Abstract:Basic helixloophelix (bHLH) transcription factors are one of the largest transcription factor families in plants. It is extensively involved in stress response of plants. In the present study, we cloned a bHLH transcription factor geneSpbHLH89 (Sol Genomics number Sopen04g001150) from Solanum pennellii. Meanwhile, we also analyzed its expression patterns under drought stress by qRTPCR and verified its biological function by prokaryotic expression. The results showed that: (1) an open reading frame (ORF) of SpbHLH89 was obtained from S. pennellii, which is 684 bp long and encodes 227 amino acids with typical basichelixbasic domain and mainly located on the nucleus. Phylogenetic tree analysis showed that SpbHLH89 was highly conserved and shared a high degree of sequence similarity with NtbHLLH094 from Nicotiana tomentosiformis. (2) qRTPCR analysis showed that the pattern of SpbHLH89 was highly expressed in flowers and also induced by drought stress. (3) SDSPAGE and Western blotting analysis showed that the molecular weight of pET30aSpbHLH89 was approximately 31 kD. (4) Heteroexpression of the pET30aSpbHLH89 could improve the growth of the recombinant strain of E. coli BL21(DE3) under salt (400 mmol/L NaCl) and drought (600 mmol/L mannitol) stress. Taken together, the heterologous expression of SpbHLH89 transcription factor could improve the tolerance of recombinant bacteria to abiotic stress.

Abstract:Stearoylacyl carrier protein Δ₉ desaturase(SAD) is a key enzyme that determines the content of plant saturated fatty acids and unsaturated fatty acids. This study obtained the ElSAD2 gene sequence based on the transcriptome database and analyzed its sequence and expression characteristics, then we identified the function of the ElSAD2 gene. The results showed that: (1) the cDNA length of ElSAD2 was 1 665 bp and ORF was 1 194 bp, encoding 397 amino acid residues. Phylogenetic analysis showed that ElSAD2 protein was closely related to RcSAD1 protein in Ricinus communis. (2) ElSAD2 was expressed in all tissues, with the highest expression level in seeds of 30 days after anthesis. (3) Genetic transformation showed that overexpression of ElSAD2 could increase unsaturated fatty acid content in defective yeast BY4389. (4) The instantaneous expression of ElSAD2 in tobacco leaves increased the contents of total fatty acid and oleic acid by 2.46% and 2.1%, respectively. It was found that ElSAD2 could efficiently catalyze the biosynthesis of monounsaturated oleic acid, which could be further applied to the improvement of oil yield and quality.

Abstract:In this study, family genes of ethylene biosynthesis (MAT, ACS and ACO) pathway in radish (Raphanus sativus L.) were genomewide identified by bioinformatics method and its tissuespecific response to biotic and abiotic stress were analyzed based on transcriptome data and quantitative realtime PCR. The results showed that: (1) a total of 8 MAT, 16 ACS and 7 ACO candidate genes were identified in radish genome and each family could be further divided into three subgroups. (2) The promoter region harbored at least one cisacting element that function in light responsiveness, and cisacting element involved in the phytohormones responsiveness were also found except for ACO1.1 and ACO3. The promoter region of some genes contains cisacting elements involved in response to biotic and abiotic stresses. (3) The analysis of transcriptome data showed that all MAT genes, ACS6.1 and ACO2/3/4 of radish have high expression levels in leaves. Agrobacterium tumefaciens infection significantly upregulated MAT24, ACS2/7.1/7.2 and ACO1.1/1.2/4 in resistance radish inbred lines, while most of them downregulated in susceptible material. The cadmium, chromium and lead stress significantly induced the expression of MAT4.2 and ACO1.1/4, while reduced the expression of MAT1 and ACO5.1. The expression of MAT2.1/2.2/4.1 and ACO1.1/5.2 were significantly suppressed by chilling stress of 4 ℃. (4) qRTPCR results indicated that both NaCl and PEG6000 stress significantly induced the expression of ACO5.1/5.2, but suppressed MAT4.1 and ACO4. Besides, exogenous fructose and sucrose may be involved in the response of radish to PEG6000 stress. Our findings in the present study will be helpful for the functional research of the ethylene biosynthesis genes in radish.

