Methyl jasmonate regulated diploid and tetraploid black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.) tolerance to salt stress

Methyl jasmonate (MeJA) is an essential and promising plant growth regulation factor that can improve plant development and growth. Here, we explored the mechanism by which MeJA regulates the tolerance of black locust (Robinia pseudoacacia L.) to salt stress. In this study, diploid and tetraploid R. pseudoacacia were subjected to three treatments: 500 mM NaCl; 100 μM MeJA; and 500 mM NaCl and 100 μM MeJA, and the changes in plant growth, endogenous MeJA levels and the anti-oxidative metabolism of leaves were investigated. The results showed that salt stress significantly inhibited plant growth and induced the accumulation of Na⁺ and Cl^? ions, malondialdehyde (MDA) content and reactive oxygen species. However, these adverse effects could be alleviated by applying MeJA, which was followed by a marked increase in the activities of antioxidant enzymes. In addition, some genes encoding several antioxidant enzymes were also up-regulated. Simultaneously, the endogenous MeJA content in MeJA-treated plants was lower than in salt-treated plants. It is noteworthy that tetraploids always possessed higher salt tolerance and obtained greater positive effects from MeJA than diploids. These results suggested that MeJA might play a protective role in defense responses, enabling diploid and tetraploid black locust, especially tetraploid, to better tolerate the adverse effects of salt stress.     

A sucrose non-fermenting-1-related protein kinase 1 gene from potato, <Emphasis Type="Italic">StSnRK1</Emphasis>, regulates carbohydrate metabolism in transgenic tobacco

Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) has been shown to play an essential role in regulating saccharide metabolism and starch biosynthesis of plant. The regulatory role of StSnRK1 from potato in regulating carbohydrate metabolism and starch accumulation has not been investigated. In this work, a cDNA encoding the SnRK1 protein, named StSnRK1, was isolated from potato. The open reading frame contained 1545 nucleotides encoding 514 amino acids. Subcellular localization analysis in onion epidermal cells indicated that StSnRK1 protein was localized to the nucleus. The coding region of StSnRK1 was cloned into a binary vector under the control of 35S promoter and then transformed into tobacco to obtain transgenic plants. Transgenic tobacco plants expressing StSnRK1 were shown to have a significant increased accumulation of starch content, as well as sucrose, glucose and fructose content. Real-time quantitative PCR analysis indicated that overexpression of StSnRK1 up-regulated the expression of sucrose synthase (NtSUS), ADP-glucose pyrophosphorylase (NtAGPase) and soluble starch synthase (NtSSS III) genes involved in starch biosynthesis in the transgenic plants. In contrast, the expression of sucrose phosphate synthase (NtSPS) gene was decreased in the transgenic plants. Meanwhile, enzymatic analyses indicated that the activities of major enzymes (SUS, AGPase and SSS) involved in the starch biosynthesis were enhanced, whereas SPS activity was decreased in the transgenic plants compared to the wild-type. These results suggest that the manipulation of StSnRK1 expression might be used for improving quality of plants in the future.     

Improvement of bioactive compound accumulation in adventitious root cultures of an endangered plant species, <Emphasis Type="Italic">Oplopanax elatus</Emphasis>

Efficiently culturing adventitious roots (ARs) has become an alternative route for the protection and utilization of endangered plant resources. In the present study, to improve accumulation of bioactive compounds (polysaccharides, phenolics, and flavonoids) in AR cultures of endangered plant species—Oplopanax elatus—effects of methyl jasmonate (MeJA) and salicylic acid (SA) were investigated. The optimal concentration of MeJA was 200 μM and SA was 100 μM for enhancement of polysaccharide, phenolic, and flavonoid contents. In addition, MeJA (200 μM) was more suitable than SA (100 μM) for polysaccharide and flavonoid production, but both elicitors were equally favorable for phenolic production. During AR bioreactor culture, MeJA was as an elicitor to study the effect of its addition time and contact time. Contents of polysaccharides, phenolics, and flavonoids increased when MeJA was added to culture medium after 40 days of culture, but the increased degree was lower and the AR biomass significantly inhibited. However, when MeJA was added to culture medium after 30 days of culture, polysaccharide, phenolic, and flavonoid contents dramatically increased without AR biomass decrease; the maximum productivity of three bioactive compounds was found on day 8 after the MeJA treatment. Therefore, a novel elicitation method during bioreactor culture of O. elatus ARs was established in the present study, the method could be applied to commercial production of O. elatus products in the future.     

