Abstract:GRAS transcription factor is one of the most important transcription factors for plants in regulating growth and abiotic stress response. However, there have no research about GRAS regulating high temperature stress. In order to further explore the functions of SlGRAS4 gene in tomato, we used heat resistant tomato LA2093 as the test material, identified the gene structure, promoter sequence and evolutionary relationship of SlGRAS4 gene, detected the expression level of SlGRAS4 gene upon abiotic stress and hormone treatments by qRTPCR, analyzed the function of SlGRAS4 gene responding to hightemperature by VIGS. The results showed that: (1) bioinformatics analysis showed that the length of SlGRAS4 protein was 666 amino acids, with 75 737.72 Da molecular weight and 6.31 isoelectric point, the typical domain of the GRAS family was specifically detected at the Cterminal between 277-657 aa in SlGRAS4 protein; the elements related to abscisic acid and salicylic acid responding were detected in promoter region of SlGRAS4 gene; evolutionary relationship analysis showed SlGRAS4 protein has the nearest relationship with Nicotiana tabacum NTGRAS1 protein, and predicted SlGRAS4 has similar biological functions with its homologous genes. (2) The expression of SlGRAS4 gene in tomato increased to the highest and upregulated 8.86, 4.86, 55.38 and 7.63 folds compared with the control after 12 h of high temperature, low temperature, salt and drought stress treatments, respectively; as well as reached the peak value after 8 h of ABA and SA treatments, which upregulated 120.72 and 3.55 folds compared with the control, respectively, indicating that SlGRAS4 may be involved in a variety of abiotic stress responses and hormone signal transduction. (3) Under high temperature stress, SlGRAS4silencing tomato plants (VSlGRAS4) were wither than the control plants (Ve), and F_v/F_m, SOD and POD activities were significantly reduced, and contents of REL and H₂O₂ were significantly increased, indicating that silencing SlGRAS4 aggravated oxidative damage of the cell membrane, and reduced photosynthetic capacity, and weakened activity of ROS scavenging enzyme in tomato plants. (4) qRTPCR analysis showed that the expression level of HsfA1b (high temperature signal response gene), ZAT10 and ZAT12 (ROS signaling response genes), CuZnSOD, FeSOD, APX1, APX2 and CAT (ROS scavenging enzyme code genes) were also significantly downregulated in VSlGRAS4 plants. The results indicated that SlGRAS4 can enhance heat tolerance of tomato through hightemperature and ROS signal transduction. The studies showed the expression of SlGRAS4 gene was significantly induced under high temperature, low temperature, drought, salt, ABA and SA, and the heat tolerance of tomato was reduced after silencing SlGRAS4 gene, indicating tomato SlGRAS4 gene has heat resistance function, and this will lay a foundation for further analysis of heat molecular mechanism.

Abstract:Histone deacetylation modification is an important kind of epigenetic regulation in plants, which played important roles in chromosome structural modification and gene expression regulation. To explore the function of the histone deacetylase 1 gene (HDT1) in the somatic embryogenesis process of longan, based on longan genomic data, we cloned the DlHDT1 by RTPCR, and analyzed its bioinformatics, protein subcellular localization observation and the expression pattern during the somatic embryogenesis of longan (FPKM value). The expression pattern of DlHDT1 gene under PEG6000 and NaCl treatments were detected by qRTPCR. The results indicated that： (1) the length of DlHDT1 CDS was 918 bp, which encoding 305 amino acid residues. DlHDT1 protein was an unstable hydrophilic protein without signal peptide and transmembrane structure, and contained a total of 43 phosphorylation sites. The relative molecular weight was 32 585.54 Da and the isoelectric point was 4.65. Phylogenetic tree analysis showed that DlHDT1 exhibited the highest sequence similarity with Acer yangbiense (78.76%). (2) Subcellular localization result showed that DlHDT1 protein was localized in the nucleus. cisacting element analysis showed that DlHDT1 gene contained a large number of light response elements, hormones such as abscisic acid, methyl jasmonate and stress responsive elements also existed. Transcriptome data analysis showed that DlHDT1 had the highest expression in the globular embryo (GE) stage, and had the lowest expression in the embryogenic callus (EC) stage. (3) qRTPCR results showed that the expression of DlHDT1 gene was downregulated under the treatments of PEG6000 and NaCl, indicating that DlHDT1 may negative regulated by drought and salt stress in longan. To sum up, DlHDT1 is a nuclear localization gene, which may participate in the somatic embryo morphogenesis of longan and play an important role in the response of longan to abiotic stress.

