Abstract:UDPflavonoid glycosyltransferase (UFGT) catalyzes the formation of stable glycosides such as flavonols and anthocyanins, which is the key to the last step of the synthesis of flavonol and anthocyanin glycosides. In this study, we used the petals of Camellia nitidissima Chi as materials, cloned two UDPflavonoid glycosyltransferase genes selected from the transcription by PCR amplification. The results show that: (1) CnUFGT14 gene, with GenBank numbers MT370521, was 1 562 bp in length, 1 380 bp in open reading frame, and encoded 459 amino acids. CnUFGT15 gene, with GenBank numbers MT370520, was 1 546 bp in length, 1 368 bp in open reading frame, and encoded 455 amino acids. Both protein sequences had a conserved region of PSPG characteristic of UFGT proteins. (2) Phylogenetic tree analysis showed that CnUFGT14 and CnUFGT15 were closely related to UFGT78A14 and UFGT78A15 in C. sinensis, respectively. (3) Quantitative PCR analysis showed that the expression levels of CnUFGT14 were positively correlated with the contents of multiple polyphenol components, while CnUFGT15 expression levels were not significantly correlated with the contents of flavonols and polyphenols. (4) The subcellular localizations showed that CnUFGT14 and CnUFGT15 proteins were in the nuclear membrane, cytoplasm and cell membrane. (5) The transform of tobacco with leaf disc method found that the total polyphenol content and the contents of multiple polyphenol components in the plants with high expression level of CnUFGT14 increased, while the changes of flavonoids and polyphenol components in the transgenic lines of CnUFGT15 were not significant. All the results indicated that CnUFGT14 gene can promote the synthesis of polyphenols and CnUFGT15 had no obvious effect on the flavonoid pathway.

Abstract:In this study, we used quantitative reverse transcriptionPCR to analyze the expression level of PnPR1, a pathogenesisrelated protein gene of Panax notoginseng. In addition, the overexpression vector of pCAMBIA2300sPnPR1 was constructed and then introduced into tobacco (Nicotiana tabacum) with Agrobacterium tumefaciens mediated method. The results showed that: (1) the methyl jasmonate pretreatment of P. notoginseng roots greatly upregulated the PnPR1 expression during Fusarium solani infection. (2) The expression level of PnPR1 gene was induced by the treatment of four signal molecules (methyl jasmonate, ethephon, salicylic acid, and hydrogen peroxide) to varying degrees. The expression of PnPR1 was downregulated by three kinds of signal molecule inhibitors. (3) PnPR1 was stably expressed in T₂ transgenic tobacco, and the resistance of transgenic tobacco lines to F. solani was significantly improved. In conclusion, the PnPR1 gene responds to the infection of F. solani at transcription level and was induced by signal molecules such as methyl jasmonate. Overexpression of PnPR1 in tobacco lines enhanced the resistance to F. solani, indicating that PnPR1 is a diseaseresistance gene involved in the defense responses of P. notoginseng to F. solani.

Abstract:In this study, the full length cDNA of CCD8b was cloned from Musella lasiocarpa using RACE technique, and was designated as MlCCD8b (GenBank accession number MW013147)，amino acid sequence alignment and phylogenetic tree were constructed. The expression patterns of MlCCD8b gene in different types and tissues of M. lasiocarpa were detected by realtime fluorescent quantitative PCR. The results showed that: (1) the full length cDNA was 2 052 bp, containing an ORF of 1 671 bp in length, encoding 556 amino acids. The relative molecular mass of coding protein is 61 574.26 Da and the isoelectric point is 6.61, which is a hydrophilic protein. This protein has a RPE65 conserved domain belonging to carotenoid oxygenase family. The subcellular localization most likely be on the thylakoid within chloroplast stroma.(2) Sequence comparison and phylogenetic tree analysis showed that the amino acid sequence of MlCCD8b had considerable similarity with those of other species, and had the closest evolutionary relationship with the CCD8b protein of Musa acuminata subsp. malaccensis and Ananas comosus. (3) Realtime PCR analysis showed that MlCCD8b exhibited a same tissue expression pattern between the two types of M. lasiocarpa, with the highest expression in rachis, followed by sucker growing point, root tip and leaf, the lowest expression or nonexpression in bract. (4) The expression of MlCCD8b in rachis, sucker growing point, root tip and leaf of RD05 were 4.47, 4.67, 2.09 and 1.10 times than those of YN01. (5) The 5DS content in RD05s root tip was 15.57 times than that in YN01s, which was consistent with the expression pattern of MlCCD8b. The study indicated that the MlCCD8b gene may participate in the synthesis and regulation of strigolactones. These results provided a basis for the further study on regulating the number of suckers in M. lasiocarpa using genetic engineering.

