chlorophyll-a and methyl-jasmonate

The commercial value of Santalum album L. lies in its aromatic heartwood and essential oil. Sesquiterpenes are the main components of sandal essential oil, and these are synthesized through the plant's mevalonate (MVA) and methylerythritol phosphate (MEP) pathways. In this study, the first key rate-limiting enzyme, 1-deoxy-d-xylulose-5-phosphate synthase (SaDXS), was investigated to provide a theoretical molecular basis for the sandalwood MEP sesquiterpene biosynthetic pathway. The biofunctions of SaDXS were also analyzed. SaDXS promoters were successfully cloned from a seven-year-old S. album tree. SaDXS1A/1B promoter activity was verified by a β-glucuronidase (GUS) assay and by analyzing cis-acting elements of the promoters, which carried light- and methyl jasmonate (MeJA)-responsive signals. In an experiment involving yellow S. album seedlings, exposure to light upregulated SaDXS1A/1B expression and increased chlorophyll and carotenoid contents when overexpressed in Arabidopsis thaliana. Analysis of the expression of SaDXS1A/1B and SaSSy, key genes of santalol biosynthesis, revealed SaDXS1A expression in all tissues whereas SaDXS1B was expressed in tissues that contained photosynthetic pigments, such as stems, leaves and flowers. Sandal seedlings exogenously treated with two hormones, MeJA and ethylene, revealed similar expression patterns for SaDXS1A/1B and SaSSy. Sandal seedlings were treated with an inhibitor of DXS, clomazone, but showed no significant changes in the contents of α-santalene, β-santalene and α-santalol between treatment and control groups. These results suggest that SaDXS1A/1B play a role in the synthesis of sandalwood sesquiterpenes, providing carbon for downstream secondary metabolites. SaDXS1A/1B also play a role in the biosynthesis of chlorophyll, carotenoids, and primary metabolites.

Topics: Chlorophyll; Cloning, Molecular; Oils, Volatile; Santalum; Sesquiterpenes

Salinity stress is the second most devastating abiotic factor limiting plant growth and yields. Climate changes have significantly increased salinity levels of soil. Besides improving the physiological responses under stress conditions, jasmonates modulate Mycorrhiza-Plant relationships. The present study aimed to evaluate the effects of methyl jasmonate (MeJ) and Funneliformis mosseae (Arbuscular mycorrhizal (AM) on morphology and improving antioxidant mechanisms in Crocus sativus L. under salinity stress. After inoculation with AM, pre-treated C. sativus corms with MeJ were grown under low, moderate, and severe salinity stress. Intense salinity levels damaged the corm, root, total leaf dry weight, and area. Salinities up to 50 mM increased Proline content and Polyphenol oxidase (PPO) activity, but MeJ increased this trend in proline. Generally, MeJ increased anthocyanins, total soluble sugars, and PPO. Total chlorophyll and superoxide dismutase (SOD) activity increased by salinity. The maximum catalase and SOD activities in + MeJ + AM were 50 and 125 mM, respectively, and the maximum total chlorophyll in -MeJ + AM treatment was 75 mM. Although 20 and 50 mM increased plant growth, using mycorrhiza and jasmonate enhanced this trend. Moreover, these treatments reduced the damage of 75 and 100 mM salinity stress. Using MeJ and AM can improve the growth of saffron under various ranges of salinity stress levels; however, in severe levels like 120 mM, this phytohormone and F. mosseae effects on saffron could be adverse.

Topics: Anthocyanins; Antioxidants; Chlorophyll; Crocus; Mycorrhizae; Plant Roots; Proline; Salinity; Salt Stress; Superoxide Dismutase

In this study, the effects of foliar applied methyl jasmonate (MeJA) on drought-stressed

Topics: Anthocyanins; Chlorophyll; Droughts; Impatiens; Plant Leaves; Water

We examined the control of chlorophyll biosynthesis and protective mechanisms during leaf senescence induced by methyl jasmonate (MeJA). After MeJA treatment, rice plants displayed evidence of great oxidative stress regarding senescence symptoms, disruption of membrane integrity, H

Topics: Antioxidants; Ascorbate Peroxidases; Chlorophyll; Cyclopentanes; Hydrogen Peroxide; Oryza

Methyl jasmonate (MeJA) plays a role in improving plant stress tolerance. The molecular mechanisms associated with heat tolerance mediated by MeJA are not fully understood in perennial grass species. The study was designed to explore transcriptomic mechanisms underlying heat tolerance by exogenous MeJA in perennial ryegrass (Lolium perenne L.) using RNA-seq. Transcriptomic profiling was performed on plants under normal temperature (CK), high temperature for 12 h (H), MeJA pretreatment (T), MeJA pretreatment + H (T-H), respectively. The analysis of differentially expressed genes (DEGs) showed that H resulted in the most DEGs and T had the least, compared with CK. Among them, the DEGs related to the response to oxygen-containing compound was higher in CKvsH, while many genes related to photosynthetic system were down-regulated. The DEGs related to plastid components was higher in CKvsT. GO and KEGG analysis showed that exogenous application of MeJA enriched photosynthesis related pathways under heat stress. Exogenous MeJA significantly increased the expression of genes involved in chlorophyll (Chl) biosynthesis and antioxidant metabolism, and decreased the expression of Chl degradation genes, as well as the expression of heat shock transcription factor - heat shock protein (HSF-HSP) network under heat stress. The results indicated that exogenous application of MeJA improved the heat tolerance of perennial ryegrass by mediating expression of genes in different pathways, such as Chl biosynthesis and degradation, antioxidant enzyme system, HSF-HSP network and JAs biosynthesis.