Abstract:In order to reveal the function of the sterol C24 methyltransferase 2 gene (DoSMT2) in the sterol metabolism process of Dendrobium officinale, we firstly transformed the DoSMT2 gene into tobacco (Nicotiana tabacum) by Agrobacterium tumefaciens mediated method. qRTPCR was then applied to detected the DoSMT2 gene expression in transgenic tobacco leaves, and the contents of brassinosterol and sitosterol were analyzed by GCMS. The results showed that: (1) a 1 119bp openreadingframe (ORF) of DoSMT2 gene was successfully obtained, thereafter the sense plant expression vector pCXSNDoSMT2 was successfully constructed too. Four positive transgenic tobacco plants were obtained and identified by tobacco leaf disc transformation through A. tumefaciens mediated method. (2) Southern blot results showed that there was a hybridization signal band in all the four transgenic tobacco plants, while it was not found in nontransgenic tobacco plants, which indicated that the foreign gene DoSMT2 was integrated into the genome of the transgenic tobacco plants in a singlecopy mode. (3) The DoSMT2 gene expression was not detected in nontransgenic tobacco, while the expression of DoSMT2 gene could be detected in all four transgenic tobacco plants by qRTPCR, and the difference of expression level was significant. The expression level of each line was P3 > P1 > P2(P4), in turn. (4) The GCMS analysis results showed that the content of campesterol in transgenic tobacco leaves was significantly lower than that in nontransgenic tobacco leaves, while the content of sitosterol in transgenic tobacco leaves was significantly higher than that in nontransgenic tobacco leaves. This study indicated that the DoSMT2 protein had the catalytic activity in the transformation from 24methylene lophenol to 24ethylidene lophenol.

Abstract:Calmodulinlike protein (CML) is a kind of important Ca²⁺ binding protein in plants, which plays a critical role in plant growth, development, and stress response. In this study, StCML gene family members were identified in potato genome by bioinformatics methods, and their expression patterns and stress response were analyzed, which laid a theoretical foundation for further understanding the mechanism of StCML gene family members in growth and development and stress response. The results showed that: (1) a total of 80 StCML genes were identified from the Solanum tuberosum L. genome, and all of them have the EFhand domains. According to the topological structure of phylogenetic tree, they were divided into 5 subfamilies, each of which has respectively 18, 12, 14, 12, and 24 members, and most of the members have relatively conservative gene structures and motifs; (2) Through the analysis of RNASeq data, it was found that StCML genes showed tissuespecific expression in flowers, petioles, shoots, stamens, stolons and tubers, they were mainly responded to salt, heat, drought stress and GA₃. (3) qRTPCR analysis showed StCML13, StCML21 and StCML53 were upregulated under cold stress, StCML11, StCML21 and StCML39 were upregulated under heat stress, StCML21 and StCML60 were upregulated under salt stress, StCML53 was upregulated under Ralstonia solanacearum infection, indicating that StCML family is able to response to multiple stresses. These results could serve as the foundation for indepth research on the mechanism of the StCML gene family regulating plant stress tolerance.

