Abstract:Heat shock transcription factor (Hsf) exists widely in eukaryotes and responds to various abiotic stresses by regulating the expression of downstream transcription factors, functional enzymes and molecular chaperones. In this study, the seedlings of wheat (Triticum aestivum)‘Cang 6005’ was used as material. The target gene ^TaHsfA25 was isolated from young leaves treated by heat shock at 37 ℃ using homologous cloning method, the subcellular location of the gene was analyzed, and the wild type Arabidopsis thaliana plants were transformed by agrobacterium tumefaciens mediated dipflower method. The positive seedlings were screened for basal and acquired thermotolerance analysis, and the expression of HSR gene of transgenic Arabidopsis under heat stress was analyzed for exploring the biological function of ^TaHsfA25. The results show that: (1) the wheat heat shock transcription factor ^TaHsfA25 was successfully obtained, which encoded 405 amino acids with a molecular weight of 44.9 kDa. Sequence alignment showed that TaHsfA25 protein of wheat had the highest similarity with HvHsfA2b protein of barley, which reached 88.07%. (2) The observation results of laser confocal microscope showed that TaHsfA25 was located in the nucleus. (3) qRTPCR analysis showed that ^TaHsfA25 was highly expressed in mature roots, stamens, pistils, sepals, mature and immature embryos of wheat, and under heat stress, ^TaHsfA25 showed different upregulated expression trends in wheat leaves and roots. (4) Phenotypic observation showed that transgenic Arabidopsis with ^TaHsfA25 could improve the basal and acquired thermotolerance of seedlings under heat stress when compared with wildtype, while restored the thermotolerance phenotype of the deletion mutant AtHsfa2. The chlorophyll content of different lines after heat stress was consistent with the phenotypes. (5) HSR gene expression analysis showed that overexpression of ^TaHsfA25 in Arabidopsis upregulated HSR gene expression levels to varying degrees, suggesting that ^TaHsfA25 may enhance thermotolerance by regulating the expression of multiple heat stress related genes in Arabidopsis.

Abstract:To understand the biological function and expression patterns of the longan WOX (DlWOX) family, we identified the members of DlWOX family, analyzed bioinformatics based on the longan genomewide database. With quantitative realtime PCR (qRTPCR) technology we detected and verified their expression patterns in the three early stages of somatic embryogenesis in longan and under different hormone treatments. The results showed that: (1) 13 longan DlWOX family members were screened, all of which are unstable proteins. The subcellular localization prediction results showed that DlWOX family members are localized on the nucleus and cytoskeleton. Phylogenetic tree analysis found that the DlWOX family is divided into ancient branches, middle branches and WUS (The WUSCHEL gene is the first gene discovered in the WOX family) branches. (2) Gene structure analysis revealed that DlWOX family members contained 0-19 number of introns, and most of their encoded proteins contained motif1 and motif2, and some members contain specific motifs. The cisacting elements of the DlWOX promoter contained a large number of light and hormone response elements. (3) Analysis of the expression patterns of DlWOX in different tissues of longan and early somatic embryogenesis revealed that some members of this family are highly expressed in the leaves, and DlWOX14.1, DlWOX14.2 and DlWOX9A were highly expressed in the embryogenic callus (EC) stage. QRTPCR analysis of DlWOX under different hormone treatments of longan EC showed that most of the DlWOX family members responded to the methyl jasmonate (MeJA) and gibberellin (GA) hormones. Except for DlWOX6, the remaining members were upregulated under the GA and MeJA treatments. Among them, the expression of DlWOX9A was significantly upregulated under the treatment of GA and MeJA. The study found that the expression levels of the longan DlWOX9A based on the transcriptome sequencing results and the qRTPCR results were different and the trends were not exactly the same. It was speculated that the WOX family plays an important role during the early somatic embryogenesis of longan, especially in the GE stage. The DlWOX genes were highly conserved during evolution. Some members of the DlWOX family may play a role during the somatic embryogenesis of longan by responding to GA and MeJA hormones.

