Plants have evolved complex signaling pathways to coordinate responses to developmental and environmental Information. The oxylipin pathway Is one pivotal lipid-based signaling network, composed of several competing b...Plants have evolved complex signaling pathways to coordinate responses to developmental and environmental Information. The oxylipin pathway Is one pivotal lipid-based signaling network, composed of several competing branch pathways, that determines the plant＇s ability to adapt to various stimuli. Activation of the oxyllpln pathway Induces the de novo synthesis of biologically active metabolltes called ＂oxyllplns＂. The relative levels of these metabolltes are a distinct indicator of each plant species and determine the ability of plants to adapt to different stimuli. The two major branches of the oxyllpln pathway, allene oxide synthase （AOS） and hydroperoxlde lyase （HPL） are responsible for production of the signaling compounds, jasmonates and aldehydes respectively. Here, we compare and contrast the regulation of AOS and HPL branch pathways In rice and Arabidopsis as model monocotyledonous and dicotyledonous systems. These analyses provide new Insights Into the evolution of JAs and aldehydes signaling pathways, and the complex network of processes responsible for stress adaptations In monocots and dicots.展开更多
Throughout their life, plants are challenged by various abiotic and biotic stress factors. Among those are attacks from herbivorous insects. The molecular mechanisms underlying the detection of herbivores and the subs...Throughout their life, plants are challenged by various abiotic and biotic stress factors. Among those are attacks from herbivorous insects. The molecular mechanisms underlying the detection of herbivores and the subsequent signal transduction are not well understood. As a second messenger, fluxes in intracellular Ca2＋ levels play a key role in mediating stress response pathways. Ca2＋ signals are decoded by Ca2＋ sensor proteins such as calmodulin-like proteins （CMLs）. Here, we demonstrate that recombinant CML37 behaves like a Ca2＋ sensor in vitro and, in Arabidopsis, AtCML37 is induced by mechanical wounding as well as by infestation with larvae of the generalist lepidopteran herbivore Spodoptera littoralis. Loss of function of CML37 led to a better feeding performance of larvae suggesting that CML37 is a positive defense regulator. No herbivory-induced changes in secondary metabolites such as glucosinolates or flavonoids were detected in cml37 plants, although a significant reduction in the accumulation of jasmonates was observed, due to reduced expression of JAR1 mRNA and cellular enzyme activity. Consequently, the expression of jasmonate-responsive genes was reduced as well. Summarizing, our results suggest that the Ca2＋ sensor protein, CML37, functions as a positive regulator in Ca2＋ signaling during herbivory, connecting Ca2＋ and jasmonate signaling.展开更多
Biosynthesis/metabolism,perception/signaling,and transport are three essential aspects of the actions of phytohormones.Jasmonates(JAs),including jasmonic acid(JA)and related oxylipins,are implicated in the regulation ...Biosynthesis/metabolism,perception/signaling,and transport are three essential aspects of the actions of phytohormones.Jasmonates(JAs),including jasmonic acid(JA)and related oxylipins,are implicated in the regulation of a range of ecological interactions,as well as developmental programs to integrate these interactions.Jasmonoyl-isoleucine(JA-Ile)is the most bioactive JAs,and perception of JA-Ile by its coreceptor,the Skp1-Cullin1-F-box-type(SCF)protein ubiquitin ligase complex SCF^(COI1)-JAZ,in the nucleus derepresses the transcriptional repression of target genes.The biosynthesis and metabolism of JAs occur in the plastid,peroxisome,cytosol,endoplasmic reticulum,and vacuole,whereas sensing of JA-Ile levels occurs in the nucleus.It is increasingly apparent that a number of transporters,particularly members of the jasmonates transporter(JAT)family,located at endomembranes as well as the plasma membrane,constitute a network for modulating and coordinating the metabolic flux and signaling of JAs.In this review,we discuss recent advances in the metabolism,signaling,and especially the transport of JAs,focusing on intracellular compartmentation of these processes.The roles of transporter-mediated cell-cell transport in driving long-distance transport and signaling of JAs are also discussed.展开更多
Mutants defective in chloroplast development or photosynthesis are liable to accumulate higher levels of anthocyanin in photo-oxidative stress.However,regulatory mechanisms of anthocyanin biosynthesis in the mutants r...Mutants defective in chloroplast development or photosynthesis are liable to accumulate higher levels of anthocyanin in photo-oxidative stress.However,regulatory mechanisms of anthocyanin biosynthesis in the mutants remain unclear.Here,we investigated the mechanism by which the deletion of thylakoid formation1（THF1） leads to an increased level of anthocyanin in Arabidopsis thaliana L.Physiological and genetic evidence showed that the increased level of anthocyanin in thf1 is dependent on coronatine-insensitive1（COM）signaling.Our data showed that thf1 had higher levels of basalα-linolenic acid（α-LeA）,and