Abstract:In this study, we used bioinformatics methods to identify the RPD3/HDA1 gene family in Brassica napus, and detected the expression level of this family gene in ‘Qianyouzao 2’ and ‘Zhongshuang 11’, and the gene expression characteristics of the family in two varieties under low temperature (4 ℃) and ABA stress, in order to explore the potential function of RPD3/HDA1 genes in Brassica napus, and provide theoretical basis and candidate genes for genetic improvement of stress resistance in early maturing rapeseed. The results showed that: (1) A total of 28 RPD3/HDA1 genes were identified in the whole genome of Brassica napus, and they were named BnHDA1-BnHDA28 with clustering into 4 subfamilies, the gene structures of members of the same subfamily were relatively similar, and a total of 16 pairs of replicated genes were detected in this gene family, all of them were fragment repeats. (2) A total of 675 cis-acting elements were found to be related to plant hormones, environmental stress, and light response. (3) qRT-PCR analysis showed that the expression of RPD3/HDA1 genes in ‘Qianyouzao 2’ was higher than that in ‘Zhongshuang 11’. Under low temperature stress, the RPD3/HDA1 genes in ‘Qianyouzao 2’ and ‘Zhongshuang 11’ showed differential expression, and compared with ‘Zhongshuang 11’, the down-regulation of RPD3/HDA1 genes in ‘Qianyouzao 2’ was greater. After ABA treatment, the expression pattern of RPD3/HDA1 genes in the two varieties was inconsistent, and the expression level of most RPD3/HDA1 genes in ‘Qianyouzao 2’ was lower than that in ‘Zhongshuang 11’. Research suggested that RPD3/HDA1 genes may play a regulatory role in rape flowering, and may participate in the regulation of rape growth and development and defense response through hormone signaling pathway and defense signaling pathway.

Abstract:In order to clarify the role of LEA gene in abiotic stress, this study identified the whole genome of the LEA gene family by bioinformatics, and analyzed its expression under different abiotic stress by qRT-PCR. The results indicated that: (1) The presence of 57 members of the LEA gene family that encoded proteins with molecular weights ranging between 6.95-104.98 kD and amino acid lengths between 62-945 aa. (2) The phylogenetic analysis classified the PtrLEA genes into eight subfamilies. LEA_2 had the most members, followed by LEA_1-LEA_6, dehydrin, and SMP. (3) Cis-acting element analysis demonstrated that the PtrLEA promoter contained a significant number of hormone, stress response, and growth and development-related response elements. (4) Transcriptome data analysis indicated tissue-specific expression patterns of the LEA gene family, with PtrLEA15, PtrLEA17, PtrLEA23, and PtrLEA51 highly expressed in all tissues, while three genes did not express in any tissues. (5) The real-time fluorescence quantitative PCR test revealed up-regulated PtrLEA gene expression when exposed to low temperature, drought, and high salt stress conditions, with 6, 2, and 6 genes up-regulated, respectively, suggesting the involvement of this gene family in the response to various non-biological stresses.