Abstract:In order to study the relationship between myelocytosis protein (MYC2) gene and insect resistance of Brassica napus, we cloned the cDNA sequence of BnMYC2 gene from B. napus restorer line R18, and analyzed the gene expression and insect resistance of transformation model plant Arabidopsis thaliana. Bioinformatics analysis showed that BnMYC2 gene gDNA lack of intron structure. The cDNA complete open reading frame (ORF) was 1 833 bp, encoding 610 amino acids. The putative gene was located on the C6 chromosome of B. napus and had the conserved domain HLH of bHLH transcription factor. The results of gene homology analysis showed that BnMYC2 had the closest genetic relationship with Arabidopsis, cabbage and radish, and the similarity of amino acids was more than 98%. Tissue specific expression analysis showed that BnMYC2 was expressed in all tested tissues including roots, stems, leaves, flowers, pods 27 days after pollination and pods 35 days after pollination, and the expression level was the highest in pods 27 days after pollination. The results of insect resistance experiment showed that the expression level of insect resistance gene VSP2 in overexpressing BnMYC2 Arabidopsis was significantly higher than that in the control. It is speculated that BnMYC2 gene in B. napus may participate in the response to insect stress as an important regulator. After 6 hours of MeJA induction, the expression of VSP2 gene in different genotypes of Arabidopsis was significantly higher than that before induction, indicating that BnMYC2 positively regulates the expression of VSP2 gene. It is speculated that BnMYC2 can make plants respond to insect stress by regulating the expression of multiple marker genes including VSP2.

Abstract:In this study, the gene encoding bHLH transcription factor, named CsbHLH137 (GenBank accession OL332046), was cloned from Camellia sinensis cv. ‘Mengshan 9’ by PCR based on the genome data of tea plant. Sequence analysis showed that the open reading frame length of CsbHLH137 was 1 023 bp, encoding 340 amino acids. Analysis of protein sequence characteristics showed that the CsbHLH137 protein contained HLH binding domain with a molecular weight of approximately 38.59 kD and the theoretical isoelectric point of 5.59. The bHLH protein involved in response and interaction to light through the constituent domains of the circadian clock. CsbHLH137 transcription factor was a hydrophilic protein, including four unordered regions and 20 phosphorylation sites, and mainly composed of αhelix and random coil. The analysis of stomatal aperture and photosynthetic parameters of tea leaves at different time points showed that compared with the dark treatment, the regulation of stomatal aperture was remarkable for the light treatment, and the photosynthetic parameters G_s, C_i, and T_r fluctuated greatly during the day and maintained a relatively stable state at night. The expression profiles of CsbHLH137 in ‘Mengshan 9’ under the regulation of the circadian clock were detected by RTqPCR. The results showed high and peak expression of the CsbHLH137 gene during the day and maintenance of low expression level at night. It was predicted that the CsbHLH137 was the DELLAresponsive gene and played a role on photomorphogenesis.

Abstract:Based on the transcriptome database of Dendrobium huoshanense, we cloned GDP mannose 4,6dehydratase gene (DhGMDS) and the promoter sequence by Genome Walking technique. The tissue expression pattern and expression under low temperature treatment were detected by realtime quantitative PCR, so as to provide a theoretical basis for further analyzing the cold resistance mechanism and genetic improvement of D. huoshanense. Results showed that: (1) DhGMDS gene (GenBank accession number MW855573) was successfully cloned, and its cDNA sequence of the DhGMDS gene was 1 134 bp, and the gDNA sequence was 1 523 bp, without introns. (2) Sequence similarity showed that the identity of DhGMDS protein and GMDS protein of D. catenatum was 99.03%; Phylogenetic tree analysis showed that DhGMDS gene of D. huoshanense and GMDS gene of D. catenatum were in the same evolutionary node, and they had the relatively close genetic relationship. (3) The promoter sequence analysis showed that the upstream promoter region of DhGMDS gene contained light response, low temperature, drought and ABA response elements, MYB transcription factor recognition and binding sites, etc. (4) qRTPCR analysis showed that the expression level of DhGMDS gene was the highest in flowers, followed by stems and leaves, and the lowest in roots. After 72 h of low temperature treatment at 4 ℃, DhGMDS gene was upregulated by low temperature stress, and the relative expression was the highest at 24 h, indicating that the DhGMDS gene was involved in the process of plant stress response. Studies have speculated that the induction of DhGMDS gene expression by low temperature may depend on the regulation of the upstream MYB transcription factor.