The Response of Physiological Characteristics,Expression of OSC Genes,and Accumulation of Triterpenoids in <Emphasis Type="Italic">Betula platyphylla</Emphasis> Sukto MeJA and SA Treatment

The pentacyclic triterpenoids from birch (Betula platyphylla suk) have broad pharmacological activities and can be potentially used for the development of anti-cancer and anti-AIDS drugs. In this study, we explored the effects of spraying 3-year-old white birch with different concentration of methyl jasmonate (MeJA) and salicylic acid (SA) on the expression of key genes in triterpenoid biosynthesis pathways and on the accumulation and physiological characteristics of triterpenoids in birch saplings. The results showed that spraying different concentration of MeJA and SA could obviously promote accumulation of total triterpenoids in 3-year-old white birch. The triterpenoid content in the stem bark was increased by 46.11 %, reaching 81.86 mg/g, after 1 day of treatment with 1 mmol·L^?1 MeJA (MJ2), and by 45.07 %, reaching 91.4 mg/g, after 14 days of treatment with 5 mmol·L^?1 SA (SA1). In addition, MeJA and SA treatment increased the contents of chlorophyll a and b, antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as photosynthetic performance, and affected the content of soluble sugar and soluble protein in birch leaf. Fluorescence quantitative polymerase chain reaction (qPCR) results showed that MeJA and SA treatment deferentially enhanced the key gene expression of cycloartenol synthase (BPX and BPX2), lupeol synthase (BPW) and beta-amyrin synthase (BPY) in triterpenoid synthesis pathway in birch bark and leaves. The results showed that MeJA and SA induced triterpenoid synthesis of birch plant is closely related with not only the expression of key genes of triterpenoid synthesis pathway but also photosynthesis, anti-stress response and physiological indexes, suggesting that regulation of triterpenoid synthesis of birch by MeJA and SA may involve in more complex mechanisms at physiological and molecular levels.     

Constitutive expression of <Emphasis Type="Italic">SlTrxF</Emphasis> increases starch content in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

The plastidic thioredoxin F-type (TrxF) protein plays an important role in plant saccharide metabolism. In this study, a gene encoding the TrxF protein, named SlTrxF, was isolated from tomato. The coding region of SlTrxF was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis thaliana. The transgenic Arabidopsis plants exhibited increased starch accumulation compared to the wild-type (WT). Real-time quantitative PCR analysis showed that constitutive expression of SlTrxF up-regulated the expression of ADP-glucose pyrophosphorylase (AGPase) small subunit (AtAGPase-S1 and AtAGPase-S2), AGPase large subunit (AtAGPase-L1 and AtAGPase-L2) and soluble starch synthase (AtSSS I, AtSSS II, AtSSS III and AtSSS IV) genes involved in starch biosynthesis in the transgenic Arabidopsis plants. Meanwhile, enzymatic analyses showed that the major enzymes (AGPase and SSS) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to WT. These results suggest that SlTrxF may improve starch content of Arabidopsis by regulating the expression of the related genes and increasing the activities of the major enzymes involved in starch biosynthesis.     

Overexpression of UDP-glucose dehydrogenase from <Emphasis Type="Italic">Larix gmelinii</Emphasis> enhances growth and cold tolerance in transgenic <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Uridine diphosphate glucose dehydrogenase (UGDH) plays an important role in biosynthesis of hemicellulose by catalyzing oxidation of UDP-glucose (UDP-Glc) to UDP-glucuronate (UDP-GlcA), a key sugar nucleotide involved in biosynthesis of the plant cell wall. In this study, a UGDH ortholog referred to as LgUGDH was isolated from Larix gmelinii using PCR and rapid amplification of cDNA ends techniques. Real-time PCR shows that the LgUGDH gene was expressed primarily in larch stems in addition to its roots and leaves, and Southern blot analysis indicates that UGDH is encoded by two paralogous genes in L. gmelinii. Overexpression of LgUGDH increased the content of soluble sugars and hemicelluloses and enhanced vegetative growth and cold tolerance in transgenic Arabidopsis thaliana. These results reveal that L. gmelinii UGDH participates in sucrose/polysaccharide metabolism and cell wall biosynthesis and may be a good candidate gene for enhancing plant growth, cold tolerance, and hemicellulose content.     

