茉莉酸及其甲酯在植物诱导抗病性中的作用

茉莉酸类物质被认为是植物抗病防卫反应的内源及中间信号分子。本文介绍了茉莉酸及其甲酯在植物抗病性中的作用,从它们在体内激活的代谢途径及相关基因表达探讨有关作用机制以及有可能在农业上应用的前景。     

Pib启动子中茉莉酸和乙烯响应元件的转基因分析

水稻Pib基因的表达受茉莉酸、乙烯等激素诱导, 为了确定该基因启动子响应茉莉酸和乙烯诱导的必需区域, 进一步阐明茉莉酸和乙烯响应分子元件, 文章用PCR制备了Pib全长启动子-3 572~2 bp及3个5′端有不同长度缺失的Pib启动子片段-2 692~2 bp、-1 335~2 bp、-761~2 bp。4个不同长度Pib启动子分别置换掉双元质粒中gus基因上游的35S构建为重组质粒, 经农杆菌介导转入水稻获得转基因植株。转基因水稻中gus活性的蛋白质水平和mRNA水平的定性和定量分析结果表明, 全长Pib启动子(-3 572~2 bp, pNAR901)启动活性最强, 茉莉酸或乙烯诱导6 h后, 其驱动gus基因在转基因植株各部组织中的表达量明显上升。而-3 572~-2 692 bp区段序列缺失后不但Pib启动子启动活性显著降低而且也丧失了对茉莉酸和乙烯的诱导活性。pNAR902(-2 692~2 bp),pNAR903(-1 335~2 bp)和pNAR904(-761~2 bp)中的Pib启动子序列的缺失长度相差达2倍和3倍以上, 但其对茉莉酸和乙烯的诱导响应没有区别。这些结果显示3个Pib启动子缺失体构建中, 其共同缺失序列即-3 572~-2 692 bp区域是Pib启动子茉莉酸和乙烯诱导响应的必需区域。软件检索证实, Pib启动子序列中只在上述共同缺失区段之内的-2 722 bp处有一个GCCGCC基序。文章报道的转基因实验表明GCCGCC基序可能是Pib基因中有关茉莉酸和乙烯诱导响应的顺式分子元件。     

外源茉莉酸和茉莉酸甲酯诱导植物抗虫作用及其机理

综述了茉莉酸(jasmonic acid, JA)和茉莉酸甲酯(methyl jasmo nate, MJA)的分子结构和应用其诱导的植物抗虫作用及其机制。植物受外源茉莉酸或茉莉酸甲酯刺激后,一条反应途径是由硬脂酸途径激活防御基因,另一条途径是直接激活防御基因。防御基因激活后导致代谢途径重新配置,并可能诱导植物产生下列4种效应：（1）直接防御,即植物产生对害虫有毒的物质、抗营养和抗消化的酶类,或具驱避性和妨碍行为作用的化合物;（2）间接防御,即产生吸引天敌的挥发物;（3）不防御,即无防御反应;（4）负防御,即产生吸引害虫的挥发物。     

水杨酸、茉莉酸和乙烯介导的防卫信号途径相互作用的研究进展

乙烯、水杨酸和茉莉酸是植物体内主要的几个防御信号途径,也是研究比较多的几个信号途径。很多试验证明不同的防御信号途径相互间存在相互作用,他们或相互抑制,或相互促进。从这三种信号途径相互间的作用,及作用的联系点进行综述。     

Enhancement of petunia and dendrobium flower senescence by jasmonic acid methyl ester is via the promotion of ethylene production