Abstract:SerotoninNacetyltransferase (SNAT) is one of the key enzymes participating in melatonin synthesis. To reveal the function of banana SNAT gene, we performed genomewide identification of banana SNAT genes and indentified two banana SNAT genes (MaSNAT1 and MaSNAT2). Gene cloning experiment showed that only MaSNAT2 was expressed, so only this gene was subjected to series of bioinformatic analysis. Moreover, its expression changes under MeJA, ABA, GA₃, melatonin and low temperature treatments were investigated by using quantitative real time PCR (qRTPCR). The results showed that: (1) the coding sequence (CDS) length of MaSNAT2 gene was 741 bp, which could encode a protein of 246 amino acids. MaSNAT2 was predicted to be chloroplastlocated and owned the typical conserved domain (Acetyltransf_7) of the GNAT superfamily. The secondary structure of MaSNAT2 protein is mainly composed of αhelix, β folding and random coils, and its tertiary structure is highly similar to rice OsSNAT1 (81.60%). (2) The MaSNAT2 protein shared the highest similarity with the SNAT protein of Musa acuminata subsp. malaccensis and their relationship was also the closest. Many phytohormone responsive elements such as MeJA, ABA and GA₃ responsive elements were identified in the MaSNAT2 promoter. (3) qRTPCR results showed that the expression of MaSNAT2 could be suppressed by ABA treatment; the expression of MaSNAT2 increased by 15.1 and 16.2 times at 8 h and 48 h after GA₃ treatment; the expression of MaSNAT2 increased by 5.2 times at 4 h after MeJA treatment; melatonin and low temperature treatment both increased the expression of MaSNAT2. MaSNAT2 belongs to the GNAT superfamily, its expression is GA₃ and MeJA inducible, but it is greatly inhibited by ABA. Moreover, the gene might play important roles in the low temperature stress response of banana.

Abstract:In this study, the spring wheat cultivar ‘Yangmai 15’ and the semiwinter cultivar ‘Yannong 19’ were used as experimental materials, which were performed low temperature treatment at 6-8 days after anthesis. Then the wheat caryopses at different developmental stages were sampled after anthesis. The microstructure characteristics of the pericarp, endosperm and nutrient transport tissue were observed using resin section technology, and the microstructure characteristics of wheat caryopsis development under low temperature conditions after flowering were explored. The results showed that: (1) the low temperature after anthesis delayed the early and middle development of caryopsis of the two wheat cultivars, delayed the filling stage of Yangmai 15, shortened the filling stage of Yannong 19, and finally reduced the grain weight of the two wheat cultivars. (2) Low temperature treatment after anthesis slowed down the apoptotic rate of pericarp cells of early wheat endosperm development and the degradation rate of amyloplast in pericarp cells. (3) The low temperature after anthesis significantly reduced the accumulation of amyloplast and protein bodies in the early and middle stages of wheat endosperm development, shortened the filling period, and reduced the degree of endosperm fullness. (4) The phloem of wheat caryopsis developed slowly under low temperature conditions after anthesis, and the distribution range of sieve tubes was reduced. At the same time, the development of endosperm transfer cells slowed down, and the number of wall ingrowths on the cell wall was significantly reduced. The study found that low temperature after anthesis delayed the early development of caryopsis of the two wheat cultivars, which was reflected in the delayed apoptosis of pericarp, the decrease of storage material accumulation, the underdevelopment of nutrient transport tissue, the decrease of endosperm fullness and the decrease of dry weight of single caryopsis. At the same time, there were differences in the response of the two wheat cultivars to low temperature. At low temperature after anthesis, the caryopsis filling period of spring wheat was prolonged and that of semiwinter wheat was shortened.