Abstract:In this study, the tobacco NtSKOR1 gene that is homologous to AtSKOR gene in Arabidopsis was identified from tobacco via NCBI Blast and RTPCR. The bioinformatics and expression characteristics of NtSKOR1 were analyzed, and the knock out materials of NtSKOR1 was obtained by CRISPR/Cas9 technology. The results showed that: (1) full length CDS of NtSKOR1 was found to be 2 466 bp, encoding a sequence of 821 amino acid residues, and successfully cloned with gene specific primer pair by RTPCR. The isoelectric point of this protein is 6.36 and the molecular weight is 94.21 kD. (2) The subcellular localization result of NtSKOR1 showed that this gene was localized in cell membrane. Amino acid sequence analysis showed that this protein contains 6 transmembrane structures, but with no signal peptide sequence. As a typical SKOR family protein, NtSKOR1 is featured by poreforming domain and ankyrin structural domains. (3) Phylogenetic analysis showed that NtSKOR1 protein is close to SKOR proteins identified from tomato and potato, while is distant from the SKOR proteins of Gramineae species. (4) Tissue specific expression analysis showed that NtSKOR1 was preferentially expressed in roots, which was in line with AtSKOR1 expression pattern in Arabidopsis. After potassium stress treatment, the expression pattern of NtSKOR1 showed a fluctuant trend. (5) CRISPR/Cas9based genome editing of NtSKOR1 significantly decreased the potassium content in the leave of transgenic lines, suggesting NtSKOR1 gene is one of the key genes in controlling potassium content in tobacco leaves. Our results provided significant evidence of the molecular mechanism of potassium intake and transport in tobacco.

Abstract:To investigate the function of GsF3′5′H and GsFNS in Gentiana sinoornata, with blue corolla during 5 different flowering stages (H₁-H₅) as the test material, we cloned the fulllength cDNA by using RTPCR techniques. The results showed that: (1) GsF3′5′H and GsFNS contain 1 560 bp and 1 590 bp open reading frame (OFR), which encode 520 and 529 amino acids, respectively. (2) Structural analysis revealed that both GsF3′5′H and GsFNS had typical conserved domains of F3′5′H and FNSⅡ. (3) Phylogenetic analysis indicated that Gentiana triflora was the closest relative species between GsF3′5′H and GsFNS. (4) qRTPCR showed that GsF3′5′H and GsFNS were expressed in roots, stems, leaves and corolla, and the expression level of GsF3′5′H was the highest in corolla H₃ stage, the expression level of GsFNS was the highest in roots, which followed by the corolla H₄ stage. It showed that the copigmentation effect of delphinin and flavone expressed by GsF3′5′H and GsFNS may make the corolla of Gentiana sinoornata more stable and bluer, which providing important genetic resources for the molecular breeding of blue flowers.