Abstract:To explore the interaction of iron (Fe) with phosphorus (P) deficiency and aluminum (Al) toxicity coupling stress in acidic soil and its effects on Al tolerance of Cunninghamia lanceolata, we conducted sand culture method with four treatments: Control (CK), Al stress (Al), P deficiency and Al toxicity coupling stress (-P+Al) and P deficiency and Al toxicity coupling stress without Fe (-P+Al-Fe) under controlled conditions in this study to investigate the effects of exogenous application of Fe on the growth, photosynthetic physiology, Al and Fe contents and resistance physiology in leaves of C. lanceolata seedlings under P deficiency and Al toxicity coupling stress by using superior genotype seedlings of C. lanceolata YX11. The results showed that: (1) Al stress could significantly inhibit the growth of Chinese fir seedlings, and the growth inhibition induced by Al was further aggravated by normal iron supply under the coupling stress of phosphorus deficiency and aluminum toxicity (-P+Al), -P+Al-Fe significantly alleviated the growth inhibition induced by -P+Al treatment. (2) Compared with CK, the photosynthetic pigment content, chlorophyll fluorescence parameters including maximal fluorescence (F_m), variable fluorescence (F_vm), PSⅡ potential photochemical activity (F_vm/F_o), PSⅡ maximal photochemical efficiency (F_vm/F_m), photochemical quenching coefficient (qP), actual maximum quantum yield (QY) and net photosynthetic rate of Chinese fir leaves all decreased in different degrees under various stress treatments. However, a more significantly decreasing amplitude of above indexes was observed in -P+Al treatment as compared with -P+Al-Fe treatment. (3) The activities of SOD, POD, CAT and APX in leaves of C. lanceolata were significantly increased under different stress condition when compared with CK, and the increasing amplitude of these enzyme activities in -P+Al treatment was significantly lower than that in -P+Al-Fe treatment, which in turn leads to higher accumulation of malondialdehyde in -P+Al treatment as resulted by the formation of hydrogen peroxide. (4) Different stress treatments all resulted in a significantly higher accumulation of Al content in both roots and leaves of C. lanceolata seedlings as compared with CK, while no significant difference of Al content was noted between -P+Al-Fe and -P+Al treatments. Moreover, a significantly higher of Fe content in both roots and leaves of C. lanceolata seedlings was found in -P+Al treatment as compared with -P+Al-Fe treatment. The above results demonstrated that under phosphorus deficiency and aluminum toxicity coupling stress, compared with Fe deficiency, normal Fe supply could significantly promote the accumulation of Fe in plants, thus the increase of antioxidant enzyme activity was inhibited, and increased the accumulation of hydrogen peroxide, which in turn caused degradation of photosynthetic pigments and irreversible damage to the plasma membrane and photosynthetic reaction center, resulted in significant decrease of photosynthetic efficiency and ultimately the growth inhibition induced by Al was aggravated.

Abstract:The authors evaluated the waterlogging tolerance of Yulania stellata and its seedling breeding cultivar Y. stellata ‘Chrysanthemiflora’ and its hybrid cultivar Y. ‘Piroutte’ with Y. salicifolia, to provide theoretical basis for subsequent selection of Y. stellata waterlogging tolerant cultivars. Through 14 days of waterlogging stress, the changes of 14 indexes related to leaf physiology, endogenous hormones and photosynthetic characteristics of three Yulania materials were studied. Using principal component analysis, the importance of superoxide dismutase (SOD), malondialdehyde (MDA), soluble protein, abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC) as indicators of waterlogging tolerance was compared and waterlogging tolerance was evaluated. The waterlogging tolerance of the five indicators was evaluated by the membership function analysis method. The results showed that: (1) The contents of P_n, G_s, T_r, chlorophyll, origin fluorescence, maximum fluorescence, PSⅡ maximum photochemical quantum yield, PSⅡ effective photochemical quantum yield and soluble protein in the leaves of the three Yulania materials were significantly decreased after waterlogging stress, and the contents of MDA, ABA and SOD activity were increased by different degrees. However, the intercellular CO₂ concentration and ACC of Y. stellata ‘Chrysanthemiflora’ and Y. stellata treatment groups increased significantly, while the C_i and ACC of Y. ‘Piroutte’ decreased significantly. (2) The importance of physiological and endogenous hormone indicators to evaluate the waterlogging tolerance of three Yulania materials was in order: ACC, SOD, ABA, soluble protein, and MDA. (3) According to the comprehensive evaluation of the three cultivars by principal component analysis and membership function analysis, the waterlogging tolerance of the three Yulania materials was in the order of Y. ‘Piroutte’, Y. stellata and Y. stellata ‘Chrysanthemiflora’.