Abstract:The Pht1 family of phosphate transporters mediate the uptake and remobilization of phosphorus (P) in plants. To investigate the structure and expression pattern of the Pht1 (GuPht1) gene family in Glycyrrhiza uralensis, this study analyzed the GuPht1 gene family by using bioinformatic approaches. The spatial and temporal expression of GuPht1 under abiotic stress was analyzed by qRTPCR and transcriptome data. And four genes were cloned by reverse transcription PCR. The results showed that: (1) there were a total of 8 Pht1 genes (named GuPht1;1—GuPht1;8) in G. uralensis, all of which located on the cell membrane and had 12 transmembrane structures, belonging to the MFS superfamily. The length of amino acid sequence ranged from 521 to 570 aa, and contained a conserved Pht1 characteristic sequence (GGDYPLSATIMSE). (2) In phylogenetic analysis, the members of the GuPht1 gene family were closely related to those of legumes. There were some elements, such as Wbox, Gbox, PHOlike and P1BS in the promoter regions with functions in P starvation. The GuPht1 were evenly distributed on the scaffold, and GuPht1 proteins were monomeric proteins. (3) Transcriptome analysis showed that the GuPht1 played a certain role in response to drought and salt stresses, and had tissuespecific expression pattern. GuPht1;1/1;6/1;8 were significantly upregulated in roots, and GuPht1;5/1;6 were significantly upregulated in leaves. Low P treatment significantly increased the relative expression of GuPht1 in roots and leaves, and more members were upregulated in roots. GuPht1;5 was significantly upregulated in roots and leaves under drought, salt and hormone treatments. (4) GuPht1;1/1;2/1;4/1;5 genes were cloned and their lengths were 1 562 bp, 1 618 bp, 1 625 bp and 1 616 bp, encoding 522, 538, 540 and 537 amino acids, respectively. This study provided reference for further study on the function of Pht1 family and the response mechanism of G. uralensis to nutrient stress.

Abstract:In this paper, five parts of the pseudobulb of P. formosana in the dormant period were used as test materials. The base of pseudobulb, the middle part of pseudobulb, the lateral part of pseudobulb, the junction between pseudobulb and leaf bud, and the junction between pseudobulb and flower bud of pseudobulb were observed and analyzed by means of paraffin section and transmission electron microscopy. The results showed that: (1) vacuoles and vacuolated cells of different degrees were observed in 5 parts of pseudobulb of P. formosa. The epidermal cells were covered with thick waxy layer. (2) There were some chloroplasts in the base, middle and lateral cells of P. formaosa pseudobulbs, and a few mitochondria were distributed around them. (3) Starch grains and powder were found in parenchyma cells of pseudobulbs, and the powder was accompanied by accumulation of starch grains. (4) There were a lot of plasmodesmata between the parenchyma cell wall at the base, middle and lateral of pseudobulb and the junction with flower bud. Plasmodesmata also existed between the sieve tubuleaccessory cell complex and the parenchyma cells, and there were intercellular spaces of different shapes between the cells. The results showed that pseudobulbs of P. formosana played their functions as water storage organs, photosynthetic sites and carbohydrate storage organs, and at the same time, material exchange and transportation were mainly through the symplast pathway during the dormancy period.

Abstract:Using processed tomato KT7 as material, under hydroponic conditions, we investigated the effects of exogenous salicylic acid (SA, 0.15 mmol/L) and hydrogen sulfide (H₂S) donor sodium hydride (NaHS, 50 mmol/L) on osmotic regulation, reactive oxygen metabolism and rapid chlorophyll fluorescence of tomato seedlings under 150 mmol/L NaCl stress, to explore the synergistic effect of H₂S and SA signal molecules and the physiological mechanism of alleviating salt stress in processed tomato seedlings in practical production. The results showed that: (1) both the treatments and their combination treatments could effectively alleviate the NaCl stress injury of processed tomato seedlings. (2) Compared with salt stress treatment, exogenous SA and H₂S treatments increased chlorophyll content, leaf relative water content and proline content to varying degrees, while decreased malondialdehyde (MDA) content, electrolyte permeability and H₂O₂ content to varying degrees. (3) The MDA content, electrolyte permeability and H₂O₂ production rate of processing tomato seedlings decreased to the minimum under the combined treatment of exogenous 0.15 mmol/L SA and 50 mmol/L H₂S, while the proline content of seedlings in the combined treatment reached the maximum. The study found that exogenous SA and H₂S under salt stress of single or compound treatment can improve the salt resistance of processing tomato seedlings, and H₂S and SA distribution treatment has a certain degree of synergy, can reduce the water loss of processing tomato leaf, induced seedling increased osmotic regulation ability, make seedling remains relatively complete the photosynthetic structure and strong vitality. Furthermore, the adaptability of processing tomato seedlings to salt stress was improved, indicating that H₂S and SA had mutual regulation mechanism in alleviating salt stress injury of processing tomato.