Methyl jasmonate (JA-Me), applied to dendrobium and petunia flowers either as an aqueous solution through the cut stem or stigma, or as a gas, accelerated senescence. The rate of appearance of wilting symptoms was directly related to the amount of JA-Me applied to the flowers. JA-Me increased ethylene production by the flowers, irrespective of application method, and this effect was also proportional to the dose of the compound. In both dendrobium and petunia flowers, the JA-Me induced increases in ethylene production and 1-aminocyclopropane-1-carboxylic acid content followed similar patterns. Aminooxyacetic acid, an inhibitor of ACC-synthase, and silver-thiosulfate, an inhibitor of ethylene action, completely inhibited the effects of JA-Me. It is concluded that JA-Me enhances petunia and dendrobium flower senescence via the promotion of ACC and ethylene production.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AOA aminooxyacetic acid - Fl flower - JA jasmonic acid - JA-Me jasmonic acid methyl ester - LOX lipoxygenase - PLase A A-type phospholipase - STS silver-thiosulfate     

Arabidopsis thaliana Atvsp is homologous to soybean VspA and VspB,genes encoding vegetative storage protein acid phosphatases,and is regulated similarly by methyl jasmonate,wounding, sugars,light and phosphate

The soybean vegetative storage proteins, VSP and VSP, are acid phosphatases that accumulate to very high levels in hypocotyls, young leaves and flowers and pods. The genes encoding the soybean VSP are activated by jasmonate, wounding, sugars and light and down regulated by phosphate and auxin. In this study, expression of an Arabidopsis thaliana gene (Atvsp) encoding a protein homologous to soybean Vsp and Vsp, was examined and compared to expression of the soybean Vsp genes. Atvsp mRNA was present at high levels in flowers and buds and at low levels in roots, stems, leaves and siliques. Expression of Atvsp in leaves could be induced by wounding or by treatment of illuminated plants with methyl jasmonate and sucrose. Roots of plants with wounded leaves also accumulated Atvsp mRNA indicating that this gene can be regulated by a transmissible wound signal. Phosphate partially inhibited expression of Atvsp. Arabidopsis proteins of 29 and 30 kDa crossreacted with antibodies against soybean VSP. These proteins were very abundant in flowers and the proteins accumulated in leaves and roots of plants treated with methyl jasmonate. The level of these proteins in flowers was similar to the levels of soybean VSP in young soybean leaves. Overall, these data indicate that Arabidopsis Atvsp and soybean VspA/B genes are regulated similarly and that in both plants, the gene products can accumulate to high levels. This suggests that genes homologous to VspA/B may be of greater general significance than previously recognized.     

Mutual antagonism of ethylene and jasmonic acid regulates ozone-induced spreading cell death in Arabidopsis

Ethylene (ET) and jasmonic acid (JA) have opposite effects on ozone (O(3))-induced spreading cell death; ET stimulates, and is required for the spreading cell death, whereas JA protects tissues. We studied the underlying molecular mechanisms with the O(3)-sensitive, JA-insensitive jasmonate resistant 1 (jar1), and the O(3)-tolerant, ET-insensitive ethylene insensitive 2 (ein2) mutants. Blocking ET perception pharmacologically with norbornadiene (NBD) in jar1, or ET signaling genetically in the jar1 ein2 double mutant prevented the spread of cell death. This suggests that EIN2 function is epistatic to JAR1, and that the JAR1-dependent JA pathway halts oxidative cell death by directly inhibiting ET signaling. JAR1-dependent suppression of the ET pathway was apparent also as increased EIN2-dependent gene expression and ET hypersensitivity of jar1. Physiological experiments suggested that the target of JA is upstream of Constitutive Triple Response 1 (CTR1), but downstream of ET biosynthesis. Gene expression analysis of 1-aminocyclopropane-1-carboxylic acid (ACC)-treated and O(3)-exposed ein2 and jar1 revealed reciprocal antagonism: the EIN2-mediated suppression of the JA pathway. The results imply that the O(3)-induced spreading cell death is stimulated by early, rapid accumulation of ET, which can suppress the protecting function of JA thereby allowing cell death to proceed. Extended spreading cell death induces late accumulation of JA, which inhibits the propagation of cell death through inhibition of the ET pathway.     

