R2R3-type Lo MYB21 affects jasmonate-regulated development and dehiscence of anthers in lily(Lilium oriental hybrids)

Lilies are widely cultivated for cut flowers,but their large anthers carry a considerable amount of colored pollen that is dispersed easily.Studying the molecular mechanism of anther development and dehiscence could help solve this problem.LoMYB21,encoding a putative R2R3v-myb avian myeloblastosis viral oncogene homolog(MYB)transcription factor,was identified from oriental lilies(Lilium‘Siberia’).Real-time quantitative PCR analysis showed that LoMYB21 was mainly expressed in the anther,filament and stigma and had high expression during the late stages of lily anther development.LoMYB21 had transactivation activity and was located in the nucleus through yeast one-hybrid assays and transient expression in Nicotiana benthamiana.Suppression of LoMYB21 by virus-induced gene silencing(VIGS)in Lilium‘Siberia’led to anther indehiscence and reduced the expression of genes related to Jasmonate acid(JA)biosynthesis and signal transduction.Induction of LoMYB21 in DEX::LoMYB21 transgenic Arabidopsis caused procumbent inflorescences that became infertile,accompanied by higher expression of JA biosynthetic and signaling genes.These results demonstrated that JA content and signaling were abnormal in silenced lily and transgenic LoMYB21 Arabidopsis,which affected anther development.Our study indicated that LoMYB21 could regulate lily anther dehiscence through JA biosynthesis and signaling during the late stages of anther development.

The Role of Jasmonates as Antibulbing Substances in the Bulb Formation of Onion

Onion plants form spherical bulbs under long-day conditions.Substances regulating bulb formation remain unknown.In the course of chemical studies on the bulb formation,α-linolenic acid was isolated from onion extracts as an antibulbing substance,the amount of which was synchronized with the bulb formation.Since allene oxide synthase inhibitor canceled the antibulbing activity ofα-linolenic acid,it was disclosed that jasmonic acid concerns this regulation.Structure-activity-relationship study revealed that its(3R,7S)stereochemistry is necessary for showing its antibulbing activity.It is concluded that(3R,7S)-jasmonate derived fromα-linolenic acid actually participates in the regulation of bulb formation.

GhWRKY33 negatively regulates jasmonate-mediated plant defense to Verticillium dahliae

Verticillium wilt,caused by Verticillium dahliae,seriously restricts the yield and quality improvement of cotton.Previous studies have revealed the involvement of WRKY members in plant defense against V.dahliae,but the underlying mechanisms involved need to be further elucidated.Here,we demonstrated that Gossypium hirsutum WRKY DNA-binding protein 33(GhWRKY33) functions as a negative regulator in plant defense against V.dahliae.GhWRKY33 expression is induced rapidly by V.dahliae and methyl jasmonate,and overexpression of GhWRKY33 reduces plant tolerance to V.dahliae in Arabidopsis.Quantitative RT-PCR analysis revealed that expression of several JA-associated genes was significantly repressed in GhWRKY33 overexpressing transgenic plants.Yeast one-hybrid analysis revealed that GhWRKY33 may repress the transcription of both AtERF1 and GhERF2 through its binding to their promoters.Protein-protein interaction analysis suggested that GhWRKY33 interacts with G.hirsutum JASMONATE ZIM-domain protein 3(GhJAZ3).Similarly,overexpression of GhJAZ3 also decreases plant tolerance to V.dahliae.Furthermore,GhJAZ3 acts synergistically with GhWRKY33 to suppress both AtERF1 and GhERF2 expression.Our results imply that GhWRKY33 may negatively regulate plant tolerance to V.dahliae via the JA-mediated signaling pathway.