Abstract:TCP genes encode a plantspecific transcription factor family, which acts as a key role in regulating stress response． In this study, the members of TCP genes family were identified in the whole genome of strawberry by bioinformatics analysis, the qRTPCR was used to detect the expression of strawberry transcription factor family in abiotic stress, while gene structure and function of its corresponding transcription factor family genes were analyzed, to provide a foundation for exploring the role of TCP transcription factor in abiotic stress of Fragaria vesca. The results showed: (1) 18 strawberry genes (FvTCP) were identified from F. vesca genome and 58 strawberry genes (FaTCP) were also identified from F. ananassa genome. According to the subcellular localization，the TCP family genes were mainly located in the nucleus. (2) qRTPCR showed that the family genes had response to adversity stress effect, but different members response under different stress level. FvTCP14 tendency in 200 mmol·L^-1 NaCl, 10% PEG, 100 μmol·L^-1 ABA, 4 ℃, 40 ℃ and 100 mmol·L^-1 H₂O₂ treatments were significantly upregulated, which were 43.78, 166.73, 38.39, 265.87, 626.24 and 451.85 times of the control, respectively which indicated that FvTCP14 strongly responded to drought stress, salt stress, ABA induction, H₂O₂, high and low temperature stresses. In addition, FvTCP12 were significantly downregulated after 4 ℃, 100 μmol·L^-1 ABA and 100 mmol·L^-1 H₂O₂ stress treatments, suggesting that this gene had a negative regulatory effect on low temperature, ABA and H₂O₂ stresses. It is found that the expression of FvTCPs were different when the encountered the adversity environments.

Abstract:In this study, Cabernet Sauvignon, the most cultivated wine grape cultivar in eastern Helan mountain of Ningxia was used as the test material. Based on the results in our previous experiments, the transcriptome sequences and the organic acids assay at different developmental stages of fruits, we further predicted the transcription factor binding sites with the functional gene promoter regions (target), combined with the differentially expressed gene analysis and the weighted gene coexpression network analysis (WGCNA), to select the transcription factors that specifically bind to the functional genes associated with malate biosynthesis in Cabernet Sauvignon fruits. In addition, qRTPCR was used to verify the regulation mechanism between these key functional genes and their transcription factors in different cultivation areas at different developmental stages. The results provide a theoretical basis and idea for genetic improvement of highquality wine grapes. The results show that: (1) GS/MS analysis found that fumarate and malate at the four developmental stages of Cabernet Sauvignon fruits had the same variation trend. Both of them gradually increased to the highest (3.63 and 626.53 μg/g) from the hard to green, then decreased slowly, and gradually decreased to the lowest level (2.14 and 244.26 μg/g) through the veraison to maturity. While the variation of oxaloacetate was opposite, the content is the highest (315.54 μg/g) at the hard, it drops to the lowest (126.11 μg/g) from the green, veraison to maturity gradually. (2) Transcriptome sequencing of Cabernet Sauvignon fruits developmental stages results showed a total of 6 411 transcription factors that may be combined with 12 functional genes of the malate biosynthetic pathway, among them there are 86 transcription factors associated with 3 functional genes of fumarate hydratase (FH), 717 transcription factors related to 10 functional genes of malate dehydrogenase (MDH). (3) Veen analysis of transcriptome sequencing data and the WGCNA analysis of organic acid contents determined 3 genes related to FH (VIT_14s0060g01700, VIT_13s0019g03330, VIT_07s0005g00880), 2 genes related to MDH (VIT_10s0003g01000, VIT_13s0019g05250) and 18 key transcription factors highly associated with malic acid biosynthesis during the ripening process in Cabernet Sauvignon fruits. (4) qRTPCR verification and correlation analysis showed that the expression levels of transcription factors VIT_01s0011g06200, VIT_08s0056g01230 of VIT_13s0019g03330, and transcription factors VIT_06s0004g04960, VIT_10s0003g02070 of VIT_13s0019g05250 are positively related to the malate accumulation, also suggested these 4 transcription factors may regulate the transcription of functional genes to influence the biosynthesis of malate comprehensively in Cabernet Sauvignon fruits.