Abstract:To analyze the function and regulatory mechanism of melatonin (N-acetyl-5-methoxytryptamine) in plant innate immunity, this study used the interaction between the pathogenic bacterium Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and tobacco as a model system. The study examined the influence of pathogen invasion on the expression of tobacco genes related to melatonin and analyzed the effects and regulatory mechanisms of melatonin on pathogen grwoth, stomatal aperture, and ROS (reactive oxygen species) content in plant leaves. The results showed that: (1) Pst DC3000 treatment increased the expression of tobacco melatonin biosynthesis (NtSNAT1) and receptor (NtPMTR1) genes, and exogenous melatonin treatment reduced the bacterial contents in plant leaves. (2) Overexpression of the soybean GmSNAT1 significantly increased the endogenous melatonin concentrations and expression of NtPMTR1 in transgenic tobacco plants GmSNAT1-OE2 and GmSNAT1-OE5, and the Pst DC3000 bacteria growth number was significantly decreased. (3) Exogenous melatonin and bacterial flagellin peptide flg22 treatments induced the production of ROS and stomatal closure in both wild-type and transgenic tobacco guard cells, and the transgenic plants were more sensitive to melatonin- and flg22-induced stomatal closure and ROS production than the wild-type plants. Taken together, this study found that melatonin could reduce the bacteria invasion, which may probably be associated with promoting ROS production in guard cells and inducing stomatal closure via NtPMTR1-mediated signaling pathway.

Abstract:In the present study, the effects of exogenous ascorbic acid (AsA) treatments on potato microtuber formation and the expression of tuberization-related genes, as well as the influence of knockout of the key tuberization-related gene Solanum tuberosum self-prunning 6A(StSP6A) on the AsA-induced tuberization were investigated. Two diploid landraces CIP-149 (Solanum phureja), CIP-178 (S. ajanhuiri) and tetraploid C-88(S. tuberosum) were treated with different concentrations (0，1，5，10，20，50 mmol/L) of AsA. The results showed that exogenous AsA treatments with 1 mmol/L to 5 mmol/L could significantly induce tuber formation. The expression analysis of 10 tuberization-related genes demonstrated that the exogenous 1 mmol/L AsA treatment also significantly affected the expression of those tuberization-related genes, in which a general trend was demonstrated with an enhancement of positive regulator or repression of negative regulator expression for tuber formation as compared with the control, especially StSP6A, which was extremely significantly up-regulated during the early stage of tuber formation and AsA treatment. Knockout of StSP6A resulted in elimination of the effect of exogenous AsA-induced tuberizations in potato. These findings indicated that AsA-induced tuber formation is triggered by regulating the tuberization-related gene expression, and StSP6A played key roles in AsA-induced tuber formation in potato.

Abstract:In order to clarify the water use strategy and adaptive mechanism of plants, this study took Stipa breviflora desert steppe of Siziwang Banner, Inner Mongolia as the research object, and set four grazing gradients: control (CK), light grazing (LG), moderate grazing (MG) and heavy grazing (HG). The stocking rates were 0, 0.93, 1.82 and 2.71 sheep units per hectare per year, respectively. The height, coverage, density, aboveground biomass and soil physicochemical properties of the established species S. breviflora were investigated, and the water use efficiency of S. breviflora was measured by stable carbon isotope method and infrared photophotoapparatus method. The objective was to elucidate the response of water use efficiency of S. breviflora under different grazing intensities and its influencing factors. The results showed that: (1) Grazing had significant effects on coverage, density and aboveground biomass of S. breviflora. With the increase of stocking rate, S. breviflora spread and its distribution area increased, especially under moderate grazing condition. (2) With the increase of grazing intensity, soil moisture content increased significantly compared with the control, soil total nitrogen content increased first and then decreased, soil available potassium showed a trend of decreasing, but had no significant effect on soil total carbon content and pH, indicating that moderate grazing could increase soil moisture content and promote the accumulation of soil nitrogen content, but grazing would lead to the decrease of soil available potassium. (3) With the increase of grazing intensity, long-term water use efficiency (WUE_l) showed a V-shaped trend, while instantaneous water use efficiency (WUE_t) and intrinsic water use efficiency (WUE_i) showed a decreasing trend. (4) Correlation analysis showed that grazing intensity was significantly positively correlated with S. breviflora density and aboveground biomass, soil total nitrogen content was significantly positively correlated with organic carbon, pH and WUE_i, and WUE_t and WUE_i were significantly positively correlated. The intrinsic water use efficiency of S. breviflora was closely related to soil organic carbon content. The results showed that heavy grazing resulted in the fragmentation of S. breviflora and increased the population diffusion area, which was the direct reason for the improvement of long-term water use efficiency of S. breviflora. The decrease of instantaneous water use efficiency with the increase of grazing intensity may be caused by the decrease of intrinsic water use efficiency of S. breviflora.