Methyl Jasmonate Reduces Chilling Injury and Maintains Postharvest Quality in Peaches

Zhaohui peaches(Prunus persica Batsch)were treated with 0(CK), 1, 10 or 100 μmol L-1 methyl jasmonate(MeJA)vapor at 20℃ for 24 h before stored at 0℃ for 35 d. The untreated fruits showed chilling injury(CD symptoms after 4 wk of storage, as indicated by increased fruit firmness and reduced ex-tractable juice, which is referred as leatheriness. Treatment with 1 and 10 μmol L-1 MeJA promoted normal ripening and softening, maintained higher levels of extractable juice, titratable acidity, pectinesterase(PE)and polygalacturonase(PC)activities, inhibited increases in fruit fresh weight loss, decay incidence, electrolyte leakage and MDA content, and improved color development, thereby preventing chilling injury symptoms development and maintaining edible quality. MeJA treatment also delayed the climacteric rise in respiratory rate, but promoted ethylene production during the later period of cold storage, suggesting that ethylene may involve in CI development of peaches. These results indicate that 1 and 10 μmol L-1 MeJA treatments could be used to reduce CI development and decay incidence in peaches.

Application of methyl jasmonate postharvest maintains the quality of Nanguo pears by regulating mitochondrial energy metabolism

The present study was conducted to investigate the effects of methyl jasmonate(Me JA)dipping treatment on mitochondrial energy metabolism and quality parameters of Nanguo pears during room temperature storage.The results showed that Me JA treatment suppressed the respiration rate and weight loss,and maintained the flesh firmness of Nanguo pears.Me JA also effectively maintained the content of ascorbic acid and titratable acidity in the fruit.Furthermore,the activities of H^(+)-ATPase,Ca^(2+)-ATPase,succinate dehydrogenase(SDH)and cytochrome C oxidase(CCO)of the Me JA-treated fruit were significantly higher than those of the untreated fruit.The contents of adenosine triphosphate(ATP)and adenosine diphosphate(ADP)and the energy charge were also enhanced by Me JA treatment.These results suggest that postharvest Me JA treatment could maintain the quality of Nanguo pears,in part by modulating mitochondrial energy metabolism during room temperature storage.

Response of Endogenous Salicylic Acid and Jasmonates to Mechanical Wounding in Pea Leaves

The roles of on endogenous jasmonates （JAs） and salicylic acid （SA） in wounding response were investigated. Pea （Pisum sativum L.） seedlings were treated with three different methods including mechanical wounding, JAs application, and SA application. The contents of endogenous JAs and SA, as well as the activities of the related enzymes were detected by enzyme-linked immunosorbent assay （ELISA）, high performance liquid chromatography （HPLC）, and spectrophotometer, respectively. The results showed that endogenous JA rapidly accumulated within 30 min after wounding. The increase in the activities of both lipoxygenase （LOX） and allene oxide synthase （AOS） lagged behind JAs burst. A second slight increase in JAs level was observed at 24 h after wounding treatment, and at the same time point, higher activities of LOX and AOS were also detected. Endogenous free SA content decreased accompanied with JAs burst. Effects of exogenous JA application were similar to those of wounding treatment on endogenous SA level and phenylalanine ammonia lyase （PAL） activity, whereas exogenous SA application led to the significant inhibition of LOX and AOS activities and the decrease of endogenous JAs level at the early stage of treatment. It is thus suggested that JAs burst and SA decrease in early response to wounding may constitute an important mechanism by which plant starts the related defense reaction and adapts to wounding stress.

Impact of Methyl Jasmonate on Antioxidant Activity and Some Biochemical Aspects of Maize Plant Grown under Water Stress Condition

A pot-culture study was undertaken to investigate the possible role of Methyl jasmonate (MeJA)-treatment on the earlier vegetative growth stage and different chemical constituents of maize cultivar (Giza-2) plants subjected to water stress. The grains were divided into two groups: first group was pre-soaked in water, and the second one was pre-soaked in 50 μM MeJA for 8 h. The plants were subjected to different levels of water field capacity (WFC) 65%, 55% and 45%. The results showed that pre-soaking maize grains with MeJA led to increases in plant growth criteria evident in terms of plant height, fresh and dry weight of plant. The pigment levels concomitantly with total carbohydrates, total soluble sugar, polysaccharides, as well as free amino acids, proline and total protein content were markedly increased. Moreover, the application of the investigated MeJA significantly improved growth hormone in terms of IAA. In contrast ABA level was markedly declined in maize plant. The activities of oxidative CAT, POX and SOD were also increased with MeJA. In addition, the N, P and K content was increased significantly in shoot. As a conclusion, soaking maize grains with MeJA could alleviate the harmful effects of water stress.