Abstract:In order to explore the relationship between the accumulation of flavane3ol and the expression of synthesisrelated enzymes and key genes in wine grape fruit, this study analyzed the white grape variety Chardonnay grown in Donglu of Helan Mountain with colorimetric method, high performance liquid chromatography (HPLC) and fluorescence quantitative PCR (FQPCR). The accumulation rule of flavane3ol monomer and the changes of related enzyme activities and related gene expression patterns during biosynthesis of grape fruit were studied. The results showed that: (1) during the whole fruit development period, the contents of gallic catechin (GC) and epicatechin gallate (ECG) of flavane3ol were much higher than those of catechin (CAT) and epicatechin (EC). The contents of ECG and EC increased at first and then decreased with the development of fruit, and reached the maximum at 50 days after anthesis, which were 47.69 mg/g and 42.73 mg/g, respectively, while the contents of GC and CAT decreased at first and then increased, and then decreased gradually with fruit ripening. (2) The activities of flavane3alcohol biosynthesis related enzymes PAL and ANS in grape fruits increased at first and then decreased with the development of fruit. The activities of F3H, F3′H and CHI peaked at 20 days after anthesis (June 13), and then decreased rapidly, while the activity of DFR increased at first and then decreased, increased again at 50 days after anthesis, and then decreased gradually with fruit ripening. (3) The expression of structural genes PAL and ANS related to flavane3ol biosynthesis was upregulated at first and then downregulated with the development of fruit, which was consistent with the change trend of ECG and EC contents, while the expression of F3H, F3′H and CHI was downregulated at first and then upregulated. The expression of DFR was upregulated at first, then downregulated, and then upregulated again with fruit ripening. (4) Correlation analysis showed that the activities of F3H, F3′H and ANS were positively correlated with the content of GC. The expression of F3H and F3′H genes was positively correlated with the contents of GC and CAT, and the expression of ANS and PAL genes was positively correlated with the contents of ECG and GC. It was found that the synthase and gene expression related to flavane3ol biosynthesis affected the accumulation of flavane3ol compounds in grape fruit, which further affected the sensory quality of grape wine.

Abstract:Taking cucumber cultivar ‘Xinchun 4’ as experimental material, we studied the effects of exogenous spraying 0.01 mg/L exogenous 2,4epibrassinolide (EBL) and 24 μmol/L brassinolide inhibitor (BZR) on the rapid chlorophyll fluorescence induction kinetics curve (OJIP) and related fluorescence parameters of cucumber seedlings under moderate salt stress (50 mmol/L NaCl), and discussed the photosynthetic physiological mechanism of EBL alleviating the damage of cucumber seedlings under moderate salt stress. The results showed that: (1) salt stress led to the decrease of net photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r), the increase of intercellular CO₂ concentration (C_i), the decrease of initial fluorescence (F_o) and maximum fluorescence (F_m), and the increase of J point and I point in the OJIP curve, which reduced the photosynthetic performance of cucumber seedlings, and the damage to PSⅡ receptor side was greater than that on the donor side, showing the damage of PSⅡ reaction center. The transfer efficiency of photosynthetic electron from Q_A to Q_B decreased, and the electron transfer was blocked. (2) Under 50 mmol/L NaCl treatment, exogenous spraying of 0.01 mg/L EBL could significantly improve P_n, G_s, T_r, and photosynthetic performance (PI_ABS) of cucumber seedlings, reduce C_i, and significantly increase the absorption per unit area (ABS/CS_m), capture (TR_o/CS_m), light energy for electron transport (ET_o/CS_m), and the number of active reaction centers (RC/CS_m). (3) Compared with NaCl + EBL treatment, the photosynthetic performance of cucumber seedlings after NaCl + EBL + BZR treatment was further reduced, indicating that EBL could alleviate PSⅡ damage caused by salt stress in cucumber seedlings. It was found that exogenous spraying of appropriate amount of 2,4epibrassinolide could effectively alleviate the damage of (PSⅡ) receptor side of photosynthetic electron transport chain on cucumber seedling leaves, increase the efficiency of electron transfer from Q_A to Q_B, and thus significantly improve the photosynthetic performance of cucumber seedling leaves under salt stress.