Abstract:TCP plays an important role in abiotic stress such as high salt and drought. The putative HrTCP were explored and identified from seabuckthorn transcriptome data and analyze their structure and bioinformation. The key genes involved in abiotic stress were obtained by homologous sequence alignment and qRTPCR., we further analyzed the gene structure and function of its corresponding transcription factors of seabuckthorn under abiotic stress. The results showed that: (1) 11 putative seabuckthorn HrTCPs were confirmed and named HrTCP2/4/7/8/11/13/15/17/18/19/20. The number of amino acids encoded by 11 HrTCPs was 218-590, the relative molecular weight of the proteins was 23.44-61.78 kD, the isoelectric point range of the proteins was 6.09-9.72, and the subcellular localization of the proteins was in the nucleus except for the subcellular localization of HrTCP13/17/18. (2) qRTPCR showed that the genes of HrTCP can response to abiotic stress, but the response degree of different members is different under stress treatments. The expression levels of HrTCP4/7/19/20 in 15% PEG6000 and 200 mmol/L NaCl were significantly upregulated and among which the expression level of HrTCP20 was the most significantly higher compared with the control, which was 24 and 23 times of the control. (3) After the ABA (0.1 mmol/L) and MeJA(0.1 mmol/L) treatments, HrTCP7/19/20 genes also showed an upregulated expression trend, especially the expression level of HrTCP19 was most significantly increased under the ABA treatment, which was 16 times of the control. The expression level of HrTCP20 was most significantly upregulated in response to MeJA treatment, which was 5 times of the control. Our present study indicated that the members of the HrTCP transcription factor family can be expressed by drought, salt, and hormones to response drought stress of seabuckthorn.

Abstract:In this paper, the establishment of seed regeneration system of Dioscorea nipponica from medicinal plant was studied, and the differences in anatomical structure between leaf, entangled stems and rhizome of tissue culture seedlings and solid seedling were investigated. The results showed that: (1) 15 min and 18 min 2% NaClO were suitable for disinfection. The optimal medium for callus induction was MS+1.0 mg·L_-16BA+2.0 mg·L_-12,4D, and its induction rate was up to 83.33%. MS+2.0 mg·L_-16BA+0.2 mg·L_-1NAA, induction rate was 90.00% in the best medium for bud induction. The best culture medium hormones ratio was 1/2MS+ 0.5 mg·L_-1NAA, generating 13.2 roots, its rooting rate was up to 86.70%. The growth of tissue culture seedlings is vigorous, the leaves are dark green, and the stems are thick and long. (2) There were significant differences in the structure of leaf and entangled stems between tissue culture seedlings and solid seedlings. The leaves of tissue culture seedlings were thin and the main vascular bundles were small and P/S low. The diameter, area and number of vascular bundles of the entangled stems were smaller than those of the solid seedlings; the catheter/vascular bundle was 0.06, which was 1/2 of the seedlings. Culture seedling proportion of cortex is large, but the differentiation between thickangle tissue and thickwalled tissue is not complete, and there are only two ductile vascular bundles with extremely dispersed arrangement. The changes in the shape and structure of tissue culture seedlings were mainly adapted to the culture environment of high humidity, low light, constant temperature and closed culture bottle.

