically elaborate succession processes, combined with several evaluation indexes, including inter-annual variation coefficient, trending slope, and degradation index. Our results showed that:(1) There was an obvious increase in area of grassland ecosystem in the loess gully region in Yanan and Yulin City with annual average vegetation coverage from 27.94% in 2000 to 40.50% in 2010. Grassland coverage increased from a low to moderate level, accompanied with a significant uptrend in temperate steppe and warm-temperate tussock coverage. (2) Most of the grassland coverage in the northern Shaanxi regions changed obviously (increasing grassland accounted for 93.98%). The grassland ecosystem showed relatively significant fluctuations in the north of Yanhe River, but remained relatively steady in the south of the river. The significant increase in grassland vegetation coverage was mainly in the hilly loess regions, with the main decrease area located in the temperate desert steppe region of the northwest of Yulin. (3) Over the 11 years, the degree of severe degradation of grassland has been reversed in northern Shaanxi (from 9594.44 km2 during 2000-2005 to 26 544.39 km2 during 2005-2010). This study suggests that grassland coverage across different grassland types in northern Shaanxi have improved to varying degrees.
Abstract:
Based on field investigation, data collection, and GIS, changes in nine lake shorelines and aquatic macrophyte diversity, as well as the relationship between aquatic plant diversity and lake morphology, were investigated in the middle and lower reaches of the Yangtze River, China. Results showed that aquatic plant species diversity, coastline length, and the box-dimension in the study area decreased markedly. Correlation analysis showed that the development coefficient and the box-dimension of the lake shorelines significantly affected aquatic plant species diversity. Shoreline morphology also significantly influenced submerged, free-floating aquatic plant diversity. These results demonstrate that lake shoreline protection plays an important role in maintaining the biodiversity of aquatic plants and lake ecosystem function.
Abstract:
We studied the phenotypic diversity of leaf traits in cultivated Houttuynia cordata Thunb. populations from Hunan Province, China. Nine phenotypic traits and six relative traits of leaves were determined. Variance analysis, coefficient of variation, correlation analysis, principal component analysis (PCA), and cluster analysis were used to study the variation of leaf morphology. Results showed that:(1) There were significant differences in leaf phenotypic characters of the 20 H.cordata populations, and the differences among populations were greater than those within populations; (2) The average coefficients of variation for the 20 populations ranged from 5.63% to 9.08%, indicating low diversity among populations. The Youxian population (P16) had the highest coefficient of variation (9.08%), whereas the Xupu population (P3) had the lowest coefficient of variation (5.63%); (3) The average coefficients of variation for the 15 traits ranged from 3.71% to 10.28%, indicating that leaf trait diversity was low. The coefficient of variation for leaf area was the largest (10.28%) among the leaf characters, whereas the leaf width to leaf middle width ratio (W2/W4) was the smallest (3.71%); (4) Correlation analysis showed that leaf area had a significant positive correlation with leaf width, leaf middle width, leaf length, distance from leaf base to leaf width, and petiole length, a significant negative correlation with leaf tip angle, and no particular relationship with leaf base angle; (5) The cumulative contribution rate of the first three principal components for the 15 characters was 83.66%. By cluster analysis, the 20 populations could be clustered into four groups:heart-shaped, small heart-shaped, narrow heart-shaped, and large heart-shaped. These cluster results showed a discontinuous distribution pattern; (6) The common garden experiment showed that the diversity of leaf phenotypic traits was mainly determined by genetic material, and the diversity analyses could provide a theoretical basis for the breeding of excellent germplasm resources.
