Chinensis Seedlings Research Articles

Mapping QTL associated with resistance to Pseudomonas syringae pv. actinidiae in kiwifruit (Actinidia chinensis var. chinensis).

Pseudomonas syringae pv. actinidiae (Psa) is a bacterial pathogen of kiwifruit. This pathogen causes leaf-spotting, cane dieback, wilting, cankers (lesions), and in severe cases, plant death. Families of diploid A. chinensis seedlings grown in the field show a range of susceptibilities to the disease with up to 100% of seedlings in some families succumbing to Psa. But the effect of selection for field resistance to Psa on the alleles that remain in surviving seedlings has not been assessed. The objective of this work was to analyse, the effect of plant removal from Psa on the allele frequency of an incomplete-factorial-cross population. This population was founded using a range of genotypically distinct diploid A. chinensis var. chinensis parents to make 28 F1 families. However, because of the diversity of these families, low numbers of surviving individuals, and a lack of samples from dead individuals, standard QTL mapping approaches were unlikely to yield good results. Instead, a modified bulk segregant analysis (BSA) overcame these drawbacks while reducing the costs of sampling and sample processing, and the complexity of data analysis. Because the method was modified, part one of this work was used to determine the signal strength required for a QTL to be detected with BSA. Once QTL detection accuracy was known, part two of this work analysed the 28 families from the incomplete-factorial-cross population that had multiple individuals removed due to Psa infection. Each family was assigned to one of eight bulks based on a single parent that contributed to the families. DNA was extracted in bulk by grinding sampled leaf discs together before DNA extraction. Each sample bulk was compared against a bulk made up of WGS data from the parents contributing to the sample bulk. The deviation in allele frequency from the expected allele frequency within surviving populations using the modified BSA method was able to identify 11 QTLs for Psa that were present in at least two analyses. The identification of these Psa resistance QTL will enable marker development to selectively breed for resistance to Psa in future kiwifruit breeding programs.

Transcriptomic and physiological analysis of atractylodes chinensis in response to drought stress reveals the putative genes related to sesquiterpenoid biosynthesis

BackgroundAtractylodes chinensis (DC) Koidz., a dicotyledonous and hypogeal germination species, is an important medicinal plant because its rhizome is enriched in sesquiterpenes. The development and production of A. chinensis are negatively affected by drought stress, especially at the seedling stage. Understanding the molecular mechanism of A. chinensis drought stress response plays an important role in ensuring medicinal plant production and quality. In this study, A. chinensis seedlings were subjected to drought stress treatment for 0 (control), 3 (D3), and 9 days (D9). For the control, the sample was watered every two days and collected on the second morning after watering. The integration of physiological and transcriptomic analyses was carried out to investigate the effects of drought stress on A. chinensis seedlings and to reveal the molecular mechanism of its drought stress response.ResultsThe malondialdehyde, proline, soluble sugar, and crude protein contents and antioxidative enzyme (superoxide dismutase, peroxidase, and catalase) activity were significantly increased under drought stress compared with the control. Transcriptomic analysis indicated a total of 215,665 unigenes with an average length of 759.09 bp and an N50 of 1140 bp. A total of 29,449 differentially expressed genes (DEGs) were detected between the control and D3, and 14,538 DEGs were detected between the control and D9. Under drought stress, terpenoid backbone biosynthesis had the highest number of unigenes in the metabolism of terpenoids and polyketides. To identify candidate genes involved in the sesquiterpenoid and triterpenoid biosynthetic pathways, we observed 22 unigene-encoding enzymes in the terpenoid backbone biosynthetic pathway and 15 unigene-encoding enzymes in the sesquiterpenoid and triterpenoid biosynthetic pathways under drought stress.ConclusionOur study provides transcriptome profiles and candidate genes involved in sesquiterpenoid and triterpenoid biosynthesis in A. chinensis in response to drought stress. Our results improve our understanding of how drought stress might affect sesquiterpenoid and triterpenoid biosynthetic pathways in A. chinensis.

First Report of Pantoea agglomerans Causing Leaf Blight on Schisandra chinensis in China.