Topics: Acetates; Antioxidants; Chlorophyll; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Ontology; Gene Regulatory Networks; Lolium; Oxylipins; Plant Growth Regulators; Plant Proteins; Reproducibility of Results; Thermotolerance

In the methyl-D-erythritol-4-phosphate (MEP) pathway, 1-deoxy-D-xylose-5-phosphate synthase (DXS) is considered the key enzyme for the biosynthesis of terpenoids. In this study,

Topics: Acetates; Chlorophyll; Chlorophyll A; Computational Biology; Cyclopentanes; Escherichia coli; Gene Expression Profiling; Nicotiana; Oxylipins; Pentosephosphates; Pigmentation; Pinus; Plant Leaves; Plant Stems; Promoter Regions, Genetic; Recombinant Proteins; Salicylic Acid; Terpenes; Transferases; Xylose

Chlorophyll degradation is the main reason for postharvest yellowing of broccoli. To uncover the role of jasmonic acid (JA) on the degradation of chlorophyll, broccoli flowers were treated with exogenous methyl jasmonate (MeJA) and diethyldithiocarbamic acid (DIECA). We found a surge of endogenous JA content with the yellowing process, and a significant correlation between JA and chlorophyll content. MeJA treatments led to increased endogenous JA, increased allene oxide cyclase (AOC) activity, and enhanced expression of JA synthesis genes. MeJA caused a stronger reduction in the maximum quantum yield (Fv/Fm), fluorescence decline ratio (Rfd), and total chlorophyll content, advanced the peak of pheide a oxygenase (PAO) activity, and up-regulated the expression of chlorophyll degradation genes. The DIECA treatment resulted in lower endogenous levels of JA, and AOC and 12-oxo-phytodienoic acid reductase (OPR) activity. This study revealed that the potential role of JA on broccoli yellowing is to promote the chlorophyll degradation.

Topics: Acetates; Brassica; Chlorophyll; Cyclopentanes; Ditiocarb; Gene Expression Regulation, Plant; Intramolecular Oxidoreductases; Oxygenases; Oxylipins

Susceptibility of plants to abiotic stresses, including extreme temperatures, salinity and drought, poses an increasing threat to crop productivity worldwide. Here the drought-induced response of maize was modulated by applications of methyl jasmonate (MeJA) and salicylic acid (SA) to seeds prior to sowing and to leaves prior to stress treatment. Pot experiments were conducted to ascertain the effects of exogenous applications of these hormones on maize growth, physiology and biochemistry under drought stress and well-watered (control) conditions. Maize plants were subjected to single as well as combined pre-treatments of MeJA and SA. Drought stress severely affected maize morphology and reduced relative water content, above and below-ground biomass, rates of photosynthesis, and protein content. The prolonged water deficit also led to increased relative membrane permeability and oxidative stress induced by the production of malondialdehyde (from lipid peroxidation), lipoxygenase activity (LOX) and the production of H2O2. The single applications of MeJA and SA were not found to be effective in maize for drought tolerance while the combined pre-treatments with exogenous MeJA+SA mitigated the adverse effects of drought-induced oxidative stress, as reflected in lower levels of lipid peroxidation, LOX activity and H2O2. The same pre-treatment also maintained adequate water status of the plants under drought stress by increasing osmolytes including proline, total carbohydrate content and total soluble sugars. Furthermore, exogenous applications of MeJA+SA approximately doubled the activities of the antioxidant enzymes catalase, peroxidase and superoxide dismutase. Pre-treatment with MeJA alone gave the highest increase in drought-induced production of endogenous abscisic acid (ABA). Pre-treatment with MeJA+SA partially prevented drought-induced oxidative stress by modulating levels of osmolytes and endogenous ABA, as well as the activities of antioxidant enzymes. Taken together, the results show that seed and foliar pre-treatments with exogenous MeJA and/or SA can have positive effects on the responses of maize seedlings to drought.

Topics: Acetates; Antioxidants; Carotenoids; Chlorophyll; Cyclopentanes; Droughts; Osmolar Concentration; Oxidative Stress; Oxylipins; Plant Growth Regulators; Plant Proteins; Principal Component Analysis; Salicylic Acid; Seeds; Soil; Stress, Physiological; Zea mays

The effects of jasmonic acid (JA) and methyl jasmonate (Me-JA) on photosynthetic efficiency and expression of some photosystem (PSII) related in different cultivars of Brassica oleracea L. (var. italica, capitata, and botrytis) were investigated. Plants raised from seeds subjected to a pre-sowing soaking treatment of varying concentrations of JA and Me-JA showed enhanced photosynthetic efficiency in terms of qP and chlorophyll fluorescence. Maximum quantum efficiency of PSII (Fv/Fm) was increased over that in the control seedlings. This enhancement was more pronounced in the Me-JA-treated seedlings compared to that in JA-treated ones. The expression of PSII genes was differentially regulated among the three varieties of B. oleracea. The gene PsbI up-upregulated in var. botrytis after treatment of JA and Me-JA, whereas PsbL up-regulated in capitata and botrytis after supplementation of JA. The gene PsbM showed many fold enhancements in these expressions in italica and botrytis after treatment with JA. However, the expression of the gene PsbM increased by both JA and Me-JA treatments. PsbTc(p) and PsbTc(n) were also found to be differentially expressed which revealed specificity with the variety chosen as well as JA or Me-JA treatments. The RuBP carboxylase activity remained unaffected by either JA or Me-JA supplementation in all three varieties of B. oleracea L. The data suggest that exogenous application of JA and Me-JA to seeds before germination could influence the assembly, stability, and repair of PS II in the three varieties of B. oleracea examined. Furthermore, this improvement in the PS II machinery enhanced the photosynthetic efficiency of the system and improved the photosynthetic productivity in terms of saccharides accumulation.

Topics: Acetates; Brassica; Carbohydrate Metabolism; Carotenoids; Chlorophyll; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins; Photosynthesis; Photosystem II Protein Complex; Plant Shoots; Ribulose-Bisphosphate Carboxylase; Seedlings; Seeds; Sugars

Ozone (O

Topics: Acetates; Air Pollutants; Anthocyanins; Antioxidants; Chlorophyll; Cyclopentanes; Flavonoids; Malus; Metabolomics; Oxylipins; Ozone; Plant Growth Regulators; Plant Leaves; Transcription Factors; Transcriptome

Phytophthora capsici has been the most destructive pathogen of pepper plants (Capsicum annuum L.), possessing the ability to quickly overcome the host defense system. In this context, the chitin-binding protein (CBP) family member CaChiIV1 regulates the response to P. capsici and abiotic stresses. The relevance of functional characterization and regulation of CaChiIV1 has not been explored in horticultural crops, especially pepper plants. The target gene (CaChiIV1) was isolated from pepper plants and cloned; the encoded protein carries a chitin-binding domain (CBD) that is rich in cysteine residues and has a hinge region with an abundance of proline and glycine residues. Additionally, the conserved regions in the promoter have a remarkable motif, "TTGACC". The expression of CaChiIV1 was markedly regulated by methyl-jasmonate (MeJA), hydrogen peroxide (H