Abstract:Phloem unloading and postphloem transport play pivotal parts in the regulation of the distribution and accumulation of photosynthate in the fruit， and largely determine the yield and quality of the crop． To uncover the phloem unloading and transport pathway of photosynthates in Ziziphus jujuba Mill. cv. lingwuchangzao fruit, the four different developmental periods fruits of Ziziphus jujuba Mill. cv. lingwuchangzao were used as experimental material to observe the microstructure of the vascular bundle of fruit in each development period, the techniques of fluorescent dye tracer in living cell and confocal laser scanning microscopy (CLSM) were used to observe the phloem unloading path of photosynthates in the fruit timely, the research results provide scientific bases of fruit photosynthates accumulation and quality regulation for Ziziphus jujuba Mill cv. lingwuchangzao． The main research results were followed: (1) not only the phloem of the fruit but also the parenchyma cells surrounding the phloem existed evidently the CF green fluorescence, the SECC complex and its surrounding cells existed symplastic integration in the early bulking period. (2) The CF green fluorescence was mainly confined to the phloem of the fruit, there is less CF green fluorescence in the parenchyma cells surrounding the phloem, the SECC complex and its surrounding cells existed mainly the symplastic isolation but existed few symplastic integration in the rapid enlargement period. (3) The CF green fluorescence was confined to the phloem of the fruit, and there was no CF green fluorescence in the parenchyma cells surrounding the phloem in the coloring period and the maturation period, the SECC complex and its surrounding cells existed entirely the symplastic isolation, the CF green fluorescence in the parenchyma cells surrounding the phloem increased significantly while leading in CFDA and Digitonin with penetrating plasma membrane function. Research suggests that the photoassimilates unloading from the phloem was symplast pathway in the early bulking period fruit, the photoassimilates unloading and transport adopted mainly apoplastic pathway in the rapid enlargement period, but existed simultaneously symplast pathway, the photoassimilates unloading and transport adopted apoplastic pathway in the coloring period and the maturation period fruit.

Abstract:In order to define the adaptability to different light intensities in genus Alcantarea, mature plants of 3 giant species of Alcantarea were treated under full sun light (CK), 40% light (S₄₀) and 10% light (S₁₀) for 4 nearly months. The variation on leaf anatomy structure and the amounts of photosynthetic pigments in the leaf of different treatments were measured and detected. The results show that： (1) the features of leaf anatomic structure of 3 Alcantarea species are similar, with single layer of small epidermal thickwalled cells on both surfaces, and the epicuticular stratum is welldeveloped. A multicellular aquiferous hypodermis is formed beneath the epidermal cells, palisade parenchyma (PP) and spongy parenchyma (SP) are well differentiated in mesophyll, and the PP is arranged in arches, an aeration channel with cross sections shaped in ellipse or oblong formed under the PP and filled with SP. These air channels are connected to the substomatic chambers on the abaxial surface, which contribute to the gas exchange in the mesophyll, ensuring that there is sufficient gas for photosynthesis although the leaf base sits in water year around. (2) The effects of environmental light intensity on leaf anatomical structure of Alcantarea varied with species, A. glaziouana is more sensitive to the changes of light intensity, with significant differences on the leaf thickness, cuticle thickness, the proportion of spongy parenchyma and the ratio of palisade and spongy under different light intensity, as for A. imperialis and A. ‘Grace’, except for the cuticle thickness, the other characteristics did not change significantly. The stomatal density on the leaf of 3 Alcantarea species has almost no change under different light treatments, and the stomatal density of A. imperialis and A. ‘Grace’ was similar and significantly higher than that of A. glaziouana, indicating the difference of anatomical features among species was determined genetically, and relatively stable. (3) Light intensity had the significant effect on the photosynthetic pigments of 3 Alcantarea species, and different species responsed to the light variation differently. The value of Chla/Chlb of 3 Alcantarea species under full light (CK) and 40% light (S₄₀) ranged from 2.73 to 3.03, which was close to the characteristics of leaves grow under sunny place, while all decreased under 10% light (S₁₀), and A. glaziouana with the lowest Chla / Chlb as to 2.53, close to the value of leaves grow in shade. The results showed that the tolerance to strong light was A. imperialis ［red leaf form］>A. ‘Grace’> A. glaziouana, while to the weak light environment, the 3 species behaved the opposite. A. imperialis［red leaf form］ and A. ‘Grace’ are suitable for outdoor with bright light or in semishade; while A. glaziouana is suitable for outdoor shade, and avoiding direct sunlight in hot summer. It also suitable to the exhibition greenhouse which is featured with weak light environment.