Abstract:Fruit drying is the main processing process of Lycium barbarum in Ningxia, and there are certain differences in the drying characteristics of different varieties of L. barbarum. Taking the fruits of ‘Ningqi No. 1’ (easy to dry) and ‘Ningqi No. 5’ (not easy to dry) with large differences in the cultivation of wolfberries in Ningxia, we used scanning electron microscopy technology and GCMS technology to observe the structure of the peel of the two varieties at different development stages (green fruit stage, color deformation stage, maturity stage) and the waxy microform, content and composition of the peel wax, and the accumulation law of wolfberry waxy skin was initially revealed from the accumulation changes of the waxy microform and components of the peel, clarify the differences in waxy composition of the peel of different wolfberry varieties, and provide a theoretical basis for the screening of suitable drying agents of different varieties and the rational use of drying agents. The results showed that: (1) the outer cell wall of the epidermal cells of ‘Ningqi No. 1’ and ‘Ningqi No. 5’ of wolfberry showed the structure of ridgelike protrusions, which were discontinuous in the green fruit stage, and the ridges and ridges were closely arranged; with the delay of the development period, the continuity of the ridgelike protrusions gradually increased, and the spacing between the ridges and the ridges gradually widened, and the wax covers the raised ridges and the grooves between the two ridges in a membranous manner. (2) In the process of fruit development, the wax content per unit area of the peel showed a trend of first decreasing and then increasing, and the wax content per unit area of the fruit reached the highest in the mature stage, and the wax content per unit area of the three developmental periods of ‘Ningqi No. 1’ was higher than that of ‘Ningqi No. 5’ in the same period, showing a trend of change that was basically consistent with the wax distribution observed by scanning electron microscopy. (3) The waxy components of the fruit epidermis of the two varieties in the three periods are composed of alkanes, ketones, alcohols, acids, aldehydes, esters and iodoalkanes, and the waxy components of the peels of the two varieties are the same at the green fruit stage and the color stage, mainly composed of alkanes, alcohols and iodoalkanes, and the waxy components of the peels at the ripe stage are mainly composed of alkanes, alcohols and esters. (4) The results of principal component analysis show that the waxy components of the peel of ‘Ningqi No. 5’ in the three growth periods are mostly alkanes, which are more conducive to blocking the loss of fruit water than ‘Ningqi No. 1’. The study found that the reason for the impact on the dried fruit of wolfberries is the wax content, structure and waxy composition of the peel. The alkane components can effectively prevent the loss of water in the fruit body, and the alkane components in the waxy skin of ‘Ningqi No. 5’ are higher, the peel is more waterretaining, and the fruit is not easy to dry.

Abstract:In this study, the functional leaves of color spotted pepper mutant were used as test materials. By observing the microstructure and ultrastructure of different leaf spots, we analyzed the color developing parts, color developing characteristics, number and morphological changes of organelles, and discussed the causes of complex leaf color of color spotted pepper at the cellular level. The results show that: (1) the color of cotyledons mutants were purple, and heterochromatic patches appeared from the first true leaf. There was no obvious regularity in patch location, frequency and color depth. (2) Leukoplakia occured when the chloroplasts in mesophyll cells were reduced or even absent. The uneven distribution of pigment glycosides in mesophyll cells was the main reason for different purple depths, which were distributed both in mesophyll cells and guard cells. (3) The cell morphology and organelle structure in the green spot region of pepper color spot mutant were good; The cells in purple and white spots were moderately swollen, and the organelles were obviously abnormal. (4) The reason for the color of leaves is that there are few or even missing chloroplasts in mesophyll cells and the uneven distribution of anthocyanins. The leaf spot type belongs to pigment type.

Abstract:In order to select the most suitable light quality ratio for the rooting of Cunninghamia lanceolata tissue cultured seedlings, we investigated the effects of different light quality treatments on the rooting rates of tissue cultured seedlings by using the superior clone of C. lanceolata ‘Yang 020’. And then, the differences of seedling growth, photosynthetic pigment content, chlorophyll fluorescence parameters, endogenous hormone content and chloroplast ultrastructure among the white light (control) treatment and the light quality treatments with highest and lowest rooting rates were analyzed, revealing the regulatory mechanism of rooting and growth of tissue cultured seedlings mediated by different light qualities, thus, providing theoretical basis for the factory production of C. lanceolata tissue culture seedlings. The results showed that: (1) under different light quality combination conditions, the rooting rate of seedlings treated with the combination of red and blue light, more specifically, red∶blue=3∶1 (R₃B₁) was the highest (71.11%), which is 45.61% higher than that of white light control, while the rooting rate of seedlings treated with blue light is the lowest (12.50%). (2) The biomass and plant height of seedlings under red and blue light treatment (R₃B₁) were higher than those of control and blue light treatments, and there was significant differences in plant height among different treatments (P＜0.05). (3) The photosynthetic pigment content and PSⅡ potential photochemical efficiency F_v/F_o value of seedlings in red and blue light (R₃B₁) treatment were significantly higher than control and blue light treatments, suggesting leaves may have strong light source capturing ability and light energy utilization ability. (4) The ultrastructure of chloroplast results showed that the number and size of chloroplast starch grains in the leaves of seedling treated with the combination of red and blue light (R₃B₁) was small and the structure of chloroplast matrix and grana lamella was clear, which might favorable for the output of assimilation products. (5) The higher rooting rate of the seedlings treated with the combination of red and blue light (R₃B₁) was associated with higher auxin (IAA), lower cytokinin (CTK) content and higher IAA/CTK ratio in its shoots, while the higher plant height was associated with higher gibberelins (GA), IAA contents, IAA/ABA and GA/ABA ratios, and lower ABA content in its shoots.