Abstract:‘Danhong’ (Populus deltoides) and ‘Tongliao 1’ (Populus simonii) were used as materials, and treatments with and without nitrogen fertilization were conducted in the field. The changes in growth traits, carbon, and nitrogen-related metabolites, and transcriptome of the developing xylem were analyzed. The physiological mechanism of nitrogen fertilizer utilization in different poplar varieties was discussed, which laid a foundation for the genetic breeding of nitrogen efficient utilization of poplar. The results showed that: (1) The total biomass of ‘Danhong’ and ‘Tongliao1’ poplar increased 1.69 times and 1.10 times, respectively, under nitrogen application treatment. The total biomass of ‘Danhong’ poplar was 13 times higher than that of ‘Tongliao 1’ poplar under the condition of nitrogen fertilization and 10 times higher than that of ‘Tongliao 1’ poplar under the condition of no nitrogen fertilization. (2) The treatment of nitrogen fertilizer significantly inhibited the contents of total nitrogen and various hydrolyzed amino acids in the bark and xylem of ‘Danhong’ and ‘Tongliao 1’, but did not significantly affect the contents of total carbon, cellulose, hemicellulose, and lignin in the xylem. (3) Nitrogen fertilizer treatment significantly affected the high expression of genes in carbon and nitrogen metabolic pathways such as carbon fixation, sugar metabolism, and amino acid synthesis in the developing xylem of two poplar species, which resulted in biomass accumulation. In this study, we found that nitrogen application treatment significantly promoted the high expression of genes related to the carbon and nitrogen metabolic pathways in the developing xylem of poplar, thus promoting the accumulation of biomass and growth of poplar. The wood yield of ‘Danhong’ poplar was much higher than that of ‘Tongliao 1’ poplar under different nitrogen environments, which was more suitable for large-scale promotion and planting of plantation.

Abstract:In this experiment, we took the cuttings of two-year-old C. bungei tree (C.bungei No.1 and 008-1) as materials, and used pot experiment to analyze the growth and physiological changes of C.bungei tree seedlings under salt stress (0.5% NaCl). The alleviating effects of different concentrations of ABA (15, 25, 35 mg/L) on salt-stressed (30 d) C.bungei seedlings and their physiological and biochemical characteristics were analyzed, so as to explore the appropriate concentration of ABA for the growth of C.bungei seedlings under severe salt stress, and to provide theoretical basis for enhancing the salt-alkali tolerance of C.bungei and improving the utilization of saline-alkali land. The results showed as follows: (1) Under 0.5% NaCl stress, the seedling leaves of the two cultivars showed different degrees of salt damage symptoms, and the salt damage symptoms of the leaves of ‘C.bungei No.1’ were more serious than ‘008-1’. As the stress time increased, the relative electrical conductivity (REC) of the seedlings of the two cultivars increased first and then decreased, chlorophyll (Chl) and relative water content (RWC) decreased, and the activities of soluble sugar (SS), soluble protein (SP), proline (Pro) and superoxide dismutase (SOD) increased first and then decreased. However, the REC of ‘008-1’ was significantly lower than that of ‘C.bungei No.1’, and the Chl, RWC, SS, SP, Pro and SOD of ‘008-1’ were significantly higher than that of ‘C.bungei No.1’, indicating that ‘008-1’ had stronger salt tolerance than ‘C.bungei No.1’. (2) The seedling height of C.bungei ‘008-1’ was significantly increased and the new leaves germinated in advance under salt stress, which indicated that exogenous ABA could alleviate the effects of salt stress on the growth of C.bungei to a certain extent. ABA treatment decreased the REC of C.bungei ‘008-1’ seedlings under salt stress, and increased contents the of Chl, RWC and activities SS, SP, Pro, SOD, peroxidase (POD) and catalase (CAT). It promoted the accumulation of endogenous hormone auxin (IAA), abscisic acid (ABA), gibberellin (GA₃) and zeatin nucleoside (ZR). The results showed that the salt-tolerance of ‘008-1’ was stronger. Exogenous ABA spraying with appropriate concentration could alleviate the effects of salt stress on the growth of C.bungei seedlings, reduce the permeability of cell membrane in seedling leaves, promote the accumulation of osmotic regulatory substances in seedlings, enhance osmotic regulation ability, and improve the antioxidant enzyme activities, and promote the regulation of endogenous hormone contents in plants of seedlings under salt stress, thus improve the salt-tolerance of C.bungei seedlings. 25 mg/L ABA treatment had the best effect.