Abstract:The material of an epilithic diatom sample (including Berkeleya fennica), collected from Lake Qinghai, was processed using 10% HCl to dissolve all solid compound containing calcium, and then adding 30% H₂O₂ to oxidize and remove the organic matter of diatom cells. As a result, the clean diatom specimens can finally be obtained. Permanent slides were prepared well by using Naphrax^ mountant. The morphological characters of B. fennica were thoroughly studied under light and scanning electron microscope. The results show: (1) under light microscope, B. fennica possesses three characters: lanceolate valve outline, acutely rounded valve apices and markedly elongated central area. (2) Under scanning electron microscope, B. fennica possesses markedly elongated areolae which are close to the central area, and their lengths are equal to the ones of 2-4 normal areolae. (3) After consulting the literature and making comparisons between similar taxa, the current paper can confirm that the unique identifying character combination of B. fennica is the combination of the acutely rounded valve apices and the markedly elongated areolae close to the central area, by which the identity of B. fennica can be confirmed. Berkeleya fennica is reported for the first time in China in this paper.

Abstract:To explore the effects of reduced light intensity on vitamin C content and enzymatic activities and sugar content in Rosa roxburghii Tratt. fruits and leaves. In this study, ‘Guinong 5’ R. roxburghii cuttings was taken as materials. The shading net was used to set three shading treatments with light intensity reduced by 20%, 40% and 60%, with natural light intensity as control. The changes of vitamin C content and related enzyme activities and sugar content in fruits and leaves of R. roxburghii under different light intensity were analyzed. The results showed that: (1) the content of vitamin C in fruits and leaves of R. roxburghii at different development stages were significantly decreased after the light intensity was weakened. The difference of vitamin C content in fruits of the control and the three treatments reached a significant level at the rapid expansion stage. (2) With the decrease of light intensity, the activities of Lgalactose1, 4lactone dehydrogenase (GalLDH), monodehydroascorbate reductase(MDHAR)and dehydroascorbate reductase(DHAR)decreased, while the activities of ascorbate oxidase(AAO)and ascorbate peroxidase(APX)increased in fruits and leaves of R. roxburghii, especially the activity of MDHAR increased rapidly and greatly in the rapid expansion stage. (3) The contents of soluble sugar, sucrose, glucose and fructose in the fruits and leaves of R. roxburghii decreased with the decrease of light intensity, while the contents of glucose increased rapidly during the rapid expansion stage. (4) The content of vitamin C in fruits was significantly positively correlated with sucrose and glucose contents in leaves at different development stages. At the rapid expansion stage, the activities of GalLDH and MDHAR in fruits were significantly positively correlated with vitamin C content in fruits, the APX activity was significantly negatively correlated with the vitamin C content in fruits, and their correlation coefficients are all at the maximum. The studied showed that light intensity effects the accumulation of vitamin C in R. roxburghii fruits by regulating the activities of key enzymes of vitamin C synthesis and related metabolism and the content of photosynthetic products in leaves; Weak light environment is not conducive to the accumulation of vitamin C and sugar in fruits and leaves of R. roxburghii, which is especially significant during the rapid fruit expansion stage; Good light was the basic condition to ensure the excellent quality of R. roxburghii fruits.