Abstract:Apple fruits of the ‘cv. Starkrimson’ were artificially wounded, dipped with sodium nitroprusside (SNP) as an exogenous donor of NO at 0.5 mmol/L for 5 minutes. To investigate the weight loss and disease index of apple fruits during healing by SNP treated, we analyzed the activities of key enzymes and content of products in phenylpropanoid metabolism, H₂O₂ content and peroxidase activity at wound sites, and explored its relevant physiological mechanism, so as to provide a method and theoretical basis for rapid postharvest healing of apple fruits. The results indicated that: (1) SNP treatment effectively reduced the weight loss and disease index of inoculated fruits with Penicillium expansum during healing, which were 40.2% and 31.4% lower than the control at the 5th day after healing. (2) The treatment significantly increased the activities of phenylalanine ammonia lyase, cinnamic acid4hydroxylase and cinnamyl alcohol dehydrogenase, the key enzymes of phenylpropanoid metabolism, and enhanced the contents of cinnamic acid, coffeic acid, ferulic acid, sinapic acid, total phenols, flavonoids, Pcoumaroyl alcohol, coniferyl alcohol, sinapyl alcohol and lignin at wound sites of fruits. SNP treatment also significantly raised H₂O₂ content and POD activity at wound sites of fruits. It was found that NO could promote the wound healing of apples by activating phenylpropanoid pathway, increasing H₂O₂ content and POD activity at wound sites.

Abstract:In order to reveale the characteristics of manganese accumulation characteristics and tolerance mechanism of Rhus chinensis, this study investigated the effects of Mn²⁺ concentrations of 0 (CK), 1, 5, 10 and 20 mmol·L^-1 on the growth, physiological and biochemical characteristics and manganese accumulation characteristics of R. chinensis seedlings of half a year old by pot experiments. The results showed that: (1) under the conditions of Mn²⁺ concentration of 0-10 mmol·L^-1, R. chinensis seedlings grew well. When Mn²⁺ concentration attained to 5 mmol·L^-1, the leaves spread, were dark in color and grew best; while Mn²⁺ concentration attained to 20 mmol·L^-1, some leaves showed brown spots and wilting and curling. With the increasing of Mn²⁺ concentration, the biomass of R. chinensis seedling increased significantly at first and then decreased, and reached the highest when the concentration of Mn²⁺ was 5 mmol·L^-1. (2) With the increasing of Mn²⁺ concentration, the photosynthetic pigment content in R. chinensis leaves increased at first and then decreased. When Mn²⁺ concentration attained to 10 mmol·L^-1, the photosynthetic pigment content in R. chinensis reached the highest. (3) With the increasing of Mn²⁺ concentration, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the contents of soluble sugar, soluble protein and free proline of R. chinensis seedling leaves increased at first and then decreased, and most of these values reached the maximum when Mn²⁺ concentration attained to 10 mmol·L^-1. Malondialdehyde (MDA) content of R. chinensis increased with the rising Mn²⁺ concentration. (4) With the increasing of Mn²⁺ concentration, the manganese content of aboveground and underground part and total manganese content of R. chinensis seedlings gradually increased. The bioconcentration factors (BCF) of R. chinensis decreased significantly with the increase of Mn²⁺ concentration, and all of them were higher than one. The translocation factor (TF) increased significantly, all of which were less than one. This study showed that R. chinensis has a strong ability of manganese accumulation, transportation, and manganese tolerance. R. chinensis belongs to the manganesetolerant plant, which stored manganese in roots. It mainly deals with manganese stress by accumulating osmotic adjustment substances, enhancing antioxidant enzyme activity and accumulating manganese in roots.