Regulatory effect of salicylic acid and methyl jasmonate supplementation on ergosterol production in Hericium erinaceus mycelia

We evaluated the biomass and ergosterol content of Hericium erinaceus mycelium, and extracellular enzyme activities in H. erinaceus liquid culture following salicylic acid（SA） and methyl jasmonic acid（Me JA）supplementation. The optimal SA concentration was100 lmoláL-1, where the highest ergosterol content of 2.33 mgág-1was obtained following 6-day cultivation with100 lmoláL-1SA supplementation, and which was significantly higher than the unsupplemented control（p ／ 0.01）. Following 4-day supplementation with50 lmoláL-1Me JA, the highest ergosterol content obtained was 1.988 mgág-1, which was 25.8 % higher than the unsupplemented control. Our data indicate that SA and Me JA supplementation improves ergosterol content in H.erinaceus mycelium.

A patatin-like protein synergistically regulated by jasmonate and ethylene signaling pathways plays a negative role in Nicotiana attenuata resistance to Alternaria alternata

Although patatin was initially identified as a major storage protein in potato tubers, patatin-like proteins(PLPs) have been recently reported to be widely present in many plant species and shown to be involved in plant-pathogen interactions. However, it is not clear whether PLPs are involved in Nicotiana attenuata resistance against the necrotrophic fungal pathogen, Alternaria alternata. In this study we identified a NaPLP gene, whose expression was highly elicited by A. alternata inoculation. Silencing NaPLP enhanced N. attenuata resistance to A. alternata, which was associated with higher induction levels of JA and ethylene biosynthetic genes, NaACS1, NaACO1 and NaLOX3. The induction of NaPLP expression by the fungus was abolished in JA-deficient plants and significantly reduced in ethylene-insensitive plants. In addition, NaPLP transcripts were highly induced by exogenous treatment with either methyl jasmonate(MeJA) or ethephon. Co-treatment with MeJA and ethephon led to a much higher induction level of NaPLP transcripts, and this synergistic induction was largely dependent on endogenous JA and ethylene signaling pathways. Thus, we conclude that the NaPLP gene is elicited by A. alternata via JA and ethylene signaling pathways in a synergistic way; however, unlike other JA-and ethylene-induced defense genes,NaPLP negatively affects plant resistance to the fungus likely by suppressing JA and ethylene biosynthetic gene expression.

Roles of jasmonates and brassinosteroids in rice responses to high temperature stress——A review

High temperature (HT) stress has become one of the most detrimental stresses in crop production among constantly changing environmental factors.Exploiting approaches to enhance crop thermotolerance would have great significance in assuaging adverse effects of HT stress on crop growth and development.As jasmonates (JAs) and brassinosteroids (BRs) are novel phytohormones and play important roles in responses to biotic and abiotic stresses and in a wide range of plant developmental processes,this paper reviewed the roles and mechanisms of JAs and BRs in mitigating HT stress,with focus on rice (Oryza sativa L.) subjected to HT stress during anthesis.It is demonstrated that JAs alleviate spikelet-opening impairment and BRs ameliorate pistil fertilization ability under HT stress during anthesis of rice,although there are controversial observations.Activating the defense system,enhancing osmotic regulation,protecting photosynthesis,and interacting with other phytohormones,especially with ethylene and abscisic acid,are main physiological mechanisms by which JAs or BRs attenuate HT stress to plants.Elevating levels of JAs or BRs in plants could be considered as an important approach to enhance crop thermotolerance through breeding new varieties.Using JAs or BRs as chemical regulators and adopting proper water and nitrogen management practices could reduce the harm of HT stress to rice.Further research is needed to elucidate the roles of JAs and BRs in different plant tissues in responses to HT stress under different genetic backgrounds and environments,reveal the molecular mechanism underlying JAs and BRs mediating HT stress,understand the cross-talk between phytohormones in modulating HT stress,and establish integrated crop management to minimize the hazard of HT stress in rice production.