A tomato plastidic ATP/ADP transporter gene <Emphasis Type="Italic">SlAATP</Emphasis> increases starch content in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

A plastidic ATP/ADP transporter (AATP) is responsible for importing ATP from the cytosol into plastids. Increasing the ATP supply is a potential way to facilitate anabolic synthesis in heterotrophic plastids of plants. In this work, a gene encoding the AATP protein, named SlAATP, was successfully isolated from tomato. Expression of SlAATP was induced by exogenous sucrose treatment in tomato. The coding region of SlAATP was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis to obtain transgenic plants. Constitutive expression of SlAATP significantly increased the starch accumulation in the transgenic plants. Real-time quantitative PCR (qRT-PCR) analysis showed that constitutive expression of StAATP up-regulated the expression of phosphoglucomutase (AtPGM), ADP-glucose pyrophosphorylase (AtAGPase), granule-bound starch synthase (AtGBSS I and AtGBSS II), soluble starch synthases (AtSSS I, AtSSS II, AtSSS III and AtSSS IV) and starch branching enzyme (AtSBE I and AtSBE II) genes involved in starch biosynthesis in the transgenic Arabidopsis plants. Meanwhile, enzymatic analyses indicated that the major enzymes (AGPase, GBSS, SSS and SBE) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to the wild-type (WT). These findings suggest that SlAATP may improve starch content of Arabidopsis by up-regulating the expression of the related genes and increasing the activities of the major enzymes invovled in starch biosynthesis. The manipulation of SlAATP expression might be used for increasing starch accumulation of plants in the future.     

Enhancement of starch content by constitutive expression of <Emphasis Type="Italic">GmTrxF</Emphasis> in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

The plastidic thioredoxin F-type (TrxF) protein plays an important role in plant carbohydrate metabolism biosynthesis. In this study, a gene encoding the TrxF protein, named GmTrxF, was isolated from soybean. The open reading frame (ORF) contained 540 nucleotides encoding 179 amino acids. The coding region of GmTrxF was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis. The starch content in GmTrxF expressing plants was increased by 57–109% compared to that in wild-type (WT). Real-time quantitative PCR (qRT-PCR) analysis showed that constitutive expression of GmTrxF up-regulated the expression of phosphoglucomutase (AtPGM), ADP-glucose pyrophosphorylase (AGPase) small subunit (AtAGPase-S1 and AtAGPase-S2), AGPase large subunit (AtAGPase-L1 and AtAGPase-L2) and soluble starch synthases (AtSSS I, AtSSS II, AtSSS III and AtSSS IV) genes involved in starch biosynthesis in the transgenic Arabidopsis plants. Meanwhile, enzymatic analyses showed that the major enzymes (AGPase and SSS) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to WT. These results suggest that GmTrxF may improve starch content of Arabidopsis by up-regulating the expression of the related genes and increasing the activities of the major enzymes invovled in starch biosynthesis. The manipulation of GmTrxF expression might be used for increasing starch accumulation of plants in the future.     

Effects of exogenous methyl jasmonate-induced resistance in <Emphasis Type="Italic">Populus</Emphasis> × <Emphasis Type="Italic">euramericana</Emphasis> ‘Nanlin895’ on the performance and metabolic enzyme activities of <Emphasis Type="Italic">Clostera anachoreta</Emphasis>

Methyl jasmonate (MeJA) is a plant chemical elicitor that has been used to artificially induce chemical defense responses and trigger induced resistance against a broad range of arthropod herbivores. This study assessed the effects of exogenous MeJA on the growth performance, chemical detoxification, and antioxidant enzyme activities of Clostera anachoreta. After feeding C. anachoreta with 10^?5 mol/L MeJA solution-treated Populus × euramericana ‘Nanlin895’ leaves, we measured the larval and pupal development time, pupal weight, eclosion rate, fecundity, and nutritional physiology of the adults. We also measured superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities, which are reactive oxygen species (ROS) scavengers, and glutathione S-transferase (GST) and carboxylesterase (CarE) activities, which are probably involved in the metabolism of induced plant allelochemicals. Methyl jasmonate (MeJA) treatment reduced larval performance in terms of prolonged developmental time of larvae and pupae and decreased growth rates, but had little effect on larval nutrition physiology. The activities of the SOD and POD antioxidant enzymes increased, but CAT activity declined at 36 and 48 h after C. anachoreta had fed on MeJA-treated leaves. The GST and CarE detoxification enzymes both were induced after the larvae had fed on MeJA-treated leaves. These results suggest that exogenous application of MeJA elicited induced resistance in Populus × euramericana ‘Nanlin895’ against C. anachoreta.     