Abstract:To explore the mechanisms of physiological change in radish fleshy roots at different hollowness levels during the middle and late growth periods, and to provide theoretical basis for the indepth study of hollowness regulation and breeding, we used such three varieties as resistance hollowness variety C70922, not resistance hollowness variety C3156 and medium resistance hollowness variety C83471. Here, the changes of physiological and quality indexes were measured under different hollowness levels of roots, and the cell changes in roots were observed by paraffin section. The results were as follows: (1) the activity of superoxide dismutase (SOD) in different radish varieties reached the highest or lowest in the first grade of hollowness, while activity of peroxidase (POD) and free proline content were the peaks in the second grade hollowness. (2) The contents of soluble sugar and reducing sugar in fleshy roots of different radish varieties reached the maximum value in the third grade hollowness. (3) With the deepening of radish hollowness, soluble starch contents decreased first, then increased and then decreased. (4) The cellulose content in the radish C70922 did not change significantly among different hollow grades, while the cellulose in the radish C3156 and C84371 are reached the highest in the third grade hollowness. (5) Additionally, the accumulation of vitamin C in fleshy roots was closely related to the grade of radish hollow. (6) In the same hollowness grade of fleshy radish roots, as the tolerance of the variety weakened, the individual cells were gradually larger, the arrangement was looser, and the cell wall became thin. As the hollowness grade increased in the same material, more cells were broken and the degree of the cell constriction increased. Therefore, SOD, POD, free proline, cellulose and vitamin C, as well as cell morphology of radish cells changed significantly during the process of hollowing in roots of radish.

Abstract:As an important ornamental plant, Bougainvillea spectabilis has many colors but lacks the rare blue color. In order to select a suitable host of genetic transformation that would be suitable for the exclusive accumulation of flavonoid pigment by absorbing dihydromyricetin (DHM) and the resulting color change toward blue, we carried out in vitro induction culture experiment on the Bougainvillea bracts of 6 varieties of red, white, yellow and purple with 4 common colors; The changes of color parameters and pigment content of bracts were measured after induction culture, and the correlation was analyzed. The result showed that：(1) the red green phase value (a^*) of bracts is the main color parameter that determines the color of bracts. Its color is mainly determined by beet pigment and flavonoid pigment, and betacyanins has the greatest influence. (2) Except that the content of flavonoids in the bracts of white varieties is higher than that of betacyanins, the content of beet pigment in the bracts of other varieties shows an upward trend, and the content of flavonoids pigment shows a downward trend. (3) The content of betalain is significantly positively correlated with the a^* value and negatively correlated with the b^* value of bracts，and the content of total flavonoids is significantly positively correlated with b^* value and extremely significantly negatively correlated with a^* value of bracts. (4) After being fed and cultured in vitro by DHM, the content and proportion of total flavonoids in the bracts of four varieties (‘Singapore White’, ‘Baolao Cheng’, ‘Chinese Beauty’, ‘Ratana Yellow’) increased significantly, and which of total beet pigment in the bracts of all varieties decreased. The increase of total flavonoids content in the bracts of ‘Singapore White’ (+65.77%) is the largest, and its change of content proportion (26.91%) is also the largest among the six varieties. (5) Through the comprehensive analysis of grey correlation degree, the white variety ‘Singapore White’ has the highest correlation degree (0.744 4) with the reference variety proposed by grey correlation degree analysis. Based on the results， Singapore White was the most appropriate transgene host for blue Bougainvillea ssp. The results of this study provide a reference for the directed breeding of blue Bougainvillea ssp..

Abstract:We used oat variety ‘Bayou 1’, which is susceptible to stem rust, as the experimental material, to study the effect of silicon application on the activity of proteases and phenolic substances in oat leaves infected with stem rust and to clarify the physiological mechanism of silicon improving resistance to oat stem rust, and provide theoretical basis for new control measures of oat stem rust. The results showed that: (1) after inoculation, the severity of oat stem rust was significantly reduced under silicon application, and the number of spores on leaves was significantly reduced. (2) No inoculation of stem rust, silicon application or not had no significant effect on the protease activity related to the disease course of oat leaves. The chitinase activity in the leaves increased rapidly and then decreased after reaching the peak on the 1st day and the 3rd day of inoculation; The β1,3 glucanase activity of leaves increased first and then decreased in both silicon and nonsilicon treatments, and reached the peak on the 3rd day of inoculation. The activities of chitinase and β1,3 glucanase in leaves were significantly increased after silicon application. (3) There was no significant effect of silicon application on the metabolism of phenolic substances in oat leaves without inoculation of stem rust, inoculation of stem rust could make oat leaves polyphenol oxidase activity (PPO), phenylalanine ammonia lyase activity (PAL), total soluble phenol content (TSP) and lignin content to increase rapidly. All treatments began to decline rapidly after reaching the peak on the 3rd day after inoculation, and application of silicon could significantly increase the content of each component in phenolic substances and related enzyme activities. In conclusion, silicon application can enhance the resistance of oat to stem rust by inducing the activity of protease related to disease course and the metabolism of phenolic substances in oat leaves.