Schisandra chinensis (Turcz.) Baill is a perennial liana, which is widely cultivated and used in China. In August 2022, Schisandra chinensis leaves with small light brown spots were found on plants growing in Fusong (127°28'E, 42°33'N) of China. There was 15% disease incidence and 50% disease severity of Schisandra chinensis in 2-ha fields of S. chinensis. As the disease progressed, the spots become darker and form round or irregular concentric circles. Leaves with brown spot symptoms were collected from the field. Leaf pieces (5 mm × 5 mm) were excised from lesion margins, surface disinfected with 75% ethanol for 1 min, followed by 1.5% sodium hypochlorite for 3 min, and incubated on Luria Bertani (LB) solid medium at 28°C for 24 hours. Eight cultures were isolated, and representative single colony (XWWZH) was selected from the pure cultures according to colony characteristics for observation The purified colonies were round, yellow, and slimy, cells were straight rod-shaped (0.40 to 0.52 × 1.12 to 1.69 µm) were observed. The isolate was Gram negative. It was positive for methyl red reaction, lysine decarboxylase reaction, gelatin hydrolysis reactionand sucrose utilization. It was negative for indole reaction and produced H2S. The bacterium was preliminarily identified as Pantoea agglomerans based on morphological and biochemical tests (Baird et al. 2007). The 16S rDNA and a portion of rpoB of strain XWWZH were amplified and sequenced. The sequences were submitted to GenBank. (Accession OP763753 and OQ813505, respectively). Phylogenetic trees were constructed based on the 16S rDNA and rpoB gene sequences. The sequences of strain XWWZH clustered with strains P. agglomerans deposited in GenBank. The pathogenicity was verified with non-wounded S. chinensis seedlings by punching holes with sterile needles and injecting a solution of 1 × 108 CFU/ml solution. Sterile ddH2O was injected in the control experiment. The inoculated seedlings were incubated in a greenhouse at 25°C with a relative humidity of 65 to 70%. Five to eight days after inoculation, inoculated leaves, exhibited symptoms which were morphologically identical to those of the originally infected leaves whereas control plants remained asymptomatic. The pathogenicity assays were repeated twice with the same results. The re-isolated pathogen had the same morphology and DNA sequences as the original isolate obtained from the field samples, completing Koch's postulates. Strains of P. agglomerans have been reported to severely infect many plants (Ren et al.2008; Lee et al. 2010; Yang et al. 2011; Guo et al. 2019; Gao et al, 2022), but to the best of our knowledge, this is the first report of a strain of P. agglomerans causing leaf blight on Schisandra chinensis in China. The identification of leaf blight caused by P. agglomerans will enable farmers to prevent and manage it ahead of time to reduce losses.

Plant Growth Stimulatory Effect of Terrein and Its Mechanism of Action in Crops under Drought Stress

Drought is one of the most important factors that limit crop yield. In this study, the growth promotive activity of terrein, a microbial metabolite, on four selected agricultural plants (Vigna radiata, Brassica chinensis, Triticum aestivum and Sorghum bicolor) under drought conditions was assessed via pot experiment. Terrein effectively stimulated the seedling growth of tested species and increased their fresh and dry weight at low concentrations (2 and 10 μg/mL), either applied as a seed soaking agent or a spray solution, especially on root growth. The maximum stimulatory effect on root growth was observed on B. chinensis seedlings (99.20%), on fresh weight was found on T. aestivum seedlings (97.23%), and on dry weight was discovered on V. radiata seedlings (58.33%), implying that this stimulatory effect was species-specific. Further study revealed that the application of terrein significantly raised the contents of GA3, IAA and CTK; meanwhile, MDA content declined significantly, whereas the activity of POD, CAT and SOD was boosted significantly, suggesting that terrein can stimulate plant growth by reducing the production of ROS. Our work is the first study focusing on terrein’s plant growth promotive activity, indicating terrein has the potential to be further explored as an environment-friendly growth regulator.

Isolation and Identification of Biocontrol Bacteria against Atractylodes Chinensis Root Rot and Their Effects.