Topics: Acetates; Antioxidants; Capsicum; Chitin; Chlorophyll; Cyclopentanes; Droughts; Gene Expression Regulation, Plant; Gene Knockdown Techniques; Hydrogen Peroxide; Malondialdehyde; Mannitol; Melatonin; Oxylipins; Phytophthora; Plant Diseases; Plant Proteins; Promoter Regions, Genetic; Stress, Physiological

Transcriptomic analysis indicates that the bacterial signalling molecule lumichrome enhances plant growth through a combination of enhanced cell division and cell enlargement, and possibly enhances photosynthesis. Lumichrome (7,8 dimethylalloxazine), a novel multitrophic signal molecule produced by Sinorhizobium meliloti bacteria, has previously been shown to elicit growth promotion in different plant species (Phillips et al. in Proc Natl Acad Sci USA 96:12275-12280, https://doi.org/10.1073/pnas.96.22.12275 , 1999). However, the molecular mechanisms that underlie this plant growth promotion remain obscure. Global transcript profiling using RNA-seq suggests that lumichrome enhances growth by inducing genes impacting on turgor driven growth and mitotic cell cycle that ensures the integration of cell division and expansion of developing leaves. The abundance of XTH9 and XPA4 transcripts was attributed to improved mediation of cell-wall loosening to allow turgor-driven cell enlargement. Mitotic CYCD3.3, CYCA1.1, SP1L3, RSW7 and PDF1 transcripts were increased in lumichrome-treated Arabidopsis thaliana plants, suggesting enhanced growth was underpinned by increased cell differentiation and expansion with a consequential increase in biomass. Synergistic ethylene-auxin cross-talk was also observed through reciprocal over-expression of ACO1 and SAUR54, in which ethylene activates the auxin signalling pathway and regulates Arabidopsis growth by both stimulating auxin biosynthesis and modulating the auxin transport machinery to the leaves. Decreased transcription of jasmonate biosynthesis and responsive-related transcripts (LOX2; LOX3; LOX6; JAL34; JR1) might contribute towards suppression of the negative effects of methyl jasmonate (MeJa) such as chlorophyll loss and decreases in RuBisCO and photosynthesis. This work contributes towards a deeper understanding of how lumichrome enhances plant growth and development.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Bacterial Proteins; Biomass; Cell Division; Cell Enlargement; Cell Wall; Chlorophyll; Cyclopentanes; Ethylenes; Flavins; Gene Expression Profiling; Indoleacetic Acids; Oxylipins; Plant Growth Regulators; Plant Leaves; Signal Transduction; Sinorhizobium meliloti

The plastidial methylerythritol phosphate(MEP) pathway provides 5-carbon precursors to the biosynthesis of isoprenoid (including artemisinin). 2-C-Methyl-D-erythritol-4-phosphate cytidylyltransferase (MCT) is the third enzyme of the MEP pathway, which catalyzes 2-C-methyl-D-erythritol-4-phosphate to form 4-(cytidine 5’-diphospho)-2-C-methyl-D-erythritol. The full-length MCT cDNA sequence (AaMCT) was cloned and characterized for the first time from Artemisia annua L. Analysis of tissue expression pattern revealed that AaMCT was highly expressed in glandular secretory trichome and poorly expressed in leaf, flower, root and stem. AaMCT was found to be a methyl jasmonate (Me JA)-induced genes, the expression of AaMCT was significantly increased after MeJA treatment. Subcellular localization indicated that the GFP protein fused with AaMCT was targeted specifically in chloroplasts. The transgenic plants of Arabidopsis thaliana with AaMCT overexpression exhibited a significantly increase in the content of chlorophyll a, chlorophyll b and carotenoids, demonstrating that AaMCT kinase plays an influential role in isoprenoid biosynthesis.

Topics: Acetates; Arabidopsis; Artemisia annua; Artemisinins; Carotenoids; Chlorophyll; Chlorophyll A; Cloning, Molecular; Cyclopentanes; DNA, Complementary; Gene Expression Regulation, Plant; Nucleotidyltransferases; Oxylipins; Plant Proteins; Plants, Genetically Modified

In plants, extensive efforts have been devoted to understanding the crosstalk between salicylic acid (SA) and jasmonic acid (JA) signaling in pathogen defenses, but this crosstalk has scarcely been addressed during senescence. In this study, the effect of SA application on methyl jasmonate (MeJA)-induced leaf senescence was assessed. We found that low concentrations of SA (1-50 μM) played a delayed role against the senescence promoted by MeJA. Furthermore, low concentrations of SA enhanced plant antioxidant defenses and restricted reactive oxygen species (ROS) accumulation in MeJA-treated leaves. When applied simultaneously with MeJA, low concentrations of SA triggered a nitric oxide (NO) burst, and the elevated NO levels were linked to the nitric oxide associated 1 (NOA1)-dependent pathway via nitric oxide synthase (NOS) activity. The ability of SA to up-regulate plant antioxidant defenses, reduce ROS accumulation, and suppress leaf senescence was lost in NO-deficient Atnoa1 plants. In a converse manner, exogenous addition of NO donors increased the plant antioxidant capacity and lowered the ROS levels in MeJA-treated leaves. Taken together, the results indicate that SA at low concentrations counteracts MeJA-induced leaf senescence through NOA1-dependent NO signaling and strengthening of the antioxidant defense.