Abstract:To reveal the role of IAA and its signaling genes in the retrieved green process of pear leaves, we took chlorotic and normal plants of ‘Dangshansuli’ (Pyrus bretschneideri Rehd.) as test material. 0.2% FeSO₄ solution was sprayed on the chlorotic leaves and distilled water was used for both normal and chlorotic leaves as control during the growing season. Then we observed the leaves phenotypic changes on the 3rd, 6th, 9th, and 12th day after FeSO₄ application, respectively. We sampled normal, chlorotic leaves in control (C_N and C_C) and retrieved green leaves on the 3rd, 6th, 9th, 12th day after FeSO₄ application, to determine the Fe²⁺ content, endogenous IAA content and IAA signaling genes expression. Furthermore, relevance analysis was performed among those indexes. The results were shown as follows: (1) application FeSO₄ could convert chlorotic leaves to green, green spots appeared on the chlorotic leaves surface on 3rd day, and green plaque appeared on the both 6th and 9th day after spraying FeSO₄. The whole leaves presented green on the 12th day. (2) The endogenous IAA content in C_N was significantly higher than that in C_C, and after spraying FeSO₄, it obviously increased in retrieved green leaves compared with both C_N and C_C in all periods. (3) AUX1.1/1.3, GH3.1/3.2/3.5, SAUR1/2/3/4 and AUX/IAA1/2/3/7 expression in C_C were prominently higher than that in C_N, and most of them were notably inhibited in all period after spraying FeSO₄. In contrast, TIR1.1, GH3.3/3.4 and AUX/IAA4/5/6 expression in C_c were distinctively lower than that in C_N, and they were all apparently promoted by FeSO₄ application. (4) ARF3/4/5/6/7/8/9/10/15/17/18/19/20/21/22/23 in C_c were clearly decreased compared with C_N, and FeSO₄ application significantly promoted the expression of ARF3/5/6/9/19/20/21/22/23; on the contrary, ARF1/2/11/12/13/14 were remarkably increased in C_c compared to C_N, and FeSO₄ application remarkably suppressed the expression of ARF1/2. (5) The relevance analysis showed that remarkably increased Fe²⁺ content in retrieved green leaves was positively correlated to the upregulation of AUX/IAA5 and AUX/IAA6, while IAA content was positively correlated with the increased GH3.3 expression and negatively correlated with the decreased SAUR1/2 expression. The network diagram of the association between the two above is complex, which can be simplified into Fe²⁺→AUX/IAA5, AUX/IAA6→(ARF14)→ARF5SAUR1, AUX/IAA1→SAUR2, TIR1.1, GH3.3→IAA. The study suggested that IAA and its signaling pathway might play a crucial role in the retrieved green process induced by spraying FeSO₄ on irondeficiency chlorotic leaves of ‘Dangshansuli’ pear.

Abstract:In order to clarify the formation of different types of bicolor lily cultivars, we used three bicolor Asiatic hybrid lilies as the materials to analyze flower color phenotype, pigment composition and content in the upper and basal tepals. The results showed that: (1) a single anthocyanin cyanidin 3Oβrutinoside was detected in the basal tepals, and the concentration of ‘Black Eye’ was the highest, while no anthocyanins were found in the upper tepals. (2) A total of 15 carotenoids were identified in the tepals of all samples, and the content of carotenoid differed significantly between the upper and basal tepals in different cultivars. The characteristic components in the tepals ‘Pieton’ were antheraxanthin, violaxanthin and βcarotene, and the characteristic components in the tepals of ‘Twosome’ was capsanthin, while no characteristic carotenoid composition were detected in the ‘Black Eye’. (3) Principal component analysis found that the carotenoid composition and content were obviously different in three lily cultivars. However, the composition in the upper and basal tepals of the same cultivar was similar and the contents were significantly different. (4) Regression analysis found that cyanidin3Oβrutinoside, capsanthin, phytoene, zeaxanthin and βcarotene were the main pigments that may affect lily flower color. The research results indicated that the accumulation of anthocyanin and carotenoids in different regions of the tepals was the major reason for the formation of bicolor lilies.

Abstract:To explore the effects of different nitrogen and phosphorus levels in water on the growth of diatoms, evaluate the indicative effect of diatoms on nutrient pollution, we chosed Navicula gregaria in this research. The response of main physiological indexes and cell morphological changes were determined and analyzed under different concentrations of nitrate nitrogen (NO^-₃N, 0.5-500 mg·L_-1), inorganic phosphorus (H₂PO^-₄P, 0.05-25 mg·L_-1) and N/P ratio (5∶1-100∶1). The results showed: (1) when the concentration of NO^-₃N, H₂PO^-₄P and the ratio of nitrogen and phosphorus were lower than 50 mg·L_-1, 1 mg·L_-1 and 50∶1, respectively, the cell density, chlorophyll a content and protein content increased gradually in the 13 days, while the MDA content, SOD and CAT enzyme activities in alga cells presented a continuous decrease trend. When the concentration of NO^-₃N was 50 mg·L_-1, the concentration of H₂PO^-₄P was 1 mg·L_-1, and the N/P ratio was 50∶1, the highest cell density, chlorophyll a content, protein content and specific growth rate were showed. Under high concentration of NO^-₃N (> 250 mg·L_-1), H₂PO^-₄P (> 5 mg·L_-1) and high N/P ratio (> 50∶1), cell density, chlorophyl a content and protein content of most of them decreased significantly, MDA content, SOD and CAT enzyme activities showed an obvious upward trend compared with other treatment groups. (2) It can be observed that at the 13th day, when the concentrations of NO^-₃N and H₂PO^-₄P are 500 mg·L_-1 and 25 mg·L_-1, respectively, the valve of Navicula gregaria showed obviously distortion, 8.6% and 7.2% of the cells were deformed, irregular surface, severe deformation of cells, widening of the central area of cells, micro tip of cell end and so on. The results indicated that the growth and physiological activity of algae could be promoted by properly increasing the concentration of nitrogen and phosphorus. However, when the ratio of nitrogen, phosphorus and nitrogen to phosphorus in the environment is high, the growth of algae will be affected, then eventually affect the structure of algae community structures in the water.