A soybean plastidic ATP/ADP transporter gene, <Emphasis Type="Italic">GmAATP</Emphasis>, is involved in carbohydrate metabolism in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

The plastidic ATP/ADP transporter (AATP) imports adenosine triphosphate (ATP) from the cytosol into plastids, resulting in the increase of the ATP supply to facilitate anabolic synthesis in heterotrophic plastids of dicotyledonous plants. The regulatory role of GmAATP from soybean in increasing starch accumulation has not been investigated. In this study, a gene encoding the AATP protein, named GmAATP, was successfully isolated from soybean. Transient expression of GmAATP in Arabidopsis protoplasts and Nicotiana benthamiana leaf epidermal cells revealed the plastidic localization of GmAATP. Its expression was induced by exogenous sucrose treatment in soybean. The coding region of GmAATP was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis to obtain transgenic plants. Constitutive expression of GmAATP significantly increased the sucrose and starch accumulation in the transgenic plants. Real-time quantitative PCR (qRT-PCR) analysis showed that constitutive expression of GmAATP up-regulated the expression of phosphoglucomutase (AtPGM), ADP-glucose pyrophosphorylase (AGPase) small subunit (AtAGPase-S1 and AtAGPase-S2), AGPase large subunit (AtAGPase-L1 and AtAGPase-L2), granule-bound starch synthase (AtGBSS I and AtGBSS II), soluble starch synthases (AtSSS I, AtSSS II, AtSSS III, and AtSSS IV), and starch branching enzyme (AtSBE I and AtSBE II) genes involved in starch biosynthesis in the transgenic Arabidopsis plants. Meanwhile, enzymatic analyses indicated that the major enzymes (AGPase, GBSS, SSS, and SBE) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to the wild type (WT). These findings suggest that GmAATP may improve starch content of Arabidopsis by up-regulating the expression of the related genes and increasing the activities of the major enzymes involved in starch biosynthesis. All these results suggest that GmAATP could be used as a candidate gene for developing high starch-accumulating plants as alternative energy crops.     

Lignan accumulation in two-phase cultures of <Emphasis Type="Italic">Taxus</Emphasis> x <Emphasis Type="Italic">media</Emphasis> hairy roots

The biosynthetic potential for six lignans accumulation in two lines of Taxus x media hairy roots was investigated. The cultures of KT and ATMA hairy root lines were supplemented with precursors: coniferyl alcohol (CA 1, 10 or 100 µM) and/or l-phenylalanine (100 µM PHEN) and/or methyl jasmonate (100 µM MeJa). Moreover the two-phase in vitro cultures supported with perfluorodecalin (PFD) as a gas carrier and in situ extrahent were used. The hairy root lines differed in lignan production profiles. In the control untreated cultures KT roots did not accumulate secoisolariciresinol and lariciresinol while ATMA roots did not accumulate matairesinol. In ATMA roots the treatment with CA (1 or 10 µM) resulted in the production of lariciresinol and secoisolariciresinol whereas solely lariciresinol was present after 100 µM CA application. Elicitation with 1 µM CA and MeJa yielded with hydroxymatairesinol aglyca and lariciresinol glucosides with their highest content 37.88 and 3.19 µg/g DW, respectively. The stimulatory effect of simultaneous treatment with 1 µM CA, PHEN and MeJa on lignan production was observed when the cultures were supplemented with PFD-aerated or degassed. In ATMA root cultures these applied conditions were the most favourable for matairesinol content which amounted to 199.86 and 160.25 µg/g DW in PFD-aerated and PFD-degassed supported cultures, respectively. In KT root cultures solely, hydroxymatairesinol and coniferin/CA content was enhanced with their highest yield 59.29 and 134.60 µg/g DW in PFD-aerated and PFD-degassed cultures, respectively.     

Effects of ALA on Photosynthesis,Antioxidant Enzyme Activity,and Gene Expression,and Regulation of Proline Accumulation in Tomato Seedlings Under NaCl Stress

This study examined the effects of 5-aminolevulinic acid (ALA) application on photosynthesis, activity and gene expression of key antioxidant enzymes, and on proline accumulation in tomato (Lycopersicon esculentum Mill. ‘Hezuo 903’) seedlings under NaCl stress. NaCl stress significantly decreased the net photosynthetic rates and inhibited the activity of photosystem II, whereas exogenous ALA application significantly restored the net photosynthetic rates, quantum yield of electron transport, and energy conversion efficiency of photosystem II of tomato under NaCl stress. Production of superoxide, hydrogen peroxide, and malondialdehyde strongly increased in response to NaCl stress, and these increases were significantly counteracted by ALA. ALA increased the activity of reactive oxygen species (ROS) scavenging antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, and upregulated the expression of SOD, APX, and POD, genes that encode these enzymes in NaCl-treated plants. ALA simultaneously increased proline accumulation in tomato seedlings under NaCl stress by regulating the expression of genes that encode ALA biosynthetic enzymes and that control proline biosynthesis and metabolism, for example, expression of GluRS and GluTR was downregulated, accompanied by a significant increase in the expression of P5CS and decline in the expression of ProDH. ALA provided protection against NaCl stress by increasing photosynthetic capacity, regulating antioxidant enzyme gene expression and proline accumulation, and decreasing ROS accumulation and lipid peroxidation in tomato.     