Abstract:Nonstructural carbohydrate is the main product of photosynthesis and the basis of plant synthesis. The nonstructural carbon content of leaves in different periods represents the characteristics of carbon intake and carbon demand of plants. Therefore, in this study, we took Lycium ruthenicum as the research object, and set four nitrogen and phosphorus applications (N∶P₂O₅=15∶1, based on pure nitrogen, g/plant), which were 13.5 (high fertilizer), 4.5 (medium fertilizer), 1.5 (low fertilizer), and no fertilization as control, to explore the dynamic characteristics of the daily and the growth period of nonstructural carbohydrate content in leaves, and the effect of fertilization on nonstructural carbohydrate content. The results showed that: (1) the nonstructural carbohydrate and its components in leaves showed the daily dynamic change of increasing first and then decreasing, reaching the highest value at 13:00 noon, and the ratio of soluble sugar to starch decreased first and then increased, reaching the lowest value at 13:00 noon. (2) With the change of growth period, the nonstructural carbohydrate and its components in the leaves showed the daily dynamic change of first increased and then decreased, and reached the highest value in the fruit development period (FDP), the ratio of soluble sugar to starch gradually decreased. (3) There was a significant positive correlation between N content and P content (P < 0.01), a significant negative correlation between N content and NSC and S contents (P < 0.05), and a significant negative correlation between P content and S content (P < 0.01). In conclusion, when the ratio of N to P was 15∶1 and the amount of pure N was 1.5 g-13.5 g, the results showed that fertilization could significantly improve the total nonstructural carbohydrate content, soluble sugar content, starch content and the conversion efficiency between soluble sugar and starch, and promoted the consumption of N and P contents. The effect was more significant with the increase of N and P application rate. Therefore, the adaptability of plants to adversity can be strengthened by fertilization to achieve the purpose of ecological restoration in Northwest China.

Abstract:The oat variety ‘Yanke 2’ was used as the experimental material, and potted plants were used in normal water supply (75% field water holding capacity), moderate drought stress (60% field water holding capacity) and severe drought stress (45% field water holding capacity). Spraying humic acid (HA) and the same amount of water (CK) under 3 water conditions, we determined the content of nonstructural carbohydrates (NSC) in oat leaves, related enzyme activities and grain yield. The effect of HA on the drought tolerance of oats and its mechanism were preliminarily discussed on the changes of nonstructural carbohydrate metabolism in oat leaves. The results showed that： (1) with the decrease of soil moisture content, the sucrose and starch contents in oat leaves gradually decreased significantly, and the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) decreased significantly, while the activities of acid invertase (SAI) and amylolytic enzyme (αGC) increased significantly. (2) The contents of total soluble sugar and reducing sugar in leaves showed a trend of increasing first and then decreasing, leading to a significant decrease in grain yield, and the heavier the drought stress, the greater the decrease. (3) Foliar spraying of HA can increase nonstructural carbohydrate content in oat leaves under moderate and severe drought stress to varying degrees, regulate related enzyme activities, significantly increase grain yield, and have a better effect under severe stress. Studies have found that humic acid can respond to drought stress by regulating the metabolism of oat leaf NSC, reducing leaf cell osmotic potential, effectively alleviating the damage caused by drought stress, and enhancing plant drought tolerance.

Abstract:We carried out pot experiments to explore the effects of graphene oxide (GO) added in soil with different dosages (1%, 2%, 3%, 4% and 5%) on the growth and physiological characteristics of stress resistance in ryegrass (Lolium perenne L.) roots. The results showed that: (1) the root growth was not affected by low dosages of GO (1% and 2%), but it was significantly inhibited by high dosages of GO (3%-5%). (2) No significant differences were observed in root volume and biomass between 1% GO treatment and the control. With the increase of GO dosage, root volume and biomass of ryegrass decreased. Root dry weight was the lowest under 5% GO treatment, which was decreased by 22.64% compared with the control. (3) 1% GO treatment did not affect the activities of protective enzymes and malondialdehyde (MDA) content. The activities of POD, SOD and CAT enzymes was higher than that of the control with increasing GO dosage, and MDA content also increased significantly. (4) When the dosage of GO exceeded 1%, the root activity of ryegrass significantly decreased. The lowest value was recorded under 5% GO treatment, which was 35.07% lower than that of the control. The findings suggest that low dosages of GO could not affect root growth of ryegrass, while high dosages of GO could induce oxidative stress on roots, resulting in root damage.