Abstract:We analyzed the dependencies of sprouting ability and the nonstructural carbohydrate (NSC) content on the stubble heights to investigate the nutrient accumulation and allocation mechanisms of sprouts in Chinese sea buckthorn (Hippophae rhamnoides ssp. sinensis). The experiment was conducted on a 15yearold Chinese sea buckthorn plantation in Dingbian County, Shaanxi Province. No stumping (as the control) and stubble height 0, 10, 20 cm were set to the process. The results showed that: (1) with the increase in stubble height, the sprouting number from stumps increased, the sprout survival and growth ability went up first and then went down, and NSC content of each component went up first then leveled off or went down. (2) The NSC contents in each part of clonal ramets for all stubble treatments were significantly higher than those of the control. (3) The NSC reserves went up first and then went down, the leaf and root NSC allocation ratios were the highest and significantly higher than the control when the stump of 10 cm. (4) The sprout growth was significantly positively correlated with the contents and reserves of NSC, while the sprout number, sprout survival number were potentially positively correlated with the contents and reserves of NSC. In conclusion, the contents and reserves of NSC and allocation ratio in leaves and roots could be increased by the appropriate height of stubble, promoting the growth and survival of stumping. The stump of 10 cm showed the best in the sprouting growth and survival ability.

Abstract:Taking the garlicwatermelon allelopathy associated cultivation model as the research object, we set up three treatments of watermelon monocropping, garlic seedling stage accompanying watermelon, garlic full growth stage accompanying watermelon, and investigated the incidence of watermelon fusarium wilt, watermelon leaf antioxidant enzyme activities and osmotic adjustment substance contents, as well as rhizosphere soil enzyme activity and microbial quantity, to explore the influence of garlic accompanying on the enzymatic antioxidant system of watermelon and soil characteristics. The results showed that: (1) in the garlicassociated cultivation system, the incidence of watermelon fusarium wilt was significantly lower than that of the monoculture control, and the associated treatment effect during the whole growth period was better. (2) The garlicassociated cultivation of watermelon leaf antioxidant enzymes (superoxide dismutase, superoxide dismutase, etc.) activities of peroxidase and catalase were significantly increased compared with the single control, and the increase in the associated treatments during the whole growth period was greater. (3) The soluble sugar and soluble protein contents in leaves of the garlicassociated cultivated watermelon were significantly increased than the single control, while its proline content was significantly reduced, and the accompanying treatments changed more throughout the growth period. (4) The number of fungi and Fusarium oxysporum in the rhizosphere soil of the garlicassociated watermelon was significantly reduced compared to the single control, while the number of bacteria and actinomycetes significantly increased. At the same time, the activities of polyphenol oxidase, peroxidase and urease in the rhizosphere soil of watermelon increased compared with the control, while the activity of invertase decreased significantly. It can be seen that garlicassociated cultivation significantly inhibited the incidence of watermelon fusarium wilt, enhanced plant leaf antioxidant enzyme activities, increased plant leaf osmotic adjustment substance contents, and effectively improved rhizosphere soil colony balance and soil enzyme activities, thereby increasing watermelon resistance and rhizosphere soil quality, effectively breaking the watermelon continuous cropping barriers.