Effect of jasmonate treatments on leaves of Rosa rugosa‘Plena’and detoxification enzymes and feeding of adult Monolepta hieroglyphica

To study the effect of jasmonates(JAs)on the resistance of economic forest plants to insects,R osa rugosa‘Plena'leaves were treated with 1 mmol/L jasmonic acid(JA),methyl jasmonate(MeJA)and Z-jasmone,then the content of tannin and total phenol in leaves and the feeding area of Monolepta hieroglyphica adults on leaves were measured.Changes in the activities of detoxification enzymes in adult M.hieroglyphica that had fed on leaves treated with JAs were also studied.Tannin and total phenol levels in leaves increased significantly after treatment with JAs,and tannin level was 1.36–1.55-fold higher than in the control after treatment with 1 mmol/L MeJA.The total content of phenol in leaves treated with 1.0 mmol/L Z-jasmone increased by 1.33–2.20-fold compared with those of the control.The activities of detoxification enzymes in adults were inhibited to differing degrees:activity of alkaline phosphatase(AKP)first increased,then decreased;the activities of acid phosphatase(ACP),glutathione S-transferases(GSTs)and carboxylesterase(CarE)following treatment with 1 mmol/L MeJA were significantly reduced and were 22%–31%,11%–26%,and 11%–31%lower than those of the control,respectively.Moreover,the feeding area of adult M.hieroglyphica on the leaves treated with JAs was significantly reduced(P<0.05).The feeding area of economic forest R.rugosa‘Plena'leaves treated with 1 mmol/L MeJA decreased by 17%–43%compared with that of the control.Moreover,the decrease in the adult M.hieroglyphica feeding area was highly positively correlated with the content of tannin and positively correlated with the contents of total phenol of economic forest R.rugosa‘Plena'leaves.The reduced feeding area of adult M.hieroglyphica was highly negatively correlated with the activities of AKP and ACP and negatively correlated with those of the GSTs.In conclusion,the use of 1 mmol/L MeJA can noticeably decrease the deleterious effects of adult M.hieroglyphica.

Effects of Methyl Jasmonate on the Composition of Volatile Compounds in Pyropia yezoensis

Volatile organic compounds in marine algae have been reported to comprise characteristic flavor of algae and play an important role in their growth, development and defensive response. Yet their biogeneration remain largely unknown. Here we studied the composition of volatile compouds in Pyropia yezoensis and their variations in response to methyl jasmonate(MeJA) and diethyldithiocarbamic acid(DIECA) treatment using gas chromatography-mass spectrometry(GC-MS). A total of 44 compounds belonging to the following chemical classes(n) were identified, including aldehydes(11), alcohols(8), acids and esters(6), alkanes(5), ketones(5), alkenes(3), and S-or N-containing miscellaneous compounds(6). External treatment with plant hormone MeJA increased the content of 1-dodecanol, 4-heptenal, and 2-propenoic acid-2-methyl dodecylester, but decreased the content of phytol, 3-heptadecene, 2-pentadecanone, and isophytol. When pretreated with DIECA, an inhibitor of the octadecanoid pathway leading to the biosynthesis of endogeneous jasmonates and some secondary metabolites, phytol and isophytol were increased, while 4-heptenal, 1-dodecanol, and 2-propenoic acid-2-methyl dodecylester were decreased, both of which were negatively correlated with their variations under MeJA treatment. Collectively, these results suggest that MeJA does affect the volatile composition of P. yezoensis, and the octadecanoid pathway together with endogenous jasmonate pathway may be involved in the biosynthesis of volatile compounds, thereby providing some preliminary envision on the composition and biogeneration of volatile compounds in P. yezoensis.

Synergistic Effects of a Night Temperature Shift and Methyl Jasmonate on the Production of Anthocyanin in Red Leaf Lettuce

The production of a secondary metabolite such as anthocyanin is coordinately regulated by plant intrinsic factors and influenced by multiple environmental factors. In red leaf lettuce, the red pigment component anthocyanin is important for the commercial value of the crop, but its synchronous regulation by multiple factors is not well understood. Here, we examined the synergistic effects of a night temperature shift and methyl jasmonate (MJ) on the production of anthocyanin in red leaf lettuce. Low or high night temperature treatment for 3 days just before harvesting induced the production of anthocyanin without affecting plant biomass. Temperature-dependent activation of anthocyanin accumulation was accelerated by treating with MJ. Night temperature shifts and MJ triggered oxidative stresses in leaves, as indicated by hydrogen peroxide accumulation and lipid peroxidation. Interestingly, these oxidative stresses were more evident in leaves simultaneously treated with both a high night temperature and MJ. The activity of the superoxide dismutase (SOD) was increased alongside the elevation of oxidative stress. Taken together, these results indicate that the combined treatment of a night temperature shift with MJ may accelerate anthocyanin production by increasing the levels of oxidative stress to the leaves of red leaf lettuce.