Abstract:In recent years, the acidity and frequency of acid rain are higher and higher, and the type of acid rain is gradually changing from sulfuric acid type to sulfuric acid nitric acid mixed type and nitric acid type. In this study, the seedlings of Cunninghamia lanceolata, Pinus massoniana, Phyllostachys edulis and Cyclobalanopsis glauca were treated with sulfuric acid rain (SAR), mixed acid rain (MAR) and nitric acid rain (NAR) and their three acid rain concentrations (pH 2.5, pH 3.5 and pH 4.5) in a pot experiment for 4 months. Along with pH value of 5.7 of distilled water as the control group, we investigated the net photosynthetic rate, chlorophyll content of plants, tree plant height variation and plant rhizosphere soil pH and exchangeable base for ion determination of plant seedlings on sensitivity and resistance characteristics of simulated acid rain, and acid for acid rain disaster area vegetation construction to provide the reference data in the cultivation of tree species.The results showed that: (1) acid rain of different concentrations and types could inhibit the net photosynthetic rate and chlorophyll synthesis of plants to a certain extent, that is, the higher the acid rain concentration, the lower the net photosynthetic rate and chlorophyll content of plants. (2) Low concentration of acid rain can promote the increase of plant height, but with the increase of concentration, the increase of plant height is severely inhibited, which is most obvious in P. massoniana and C. glauca. (3) Under low concentration acid rain stress, plant rhizosphere soil can effectively release base ions to neutralize acid ions, thus reducing acid rain toxicity. With the increase of acid rain concentration, the content of base ions decreases continuously, and the soil pH value decreases gradually. (4) The average membership values of C. lanceolata, P. massoniana, P. edulis and C. glauca showed different performances under different acid rain types. Comprehensively, C. lanceolata showed the strongest resistance to acid rain of sulfuric acid type and mixed acid type, while P. edulis could tolerate acid rain of nitric acid type and mixed acid type. C. glauca had the weakest resistance to acid rain compared with the other three species. The results showed that P. massoniana was the most sensitive to nitric acid rain, and the pH threshold was 2.5-3.5, but it showed significant resistance to sulfuric acid rain. C. lanceolata had stronger resistance to acid rain than the other three species. P. edulis had stronger resistance to nitric acid rain than the other two types, while C. glauca had stronger resistance to sulfuric acid rain than the other two types species, and the resistance was the weakest. The pH threshold of P. edulis, C. lanceolata and C. glauca under acid rain stress was 3.5-4.5.The comprehensive resistance of the four plants to acid rain was C. lanceolata > P. edulis > P. massoniana> C. glauca.

Abstract:In this study, the potted method was used. We sprayed triadimefon (TD) with different concentrations (100, 150, 200, 250, 300 mg·kg^-1) on the leaves of Zinnia elegans at the seedling stage, and then treated with natural drought and rehydration. The changes of agronomic and physiological characteristics of Z. elegans were analyzed, and the TD concentration with the best drought resistance effect was also selected to clarify the effect mechanism of TD on the growth of Z. elegans seedlings under drought stress, so as to provide a theoretical basis for the application of drought resistance cultivation and the breeding of resistant varieties. The results showed that: (1) different concentrations of TD pretreatment can significantly improve the drought resistance of Z. elegans seedlings, such as increasing the root length, stem diameter and root shoot ratio of seedlings, reducing the plant height and leaf area, so as to alleviate the damage caused by drought; it can also promote the increase of chlorophyll (Chl), soluble protein (SP) and proline (Pro) contents, improve the activities of peroxidase (POD) and superoxide dismutase (SOD) as well as slow down the increase of relative conductivity (REC) and malondialdehyde (MDA) contents. (2) After rehydration, the plant height, root length and stem diameter of each treatment increased, the contents of Chl, SP and Pro, and activities of POD and SOD increased, while REC and MDA contents decreased gradually. (3) Subordinate function analysis showed that TD with a concentration of 250 mg·kg^-1 had the best drought resistance effect on Z. elegans seedling.