Abstract:To reveal the changes of photosynthetic physiology and leaf structure of U. szechuanica seedlings under different light conditions and infer its shading tolerance, four different treatments, including L₀ (100% radiation intensity), L₁ (45% radiation intensity), L₂ (25% radiation intensity) and L₃ (18% radiation intensity), photosynthesis parameters, leaf morphology and leaf anatomical structure characteristics of seedlings under shading were studied. Results showed that P_n showed asymmetric convex linear changes under different shading treatments. The variation of P_n under L₀ treatment was strong, the maximum value of P_n appeared at 12:00, it began to decline sharply over it. However, the photosynthetic effective radiation under shading treatment was insufficient, the P_n of each time decreased significantly, and the peak value decreased. Correspondingly, the G_s basically showed the change of firstly rise and late decline, and C_i showed convex shape. The daily average sequence of P_n under different light environments was L₀＞L₁＞L₂＞L₃. Shading had a significant effect on photosynthetic response parameters of U. szechuanica seedlings, which caused a significant decrease of LCP, LSP, and changes of P_nmax and R_d was so. Shading affected the leaf morphology. With the increase of shading intensity, single leaf area (SLA) increased, lamina mass per unit area (LMA) decreased, and lamina area per unit mass (LAM) increased. There was significant difference between these indexes of seedlings under shading compared with the control. Under shading, leaves of U. szechuanica became thinner, thickness of epidermal cells (EP) decreased significantly, thickness of both palisade tissue (PT) and sponge tissue (ST) reduced. U. szechuanica seedlings like light, which has certain physiological regulation ability to weak light, but strong shading will lead to poor malnutrition. Light conditions might be an important external factor affecting the living and population renewal of seedlings, so it was suggested to carry out moderate thinning of natural forest, reduce canopy density in forest, clean up the litter, and create a favorable condition for propagating of wild population.

Abstract:In this study, the reserve was divided into six vegetation vertical zones ［steppe zone (1 800-2 000 m), mountain scrub zone (2 000-2 200 m), subalpine coniferous forest zone (2 200-2 900 m), subalpine dwarf forest zone (2 900-3 000 m), alpine scrub zone (3 000-3 500 m) and alpine meadow zone (>3 500 m)］ according to the altitude gradient by field survey and collection of relevant literature, On the basis of the plant lists of the six vegetation vertical zones, we used seed plants as the study objects to analyze the seed plant richness, life type, zonal composition and phylogenetic structure of each vegetation vertical zone, and to explore the vertical change pattern of plant diversity along the elevation of the vegetation vertical zones, with the aim of understanding the ecological adaptability of plants to the environment. The aim was to understand the ecological adaptability of plants to the environment and to provide a theoretical basis for the conservation and exploitation of plant diversity in mountainous areas. The results show that: (1) According to the latest classification system, the seed plants of Xinglong Mountain Nature Reserve belonged to 87 families, 387 genera and 889 species, and the richness of plant families, genera and species followed a unimodal distribution pattern with the elevation of the vegetation vertical zone, reaching a peak in the subalpine coniferous forest zone (81 families, 304 genera and 661 species); the Jaccard similarity coefficient among the vegetation vertical zones was moderately dissimilar and extremely dissimilar. The higher the similarity coefficient between vegetation vertical zones, the closer the altitude was to the vegetation vertical zone. (2) There were differences in the pattern of vertical variation in the different life types of seed plants in the reserve, with the proportion of woody plants increasing and then decreasing along the elevation of the vegetation vertical zone, while the herbaceous plants showed the opposite variation pattern, and the proportion of herbaceous plants in each vegetation vertical zone was always higher than that of woody plants. (3) Seed plants of the reserve at the genus level, the proportion of tropical components in protected areas tended to decrease as the elevation of vegetation zones increases, while the proportion of temperate components tended to increase. (4) The phylogenetic structure was dispersed in the subalpine coniferous forest zone at middle and low altitudes, and aggregated in the three vegetation zones at high altitudes (>2 900 m), indicating that the non-random distribution pattern of the Xinglong Mountain Nature Reserve played a major role in the community construction mechanism.