Abstract:In order to explore the influence of shade on the color changes of different color Chinese rose (Rosa chinensis Jacq.) during their development, we took red variety ‘Rouge Meilland’, yellow variety ‘The Pilgrim’, and blue purple variety ‘Kinda Blue’ as experimental materials. Under the condition of normal light (CK), 25% shading (S_Ⅰ) and 50% shading (S_Ⅱ), we measured petals 6 stages of CIE value, total flavonoids and total cyanine glycosides, pH value, and the correlation between the measured parameters of various varieties. The study found that: (1) shading treatment can lead to lighter coloring and increased brightness of the petals of ‘Kinda Blue’, and the accumulation of blueness was the largest under S_Ⅱ treatment, so appropriate shading can facilitate its blueness. Under S_Ⅰ treatment, ‘The Pilgrim’ petal color was stable, and the chroma accumulation was similar to CK. Under S_Ⅱ condition, the petal color fluctuated greatly, but the saturation degree was the highest at the full flowering stage. Treatment S_Ⅰ has little influence on the petal color of ‘Rouge Meilland’, while treatment S_Ⅱ has less redness and more yellowness, and the color fluctuation was large. A large amount of shade will lead to lighter red and yellow petals of ‘Rouge Meilland’. (2) Shade could affect the stability of anthocyanin by affecting the pH value of the ‘Kinda Blue’ petals, and finally, under the coordinated action of anthocyanin and pH, it made the petals blue and purple. Proper shade increased the correlation between pH and color of the petals of ‘Rouge Meilland’, while the accumulation of anthocyanin decreased and flavonoid increased, leading to light red and yellow of the petals. Shade could cause a synergistic effect between pH and flavonoids of ‘The Pilgrim’ petals, thus enhancing their yellow and chromatism. There were significant differences in the influence of shading on the color changes of different color Chinese rose during the development process. Shading 50% increased the ornamental ability of blue and yellow Chinese rose, but decreased the ornamental ability of red Chinese rose. Shading 25% had little effect on the appreciation of the three Chinese rose varieties.

Abstract:Taking the annual seedlings of Xanthoceras sorbifolia infected by root knot nematode (Meloidogyne incognita) as materials, we observed the morphology and microstructure of root system, plant growth and development and the distribution characteristics of main mineral nutrients in the seedlings, analyzed the relationship between different mineral elements and nematode infection, and clarified the effect of root knot nematode on the growth and development characteristics of X. sorbifolia seedlings. The results showed that: (1) root knots were formed in the seedlings infected with root knot nematodes, which were divided into grade 0 (control, normal plants), grade 2, grade 3 and grade 4 according to the degree of root knot occurrence. The root anatomical structure of X. sorbifolia plants with root nodes showed typical changes: the cortex is relatively thick, the xylem is twisted, the vessels are less, and the rays were less and not evenly distributed. The contents of phloem cells were significantly more. Several giant cells and cell cavities were mainly found in phloem. (2) Compared with the control, the height and ground diameter of seedlings with root knot increased significantly (P<0.05). (3) The contents of N and P in roots, stems and leaves all decreased, and the contents of N in roots with grade 2, 3 and 4 roots decreased by 7.8%, 16.0% and 29.5%, and the content of P decreased by 15.6%, 7.1% and 43.3%, respectively, compared with normal plants. The contents of Fe and Zn in roots increased significantly. The content of Fe in roots of different roots increased 1.56, 0.81 and 3 times, respectively, and the content of Zn in roots increased 1.11, 1.56 and 1.78 times, respectively, compared with normal plants. Compared with normal plants, K content in roots of seedlings with grade 3 and 4 root knots significantly increased (P<0.05), while K content in leaves of seedlings with grade 2 and 4 root knots significantly decreased by 61.5% and 47.0%, respectively. (4) Overall analysis showed that N content in roots and stems had the most obvious response to rootknot nematode infection, and its content decreased with the increase of infection degree. There was a significant negative correlation between leaf Mg content and infection rate, and K content and seedling biomass (P<0.05). This study provided a theoretical basis for the effect of rootknot nematodes on nutrient uptake and utilization of X. sorbifolia seedlings.