Topics: Acetates; Aging; Arabidopsis; Chlorophyll; Cyclopentanes; Lipid Peroxidation; Nitric Oxide Synthase; Oxylipins; Plant Growth Regulators; Plant Leaves; Real-Time Polymerase Chain Reaction; Salicylic Acid; Up-Regulation

Chlorophyllase (CLH) is a common plant enzyme that catalyzes the hydrolysis of chlorophyll to form chlorophyllide, a more hydrophilic derivative. For more than a century, the biological role of CLH has been controversial, although this enzyme has been often considered to catalyze chlorophyll catabolism during stress-induced chlorophyll breakdown. In this study, we found that the absence of CLH does not affect chlorophyll breakdown in intact leaf tissue in the absence or the presence of methyl-jasmonate, which is known to enhance stress-induced chlorophyll breakdown. Fractionation of cellular membranes shows that Arabidopsis (Arabidopsis thaliana) CLH is located in the endoplasmic reticulum and the tonoplast of intact plant cells. These results indicate that CLH is not involved in endogenous chlorophyll catabolism. Instead, we found that CLH promotes chlorophyllide formation upon disruption of leaf cells, or when it is artificially mistargeted to the chloroplast. These results indicate that CLH is responsible for chlorophyllide formation after the collapse of cells, which led us to hypothesize that chlorophyllide formation might be a process of defense against chewing herbivores. We found that Arabidopsis leaves with genetically enhanced CLH activity exhibit toxicity when fed to Spodoptera litura larvae, an insect herbivore. In addition, purified chlorophyllide partially suppresses the growth of the larvae. Taken together, these results support the presence of a unique binary defense system against insect herbivores involving chlorophyll and CLH. Potential mechanisms of chlorophyllide action for defense are discussed.

Topics: Acetates; Animals; Arabidopsis; Bombyx; Carboxylic Ester Hydrolases; Chlorophyll; Chlorophyllides; Cyclopentanes; Endoplasmic Reticulum; Gastrointestinal Tract; Herbivory; Larva; Mastication; Mutation; Oxylipins; Photosynthesis; Plant Leaves; Protein Transport; Spodoptera; Subcellular Fractions; Vacuoles

Senescence is the last step of leaf development in the life span of an annual plant. Senescence can be induced prematurely by treating leaf tissues with jasmonic acid methyl ester (methyl jasmonate, MeJA). During both senescence programmes, drastic changes occur at the biochemical, cellular and ultra-structural levels that were compared here for primary leaves of barley (Hordeum vulgare L.). Our findings indicate that both types of senescence are similar with respect to the morphological changes including the loss of chlorophyll, disintegration of thylakoids, and formation of plastoglobules. However, the time elapsed for reaching senescence completion was different and ranged from 7 to 8 days for artificially senescing, MeJA-treated plants to 7-8 weeks for naturally senescing plants. Pulse-labelling studies along with RNA and protein gel blot analyses showed differential changes in the expression of both plastid and nuclear genes coding for photosynthetic proteins. Several unique messenger products accumulated in naturally and artificially senescing, MeJA-treated leaves. Detailed expression and crosslinking studies revealed that pheophorbide a oxygenase (PAO), a previously implicated key enzyme of chlorophyll breakdown, is most likely not rate-limiting for chlorophyll destruction under both senescence conditions. Metabolite profiling identified differential changes in the composition of carotenoid derivatives and prenyl-lipids to occur in naturally senescing and artificially senescing plants that underscored the differences between both senescence programmes.

Topics: Acetates; beta Carotene; Cell Nucleus; Chlorophyll; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Plant; Hordeum; Oxygenases; Oxylipins; Plant Leaves; Plant Proteins; RNA, Messenger; Singlet Oxygen; Thylakoids

Singlet oxygen (¹O₂) is a reactive oxygen species that can function as a stress signal in plant leaves leading to programmed cell death. In microalgae, ¹O₂-induced transcriptomic changes result in acclimation to ¹O₂. Here, using a chlorophyll b-less Arabidopsis thaliana mutant (chlorina1 [ch1]), we show that this phenomenon can also occur in vascular plants. The ch1 mutant is highly photosensitive due to a selective increase in the release of ¹O₂ by photosystem II. Under photooxidative stress conditions, the gene expression profile of ch1 mutant leaves very much resembled the gene responses to ¹O₂ reported in the Arabidopsis mutant flu. Preexposure of ch1 plants to moderately elevated light intensities eliminated photooxidative damage without suppressing ¹O₂ formation, indicating acclimation to ¹O₂. Substantial differences in gene expression were observed between acclimation and high-light stress: A number of transcription factors were selectively induced by acclimation, and contrasting effects were observed for the jasmonate pathway. Jasmonate biosynthesis was strongly induced in ch1 mutant plants under high-light stress and was noticeably repressed under acclimation conditions, suggesting the involvement of this hormone in ¹O₂-induced cell death. This was confirmed by the decreased tolerance to photooxidative damage of jasmonate-treated ch1 plants and by the increased tolerance of the jasmonate-deficient mutant delayed-dehiscence2.

Topics: Acclimatization; Acetates; Arabidopsis; Arabidopsis Proteins; Biosynthetic Pathways; Chlorophyll; Cyclopentanes; Gene Expression Regulation, Plant; Light; Lipid Peroxidation; Mutation; Oligonucleotide Array Sequence Analysis; Oxidation-Reduction; Oxygenases; Oxylipins; Photosystem II Protein Complex; Plant Growth Regulators; Plant Leaves; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; Singlet Oxygen; Transcriptome

Methyl jasmonate (MeJA) elicits protective effects as form of plant response to abiotic stress. However, related studies on plant response to metal stress are insufficient. This study aimed to examine the effects of MeJA on growth and physiological responses of Capsicum frutescens seedlings exposed to cadmium (Cd) stress. The study was performed in an artificial climate chamber. Results showed that 50 mg L⁻¹ Cd significantly impaired the growth of the seedlings by increasing leaf MDA content and decreasing chlorophyll b. These effects were significantly mitigated by MeJA at low concentrations (0.1 µmol L⁻¹). The dry weights of different plant parts, chlorophyll content, and leaf catalase and ascorbate peroxidase activities were increased by a low MeJA concentration (0.1 µmol L⁻¹) but were decreased by a high MeJA concentration (1000 µmol L⁻¹). Significant increases in endogenous jasmonic acid were observed at 48 h after the samples were treated with Cd and 0.1 µmol L⁻¹ MeJA. These results suggested that low exogenous MeJA concentrations exhibited protective effects on the growth and physiology of C. frutescens seedlings under Cd stress.