Abstract:To explore the rhizospheric AMF community structure and diversity of three licorice varieties, as well as their relationship with the host plant, soil depth, physical and chemical properties, we collected the soil from a depth of 0-20 cm, 20-40 cm, 40-60 cm from licorice plants root rhizosphere of Xinjiang region, and employed the Illumina Miseq highthroughput sequencing platform to investigate the structure and diversity of these AM fungal communities, combined with the soil physical and chemical properties. (1) In this study, a total of 1 phyla, 1 class, 5 orders, 5 families, 5 genera, 34 species of AM fungi were isolated, Glomeromycota emerged as the dominant phyla, Glomus and Paraglomus emerged as the dominant genera as per the bioinformatics analysis. (2) Paraglomus is positively correlated, and Glomus is also positively correlated, while Paraglomus is general negatively correlated with Glomus. (3) The PCOA analysis showed that the AM fugal communities of the three licorice were completely separated, the same licorice partially overlapped in different soil depths. The genus Glomus was found to be positively correlated to total phosphorus (P<0.01), and negatively correlated to total potassium (P<0.001) and Organic of soil content (P<0.01). The genus Paraglomus was found to be negatively correlated to the total phosphorus of soil (P<0.001), and significantly positively correlated to total potassium (P<0.001), soil total salt (P<0.01), and soil organic content (P<0.01). The differences among the three species of licorice were obvious. The two dominant genera were in mutualism within the genus, but in competition among the genera. soil organic content had a certain influence on the two dominant genera. The tolerance of Paraglomus to salt is stronger and mostly found in the soil of Glycyrrhiza inflata Bat., G. inflata has strong salttolerant ability may be related to it.

Abstract:The SSR loci which exist in 42 362 Unigenes in Elsholtzia densa transcriptome were detected by MISA software, additionally, the structure and distribution characteristics were analysed. The results indicated that: (1) a total of 17 564 SSR repeating sequences have been searched, which were distributed on 11 903 Unigenes, and the frequency of occurrence of SSR loci was 28.10% with an average of one SSR locus per 3 200 bp. (2) The dominant repeat motifs in Elsholtzia densa transcriptome were mononucleotide, dinucleotide and trinucleotide, accounting for 97.27% of the total SSR loci, and among the three dominant motif types, the number of motif type formed by mononucleotide was the largest with a total of 169 motif types (51.22%), the (A/T)n in mononucleotide repeats and (AG/CT)n in dinucleotide repeats, were dominating motifs, accounting for 50.60% and 12.17%, respectively. (3) The mononucleotide motif was the type which repeated the most (49), the repetition times were between 10 and 66, and the difference of the SSR number was widely showed in the same motif with different repetition, the number of SSR was declined as the increase of repetition times. (4) The length of SSR was concentrate on a range from 12 to 30 bp which contained a total of 8 190 SSR loci, accounting for 95.60% of the total SSR in dinucletide to six nucleotide motifs, and the number of highly polymorphic SSR sequences was 1 589 (≥20 bp) which accounting for 18.54% of the total SSR. The SSR sequences showed higher potential polymorphism and greater value for development, based on the results of multiple studies, such as occurrence frequency, distribution density, motif repetition and length variation. This study laid a theoretical foundation for the development of SSR primers in a followup studies for Elsholtzia densa.