Abstract:To clarify the correlation between the growth characteristics of Fokienia hodginsii and nutrient content, we took F. hodginsii of different ages as the research object, compared the differences in the growth indexes and organ nutrients of F. hodginsii at different stages under the two stand models, and combined the changes in the nutrients of each organ with the growth of the forest age trend. The results showed that: (1) with the increase of the forest age, the density of the two forest models decreased significantly, but the total accumulation gradually increased, and the growth indicators of the different growth periods of F. hodginsii under the mixed model were better than those of pure forests of the same age. (2) The contents of carbon (C) and nitrogen (N) elements in the leaves of F. hodginsii under the two forest management models showed an upward trend with the increase of forest age; the phosphorus (P) content was the highest at 15 years of age, and was significantly higher than that of pure forest in early and middle growth period; the potassium (K) content reached the peak at 21 years old, while the K content of mixed forest leaves was lower than that of pure forest, and this difference reached significant at 33 years old. (3) The N and K contents of branches decreased with the increase of forest age. The content of K in branches of pure forest was higher than that of mixed forest, and the content of N in mixed forest was higher than that of pure forest. There was no significant difference in C content in the branches of the two forests of F. hodginsii, but the P content showed an opposite trend. (4) The trunk C content increased with the growth of the forest, the N content first decreased and then increased, the trunk P content decreased significantly with the increase of the forest age, and the P content of the mixed forest was lower than that of the pure forest, but the difference was not significant. The K content in the trunk of the pure forest was slightly higher than that of the mixed forest in the early growth period, but its content was significantly reduced in the middle and late growth period, and the K content in the mixed forest was significantly increased. (5) The C and N contents of roots decreased with the increase of forest age, and the mixed benefit significantly reduced the C content of roots and increased its N content. The contents of P and K varied greatly, and the mixing benefits also promote the contents of the two in F. hodginsii.

Abstract:This study understand the characteristics of soil seed bank in natural forest community dominated by Picea purpurea in Taohe National Nature Reserve Dayu forest regions (TH), Yeliguan forest regions (YLG) and GahaiZecha National Nature Reserve Zecha forest regions (GZ), Gansu Province, which revealed the characteristics of soil seed bank and its relationship with aboveground vegetation in P. purpurea community of Taohe River upstream. It provided basis for recovery and management of community of P. purpurea. The results showed that: (1) there were 50 species of soil seed bank in the 3 forest regions, which belonged to 45 genera and 27 families, the density of soil seed bank ranged from 958 to 1 129 ind/m², herbaceous plants composed the majority of the soil seed bank. (2) It was obvious of the vertical structure of soil seed banks, presenting species and density decreased with the increase of soil depth. (3) It showed that species of aboveground vegetation were more than soil seed bank, similarity coefficient between 0.15 and 0.23, which had extreme dissimilarity; Margalef richness index, ShannonWiener diversity index, Simpson dominance index of soil seed bank were lower than that of aboveground vegetation, but Pielou evenness index was higher. All in all, this study indicated that the soil seed bank in P. purpurea community of Taohe River upstream consisted largely of herbaceous plant. Thus, arbors and shrubs had smaller reserves, especially P. purpurea that was the constructive species. The contribution was lower between aboveground vegetation and soil seed bank, this implied that it was far from being able to alleviate the degradation of P. purpurea forest only by natural restoration of soil seed bank. Therefore, artificial seedling and afforestation measures will be needed to promote the regeneration and development of P. purpurea forest.

Abstract:Eritrichium pseudostrictum, a new record from Kashgar, Xinjiang, China, is described and illustrated here, which is previously known only from Tajikistan. Supplementary description of its fruits is also provided. The voucher specimen is deposited in the herbarium of Beijing Normal University (BNU).