Abstract:
A meteorological factor evaluation system for ‘Golden Delicious’ apple quality was investigated through correlation and regression analyses of fruit quality and meteorological factors of ‘Golden Delicious’ apple varieties in four ecological regions in Tibet. Results showed that the qualities of the ‘Golden Delicious’ apple exhibited significant differences in the four regions, with the highest quality found in Nyingchi. The mean annual temperature, average temperature in July, mean annual temperature diurnal range, ≥ 10℃ accumulated annual temperature, average annual sunshine hours, average annual rainfall, and altitude were the main meteorological factors that affected fruit quality in the high attitude areas of Tibet. An altitude of 2857.9 m, annual average temperature of 13.2℃, average temperature in July of 15.9℃, mean annual temperature diurnal range of 12.7℃, ≥ 10℃ accumulated annual temperature of 2310.5℃, average annual sunshine of 2532.6 h, and average annual rainfall of 636.7 mm were the optimum values for the highest quality ‘Golden Delicious’ apple. Thus, the larger the mean annual temperature diurnal range, the better the fruit quality. In this study, the main meteorological factor evaluation system on ‘Golden Delicious’ fruit quality was obtained for the high attitude area of Tibet, with mean annual temperature diurnal range found to be the primary evaluation factor.
Abstract:
Chinese cabbage (Brassica pekinensis), mung bean (Vigna radiata), and wheat (Triticum aestivum) seeds were treated with different concentrations of aqueous extracts from Paris polyphylla episperm and endosperm. We studied the germination rate, seedling growth, and protective enzyme activity of the three plants through exposure to the aqueous extracts, and explored the activity and ingredients of endogenous inhibitors in P. polyphylla seeds. Results showed that different extract concentrations had certain effects on the germination rate, seedling height, seedling root length, and fresh weight of the seeds from the three plants. The strength of these effects increased at relatively low concentrations and decreased at relatively high concentrations. The effect on Chinese cabbage was stronger than that on wheat and mung bean, and the effect of the extract from the endosperm was significantly greater than that from the episperm. The extracts also influenced the protective enzyme activities of Chinese cabbage, mung bean, and wheat. Superoxide dismutase (SOD) and peroxidase (POD) activities significantly increased with increasing concentrations. Catalase (CAT) activity of Chinese cabbage and wheat significantly decreased, whereas that of mung bean showed a non-significant increase. GC-MS was applied to test eight substances from the endosperm aqueous extract and two from the episperm aqueous extract, with benzoic acid demonstrating germination inhibitory activity. Therefore, P. polyphylla seeds contain an endogenous inhibitor, whose activity changes with concentration, and may be the cause of seed dormancy. Aqueous extracts from P. polyphylla seeds may affect the normal growth of recipient seedlings by affecting the protective enzyme activity of recipient seedlings; furthermore, organic acids may be endogenous inhibitors of P. polyphylla seeds.
Abstract:
Karst rocky desertification is a serious geological disaster in southwestern China. Viburnum chinshanense Graebn. shrubs were selected to study how growth of its terminal twigs responded to different degrees of rocky desertification by assessing its biomass accumulation and allocation and morphological plasticity. Results showed that in the rocky desertification area, twig biomass accumulation was significantly restrained, and the degree of restraint increased with the degree of rocky desertification. Compared with leaf and stem biomass, the decrease in flower biomass was minimal. Compared with non-rocky desertification, the morphological growth indexes (leaf number, leaf area, specific leaf area, stem length, and stem diameter) of V. chinshanense significantly decreased, and the inhibition of rocky desertification on stem length was greater than that of stem diameter, whereas leaf area was the most inhibited. Leaf biomass and stem biomass ratios in the slight and moderate rocky desertification habitats increased as an adaptation to such habitats. However, in three of the habitats with different degrees of rocky desertification, the reproductive investment of V. chinshanense increased by increasing the flower biomass ratio to ensure reproductive capacity and population continuity. V. chinshanense uses strategies to reduce the investment of vegetative organs, such as leaves and stems, to adapt to harsh habitats and maintain ecosystem structure and stability at the maximum degree.