methyl jasmonate（JA）-induced α-LeA and 12-oxophytodienoic acid（OPDA） than the wild type（WT）.Consistently,expression levels of phospholipase genes including pPLAIIα and PLA-Iγ1 were elevated in thf1.Furthermore,inhibition of lipase activity by bromoenol lactone,a specific inhibitor of plant pPLA,led to producing identical levels of anthocyanins in WT and thf1 plants.Interestingly,OPDA biosynthesis was triggered by light illumination in isolated chloroplasts,indicating that new protein import into chloroplasts is not required for OPDA biosynthesis.Thus,we conclude that the elevated anthocyanin accumulation in thf1 is attributed to an increase in JA levels.This JA-mediated signaling to coordinate plant metabolism and growth in stress may be conserved in other photosensitive mutants.展开更多
Jasmonates （JAs） are a class of plant hormones that play important roles in the regulation of plant development and plant defense. It has been shown that Arabidopsis plants produce much higher levels of anthocyanins...Jasmonates （JAs） are a class of plant hormones that play important roles in the regulation of plant development and plant defense. It has been shown that Arabidopsis plants produce much higher levels of anthocyanins when treated exogenously with methyl jasmonate （MeJA）. However, a molecular link between the JA response and anthocyanin production has not been determined. The CORONATINE INSENTITIVE1 （COI1） gene is a key player in the regulation of many JA-related responses. In the present study, we demonstrate that the COI1 gene is also required for the JA-induced accumulation of anthocyanins in Arabidopsis. Furthermore, the MeJA-inducible expression of DIHYDROFLAVONOL REDUCTASE （DFR）, an essential component in the anthocyanin biosynthesis pathway, was completely eliminated in the coil mutant. Jasmonateinduced anthocyanin accumulation was found to be independent of auxin signaling. The present results indicate that the expression of both COI1 and DFR genes is required for the regulation of JA-induced anthocyanin accumulation and that DFR may be a key downstream regulator for this process.展开更多
基金Supported by UC discovery and NSF grants to KD. Publication of this paper is supported by the National Natural Science Foundation of China （30624808） and Science Publication Foundation of the Chinese Academy of Sciences.Acknowledgements The authors would like to acknowledge G. Raman for performing the jasmonate and aldehyde measurements.
文摘Plants have evolved complex signaling pathways to coordinate responses to developmental and environmental Information. The oxylipin pathway Is one pivotal lipid-based signaling network, composed of several competing branch pathways, that determines the plant＇s ability to adapt to various stimuli. Activation of the oxyllpln pathway Induces the de novo synthesis of biologically active metabolltes called ＂oxyllplns＂. The relative levels of these metabolltes are a distinct indicator of each plant species and determine the ability of plants to adapt to different stimuli. The two major branches of the oxyllpln pathway, allene oxide synthase （AOS） and hydroperoxlde lyase （HPL） are responsible for production of the signaling compounds, jasmonates and aldehydes respectively. Here, we compare and contrast the regulation of AOS and HPL branch pathways In rice and Arabidopsis as model monocotyledonous and dicotyledonous systems. These analyses provide new Insights Into the evolution of JAs and aldehydes signaling pathways, and the complex network of processes responsible for stress adaptations In monocots and dicots.
文摘为揭示伤害信号——茉莉酸类(JAs)对倍半萜可能的调控作用,以 3 年生白木香[Aquilaria sinensis(Lour.)Gilg]树苗为试材进行机械伤害和外施茉莉酸甲酯(MeJA)处理,测定其茎中内源 JAs和倍半萜含量。结果表明,机械伤害处理 1 h 后,内源 JAs 含量显著增加,随后迅速下降;伤害处理 24 h后又有小幅升高。伤害处理诱导白木香产生 3 种倍半萜(δ–愈创木烯、α–愈创木烯和α–葎草烯)且含量随着伤害时间延长而增多。外源 MeJA 处理也能够诱导产生相同种类的倍半萜且诱导强度大于伤害处理。伤害早期(1 h)内源 JAs 含量升高和伤害后期(48 h)倍半萜含量增多是植物启动相应的防御反应和抵御伤害胁迫的重要机制。
文摘Throughout their life, plants are challenged by various abiotic and biotic stress factors. Among those are attacks from herbivorous insects. The molecular mechanisms underlying the detection of herbivores and the subsequent signal transduction are not well understood. As a second messenger, fluxes in intracellular Ca2＋ levels play a key role in mediating stress response pathways. Ca2＋ signals are decoded by Ca2＋ sensor proteins such as calmodulin-like proteins （CMLs）. Here, we demonstrate that recombinant CML37 behaves like a Ca2＋ sensor in vitro and, in Arabidopsis, AtCML37 is induced by mechanical wounding as well as by infestation with larvae of the generalist lepidopteran herbivore Spodoptera littoralis. Loss of function of CML37 led to a better feeding performance of larvae suggesting that CML37 is a positive defense regulator. No herbivory-induced changes in secondary metabolites such as glucosinolates or flavonoids were detected in cml37 plants, although a significant reduction in the accumulation of jasmonates was observed, due to reduced expression of JAR1 mRNA and cellular enzyme activity. Consequently, the expression of jasmonate-responsive genes was reduced as well. Summarizing, our results suggest that the Ca2＋ sensor protein, CML37, functions as a positive regulator in Ca2＋ signaling during herbivory, connecting Ca2＋ and jasmonate signaling.