Topics: Acetates; Ascorbate Peroxidases; Cadmium; Capsicum; Catalase; Chlorophyll; Cyclopentanes; Hydrogen Peroxide; Lipid Peroxidation; Oxylipins; Plant Leaves; Seedlings; Soil Pollutants; Stress, Physiological

Effect of pre-harvest methyl jasmonate (MeJA) and post-harvest 1-methylcyclopropene (1-MCP) treatments on broccoli floret glucosinolate (GS) concentrations and quinone reductase (QR, an in vitro anti-cancer biomarker) inducing activity were evaluated two days prior to harvest, at harvest and at 10, 20, and 30 days of post-harvest storage at 4 °C. MeJA treatments four days prior to harvest of broccoli heads was observed to significantly increase floret ethylene biosynthesis resulting in chlorophyll catabolism during post-harvest storage and reduced product quality. Post-harvest treatment with 1-methylcyclopropene (1-MCP), which competitively binds to protein ethylene receptors, maintained post-harvest floret chlorophyll concentrations and product visual quality in both control and MeJA-treated broccoli. Transcript abundance of BoPPH, a gene which is responsible for the synthesis of pheophytinase, the primary enzyme associated with chlorophyll catabolism in broccoli, was reduced by 1-MCP treatment and showed a significant, negative correlation with floret chlorophyll concentrations. The GS, glucobrassicin, neoglucobrassicin, and gluconasturtiin were significantly increased by MeJA treatments. The products of some of the GS from endogenous myrosinase hydrolysis [sulforaphane (SF), neoascorbigen (NeoASG), N-methoxyindole-3-carbinol (NI3C), and phenethyl isothiocyanate (PEITC)] were also quantified and found to be significantly correlated with QR. Sulforaphane, the isothiocyanate hydrolysis product of the GS glucoraphanin, was found to be the most potent QR induction agent. Increased sulforaphane formation from the hydrolysis of glucoraphanin was associated with up-regulated gene expression of myrosinase (BoMyo) and the myrosinase enzyme co-factor gene, epithiospecifier modifier1 (BoESM1). This study demonstrates the combined treatment of MeJA and 1-MCP increased QR activity without post-harvest quality loss.

Topics: Acetates; Brassica; Chlorophyll; Cyclopentanes; Cyclopropanes; Enzyme Activation; Ethylenes; Gene Expression Regulation, Plant; Glucosinolates; Hydrolysis; Models, Biological; NAD(P)H Dehydrogenase (Quinone); Oxidation-Reduction; Oxylipins; Pigmentation; Plant Growth Regulators; Time Factors

Ethylene-response factors (ERFs) play an important role in regulating gene expression in plant responses to biotic and abiotic stresses. In this study, a new ERF transcription factor, GmERF7, was isolated from soybean. Sequence analysis showed that GmERF7 contained an AP2/ERF domain with 58 amino acids, two putative nuclear localization signal (NLS) domains, an acidic amino acid-rich transcriptional activation domain and a conserved N-terminal motif [MCGGAI(I/L)]. The expression of GmERF7 was induced by drought, salt, methyl jasmonate (MeJA), ethylene (ETH) and abscisic acid (ABA) treatments. However, the expression of GmERF7 decreased under cold treatment. GmERF7 localized to the nucleus when transiently expressed in onion epidermal cells. Furthermore, GmERF7 protein bound to the GCC-box element in vitro and activated the expression of the β-glucuronidase (GUS) reporter gene in tobacco leaves. Activities of GmERF7 promoter (GmERF7P) upregulated in tobacco leaves with 10h drought, salt and ETH treatments. However, activities of GmERF7P decreased with 10h cold and ABA treatments. Overexpression of GmERF7 in tobacco plants led to higher levels of chlorophyll and soluble carbohydrates and a lower level of malondialdehyde compared with wild-type tobacco plants under salt stress conditions, which indicated that GmERF7 enhanced salt tolerance in transgenic plants.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Base Sequence; Carbohydrates; Cell Nucleus; Chlorophyll; Cold Temperature; Cyclopentanes; DNA-Binding Proteins; Droughts; Ethylenes; Gene Expression Regulation, Plant; Glucuronidase; Glycine max; Malondialdehyde; Molecular Sequence Data; Nicotiana; Onions; Oxylipins; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Salt Tolerance; Salt-Tolerant Plants; Signal Transduction

Methyl jasmonate (MeJA) is an important signalling molecule that has been reported to be able to promote plant senescence. The cell death suppressor Bax inhibitor-1 (BI1) has been found to suppress stress factor-mediated cell death in yeast and Arabidopsis. However, the effect and the genetic mechanism of Arabidopsis thaliana BI1 (AtBI1) on leaf senescence remain unclear. It was found here that the AtBI1 mutant, atbi1-2 (a gene knock-out), showed accelerated progression of MeJA-induced leaf senescence, while the AtBI1 complementation lines displayed similar symptoms as the WT during the senescence process. In addition, over-expression of the AtBI1 gene delayed the onset of MeJA-induced leaf senescence. Further analyses showed that during the process of MeJA-induced senescence, the activity of MPK6, a mitogen-activated protein kinase (MAPK), increased in WT plants, whereas it was significantly suppressed in AtBI1-overexpressing plants. Under the MeJA treatment, cytosolic calcium ([Ca(2+)](cyt)) functioned upstream of MPK6 activation and the elevation of [Ca(2+)](cyt) was reduced in AtBI1-overexpressing leaves. These results suggested a role of AtBI1 over-expression in delaying MeJA-induced leaf senescence by suppressing the [Ca(2+)](cyt)-dependent activation of MPK6, thus providing a new insight into the function and mechanism of AtBI1 in plant senescence.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Calcium; Calcium Signaling; Cell Death; Cellular Senescence; Chlorophyll; Cyclopentanes; Enzyme Activation; Gene Expression Regulation, Plant; Gene Knockout Techniques; MAP Kinase Signaling System; Membrane Proteins; Mitogen-Activated Protein Kinase 6; Models, Biological; Oxylipins; Plant Growth Regulators; Plant Leaves; Plants, Genetically Modified; Sequence Deletion; Signal Transduction; Time Factors