Abstract:Based on the field survey data, the relationship between A. squarrosum communitys distribution and soil factors in southeast margin of Badain Jaran Desert was discussed by quantitative classification and ordination, in order to provide theoretical support for artificial domestication and cultivation of A. squarrosum. The results showed that A. squarrosum community consists of 21 species, including 8 species of Amaranthaceae, 3 species of gramineae, 3 species of Compositae, 2 species of Tamaricaceae, each 1 species of Zygophyllaceae, Fabaceae, Solanaceae and Plumbaginaceae. TWINSPAN divided the A. squarrosum community into seven associations. The soil moisture decreased from 5.12% to 1.01%, and soil clay content gradually decreased from 6.32% to 2.53% in the process of associations Ⅰ to Ⅶ. The soil sand content of cluster Ⅰ increased from 78.25% to 89.84% of cluster Ⅵ and 87.78% of cluster Ⅶ. Soil organic matter, total nitrogen, available phosphorus, pH and electrical conductivity fluctuated in each cluster. CCA ordination results showed that soil factors explained 30.8 % of the total variation of A. squarrosum associations. The order of variance explained by soil factors was soil moisture (6.8%)> pH(5.3%) > available phosphorus (4.4%) > soil organic matter (4.4%) > total nitrogen (3.6%) > silt(2.3%) >electrical conductivity (2.2%) > sand(1.9%)。Among them, pH, soil moisture, organic matter, and available phosphorus were important environmental regulatory factors that affect the distribution of A. squarrosum communities. In addition to ensuring the normal water supply, the artificial cultivation of A. squarrosum should also focus on the supplement of soil organic matter and available phosphorus.

Abstract:Open-pit coal mining has caused great disturbances to the geomorphology, hydrological cycle, soil and vegetation, and other ecological environmental factors, but the scope and extent of open-pit mining on the plant communities and its stability around the mining area still need to be further studied, and it is only when this issue is clarified that a scientific basis can be provided for the precise policy of revegetation on mining sites. In this paper, the influencing scope and extent of open-pit coal mining on plant communities were analyzed at different distances from the mining area in arid gravel desert areas by quantitative comparing the composition, diversity, productivity and stability of plant communities, and the factors affecting the characteristics of plant communities were explored in combination with the soil and micrometeorological factors. The results showed that: (1) Original vegetation disappeared completely in dump sites, the important value (IV) of dominant species decreased within 0-500 m around the mining area, but the IV of companion species increased. The IV of dominant plants gradually increased with the increasing distance from mining area, and the composition of plant community tended to be stable 800 m away from the mining area. (2) The plant communitys aboveground biomass, diversity and stability within 0-500 m around the mining area decreased by 53%, 70% and 37% averagely compared with 5 000 m areas, respectively. The above plant community indicators did not change significantly beyond 500 m of the mining area, while the vegetation coverage did not show a significant change at different distances around the mining area. (3) Soil water content, organic matter, available nitrogen, phosphorus, potassium and soluble salt were positively correlated with plant communitys aboveground biomass, diversity and stability, while soil pH, light intensity and surface temperature correlated negatively with these plant community indicators. These results indicated that the dump sites and 0-500 m around mining area were the priority area to be considered in the process of ecological restoration in open-pit coal mining in arid gravel desert areas. Meanwhile, vegetation was mainly distributed in the depressed micro-topography with relatively good habitats such as shallow gullies and seasonal river channels in study area. Therefore, it was necessary to micro-topography shaping, improve soil quality, and use local species in the process of vegetation restoration. In these ways, a stable and sustainable ecosystem can be achieved in the arid coal mining area.