Abstract:As a potential source of vegetation regeneration above ground, soil seed bank plays an important role in the natural restoration and succession process of vegetation and the restoration of ecosystems. the relationship between the changes of soil physicochemical properties and the characteristics of soil seed banks (SSBs) of plant communities at different altitudes in the low mountain area of Helan Mountain, was discussed, in order to reveal the spatial distribution characteristics and natural restoration potential of SSBS of various plant communities. The results showed that: (1) the seeds resources of SSBs at 1 200 m were from annual herbs, at 1 600 m perennial herbs, and at 2 000 m shrubs and small shrubs. With the increase of altitude, the annual herbs were the dominant species in SSBs at all five elevations. (2) The stability index, dominance index, evenness index and richness index of SSB at 1 400 m were significantly lower than those at the other four elevations, that is, the SSB diversity at 1 400 m was the lowest. (3) Soil pH and electrical conductivity were the most significant factors among physical and chemical properties that effected SBB diversity on species of seed bank. The SSB density and species diversity at five elevations in the low mountainous area of Helan Mountain were low, which could not meet the demand of natural vegetation restoration. Ecological restoration measures such as aerial seeding could be adopted to make up for the shortage of seeds in surface soil, so as to meet the provenance required for aboveground vegetation restoration.

Abstract:Pinus massoniana is a widely planted native tree species in China. The simple community structure and low biodiversity of P. massoniana plantation are common ecological problems. Exploring the influence of different forest gap sizes on the understory vegetation community of P. massoniana plantation can provide a theoretical basis for the nearnatural management of P. massoniana plantation. To explore the distribution of shrub and herb layer plant composition, niche breadth and niche overlap of dominant species in the gap after natural regeneration for 1 year after cutting, we set four different sizes of gaps A (50 m²), B (100 m²), C (200 m²) and D (667 m²) in 45yearold P. massoniana plantation, with the untreated P. massoniana plantation as control in this study. The results showed: (1) except that there was no significant difference in the number of species in the shrub layer under the 100 m² gap, the number of species in the shrub and herb layer in the other gaps was significantly higher than that in the control (P < 0.05), and the number of species in the shrub and herb layer under the 200 m² gap was the most, with 35 and 20 species, respectively. The species richness index of the shrub and herb layer under the four forest gaps significantly increased compared with the control (P < 0.05), the maximum values all appeared under the 200 m² gap, and their values were respectively 1.5 times and 2.6 times that of the control. (2) The species of sun plants of the shrub and herb layer increased in the forest gap, and there were the most species under the 200 m² gap. There were 13 species of sun plants in the shrub layer and 5 species of sun plants in the herb layer. (3) Among the dominant species in the shrub and herb layer under the four forest gaps, the niche breadth of the sun plants was larger, the average niche width of the shrub and herb layer under the 200 m² gap was the smallest, the degree of resource utilization was low, and there was no significant correlation between the important value and the niche breadth (P > 0.05). (4) The niche overlap index of the dominant species in the shrub and herb layer under the forest gap was small. Under 667 m² gap, the average niche overlap indexes of dominant species in shrub and herb layer were the lowest, 0.029 and 0.024, respectively. The proportions of high niche overlap of dominant species in 200 m² gap were the highest, 20% and 23.8%, respectively. Studies have shown that cutting and opening windows promote the development of understory vegetation in the P. massoniana plantation, enriche the diversity of understory plants, which is conducive to the stable and sustainable development of the P. massoniana forest, and is of great significance to accurately improve the quality of the P. massoniana plantation.