Abstract:Clintonia udensis belongs to the genus Clintonia of Liliaceae, is a perennial herb with two cytotypes, the diploidy (2n = 14) and tetraploidy (4n = 28). In Hualong Mountains of Shaanxi Province, the diploidy mainly distributes at 2 450 m in the south slope, while the tetraploidy mainly grows at 1900m in the north slope, which making them as an ideal material for the study of intraspecific polyploid differentiation. In this study, based on the nutritional and reproductive system of C. udensis, we would analyze the phenotypic differentiation of different cytotypes, reveal the ecological adaptation characteristics of the two cytotypes, and provide some clues for the evolution of C. udensiss polyploid. The results showed that: (1) the fruit volume of the diploidy was the most stable (CV=0.02), and the genetic diversity of the leaf length was the highest (CV=0.85) among eleven traits. Meanwhile, the fruit volume was also the most stable one in the tetraploidy (CV=0.06), while the flower quantitative had the highest diversity (CV=0.42). (2) The average of fruit volume for the tetraploidy was significantly higher than that of the diploidy, but the average of seed number was significantly lower than that of the diploidy, and the differentiation proportion of fruit and seed volume between different ploidy types was the highest (V_st=0.69). (3) On the other hand, the genetic variation of the phenotypic traits for the tetraploidy nutritional organs was lower than that of the diploidy, and the average coefficient of variation (CV=0.16) was also lower than that of the diploidy(CV=0.44). For the reproductive system, the genetic variation of the tetraploidy was higher than that of the diploidy, and the mean variation coefficient (CV=0.30) was higher than that of the diploidy (CV=0.26). (4) According to the significant, there was a differentiation occurred in phenotype traits between the diploid and tetraploid (P<0.05). However, no significant difference was found in the reproductive system between the different ploidies (P>0.05). PCA analysis also showed significant difference between the diploidy and tetraploidy. The significant phenotypic difference of the tetraploidy would be resulted from the longterm adaptation to low altitude environment.

Abstract:The differentiation of plant height is the result of longterm adaptability of plants to environment. It is helpful to understand the diversity of germplasm resources by studying the response of plant phenotype and biomass distribution to plant size. Based on the research materials of wild Bromus inermis, we studied 8 phenotypic traits and biomass of 3 species of small, medium and large plants, and investigated the effect of plant height difference on phenotype and biomass distribution by ANOVA, coefficient of variation and linear regression model. The results show: (1) with the increase of plant height, the number of tillers decreased by 46.7%, stem diameter, number of stem nodes, panicle length and spikelet length were the opposite, and the variation of tiller number among these phenotypic traits was the greatest can reach 106.32%. (2) There was no significant relationship between the biomass variation of each component and plant height. The small plants put more biomass into leaf and underground organs, medium and large plants put into panicle and stem organs. There is a linear growth relationship between aboveground and underground biomass. (3) In addition to spikelet width and root length, other phenotypic traits, panicle biomass and aboveground biomass have sizedependent effects (P＜0.05).

Abstract:Climate change leads to the evolution of the tundra in Changbai Mountain from shrub tundra to herbshrub tundra, which has an important impact on soil respiration and carbon cycle. In order to study the effect of vegetation change on soil respiration of tundra, we selected typical communities of tundra in Changbai Mountain to measure and compare the seasonal dynamics and differences of soil respiration under different herbaceous coverage. The results showed that: (1) during the growing season, the soil respiration rate varied significantly in different change stages among the three communities, and all showed singlepeak changes. The seasonal changing trend of soil respiration was not affected by the increase of herbaceous coverage. (2) The increase of herbaceous coverage significantly affected soil respiration. With the increase of herbaceous coverage, soil respiration rate gradually increased. (3) Soil respiration was different in different plant communities. Under the condition of the same herbaceous coverage, the soil respiration rate of Rhododendron aureumDeyeuxia purpurea community > R. aureumSanguisorba officinalis community> Vaccinium uliginosumCarex siderosticia community. (4) The growth effect of soil respiration in different communities was different. The growth rate of soil respiration was the fastest in the R.aureumD.purpurea community, followed by V.uliginosumC.siderosticia community, and R.aureumS.officinalis community was the slowest. At the same time, the increase of herbaceous coverage significantly altered the gap of soil respiration among the three communities.