Reactive oxygen species (ROS) are not only cytotoxic compounds leading to oxidative damage, but also signaling molecules for regulating plant responses to stress and hormones. Arabidopsis cytosolic ascorbate peroxidase 1 (APX1) is thought to be a central regulator for cellular ROS levels. However, it remains unclear whether APX1 is involved in plant tolerance to wounding and methyl jasmonate (MeJA) treatment, which are known to enhance ROS production.. We studied the effect of wounding and MeJA treatment on the levels of H(2)O(2) and oxidative damage in the Arabidopsis wild-type plants and knockout mutants lacking APX1 (KO-APX1).. The KO-APX1 plants showed high sensitivity to wounding and MeJA treatment. In the leaves of wild-type plants, H(2)O(2) accumulated only in the vicinity of the wound, while in the leaves of the KO-APX1 plants it accumulated extensively from damaged to undamaged regions. During MeJA treatment, the levels of H(2)O(2) were much higher in the leaves of KO-APX1 plants. Oxidative damage in the chloroplasts and nucleus was also enhanced in the leaves of KO-APX1 plants. These findings suggest that APX1 protects organelles against oxidative stress by wounding and MeJA treatment.. This is the first report demonstrating that H(2)O(2)-scavenging in the cytosol is essential for plant tolerance to wounding and MeJA treatment.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Ascorbate Peroxidases; Blotting, Western; Chlorophyll; Cyclopentanes; Cytosol; Hydrogen Peroxide; Organelles; Oxidative Stress; Oxylipins; Plant Diseases; Plant Growth Regulators; Plants, Genetically Modified; Reactive Oxygen Species; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Plant; Wound Healing

Effects of methyl jasmonate (MeJA), salicylic acid (SA) or 2-aminoindane-2-phosphonic acid (AIP) pre-treatments on the sensitivity of Xanthoria parietina exposed to UV-A were studied. UV decreased chlorophylls and stimulated increase in hydrogen peroxide and superoxide level. Accumulation of soluble phenols and flavonoids increased in response to UV treatment. Metabolic modulators had negligible impact on these UV-induced changes. Within free amino acids, AIP (-UV variant) and SA and MeJA (+UV variants) altered their accumulation. AIP had no effect on the amount of phenylalanine. Benzoic and cinnamic acids were elevated by UV and mainly MeJA influenced their accumulations. Among lichen specific metabolites, vulpinic acid and ergosterol increased while usnic acid and atranorin decreased after exposure to UV; accumulation of parietin was not affected. Applied modulators showed a different effect on these lichen metabolites but biosynthetic pathway-specific trend of alteration was visible. Overall, MeJA showed the most pronounced effect among studied parameters. Accumulation of selected phenolics in response to UV-A seems to be an important feature of Xanthoria tolerance. Present finding in the context of phenolic metabolism in non-vascular plants and with respect to limited data about effect of studied modulators on non-vascular plants are discussed.

Topics: Acetates; Amino Acids; Ascomycota; Benzoic Acid; Chlorophyll; Cinnamates; Cyclopentanes; Flavonoids; Indans; Lichens; Organophosphonates; Oxylipins; Phenols; Reactive Oxygen Species; Salicylic Acid; Ultraviolet Rays

Taking the flue-cured tobacco variety of "Longjiang 911" from Heilongjiang Province of Northeast China as test material, a pot experiment was conducted to study the effects of foliar spraying different concentration methyl jasmonate (MeJA) on the seedlings leaf chlorophyll content and chlorophyll fluorescence characteristics during the transplantation stage under drought and re-watering. Under drought condition, the leaf chlorophyll content, maximum fluorescence (F(m)), potential activities of PSII (F(v)/F(o)), maximum photochemical efficiency (F(v)/F(m)), actual photochemical efficiency (psi(PSII)), apparent electron transport rate (ETR), and photochemical quenching (q(P)) decreased, but the minimal fluorescence (F(o)) and non-photochemical quenching (q(N)) increased. Foliar spraying 0.2 and 0.5 mmol x L(-1) of MeJA had obvious positive effects in mitigating the decrease of F(v)/F(m), F(v)/F(o), phi(PSII), ETR, and q(P) and the increase of q(N) under drought stress, while spraying 1.0 mmol x L(-1) of MeJA had lesser effects. After re-watering, all the leaf chlorophyll fluorescence indices had obvious recovery, and spraying MeJA made the indices more close to the original levels before drought. It was suggested that foliar spraying MeJA could alleviate the degradation of chlorophyll and play definite role in protecting the PSII under drought stress, decrease the damage of drought stress on the seedlings, promote the rapid MeJA recovery of chlorophyll fluorescence parameters after re-watering, and thus, ensure the regrowth of flue-cured tobacco seedlings.

Topics: Acetates; Chlorophyll; Cyclopentanes; Droughts; Fluorescence; Nicotiana; Oxylipins; Photosynthesis; Photosystem II Protein Complex; Plant Growth Regulators; Seedlings; Water

The Arabidopsis thaliana transcription factor gene AtMYB44 was induced within 10 min by treatment with methyl jasmonate (MeJA). Wound-induced expression of the gene was observed in local leaves, but not in distal leaves, illustrating jasmonate-independent induction at wound sites. AtMYB44 expression was not abolished in Arabidopsis mutants insensitive to jasmonate (coi1), ethylene (etr1), or abscisic acid (abi3-1) when treated with the corresponding hormones. Moreover, various growth hormones and sugars also induced rapid AtMYB44 transcript accumulation. Thus, AtMYB44 gene activation appears to not be induced by any specific hormone. MeJA-induced activation of jasmonate-responsive genes such as JR2, VSP, LOXII, and AOS was attenuated in transgenic Arabidopsis plants overexpressing the gene (35S:AtMYB44), but significantly enhanced in atmyb44 knockout mutants. The 35S:MYB44 and atmyb44 plants did not show defectiveness in MeJA-induced primary root growth inhibition, indicating that the differences in jasmonate-responsive gene expression observed was not due to alterations in the jasmonate signaling pathway. 35S:AtMYB44 seedlings exhibited slightly elevated chlorophyll levels and less jasmonate- induced anthocyanin accumulation, demonstrating suppression of jasmonate-mediated responses and enhancement of ABA-mediated responses. These observations support the hypothesis of mutual antagonistic actions between jasmonate- and abscisic acid-mediated signaling pathways.