Abstract:To explore the reproductive strategy of Davidia involucrata in Fanjingshan Nature Reserve, so as to reveal the role of sprouting seedling and seeds seedling on the population maintaining, we investigated the population of D. involucrata in Biaoshuiyan of Fanjingshan Nature Reserve by per-tree survey. The diameter class structure chart was drawn according to the survey data, and which was used to replace the age structure. Then, the population static life tables of sprouting seedling and seeds seedling were compiled by using the uniform sliding technique. The survival curve, the mortality curve, the disappearance rate curve and other four survival function curves were plotted. The results showed that: (1) There was a certain fluctuation in the population age structure of D. involucrata. The young individuals were counted 78.78% according to the statistics of sprouting seedlings, while it was 21.45% when according to the statistics of seeds seedlings. However, the survival curve of either kind of statistics was close to Deevey Ⅱ. (2) The population of D. involucrata was growing, and the V_spi of sprouting seedling was higher than that of V_sepi(6.50%＞2.30%). (3) The population of D. involucrata was decreased monotonically, and the sprouting seedling was more obvious. (4) The population cumulative mortality of D. involucrata showed a monotonically increasing trend, and the sprouting seedling was also more obvious. (5) The curve of survival rate and vanish rate of D. involucrata showed a monotonically upward trend, both sprouting seedling and seeds seedling kept a same trend. All of the above indicated that, the population of D. involucrata was a growing type, its survival curve belonged to Deevey Ⅱ, and the population would be stable in the later developing stage. The sprouting reproduction was more advantageous to maintain the population seedling quantity, and which had a very important role in maintaining the population stability of D. involucrata.

Abstract:In this study, the authors reviewed past advances in the taxonomy and phylogeny of Linderniaceae, and summarized the taxonomic changes of Linderniaceae in China. And also analyzed distribution pattern of Linderniaceae in China by collecting specimen information from the Chinese Virtual Herbarium (CVH), National Specimen Information Infrastructure (NSII), Flora Reipublicae Popularis Sinicae (FRPS), Flora of China (FOC), and China Checklist of Higher Plants. These results indicated that Linderniaceae was mainly composed of the taxa of tribe Lindernieae and Stemodieae of the traditional Scrophulariaceae and the genus Cubitanthus of the Gesneriaceae, with a total of 22 genera and more than 220 species. There were eight genera and 43 species of the Linderniaceae in China, among which 15 species were endemic. In China, Guangxi and Guangdong provinces had the most abundant species of Linderniaceae, while no species of this family were found in Xinjiang, Qinghai, and Ningxia. This study corrected the generic circumscription and geographic distribution of Linderniaceae in China, which may provide a reference for further research on the taxonomy and biodiversity of Linderniaceae.

Abstract:Leaf senescence is an important developmental process involving orderly disassembly of macromolecules for relocating nutrients from leaves to other developing organs and is critical for plant survival and adaptation. Leaf senescence is primarily regulated by plant development, but is also influenced by internal and external environmental factors. Leaf senescence involves highly intricate regulatory networks and multilayered regulatory mechanisms. Recent studies had shown that epigenetics was an important mode of regulation of leaf senescence in plants. This review provided an overview of the known epigenetic regulation of plant leaf senescence, including histone modifications, DNA methylation modification, ATP-dependent chromatin remodeling and non-coding RNA mediated regulation. The future research trends in this area were also prospected.