Fusarium root rot (FRR) seriously affects the growth and productivity of A. chinensis. Therefore, protecting A. chinensis from FRR has become an important task, especially for increasing A. chinensis production. The purpose of this study was to screen FRR control strains from the A. chinensis rhizosphere soil. Eighty-four bacterial strains and seven fungal strains were isolated, and five strains were identified with high inhibitory effects against Fusarium oxysporum (FO): Trichoderma harzianum (MH), Bacillus amyloliquefaciens (CJ5, CJ7, and CJ8), and Bacillus subtilis (CJ9). All five strains had high antagonistic effects in vitro. Results showed that MH and CJ5, as biological control agents, had high control potential, with antagonistic rates of 86.01% and 82.78%, respectively. In the pot experiment, the growth levels of roots and stems of A. chinensis seedlings treated with MH+CJ were significantly higher than those of control plants. The total nitrogen, total phosphorus, total potassium, indoleacetic acid, and chlorophyll contents in A. chinensis leaves were also significantly increased. In the biocontrol test, the combined MH + CJ application significantly decreased the malondialdehyde content in A. chinensis roots and significantly increased the polyphenol oxidase, phenylalanine ammonolyase, and peroxidase ability, indicating a high biocontrol effect. In addition, the application of Bacillus spp. and T. harzianum increased the abundance and diversity of the soil fungal population, improved the soil microbial community structure, and significantly increased the abundance of beneficial strains, such as Holtermanniella and Metarhizium. The abundance of Fusarium, Volutella, and other pathogenic strains was significantly reduced, and the biocontrol potential of A. chinensis root rot was increased. Thus, Bacillus spp. and T. harzianum complex bacteria can be considered potential future biocontrol agents for FRR.

First Report of Fusarium acuminatum Causing Leaf Spot on Schisandra chinensis in China.

Schisandra chinensis (Turcz.) Baill. is a popular and widely cultivated medicinal herb in China, which has rich nutritional value and medicinal effect. In August 2022, leaves with oval and irregularly circular light brown spots from 2 to 10 mm wide with white centers were found on Schisandra chinensis growing in Fusong district (127°28'E, 42°33'N) of Jilin, China. The symptoms were observed in 20% of the plants of a 2 ha-1 field of Schisandra chinensis. About 50% of the leaf areas were affected. As the disease developed, the lesions grew larger and developed necrotic centers. Leaves with light brown spot symptoms from five plants were collected from the field. Five leaf pieces (3 to 5 mm2) were excised from lesion margins, surface sterilized based on Ju et al. (Ju et al. 2021), and incubated on potato dextrose agar (PDA) at 25°C. Six single spores were isolated from five independently infected isolates for pure culture using the single spore isolation technique (Zhang. 2003). Representative single spore isolate (ZWWZH) was selected from pure cultures for further culture. After 5 days, fluffy white aerial mycelium with pink pigmentation on the underside of the colony were observed on PDA. Mycelia became pinkish-brown as the culture aged. Microscopic observations showed the presence of elongated or pointed, and thick-walled macroconidia (n = 50), predominantly three septate, 3.40 to 7.50 × 40.34 to 61.29 μm were observed. Chlamydospores formed in chains within or on top of the mycelium. The primers ITS1/ITS4 (White et al. 1990) and Bt-2a/Bt-2b (Robideau et al., 2011) were used to amplify the internal transcribed spacer (ITS) rDNA and β-tubulin (TUB2) region, respectively. The obtained sequences were submitted to GenBank under accession numbers for OQ629789 (ITS) and OQ803521(TUB2). BLASTn analysis of both ITS sequence and TUB2 sequence, revealed 100% and 99.92% sequence identity with F. acuminatum MT566456, MT560377 and KJ396328, respectively. The pathogen was identified as F. acuminatum based on morphological and molecular data. Pathogenicity tests were carried out in the greenhouse. Select five healthy Schisandra chinensis seedlings, each with each healthy leaf surfaces inoculated a 1 × 106 spores/mL solution, 3 wells on one side, 10 µL per well. Sterile ddH2O was used in the control experiment. The inoculated seedlings were incubated at 25°C with a relative humidity of 65 to 70% in a greenhouse. Four days after inoculation, all inoculated leaves exhibited the same symptoms as observed in the field, while the controls showed no symptoms. The experiment was repeated three more times with similar results. The re-isolated fungi from the inoculated plants had the same morphology and DNA sequences as the original isolate (ZWWZH) obtained from the field samples, completing Koch's postulates. To our knowledge, this is the first report of F. acuminatum causing leaf spot on Schisandra chinensis in China. F. acuminatum has seriously affected the quality of Schisandra chinensis production. The identification of leaf spot caused by F. acuminatum will enable farmers to identify practices to minimize disease on this important crop.