Abstract:Shrub encroachment is widespread in the grasslands of northern China. Shrub encroachment changes the plant community structure, plant diversity and productivity, which directly influence the grassland conservation and its sustainable utilization. This study elucidated the differences of plant community structure and aboveground biomass between shrub and grass patches with different slopes which formed after shrub encroachment on the Loess Plateau. We observed species composition, species diversity and aboveground biomass in these patches. The result showed that: (1) there are significant differences in plant community structure (P = 0.001) and aboveground biomass (P < 0.001) in shrub patches and grass patches. But there is no significant effect in different slopes (P > 0.1). (2) In shrub encroched grassland, we found 29 species, of which 27 species were found in grass patches and 18 species in shrub patches. Shrub encroachment significantly altered species composition. The dominant species Stipa bungeana was replaced by Caragana brachypoda in shrub patches. The species richness was lower than that of grass patches, but the community evenness was increased. (3) The aboveground biomass of shrub patches was higher 251.2 g·m^-2 than that of grass patches. In the shrub patches, the aboveground biomass of shrubs and semishrubs were increased by 452.1 g·m^-2, perennial grasses decreased by 176.5 g·m^-2, and other functional groups decreased by 24.4 g·m^-2. (4) The loss of species has less negative impact on the aboveground biomass. However, the newly emerging species and dominant species promoted the aboveground biomass. Although shrub encroachment have improved the aboveground biomass, its negative effect of species richness and shift in dominant species may change the maintaining mechanism of palnt diversity and community stability.

Abstract:Based on the theory of tree ring and climatology, Populus euphratica along the lower reaches of Yurungkash River and Cele River in Hotan area of Xinjiang was taken as the research object. Based on the corresponding meteorological factors in the watershed, dust weather days, the runoff of Cele River, the response characteristics of P. euphratica in two basins to meteorological factors were analyzed to determine the characteristics of P. euphratica in the growth process of the arid desert area. The climate limiting factors provide theoretical basis for promoting the ecological restoration of P. euphratica and sanddustweather prevention. The results showed that: (1) during 1976-2018, the meteorological conditions of these two river basins were basically the same. The average annual temperature showed an obvious upward trend, the average annual precipitation showed a fluctuating upward trend, the relative humidity of the atmosphere showed a downward trend, the average annual sandstorm, blowing sand, and floating dust days all show a significant downward trend; the P. euphratica annual ring index in the Yurungkash River Basin showed a significant increase first and then the overall trend of gentle changes, while the P. euphratica annual ring index in the Cele River Basin has shown a significant upward trend since 1985. (2) The response of tree ring index of P. euphratica in the Cele River Basin to annual meteorological factors was significantly higher than that in the Yurungkash River Basin, and tree ring index of the Cele River Basin had a significant positive correlation with annual temperature (P<0.01). However, the ring index of P. euphratica has no significant effect on annual precipitation and relative index of atmosphere. (3) There was a significant negative correlation between ring index of P. euphratica and relative humidity in February in the Yurungkash River Basin (P<0.05); there was a significant positive correlation between ring index of P. euphratica and temperature in March, April, September and October in the Cele River Basin, and there was a significant negative correlation between ring index of P. euphratica and relative humidity in June (P<0.05), and there was a significant negative correlation between ring index of P. euphratica and runoff in February and April. (4) The annual ring index of P. euphratica in the Yurungkash River Basin has a significant negative correlation with the days of dust storms and blowing sand in autumn and winter; except January and February, and the annual ring index of P. euphratica in the Cele River Basin has a significant negative correlation with monthly sand dust weather days. The study showed that two basins have sparse precipitation and large evaporation. The water source for the growth of P. euphratica mainly depends on the supply of groundwater and surface runoff. The annual ring index of P. euphratica in the Cele River Basin is obviously affected by temperature, runoff and reservoir construction.

Abstract:Tree size is a fundamental attribute of forest stand, reflecting the role and status of individuals in the process of forest ecosystem. We established three permanently fixed plots (A, B and C) in a mixed forest of pineoak in the Nanpan River basin, southwestern China in 2016-2018. We analyzed the spatial structures of snags of different tree size using pair correlation function g(r), mark correlation function k_mm(r), mark variogram function γ(r), and distance distribution function k^th neighbor D^k(r), with the purpose to disclose their relationships at stand level. Our results showed that: (1) distribution pattern tended to be clumped at small scale (r = 0-5 m) when the minimum measured diameter (mmd) of snags was small. Random distribution pattern, however, dominated the majority of scales (r = 0-20 m) with the increasing of minimum measured diameter (mmd = 5-8 cm). (2) Tree size approximated aggregation at small scale (r = 0-1 m) when the minimum measured diameter was equal to 1-2 cm. Otherwise, it maintained a random pattern. (3) Tree species showed a clump pattern when the minimum measured diameter was smaller than 4 cm. On the contrary, it was in or became random at each scale. (4) The abundance of neighbors decreased and the distances between any pair increased within r = 0-10 m with the increasing of the minimum measured diameter from 1 cm to 8 cm. These results suggest that the minimum measured diameter of snags is closely related to distribution pattern, tree mark and distance, implying the smallsized snags of conspecific have a clump pattern while the largesized ones are likely to be distributed randomly. A uniform minimum measured diameter of snags should be used when analyzing spatial structure.