Abstract:To further understand the ecological stoichiometric characteristics of coniferous forest ecosystem plants and soli carbon, nitrogen, phosphorus and their internal relationships, we selected Pinus tabuliformis, Picea asperata, Abies faxoniana coniferous forest in subalpine areas on the eastern edge of QinghaiTibet plateau. We analyzed the carbon, nitrogen, phosphorus stoichiometric characteristics in needle, shrub, herb leaf and soil in each coniferous forest. The results indicated that: (1) C, N contents followed herb leaf > needle leaf > shrub leaf > soil. C∶N, C∶P and N∶P were the highest in shrub leaf, followed by needle and herb leaf, and the lowest in soil. There was a significantly positive correlation between the content of N and P in coniferous forest, the content of C was negatively correlated with the contents of N and P. And C content between needle and shrub leaf, N, P content, C∶N, C∶P in leaves also showed a significantly positive correlation. There was a significantly negative correlation between needle leaf and soil P, N∶P, shrub leaf and soil P, herb leaf and soil N∶P. (2) Our results demonstrated that the contents of C, N and P in the subalpine coniferous forest ecosystem were ranked in the order of P. asperata forest > A. faxoniana forest > P. tabuliformis forest. (3) The contents of C, N and P of different components were followed the order of herb leaf > needle leaf > shrub leaf. C∶N and C∶P all showed P. tabuliformis forest > A. faxoniana forest > P. asperata forest, and C∶N and C∶P showed shrub leaf > needle leaf > herb leaf. Plant growth is limited by N, and mineralization of soil organic matter was slow. Therefore, in the process of coniferous forest protection and management, we suggested to increase the protection of undergrowth and improve soil fertility, so as to maintain the longterm productivity of forests.

Abstract:In order to reveal the survival potential and endangered mechanism of alpine Rhododendron species, we conducted the studies of population structure and dynamics on two natural populations of Rhododendron rex subsp. rex, which is a rare and endangered plant that endemic to southwest of China, based on field survey. The age structure and static life tables of R. rex subsp. rex were established, and the survival, mortality and vanish curves were plotted to character the species population structure. Meanwhile, the population dynamics were predicted by the results of a time sequence model and the quantitative dynamic index. The results indicated that: (1) the lack of the age classⅠ~Ⅱ was occurred in both Jiaozi snow Mountain (JM) and Xiaobaicaoling Mountain (XM) populations. Although the populations showed a stable type, both populations of R. rex subsp. rex were sensitive to external disturbance. (2) The population survival curves of JM and XM populations were trended to the DeeveyⅡ type. The life expectancy of R. rex subsp. rex was the highest in size class Ⅰand Ⅱ. The change trend of mortality curve is consistent with the vanish curve in each population. However, this change was different between the two natural populations of R. rex subsp. rex. (3) Timesequences prediction analysis showed a decreasing trend in the number of individuals in JM population after 2, 4 and 6 years of age class in the future. However, the XM populations showed an increasing trend after 2, 4 and 6 years. Therefore, we suggest that the protection and management of wild habitat of R. rex subsp. rex populations should be strengthen to maintain its natural regeneration.

Abstract:Plant developed safty and efficient xylem vascular system to support long distance water transport so as to provide sufficient water to photothesysis organs. Xylem water transportion play an important role in transpiration, stomental movement, carbon assimilation regulation, therefore be termed “backbone of plant physiology”. Plant hydraulics is the central hub integrating plant and ecosystem function. The present paper summarized the hydraulic mechanism of water transport and the limitation of transport system in plants, highlighted the relationship between the structure and function of xylem vascular. The formation mechanism and induce methods of xylem embolism were described. Tradeoffs between safety and efficiency of water transport system were analyzed. The molecular biology of cavitation and the importance of aquaporin in xylem refilling were discussed. Prediction model as for plant response to environment and drought induced mortality were summarized. The methodological issues were introduced, and the debates on the validity of xylem against pressure refilling and exponential xylem embolization vulnerability curve were discussed. Finally, achievements in xylem hydraulics were summarized, and research chances and prospect were also discussed.