Topics: Abscisic Acid; Acetates; Anthocyanins; Arabidopsis; Arabidopsis Proteins; Chlorophyll; Cyclopentanes; DNA-Binding Proteins; Ethylenes; Gene Expression Regulation, Plant; Genes, abl; Oxylipins; Plant Growth Regulators; Plants, Genetically Modified; Receptors, Cell Surface; Signal Transduction; Transcription Factors; Transcriptional Activation

The effects of short-term darkening and methyl jasmonate (MeJA) on cotyledon senescence were studied 24h after transfer of intact 7-day-old Cucurbita pepo (zucchini) seedlings to darkness or spraying with 100 microM MeJA. The jasmonate inhibitory effect on chlorophyll content and chloroplast transcriptional activity was stronger compared with darkness. Further, MeJA reduced the photosynthetic rate whereas darkness did not affect photosynthesis. Neither stress factor affected the photochemical quantum efficiency of photosystem II (PSII) estimated by the variable fluorescence (F(v))/maximal fluorescence (F(m)) ratio, suggesting the existence of mechanisms protecting the functional activity of PSII at earlier stages of senescence, thus making this parameter more stable compared to others used to quantify senescence. Both stress factors caused a decrease in the content of physiologically active cytokinins, especially trans-zeatin (Z), with the jasmonate effect being much more pronounced when compared to darkness. Our results indicate that MeJA is a more potent inducer of senescence in zucchini cotyledons, at least within the relatively short period of the 24h treatment. This is likely due to its stronger down-regulatory effect on the levels of physiologically active cytokinins.

Topics: Acetates; Chlorophyll; Chloroplasts; Cotyledon; Cucurbita; Cyclopentanes; Cytokinins; Darkness; Gene Expression Regulation, Plant; Oxylipins; Photosynthesis; Photosystem II Protein Complex; Time Factors; Transcription, Genetic

Senescence is a phase of leaf ontogeny marked by declining photosynthetic activity that is paralleled by a decline in chloroplast function. The photosystem II in a plant is considered to be the primary site where delayed fluorescence (DF) is produced. We report here a simple, rapid, and non-invasive technique for detecting plants senescence based on quantitative measurements of DF. In the experimental study, various senescence symptoms induced by age or hormones were examined in the Catharanthus roseus L. G. Don plants. Detecting the DF emissions from leaves with a home-made DF biosensor enables DF parameters of C. roseus to be produced in a short time. Meanwhile, evaluations of leaves senescence were made from measurements of chlorophyll content, ion leakage, and net photosynthesis rate (Pn) based on the consumption of CO2 in the tested plants. The results of our investigation demonstrate that the changes in DF intensity of green plants can truly reflect the changes in photosynthetic capacity and chlorophyll content during age-dependent and hormone-modulated senescence. Moreover, the DF intensity negatively correlates with ion leakage in both types of senescence. With proper calibration, DF may provide an important approach for monitoring senescence process in vivo and quantitatively evaluating senescence extent. Therefore, a DF technique could be potentially useful for less time-consuming and automated screening of the interesting mutants with genetic modifications that change the plant senescence progress.

Topics: Acetates; Benzyl Compounds; Catharanthus; Cellular Senescence; Chlorophyll; Cyclopentanes; Fluorescence; Kinetin; Oxylipins; Photosynthesis; Photosystem II Protein Complex; Plant Growth Regulators; Plant Leaves; Purines; Spectrometry, Fluorescence

Tropical fruits cannot be stored at low temperatures due to the chilling injury phenomena. With the goal of reducing the chilling injury, we tested 10(-4) and 10(-5) M of methyl jasmonate (MJ) treatment before the storage of red and white cultivars of guava fruits at 5 degrees C for up to 15 days plus two days at 20 degrees C. Every five days, we evaluated chilling injury index, ion leakage percentage, vitamin C, sugars, total phenols, and the activity of the enzymes lipoxygenase (LOX) and phenylalanine-ammonia lyase (PAL). We found that methyl jasmonate treatments reduce the chilling injury index and the ion leakage percentage. Furthermore, MJ did not affect vitamin C, chlorophyll, and total phenols. MJ increased sugar content, PAL, and LOX activities. We concluded that MJ reduces chilling injury and activates the fruit defense response as indicated by the behavior of total phenols and the increase in sugar content, PAL, and LOX activities.

Topics: Acetates; Ascorbic Acid; Carbohydrate Metabolism; Chlorophyll; Cyclopentanes; Dose-Response Relationship, Drug; Fructose; Glucose; Ions; Lipoxygenase; Oxylipins; Phenols; Psidium; Sucrose; Temperature

Methyl jasmonate (MeJA) and norflurazon (NF) treatments resulted in a substantial decrease in photosynthetic activities and chlorophylls (Chls) in Arabidopsis thaliana plants, causing a senescence-like yellowing and a bleaching in MeJA- and NF-treated plants, respectively. Non-radiative energy dissipation through q(N) and non-photochemical quenching increased greatly in NF-treated plants in concomitance with an increase in photoprotectants antheraxanthin and zeaxanthin from interconversion of violaxanthin, although they were not changed in MeJA-treated plants. A significant accumulation of anthocyanin was observed only in MeJA-treated plants, not in NF-treated plants. Total activities of catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), superoxide dismutase (EC 1.15.1.1) and glutathione reductase (EC 1.6.4.2) increased greatly in response to MeJA, particularly a 100-fold increase in POD activity 7 days after MeJA treatment. NF application to plants exhibited less increase in antioxidant enzymes than MeJA-treated plants. NF-treated young leaves had a greater decline in Chls and CAT activity, and less zeaxanthin accumulation compared to NF-treated mature leaves, indicating that NF-treated young leaves are more susceptible to excess light exposure and a possible photooxidative stress. Both MeJA- and NF-treated Arabidopsis plants suffered destruction of Chls, however, they developed differential antioxidant responses during the stress, in large part by an increased anthocyanin level in the epidermis and enzymatic antioxidants in MeJA-treated plants and by accumulation of antheraxanthin and zeaxanthin, and enhanced energy dissipation in NF-treated plants.