Abstract:Taking Wulat desert as the research area, we investigated and analyzed the natural vegetation and the soil characteristics with the sampling method. The results show that: (1) there are 137 species of plants in the study area, belonging to 25 families and 80 genera. Herbaceous plants are the main life forms, accounting for 67.88% of the total plant species. Xerophytes are the main water ecological types, accounting for 76.64% of the total. (2) According to the vegetation of China, the vegetation types of Wulat desert can be divided into 3 vegetation subtypes, 5 formation groups and 14 formations. The dominant formation is Salsola paserina desert, and the number of its clusters accounts for 16.35% of the total desert clusters. (3) The species composition of vegetation is relatively single, ranging from 5 to 25 species. (4) The evenness index was negatively correlated with soil bulk density, water content and porosity, while the richness index and diversity index were negatively correlated with soil bulk density, total nitrogen, total phosphorus and organic matter.

Abstract:Shuijiang Nature Reserve is located in Yushan Mountains in the middle of Jiangxi Province, is close to the boundary between the north and south of the midsubtropical zone of China, and is rich in byophytes. In this study, more than 700 bryophyte specimens collected from the comprehensive scientific investigation of Shuijiang Nature Reserve in 2019 (used the methods of line transect and quadrat) were identified and statistically analyzed, with related literature consulted to analyze the floristic geographical characteristics of bryophyte groups in the study area, and compared with the adjacent 12 nature reserves. The results show that: (1) a total of 197 bryophytes belonging to 57 families and 102 genera were collected and identified during the investigation. (2) There are 10 species of bryophyte floristic components in Shuijiang Nature Reserve, the main constituents are East Asian, Tropical Asia and North Temperate, accounting for 35.91%, 19.89% and 17.68% of the total species, respectively, and the endemic distribution in China accounts for 12.71%. (3) Compared with 12 nature reserve in South China, the similarity coefficient between Shuijiang and Taohonglin is the highest, reaching 0.44; Cluster analysis and principal component analysis based on the genealogy of floristic components show that Shuijiang is closely related to Northwest Hunan, Tongbo Mountains and Leigong Mountains. (4) The distribution of most species of mosses endemic to China in the Shuijiang reserve conforms to the theory of origin and spread from the Himalayas and adjacent areas; whereas other species are distributed and spread in the vicinity, which is related to the preservation of numerous plant groups in the mountains of eastern China as glacial refugia.

Abstract:One species of Pertusaria, Pertusaria australis Vian and one species of Toninia, Toninia arctica Timdal are reported from China for the first time. The detailed description of their morphology, anatomy and chemistry is provided in this paper. The specimens examined are deposited in the Lichen Section of the Botanical Herbarium, Arid land Lichen Research Center of Western China, Xinjiang University, Urumqi, China (XJUNALH).

Abstract:The genus Deinostema T. Yamaz. and the speices D. violacea (Maxim.) T. Yamaz. were reported for the first time as a new record from Jiangxi Province, China. The field habitat and morphological characteristics of the new record species were provided and described. The voucher specimens were deposited in the Herbarium of the College of Forestry, Jiangxi Agricultural University (JXAU). At the same time, some morphological characteristics of D. violacea in The morphological Description of Flora Reipublicae Popularis Sinicae and Flora of China have not described was supplemented： Annual herb, glabrous or glandular hairs on pedicel, the back of calyx and corolla tube. single flower axillary, without pedicel or pedicel, pedicel can be as long as 20 mm.