An Experimental Study of the Atmospheric Oxidation of a Biogenic Organic Compound (Methyl Jasmonate) in a Thin Water Film as in Fog or Aerosols

Experiments on the reactions of OH radicals in thin films of water were conducted in a photochemical reactor. The OH radical reactivity of a biogenic molecule (methyl jasmonate) was observed to be much larger in thin films of water than in the bulk aqueous phase. The pseudo-first order reaction rate was enhanced by an order of magnitude on a 38-micron film compared to the bulk liquid. However, the first order rate constant increased by 349%. This has implications in atmospheric systems like fog and mist which have large specific surface areas. The enhanced reactivity is attributable to both the partial solvation and faster diffusion at the air-water interface compared to the bulk liquid.

Effect of Postharvest Methyl Jasmonate Treatment on Early-Matured “Hass” Avocado Fruit Exocarp Colour Development during Ripening

Poor exocarp colour development is a common postharvest problem for early harvested “Hass” avocado fruit during ripening, which affects fruit quality and consumer preference. Therefore, measures to improve “Hass” avocado fruit colour developments are of great importance in the industry. This study investigated the effectiveness of postharvest methyl jasmonate treatment to improve early matured “Hass” avocado fruit exocarp colour during ripening. The results showed that T1 (10 μmol∙L−1) and T2 (100 μmol∙L−1) MeJA treatment increased visual colour, and decreased objective colour parameters (L*, C* and h˚) during ripening when compared with control fruit. Moreover, MeJA treated “Hass” avocado fruits had lower total chlorophyll content and higher total anthocyanin and cyanidin-3-O-glucoside concentration during ripening. In conclusion, “Hass” avocado fruit post-harvest treated with either T1 (10 μmol∙L−1) or T2 (100 μmol∙L−1) MeJA concentration improved exocarp quality attributes such as colour parameters (L*, C* h˚ and visual colour) and pigments (total anthocyanin and cyanidin-3-O-glucoside) during ripening, therefore, can be recommended for avocado fruit.

The Arabidopsis P450 protein CYP82C2 modulates jasmonateinduced root growth inhibition, defense gene expression and indole glucosinolate biosynthesis

Jasmonic 酸(JA ) 是对草食动物和一些微生物引起的病原体调整大量植物防卫回答的一个丰满的导出酸的发信号分子。分子的基因研究证实了 JA 也在植物开发的几个方面执行一个关键角色。这里，我们描述 Arabidopsis 变异的 jasmonic acid-hypersensitive1-1 (jah1-1 ) 的描述，它在 JA 回答的几个方面是有缺点的。尽管异种在根生长抑制展出增加的敏感到 JA，它显示出 JA 可诱导的防卫基因和减少的抵抗的减少的表示到 necrotrophic 真菌 Botrytis cinerea。基因克隆研究显示这些缺点被一个变化在细胞色素 P450 蛋白质 CYP82C2 引起。我们提供证明的证据到 B 的 jah1-1 异种的损害抵抗。cinerea 被导致 JA 的防卫基因的减少的表示伴随并且减少了导致 JA 的吲哚 glucosinolates (IG ) 的累积。相反地，提高的抵抗到 B。在 CYP82C2-overexpressing 植物的 cinerea 被导致 JA 的防卫基因的增加的表示伴随并且提高了导致 JA 的 IG 的层次。我们证明 CYP82C2 影响 IG biosynthetic 先锋的导致 JA 的累积色氨酸(Trp ) ，然而并非导致 JA 的 IAA 或导致病原体的 camalexin。一起，我们 CYP82C2 可以在导出 Trp 的第二等的代谢物的新陈代谢扮演在下面的一个假设在 JA 在哪个铺平调节的结果支持被提高。jah1-1 异种应该因此在向理解位于调停 JA 的微分回答的复杂性下面的机制的未来研究是重要的，它是重要的让植物使他们的生长适应千变万化环境。