Abscisic acid,sucrose, and auxin coordinately regulate berry ripening process of the Fujiminori grape

The aim of this study was to examine the effect of abscisic acid (ABA), sucrose, and auxin on grape fruit development and to assess the mechanism of these three factors on the grape fruit ripening process. Different concentrations of ABA, sucrose, and auxin were used to treat the grape fruit, and the ripening-related indices, such as physiological and molecular level parameters, were analyzed. The activity of BG protein activity was analyzed during the fruit development. Sucrose, ABA, and auxin influenced the grape fruit sugar accumulation in different ways, as well as the volatile compounds, anthocyanin content, and fruit firmness. ABA and sucrose induced, but auxin blocked, the ripening-related gene expression levels, such as softening genes PE, PG, PL, and CELL, anthocyanin genes DFR, CHI, F3H, GST, CHS, and UFGT, and aroma genes Ecar, QR, and EGS. ABA, sucrose, and glucose induced the fruit dry weight accumulation, and auxin mainly enhanced fruit dry weight through seed weight accumulation. In the early development of grape, starch was the main energy storage; in the later, it was glucose and fructose. Sucrose metabolism pathway-related gene expression levels were significant for glucose and fructose accumulation. BG protein activity was important in the regulation of grape ABA content levels. ABA plays a core role in the grape fruit development; sucrose functions in fruit development through two pathways: one was ABA dependent, the other ABA independent. Auxin blocked ABA accumulation to regulate the fruit development process.     

Characteristic of Polysaccharide Complexes from <Emphasis Type="Italic">Centaurea scabiosa</Emphasis> L. and <Emphasis Type="Italic">Centaurea pseudomaculosa</Emphasis> Dobrocz.

We characterized polysaccharide complexes from Centaurea scabiosa L. and Centaurea pseudomaculosа Dobrocz. We proposed the technique of sequential selection of water-soluble polysaccharides and pectin substances from the aerial parts of studied objects. We have discovered that the content of water-soluble polysaccharides in the aerial parts of C. scabiosa was 2.8 times higher (2.7 ± 0.3%, n = 3) than in C. pseudomaculosа (0.97 ± 0.50%, n = 3). The content of pectin substances in the aerial parts of C. scabiosa was 2 times higher (7.6 ± 0.4%, n = 3) than in C. pseudomaculosа (3.9 ± 0.3%, n = 3). The residues of D-galacturonic acid, L-rhamnose, D-xylose, D-mannose, D-glucose, and D-galactose are the monomeric units of polysaccharide complexes from C. scabiosa and C. pseudomaculosa. Using ion-exchange chromatography, three polysaccharide fractions (molecular weights 667, 722, and 1027 kDa), whose monomer units are D-galacturonic acid, L-rhamnose, D-galactose, D-xylose, and D-glucose were isolated from the water-soluble polysaccharides of C. scabiosa.     

MeJA is more effective than JA in inducing defense responses in <Emphasis Type="Italic">Larix olgensis</Emphasis>

The roles of jasmonic acid (JA) and methyl jasmonate (MeJA) in improving the inducible resistance of plants to biotic and abiotic stimuli/stresses have been well investigated. However, the differences in inducing effects between exogenous applications of JA and MeJA are poorly understood. In this study, we compared the inducing effects of exogenous spray applications of 0.1 mmol/L JA and MeJA onto four un-bagged lateral branches on defense response of Larix olgensis seedlings against the gypsy moth (Lymantria dispar). The bio-activities of three major defense enzymes (SOD, PAL, and PPO) plus two protease inhibitors (TI and CI) of the unsprayed larch seedling needles, and the growth, development and reproductive capacity of the gypsy moth were examined. The results show that partial spray of JA or MeJA on L. olgensis seedlings significantly increased the bio-activities of SOD, PAL, PPO, TI, and CI (P < 0.05), and strongly decreased the larval/pupal weights and survivals, as well as the fecundity of L. dispar that fed on the seedlings relative to the control. However, the MeJA treatment showed quicker inductive effects on SOD and PAL activities; longer and more significant effects on PPO, TI, and CI activities; better inhibitory effects on the larval/pupal weights and survivals, as well as the fecundity of L. dispar than did the JA treatment. Comparatively, MeJA in the current study showed stronger effects on inducing systemic resistance to the defoliator (L. dispar) in L. olgensis than did JA.