Abstract:
To explore the mechanism and provide a theoretical basis for the development and utilization of color mutants, Cymbidium tortisepalum Fukuy. var. longibracteatum with verge line pattern leaves and its parent leaves were used to investigate the characteristics of leaf variegation by paraffin section, scanning electron microscopy, and transmission electron microscopy. Results showed significant differences in the anatomical structure between the mutant and its parent. The epidermal thickness and mesophyll cell area of the mutant leaves were larger than those of the parent, whereas the number of vessels was lower. Scanning electron microscopy showed obvious differences in the micro-characteristics of the leaf surface between the mutant and parent. Stomatal area and density were smaller in the mutant leaves than that of the parent; furthermore, stomatal closure was higher in the mutant leaves than in the parent, with a frequency of 56% of the total number of stomata. Transmission electron microscopy showed no grana lamellae or starch grains, but many osmiophilic droplets in the mutant leaves, and the membrane of the chloroplast was disjointed. These results showed significant differences in the leaf structure between the mutant induced by tissue culture and its parent.
Abstract:
In general, biological samples must be dehydrated and dried before high vacuum scanning electron microscopy (SEM) analysis. However, during the critical point-drying or freeze-drying treatment process, samples with high water content will shrink or collapse, whereas for starch rich plant samples, tissues are prone to starch loss and cell wall deformation, resulting in poor quality scanning images. By comparing three pre-treatment methods of SEM, including CO2 critical point drying, freeze drying of chemically fixed samples, and freeze drying of fresh samples, we optimize suitable methods as follows:(1) Sample are first chemically fixed and then freeze dried, followed by brittle fracture with liquid nitrogen, with the cross-sections finally spray-coated with gold. With this treatment, the SEM images are of high quality, with the cell structure maintained and starch grains and protein complexes clear. This method can be used for analysis of the intracellular distribution of starch grains and protein. (2) Fresh samples are freeze dried directly, and after brittle fracture with liquid nitrogen, the cross-sections are finally spray-coated with gold. With this treatment, the SEM images are of high quality, with complete cell walls and clear starch granules. This is an optimal method for observation of starch granule distribution.
Abstract:
Nelumbo nucifera Gaertn. (sacred lotus) is not only an important aquatic vegetable crop, but also good material for basic scientific research. The extraction of sacred lotus seed proteins was optimized using four protein extraction methods (new TCA/acetone, traditional TCA/acetone, improved Tris-HCl, and Tris-saturated phenol methods) combined with two-dimensional electrophoresis (2-DE) technology. The 2-DE analysis showed that the resulting protein profile/map exhibited consistency with the composition and distribution of the sacred lotus seed proteome in ‘Tielian’. Analysis by PDQuest software showed that the new TCA/acetone method was suitable for 2-DE protein extraction of lotus cotyledons and plantules, whereas the traditional TCA/acetone method was suitable for the 2-DE protein extraction of hypocotyls. This work lays a foundation for further research on the sacred lotus seed proteome by mass spectrometry.
Abstract:
Sanicula exhibits a typical Eastern Asian-North American discontinuous distribution pattern typical of relicts from the Arcto-Tertiary flora. The genus comprises 40 species with two main centers of diversity:China (17 species, 11 endemics) and the United States (22 species, 13 endemics). Molecular phylogenetic analysis shows that the genus may not be monophyletic. The delimitation of subgenera is controversial, with different criteria emphasized in past studies, and infraspecific relationships remaining unclear (especially among species used as traditional Chinese medicine). However, previous studies have focused on the Sanicula DC. complex in North America or the Sandwicensis Shan and Constance group in Hawaii, excluding samples of endemic species from China. Therefore, explanations of the systematic position, place of origin, and migratory and dispersal patterns of the genus are not complete, nor are the evolutionary relationships among all its constituent taxa known. We present a review of recent research on the classification, origin, and evolution of Sanicula, summarize unsettled taxonomic problems, and discuss plans for future research to resolve these issues.
Abstract:
Heterotrimeric GTP-binding proteins, which are comprised of Gα, Gβ, and Gγ subunits, are evolutionarily conserved signal transduction molecules in eukaryotes. In plants, heterotrimeric G not only plays an important regulatory role in growth and development, but also participates in the regulation of multiple abiotic stress responses. This review focuses on the roles and possible regulation mechanisms of heterotrimeric G in the abiotic stress responses of plants, and puts forward prospects for future research. This paper will provide reference for further studies on the detailed regulation mechanism of heterotrimeric G proteins in the abiotic stress responses of plants.