Exogenously applied methyl Jasmonate induces early defense related genes in response to Phytophthora infestans infection in potato plants

In order to elucidate the contributions of JA in orchestrating disease resistance in potato plants,the potato genotype‘SD20’,which exhibits strong resistance against the highly virulent Phytophthora infestans isolate CN152,while infected by the super virulent isolate 2013-18-306,was treated with exogenous JA and then challenged by inoculation with 2013-18-306.The results showed that exogenously applied JA significantly delayed the onset and alleviated the symptoms of late blight,indicating exogenous JA could induce resistance to P.infestans in the early biotrophic stage of infection in‘SD20’plants.To further clarify the role of JA in the early defense response and identify key genes involved in JA signal transduction,gene expression profiling via RNA sequencing(RNA-seq)in‘SD20’plants treated with exogenously applied JA was performed.A total of 2927 differentially expressed genes were specifically induced,the majority encoded transcription factors,protein kinases,secondary metabolites,defense enzymes and disease resistance related proteins.GO functional annotation and KEGG metabolic pathway analysis showed that exogenously applied JA rapidly induced the expression of genes related to immune response regulation,pathogen defense,and other biological processes,and stimulated endogenous JA synthesis and signal transduction,and the overall early pathogen defense response in‘SD20’.These results provide useful information in understanding the JA’s function involved in pathogen defense responses and a theoretical basis for the application of JA in potato production.

Genome-wide association study reveals that JASMONATE ZIM-DOMAIN 5 regulates seed germination in rice

Seed germination is a complex trait regulated by multiple genes in rice.However,the regulators of rice seed germination have yet to be sufficiently determined.Here,a quantitative trait locus(QTL)for rice seed germination was identified in a genome-wide association study.The candidate gene JASMONATE ZIM-DOMAIN 5(OsJAZ5)of the QTL was verified that positively regulates seed germination.OsJAZ5 regulation of seed germination involves an OsABI3-mediated abscisic acid pathway.Overexpression of OsJAZ5 facilitated seed germination.The application of OsJAZ5 might be useful for increasing seed germination for rice direct seeding.

Jasmonate perception: Ligand-receptor interaction, regulation, and evolution

Phytohormones integrate external environmental and developmental signals with internal cellular responses for plant survival and multiplication in changing surroundings.Jasmonate(JA),which might originate from prokaryotes and benefit plant terrestrial adaptation,is a vital phytohormone that regulates diverse developmental processes and defense responses against various environmental stresses.In this review,we first provide an overview of ligand-receptor binding techniques used for the characterization of phytohormone-receptor interactions,then introduce the identification of the receptor COI1 and active JA molecules,and finally summarize recent advances on the regulation of JA perception and its evolution.

Histone H3 lysine 27 trimethylation suppresses jasmonate biosynthesis and signaling to affect male fertility under high temperature in cotton

High-temperature(HT)stress causes male sterility in crops,thus decreasing yields.To explore the possible contribution of histone modifications to male fertility under HT conditions,we defined the histone methylation landscape for the marks histone H3 lysine 27 trimethylation(H3K27me3)and histone H3 lysine 4 trimethylation(H3K4me3)by chromatin immunoprecipitation sequencing(ChIP-seq)in two differing upland cotton(Gossypium hirsutum)varieties.We observed a global disruption in H3K4me3 and H3K27me3 modifications,especially H3K27me3,in cotton anthers subjected to HT.HT affected the bivalent H3K4me3–H3K27me3 modification more than either monovalent modification.We determined that removal of H3K27me3 at the promoters of jasmonate-related genes increased their expression,maintaining male fertility under HT in the HT-tolerant variety at the anther dehiscence stage.Modulating jasmonate homeostasis or signaling resulted in an anther indehiscence phenotype under HT.Chemical suppression of H3K27me3 deposition increased jasmonic acid contents and maintained male fertility under HT.In summary,our study provides new insights into the regulation of male fertility by histone modifications under HT and suggests a potential strategy for improving cotton HT tolerance.