Physiological and molecular responses of Trollius chinensis seedlings to waterlogging stress and subsequent drainage

Waterlogging led by extreme rainfall events is one of the major natural disasters under the global climate change context, putting plants under water stress. However, systematical studies on the response mechanisms in leaves to waterlogging are limited. We explored major leaf characteristics of oxidative stress and scavenging, photosynthesis, and osmotic regulations of Trollius chinensis. Two levels of waterlogging serverities (moderate level, W1, and severe level, W2) were studied on the 1st (D1), 5th (D5), 10th (D10), and 15th day (D15) upon waterlogging and on the subsequent 10th day after drainage (R10). In addition, based on physiological indicators, the leaves in control and W2 on D10 were selected for RNA-Seq. We found that most of physiological characteristics presented the greatest differences between control and waterlogging groups on D10 such as O2.-, SOD, and proline, while some other characteristics such as H2O2, POD, and GR showed highest change from control on D15. Furthermore, on R10, most of the physiologcial characteristics recovered in different levels, which indicates that this species is relative waterlogging-tolerant. The results also showed that out of 1182 differentially expressed genes (307 up-regulated and 875 down-regulated) obtained in W2 vs control, ‘photosynthesis’, ‘plastid’, ‘chloroplast’, ‘thylakoid’, and ‘chlorophyll-binding’ were the Gene Ontology (GO) enrichment hotspots, and ‘photosynthesis’, ‘photosynthesis-antenna proteins’, and ‘carbon fixation in photosynthetic organisms’ were the most enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The expression of genes related to the photosynthesis, amylase, calcineurin interacting protein kinases (CIPKs), glutathione-S-transferase (GST), and ethylene response factor (ERF) decreased, while the expression of some genes related to antioxidation, osmoregulation, and transcription factors belonging to MYB (Myb proto-oncogene protein) and NAC ((NAM, ATAF1/2, and CUC2) families increased, implying that these genes play key roles in T. chinensis to cope with waterlogging stress. We conclude that T. chinensis is a waterlogging-tolerant species and 10 days of severe waterlogging has induced changes of antioxidant, photosynthesis, and osmoregulation in physiological and transcriptome level. The present study provides candidate genes that can be used for waterlogging-resistant breeding in T. chinensis.

Study on the Rooting Physiological Mechanism of Schisandra chinensis (Turcz.) Baill. Green-Branched Cuttings

Schisandra chinensis (Turcz.) Baill. is an important medicinal plant in northeast China. Cutting propagation is an effective method for the rapid propagation of many tree species. This research aimed to determine a suitable growing medium and appropriate root hormone type, concentration and treatment time through the utilization of different substrates and hormones to treat one-year-old branches of S. chinensis. The optimal treatment achieved a rooting rate of 60% with 225 ppm ABT and 75 ppm NAA for 2.5 h. The substrate of vermiculite/perlite = 1:1 (urea+potassium) was beneficial to the adventitious root formation, which reached 79%. The adventitious root primordium of S. chinensis originated from the junction of the xylem and cambium. ABT and NAA treatments altered the peak timing of POD, PPO and IAAO in S. chinensis cuttings. During the adventitious root formation of S. chinensis cuttings, the high endogenous IAA concentration promoted the occurrence of adventitious roots in the early stage and the lower endogenous IAA and GA3 concentrations promoted the elongation and growth of adventitious roots in the later period. Low ABA and ZR concentrations enabled adventitious root formation and elongation. An efficient cutting propagation system would enable the mass propagation of S. chinensis seedlings.