基金supported by the Natural Science Foundation of China(NSFC)(no.31970310,31470326,and 30870358)the Major Research Plan from the Ministry of Science and Technology of the People’s Republic of China(no.2013CB945100)the Program for New Century Excellent Talents in University(NECT-08-0529)to P.L.
文摘Biosynthesis/metabolism,perception/signaling,and transport are three essential aspects of the actions of phytohormones.Jasmonates(JAs),including jasmonic acid(JA)and related oxylipins,are implicated in the regulation of a range of ecological interactions,as well as developmental programs to integrate these interactions.Jasmonoyl-isoleucine(JA-Ile)is the most bioactive JAs,and perception of JA-Ile by its coreceptor,the Skp1-Cullin1-F-box-type(SCF)protein ubiquitin ligase complex SCF^(COI1)-JAZ,in the nucleus derepresses the transcriptional repression of target genes.The biosynthesis and metabolism of JAs occur in the plastid,peroxisome,cytosol,endoplasmic reticulum,and vacuole,whereas sensing of JA-Ile levels occurs in the nucleus.It is increasingly apparent that a number of transporters,particularly members of the jasmonates transporter(JAT)family,located at endomembranes as well as the plasma membrane,constitute a network for modulating and coordinating the metabolic flux and signaling of JAs.In this review,we discuss recent advances in the metabolism,signaling,and especially the transport of JAs,focusing on intracellular compartmentation of these processes.The roles of transporter-mediated cell-cell transport in driving long-distance transport and signaling of JAs are also discussed.
基金supported by grants to J.H.from the Ministry of Science and Technology of China(2013CB127000)the CAS/SAFEA International Partnership Program for Creative Research Teamsthe National Science Fund for Distinguished Young Scholars(30925005)
文摘Mutants defective in chloroplast development or photosynthesis are liable to accumulate higher levels of anthocyanin in photo-oxidative stress.However,regulatory mechanisms of anthocyanin biosynthesis in the mutants remain unclear.Here,we investigated the mechanism by which the deletion of thylakoid formation1（THF1） leads to an increased level of anthocyanin in Arabidopsis thaliana L.Physiological and genetic evidence showed that the increased level of anthocyanin in thf1 is dependent on coronatine-insensitive1（COM）signaling.Our data showed that thf1 had higher levels of basalα-linolenic acid（α-LeA）,and methyl jasmonate（JA）-induced α-LeA and 12-oxophytodienoic acid（OPDA） than the wild type（WT）.Consistently,expression levels of phospholipase genes including pPLAIIα and PLA-Iγ1 were elevated in thf1.Furthermore,inhibition of lipase activity by bromoenol lactone,a specific inhibitor of plant pPLA,led to producing identical levels of anthocyanins in WT and thf1 plants.Interestingly,OPDA biosynthesis was triggered by light illumination in isolated chloroplasts,indicating that new protein import into chloroplasts is not required for OPDA biosynthesis.Thus,we conclude that the elevated anthocyanin accumulation in thf1 is attributed to an increase in JA levels.This JA-mediated signaling to coordinate plant metabolism and growth in stress may be conserved in other photosensitive mutants.
基金Supported by the Hunan Provincial Natural Science Foundation of China （99jjy20016） the National Natural Science Foundation of China （30470990） the Fu-Rong Scholar Program of Hunan Provincial Govemment and Hunan Agricultural University and Scientific Research Fund of Hunan Provincial Education Department （04A024）.
文摘Jasmonates （JAs） are a class of plant hormones that play important roles in the regulation of plant development and plant defense. It has been shown that Arabidopsis plants produce much higher levels of anthocyanins when treated exogenously with methyl jasmonate （MeJA）. However, a molecular link between the JA response and anthocyanin production has not been determined. The CORONATINE INSENTITIVE1 （COI1） gene is a key player in the regulation of many JA-related responses. In the present study, we demonstrate that the COI1 gene is also required for the JA-induced accumulation of anthocyanins in Arabidopsis. Furthermore, the MeJA-inducible expression of DIHYDROFLAVONOL REDUCTASE （DFR）, an essential component in the anthocyanin biosynthesis pathway, was completely eliminated in the coil mutant. Jasmonateinduced anthocyanin accumulation was found to be independent of auxin signaling. The present results indicate that the expression of both COI1 and DFR genes is required for the regulation of JA-induced anthocyanin accumulation and that DFR may be a key downstream regulator for this process.