Abstract:The stability of artificial sandfixing vegetation community is an important criterion to evaluate the success of vegetation restoration in arid and semiarid sandy areas. In this paper, we used the fuzzy comprehensive evaluation theory to evaluate the stability of seven dominant plants of artificial sand fixation at the slope scale (upslope, midslope and downslope) in the windsand area of northwestern Shanxi Province. The growth status of dominant plants, soil quality, biomass and diversity of understory plants and Godron index were selected to evaluate the stability of plants by calculating the average membership degree. The results showed that: (1) the biomass of branches and leaves of Pinus tabuliformis in trees was the largest (1 457.1 g), the biomass of branches and leaves of Caragana korshinskii in shrubs was the largest (1 429.1 g), and the biomass of branches and leaves of dominant plants was the largest under slope. (2) The soil moisture of shrub surface layer (0-20 cm) was better than that of tree surface layer, and different plant forests showed the largest soil moisture under slope. The soil organic matter, alkalihydrolyzable nitrogen, available potassium and available phosphorus in the surface soil of each plant were much higher than those in the abandoned land. The soil nutrient indexes of P. tabuliformis and C. korshinskii were significantly higher than those of other plants, and the nutrients under different plants were also the best in the slope. (3) The biomass of understory plants: Populus cathayana tree was the largest (87.2 g), C. korshinskii shrub was the largest (50.4 g), and the biomass of slope was the largest. The richness index of understory plants in tree was the highest in P. cathayana, the diversity index and evenness index of understory plants in tree were the highest in Pinus sylvestris and P. tabuliformis, and the diversity index of understory plants in shrubs was basically similar. (4) Godron index: the intersection coordinates of Robinia pseudoacacia in trees were closest to the community stability point, and the intersection coordinates of C. korshinskii in shrubs were closest to the community stability point. Based on the average membership of each index, the order of tree stability index was as follows: P. tabuliformis (0.69) ＞ R. pseudoacacia (0.67) ＞ P. cathayana (0.66) ＞ P. sylvestris (0.39) ＞ Salix matsudana (0.28). The order of shrub stability was as follows: Caragana microphylla (0.82) ＞ Amorpha fruticosa (0.64). The stability of trees and shrubs was much higher than that of abandoned land (0.20). As a whole, P. tabuliformis tree and C. korshinskii shrub have the highest stability, which are suitable for afforestation. Downhill is a better choice of slope position. This study can provide a basis for the restoration and scientific management of artificial sandfixing vegetation in the windsand area of northwestern Shanxi and the Loess Plateau.

Abstract:To reveal the phytoplankton community structure in the eutrophic lake water during the icesealed period in cold and arid regions and its response relationship with water quality indicators, this study took Ulansuhai as the object, and set up 12 sampling points in the lake area in January 2019 to collect water samples and phytoplankton. Through the qualitative and quantitative detection of phytoplankton and the determination and analysis of physical and chemical properties of water bodies, we clarified the spatial variation characteristics of phytoplankton community structure and the distribution law of main water quality indicators in Ulansuhai during the icesealed period; combined with RDA analysis and Pearson correlation analysis, we revealed the response relationship between phytoplankton and water quality indicators, which provided a theoretical basis for the assessment and prevention of water eutrophication. The results show that: (1) the water quality indicators of 12 sampling sites in Ulansuhai during the icesealed period were significantly different, and the water quality indicators had different trends from north to south. (2) A total of 61 species of phytoplankton were detected in Ulansuhai during the icesealed period, among which Cryptophyta had the highest abundance (4.76×10⁶ cells·L^-1), and Pyrrophyta had the highest biomass (18.09 mg·L^-1), but the dominant phytoplankton groups at different locations in the lake area were different, and the abundance of Chroomonas sp. and Pseudoanabaena sp. in the North Lake area was significantly higher than that in the South Lake area. (3) There are obvious differences in the spatial distribution of different species of phytoplankton, and the diversity of the P3 sample site is the lowest, and the diversity of the P8 sample site is the highest. (4) The abundance of phytoplankton was significantly positively correlated with TP, the biomass was extremely significantly positively correlated with TP, and the diversity index was positively correlated with TP. Studies have shown that the Ulansuhai water was at a moderate nutrient level during the icesealed period, and the total phosphorus (TP) content in the water body was the main factor affecting the species abundance and biomass of phytoplankton; The distribution characteristics of plants were that Cryptophyta, Cyanophyta and Pyrrophyta were dominant in the North Lake area; Chlorophyta was the most abundant in the South Lake area.

Abstract:CRISPR/Cas9 technology is an editing tool that can rapidly modify specific DNA of genomic targets. This paper reviews the research progress of CRISPR/Cas9 technology in improving tomato agronomic traits and improving biotic and abiotic stress resistance at home and abroad in recent years, and focuses on some problems faced by CRISPR/Cas9, so as to provide reference for the application of CRISPR/Cas9 gene editing technology in germplasm innovation and gene function research of tomato.