Effect of Pb Stress on Ionome Variations and Biomass in Rhus chinensis Mill

This study examined changes in the ionome of Rhus chinensis in response to Pb stress so as to understand Pb phytotoxicity-related processes and provide theoretical support for improving the efficiency of this plant in remediating heavy metal-polluted soils. Rhus chinensis seedlings were cultured in pots with soil. The concentrations of 12 elements in the roots, stems, and leaves of the seedlings under treatments of 0, 500, and 1000 mg·kg−1 Pb(NO3)2 were determined. Principal component analysis (PCA), correlation analysis, and partial least squares path modeling (PLS-PM) were used to analyze the contributions of the affected elements in the ionomes of different organs of the seedlings under Pb stress. PCA showed that 74% of the total ionome variation was caused by the difference in organ types. N, Mg, K, Cu, Ca, and Zn were the important elements contributing to the variation of the ionome. Pb disturbed the ionome of different organs at varying levels, and the order of the interference levels between the organs was: stem > root > leaf. Correlation analysis showed that biomass had a significant positive correlation with N and K and a significant negative correlation with Pb, Mn, and the C:N ratio. Stem biomass had a significant positive correlation with Ca, Cu, and the N:P ratio. Root biomass had a significant negative correlation with the C:P ratio. PLS-PM analysis indicated that Pb stress had a major, direct, and inhibitory effect on biomass. The variation of ionomic profiles caused by Pb stress was mainly caused by the difference in organ types; the variation of the ionomic profiles of each organ was mainly caused by Pb stress. The elements that caused the variation of ionomic profiles varied with organ types, and the plant biomass was directly affected by a strong Pb poisoning effect and indirectly affected by a weak ionomic profile variation effect.

Genes related to osmoregulation and antioxidation play important roles in the response of Trollius chinensis seedlings to saline-alkali stress.

Saline-alkali stress is one of the main abiotic stress factors affecting plant growth and development. Trollius chinensis is a perennial herbal medicinal plant with high values for garden application. However, its response and tolerance to saline-alkali stress is unclear. In this study, we mixed four salts (NaCl: Na2SO4: NaHCO3: Na2CO3) with a concentration ratio of 1:9:9:1, and applied low (40 and 80 mM) and high (120 and 160 mM) saline-alkali stress to analyze osmotic regulation substances, antioxidant systems and the gene expression of T. chinensis. Along with higher saline-alkali stress, the leaf relative water content (RWC) started to decrease only from high stress, while the malondialdehyde (MDA) content in leaves decreased continuously, and the contents of proline (Pro), soluble sugar (SS) and soluble protein (SP) increased compared with control. The activities of antioxidant enzymes and the contents of non-enzymatic antioxidants were increased positively with the accumulation of superoxide anion (O2 •-) and hydrogen peroxide (H2O2). For instance, the ascorbic acid-glutathione (AsA-GSH) cycle was enhanced in T. chinensis seedling leaves subject to saline-alkali stress. Principal Component Analysis (PCA) indicates that MDA, Pro, SS, SP, H2O2, O2 •-, and GSH are important indexes to evaluate the response and tolerance of T. chinensis to saline-alkali stress. Through RNA-Seq, a total of 474 differentially expressed genes (DEGs) were found in plant under low saline-alkaline stress (40 mM, MSA1) vs. control. Among them, 364 genes were up-regulated and 110 genes were down-regulated. DEGs were extensively enriched in carbohydrate transport, transferase activity, zeatin biosynthesis, ABC transporters, and spliceosome. The transcription factor family MYB, BZIP, WRKY, and NAC were related to its saline-alkali tolerance. In addition, some DEGs encode key enzymes in the processes of osmoregulation and antioxidation, including betaine aldehyde dehydrogenase (BADH), inositol monophosphatase (IMP), chloroperoxidase (CPO), thioredoxin (Trx), and germin-like protein (GLPs) were found. Overall, these findings provide new insights into the physiological changes and molecular mechanism of T. chinensis to saline-alkali stress and lay a foundation for application of T. chinensis in saline-alkali environment.