Topics: Acetates; Antioxidants; Arabidopsis; Catalase; Chlorophyll; Cyclopentanes; Glutathione Reductase; Oxylipins; Peroxidase; Photosynthesis; Plant Leaves; Pyridazines; Superoxide Dismutase

The role of methyl jasmonate (MeJa) in promoting senescence has been described previously in many species, but it has been questioned in monocarpic species whether induced senescence is a result of a potential death hormone like MeJa, or a consequence of an increased metabolic drain resulting from the growth of reproductive tissue. In oilseed rape (Brassica napus L.), a polypeptide of 23 kDa has been recently identified as a putative vegetative storage protein (VSP). This polypeptide could be used as a storage buffer between N losses from senescing leaves putatively promoted by methyl jasmonate that might be produced by flowers, and grain filling which occurs later on, while N uptake is strongly reduced. In order to describe causal relationships during Brassica napus L. plant responses to MeJa treatment, a kinetic experiment was performed to determine the order and the amplitude with which general processes such as growth, photosynthesis, chlorophyll content, N uptake, and N storage under the form of the 23 kDa VSP are affected. One of the most immediate consequences of MeJa treatment was the strong reduction of nitrate uptake within 6 h, relative to control plants. However, this was not a specific effect as K(+) uptake was similarly affected. Photosynthesis was reduced later (after 24 h), while chlorophyll content as well as leaf growth also decreased in a similar way. Moreover, this was concomitant with a remobilization of endogenous unlabelled N from senescing leaves to roots. Accumulation of the 23 kDa VSP was induced in the taproot after 24 h of MeJa treatment and was increased 10-fold within 8 d. On the other hand, the reversible effect of a MeJa pretreatment was tested in the long term (i.e. along the growth cycle) using plants previously grown in field conditions induced for flowering. Results show that a MeJa pulse induced a reversible effect on N uptake inhibition. In parallel, protein immunologically related to the 23 kDa VSP was detected in stems with a similar molecular weight (23 kDa), and in flowers and leaves with a molecular weight of 24 kDa. This accumulation was concomitant with the remobilization of both subunits of Rubisco. During stem and pod development, this protein induced by MeJa is fully hydrolysed. The external and intermittent supply of MeJa mimic some of the plant physiological processes previously reported under natural conditions. This suggests that in oilseed rape, methyl jasmonate could be considered as a possible monocar

Topics: Acetates; Biological Transport; Brassica napus; Chlorophyll; Cyclopentanes; Kinetics; Nitrates; Nitrogen; Oxylipins; Photosynthesis; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plant Roots; Plant Stems; Potassium; Ribulose-Bisphosphate Carboxylase

Effects of simulated microgravity and hypergravity on the senescence of oat leaf segments excised from the primary leaves of 8-d-old green seedlings were studied using a 3-dimensional (D) clinostat as a simulator of weightlessness and a centrifuge, respectively. During the incubation with water under 1-g conditions at 25 degrees C in the dark, the loss of chlorophyll of the segments was found dramatically immediately after leaf excision, and leaf color completely turned to yellow after 3-d to 4-d incubation. In this case kinetin (10 micromolar) was effective in retarding senescence. The application of simulated microgravity conditions on a 3-D clinostat enhanced chlorophyll loss in the presence or absence of kinetin. The loss of chlorophyll was also enhanced by hypergravity conditions (ca. 8 to 16 g), but the effect was smaller than that of simulated microgravity conditions on the clinostat. Jasmonates (JAs) and abscisic acid (ABA) promoted senescence under simulated microgravity conditions on the clinostat as well as under 1-g conditions. After 2-d incubation with water or 5-d incubation with kinetin, the endogenous levels of JAs and ABA of the segments kept under simulated microgravity conditions on the clinostat remained higher than those kept under 1-g conditions. These findings suggest that physiological processes of leaf senescence and the dynamics of endogenous plant hormone levels are substantially affected by gravity.

Topics: Abscisic Acid; Acetates; Adenine; Avena; Centrifugation; Chlorophyll; Cyclopentanes; Darkness; Gravitation; Hypergravity; Kinetin; Oxylipins; Plant Growth Regulators; Plant Leaves; Rotation; Weightlessness Simulation

Chlorophyllase (Chlase) is the first enzyme involved in chlorophyll (Chl) degradation and catalyzes the hydrolysis of ester bond to yield chlorophyllide and phytol. In the present study, we isolated the Chlase cDNA. We synthesized degenerate oligo DNA probes based on the internal amino acid sequences of purified Chlase from Chenopodium album, screened the C. album cDNA library, and cloned a cDNA (CaCLH, C. album chlorophyll-chlorophyllido hydrolase). The deduced amino acid sequence (347 aa residues) had a lipase motif overlapping with an ATP/GTP-binding motif (P-loop). CaCLH possibly was localized in the extraplastidic part of the cell, because a putative signal sequence for endoplasmic reticulum is at the N terminus. The amino acid sequence shared 37% identity with a function-unknown gene whose mRNA is inducible by coronatine and methyl jasmonate (MeJA) in Arabidopsis thaliana (AtCLH1). We expressed the gene products of AtCLH1 and of CaCLH in Escherichia coli, and they similarly exhibited Chlase activity. Moreover, we isolated another full-length cDNA based on an Arabidopsis genomic fragment and expressed it in E. coli, demonstrating the presence of the second Arabidopsis CLH gene (AtCLH2). No typical feature of signal sequence was identified in AtCLH1, whereas AtCLH2 had a typical signal sequence for chloroplast. AtCLH1 mRNA was induced rapidly by a treatment of MeJA, which is known to promote senescence and Chl degradation in plants, and a high mRNA level was maintained up to 9 h. AtCLH2, however, did not respond to MeJA.

Topics: Acetates; Amino Acid Sequence; Base Sequence; Carboxylic Ester Hydrolases; Chenopodiaceae; Chlorophyll; Cyclopentanes; Enzyme Induction; Gene Library; Genes, Plant; Isoenzymes; Molecular Sequence Data; Oxylipins; Plant Leaves; Recombinant Proteins; Sequence Analysis, DNA; Sequence Homology, Amino Acid