Physiological and Molecular Responses of Trollius Chinensis Seedlings to Waterlogging Stress and Subsequent Drainage

Physiological and Molecular Responses of Trollius Chinensis Seedlings to Waterlogging Stress and Subsequent Drainage

Hazel (Corylus L.) and hazelnut (Corylus domestica Kos. Et Opal.) pollen

Aim. Wild hazel species (Corylus L.), and hazelnut (Corylus domestica Kos. et Opal.) cultivars are the monoecious anemophilous plants of the birch family (Betulaceae Gray). Due to the early spring catkins bloom of most Corylus, which occurs in March–April in Ukraine, their flowers may be damaged by late spring frosts, causing a decrease in the yield of nuts. That's why the study of the characteristics of the male gametophyte is of general scientific and applied importance for breeding and fruit growing. Methods. Study of pollen of hazelnut cultivars, representatives of C. avellana L., and C. chinensis Franch. from the collection of NDP "Sofiyivka" of the National Academy of Sciences of Ukraine was done using standard methods. Results. It turned out that the pollen of the ‘Sofiyivsky 15’ (cultivar selected from the hybrid population of ‘Garibaldi’×C. chinensis seedlings) had a greater likeness to paternal parent pollen than maternal parent pollen. According to the fertility, size, and shape of pollen grains, the pollen studied by Corylus spp. is characterized by a slight cultivar-form-species polymorphism. Conclusions. The studied species and forms of Corylus L., and Corylus domestica Kos. et Opal. cultivars were characterized by sufficient levels of pollen fertility for their cultivation in hazelnut orchards of all agro-climatic zones of Ukraine.

Trait value and phenotypic integration contribute to the response of exotic Rhus typhina to heterogeneous nitrogen deposition: A comparison with native Rhus chinensis

The temporal heterogeneity of nitrogen availability in soils is increasing due to agricultural deposition. We here compared the effects of gradually increasing nitrogen deposition rate and its increasing temporal heterogeneity patterns on the functional traits of seedlings of exotic species Rhus typhina and the native species Rhus chinensis. Nitrogen deposition rates of 0, 8, 20 g N m−2 year−1 and constant, single-peak, and double-peak nitrogen were added to simulate deposition rate and temporal heterogeneity. After 60 days of treatment, R. typhina seedlings had several advantageous growth trait values, such as higher total biomass production, but lower phenotypic plasticity than R. chinensis seedlings. R. typhina seedlings also had higher phenotypic integration, measured as the correlation among functional traits. The increased nitrogen deposition rate affected several traits of the two species differently. Thus, while R. chinensis seedlings allocated more biomass to leaves and less to roots with increasing N deposition, R. typhina seedlings had stable biomass allocation among all N treatments. Chlorophyll content, leaf phosphorus concentration, and water use efficiency increased, but the maximum net photosynthetic rate decreased, with N availability in R. chinensis, but not in R. typhina. Temporal heterogeneity had no significant effect on the total biomass of R. typhina and R. chinensis seedlings. Overall, the performance of R. typhina is better than that of R. chinensis seedlings under different nitrogen deposition treatments, which is due to the significantly advantageous trait values and greater phenotypic integration of R. typhina seedlings, whereas R. chinensis seedlings have higher phenotypic plasticity.

Physiological and Metabolic Responses of Leymus chinensis Seedlings to Alkali Stress.

To elucidate the physiological and metabolic mechanism of perennial grass responses to alkali stress, we selected Leymus chinensis (L. chinensis), a salt-tolerant perennial rhizomatous species of the family Poaceae as experimental material. We conducted a pot experiment in a greenhouse and measured the biomass, physiological characteristics, metabonomic, and corresponding metabolites. Our results showed that alkali stress significantly inhibited seedling growth and photosynthesis, which caused ion imbalance and carbon deficiency, but the alkali stress significantly increased the nitrogen and ATP contents. The metabolic analysis indicated that alkali stress markedly enhanced the contents of nucleotides, amino acids, and organic acids, but it decreased soluble sugar contents. Pathway enrichment analysis showed that the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle, which was related to nitrogen metabolism, was most significantly affected by alkali stress. The contents of glutamine synthetase (GS) and glutamate synthetase (GOGAT) involved in this pathway were also significantly increased. Our results not only verified the important roles of some amino acids and organic acids in resisting alkali stress, but also further proved that nucleotides and the GS/GOGAT cycle related to nitrogen metabolism played critical roles for seedlings in response to alkali stress.

Growth of Falcataria moluccana and Albizia chinensis seedling under aluminum exposure

Abstract. Salim MA, Setyaningsih L, Wahyudi I, Budi SW. 2021. Growth of Falcataria moluccana and Albizia chinensis seedling under aluminum exposure. Biodiversitas 22: 3693-3701. Aluminum (Al) is an element found in acid soils and is one of the limiting factors for plant growth. This study aims to examine the growth of Falcataria moluccana (Miq.) Barneby & J.W.Grimes and Albizia chinensis (Osbeck) Merr seedlings under exposure of aluminum. This study used an one-factor completely randomized design (Al concentration) consisting of 5 levels, namely 0, 2, 4, 6, and 8 mM. Each treatment was repeated 3 times and each replication consisted of 3 plant units. The results showed that the Al exposure treatment gave significant differences in the growth of height, root length, dry weight (root, shoot, and total) of F. moluccana and A. chinensis seedlings. The 2 mM Al concentration stimulated the growth of height, root length and dry weight (root, shoot, and total) of A. chinensis seedlings. The tolerance index for F. moluccana and A. chinensis seedlings was highest when the Al 2 mM concentration was 147.55% and 115.32%, respectively. 2 mM Al exposure treatment increased the chlorophyll content a, b, total chlorophyll and carotenoids of F. moluccana and A. chinensis seedlings. Al exposure treatment did not significantly differ from the rate of photosynthesis and MDA content in F. moluccana and A. chinensis seedlings. The Al content in the roots was higher than in the shoots, and the increase in Al concentration increased the Al content in the roots and shoots of F. moluccana and A. chinensis seedlings.

Emergence and development of Dianthus chinensis and Limonium sinuatum seedlings on commercial substrate

Limonium sinuatum and Dianthus chinensis are plant species of great importance in Brazilian floriculture, being propagated by seed, therefore, the characteristics of the substrates used are respectable in seedlings emergence and development process. Thus, the objective of this research was to evaluate the influence of two commercial substrates on emergence and development of Limonium sinuatum and Dianthus chinensis seedlings. The experiment was conducted in a greenhouse (Pad & Fan type) at São Paulo State University. The treatments were: T1 – Basaplant® and T2 – Tropstrato®, for both species, whose seeds were germinated in expanded polystyrene trays of 128 cells, being eight replicates, containing 8 seeds/replicate. The evaluated traits were: percentage of emergence, emergence speed index, mean emergence time, shoot height, root length and seedlings fresh and dry mass. The substrate characteristics evaluated were: pH, electrical conductivity, macroporosity, microporosity, total porosity, density and water retention capacity. The experimental design was completely randomized, and data were submitted to analysis of variance to Tukey test at 5% to compare the means. The emergence of Limonium sinuatum and Dianthus chinensis were impaired, possibly due to low electrical conductivity provided by substrates. However, Basaplant® substrate favoured the development of evaluated species in relation to aerial part length, root length and total fresh and dry mass, which is recommended for using as substrate for both species.

Isolation and identification of pathogen causing damping off at seedling stage of Trollius chinensis

Trollius chinensis is a traditional Chinese medicinal material in China, the wild resource of T. chinensis are now exhausted, and commercial medicinal T. chinensis mainly depends on artificial cultivation. As one of the most severely happened diseases at the seedling period, damping off has been a serious threaten to the breeding of T. chinensis seedlings. However, no related research have been reported so far. So, the authors collected damping-off samples of T. chinensis in 2018 from seedling breeding nursery in Guyuan, Hebei province, and carried out study on taxonomic identification of the pathogen. Damping off occurs in the T. chinensis production area from mid-May to late June every year. At the beginning, brown lesions were observed on the basal stem, then the lesions circumferential expanded and constricted, and finally resulted in the fall and death of T. chinensis seedlings. Pathogenic isolate was growing rapidly on the PDA medium, well developed aerial mycelia were grey white at first, then turned brown gradually, and a great number of small dark brown sclerotia were developed in the middle and periphery of the colony. Mycelial diameter of the pathogen was about 7 to 10 μm, near right angle or acute angle branches, near branches with septa, branches and septa with constriction. After the healthy T. chinensis seedlings were inoculated by pathogenic isolate, damping-off was observed soon, and the symptom was as same as those observed in the field. Through homogenous blast, the rDNA-ITS sequence of the pathogenic isolate shown 99.49% to 99.84% homology with Rhizoctonia solani, R. solani AG-1 IC mycelium anastomosis group and Thanatephorus cucumeris, the sexual type of Rhizoctonia. Furthermore, obvious mycelial anastomosis phenomena were observed when the pathogenic isolate and R. solani AG-1 IC strain were confronting cultured. Based on the results above, the pathogenic isolate causing damping off of T. chinensis was identified as R. solani AG-1 IC mycelial anastomosis group. RESULTS:: in the present work have important significance for further research on basic biology of the pathogen and integrated control of damping off causing by it on T. chinensis.

Nitrogen deposition regulates the clonal growth of Leymus chinensis, a typical clonal plant in arid and semi-arid regions

Purpose The purpose of this study is to examine the effects of nitrogen (N) deposition on clonal growth in a rhizome clonal plant, Leymus chinensis (Trin.) Tzvel. Design/methodology/approach The study established seven N concentration gradients (0, 2, 4, 8, 16, 32 and 64 g N m−2) to simulate the continuous increase in N deposition for the cultivation of L. chinensis seedlings and assess the response mechanism of the cloned L. chinensis plant at different N levels by analyzing the aboveground and belowground plant appearance traits, parent ramets and daughter ramets of resource allocation and biomass allocation. Findings The results of this study showed that the different N treatment levels could promote clonal growth and had certain regularity under the seven treatments. The addition of N could significantly increase the ramet number, rhizome length, rhizome spacer length, biomass of mother ramets, daughter ramets and belowground L. chinensis population when the N addition was greater than 4 g m−2; however, the clonal growth ability of L. chinensis decreased and the rhizome length, ramet number, stem and leaf biomass of daughter ramets and stem biomass of mother ramets significantly decreased when the N addition was greater than 32 g N m−2. Originality/value With global warming, atmospheric N deposition is increasing and it is of great significance to explore the response mechanism of different N levels for the growth of clone plants. This study provides basic data and a theoretical basis for the survival prediction of cloned plants under the background of a global climate change strategy and has important theoretical and practical significance for the scientific management of grasslands in the future.

Effects of 1-aminobenzotriazole on the growth and physiological characteristics of Tamarix chinensis cuttings under salt stress

Vegetation restoration is a main ecological remediation technology for greening saline and alkaline soils. The objectives of this study were to determine the effect of 1-aminobenzotriazole (ABT-1) on the growth and physiology of Tamarix chinensis under salt stress and to determine a suitable ABT-1 concentration and soil salinity (Sc) for propagating T. chinensis-cuttings. Cuttings were soaked in water and ABT-1 solutions at three concentrations(50, 100, and 200 mg L−1) and propagated in pots containing four soil salinity levels, mild (0.3%), moderate (0.6%), and severe (0.9% and 1.2%), and compared with a control. The cuttings were measured to determine growth indices and physiological and biochemical indices (e.g., chlorophyll content, superoxide dismutase activity, peroxidase activity, and malondialdehyde content). ABT-1 was effective in improving survival, growth, and physiological processes of cuttings under salt stress. However, there was a threshold effect when using ABT-1 to facilitate propagation under salt stress. ABT-1 effects were insignificant when applied at low concentrations ( 100 mg L−1), ABT-1 limited growth and physiological activities. Under a salt stress level (Sc ≤ 0.9%), ABT applied at a 100 mg L−1 concentration increased chlorophyll content and superoxide dismutase and peroxidase activities in the leaves and reduced malondialdehyde accumulation and membrane lipid peroxidation effects. As a result, ABT-1 enhanced the resistance of T. chinensis to salt stress. However, under high salt stress (> 0.9%) and ABT-1 concentration (> 100 mg L−1), the physiological regulatory ability of T. chinensis seedlings weakened. T. chinensis grew well at a salt stress ≤ 0.9% and ABT ≤ 100 mg L−1 and exhibited relatively high physiological regulatory ability and high salt adaptability

Effects of Simulated Nitrogen Deposition on the Growth and the Content of Non-structure Carbohydrate of Sinocalycanthus chinensis Seedlings

Effects of Simulated Nitrogen Deposition on the Growth and the Content of Non-structure Carbohydrate of Sinocalycanthus chinensis Seedlings