Stomatal responses to jasmonic acid, linolenic acid and abscisic acid in wild-type and ABA-deficient tomato plants

Wild-type and abscisic acid (ABA) -deficient (sitiens) tomato plants were used to analyse the effects of abscisic acid (ABA), butyric acid (BA), jasmonic acid (JA) and linolenic acid (LA) on assimilation and transpiration rates in detached leaves taking up those substances into the transpiration stream. BA did not affect assimilation and transpiration rates. ABA decreased assimilation and transpiration in both wild-type and ABA-deficient mutants. JA reduced the assimilation rate in both lines but induced a significant reduction of transpiration in the wild type only. The response to LA in both lines was slower than that to JA.     

The effect of Aminooxyacetic acid on ethylene production induced by methyl jasmonate in tomatoes

Aminooxyacetic acid (AOA), an inhibitor of ACC biosynthesis, applied together with methyl jasmonate (JA-Me) to mature green and light-green tomatoes cv. Venture greatly inhibited ethylene production stimulated by JA-Me, when analyzed in ripe and overripe stages. AOA applied alone did not affect ethylene production in the same conditions of treatment and analysis. It is suggested that after JA-Me treatment of tomatoes the turnover rate of ACC is higher (JA-Me stimulates EFE activity) in comparison to control tissues, and, consequently, AOA inhibited ethylene production stimulated by methyl jasmonate.     

Occurrence of jasmonic acid in Dunaliella (Dunaliellales, Chlorophyta)

The occurrence of jasmonic acid and related compounds in Dunaliella species was investigated using gas-liquid chromatography/mass spectroscopy (GCY MS). Jasmonic acid was identified in the ethyl acetate soluble-acidic fraction of Dunaliella tertiolecta and Dunaliella salina (Dunal) Teodoresco, The concentration of jasmonic acid in D. salina. which is extremely halophilic, was much higher than that in D. tertiolecta Butcher, These results indicate that jasmonic acid might play an important role in salt-tolerance in Dunaliella.     

外源水杨酸和茉莉酸诱导巨峰葡萄抗根瘤蚜

【目的】水杨酸和茉莉酸在植物诱导防御虫害反应中发挥着重要作用。本研究旨在探讨水杨酸和茉莉酸诱导葡萄对根瘤蚜的抗性。【方法】以盆栽巨峰为试材,在接种葡萄根瘤蚜Daktulosphaira vitifoliae的同时喷施水杨酸和茉莉酸,测定和评估了对根瘤蚜生长发育及产卵量的影响,以及对葡萄根系抗氧化相关酶［过氧化物酶(POD)和过氧化氢酶(CAT）］活性、丙二醛（MDA）含量、新梢生长量及光合速率的影响。【结果】水杨酸和茉莉酸诱导处理显著降低了根瘤蚜卵量及下代1,2龄若蚜总数,接种35 d后根瘤蚜的产卵量分别减少了41.35％和50.00％,1龄和2龄若蚜总数分别减少了42.31％和50.00％;根瘤蚜侵染后根系中POD和CAT活性均呈先升高后降低的趋势,且水杨酸和茉莉酸诱导处理在各测定时期均高于仅接种根瘤蚜处理;水杨酸和茉莉酸处理的根系中MDA含量在各测定时期均低于仅接种根瘤蚜处理;水杨酸和茉莉酸处理降低了根瘤蚜侵染对植株地上部生长及光合的抑制。接种处理后第30天,仅接种根瘤蚜处理的植株地上部生长量减少了48.11%,光合速率降低了58.77％,而水杨酸和茉莉酸处理后的新梢生长量分别减少了31.57％和25.71％,光合速率分别降低了32.89％和24.67％。【结论】叶片喷洒茉莉酸和水杨酸能够降低根瘤蚜种群密度,并提高葡萄根系活性氧清除能力和防御酶活性,缓解树势衰退。     

Oxidative burst, jasmonic acid biosynthesis, and taxol production induced by low-energy ultrasound in Taxus chinensis cell suspension cultures

This work aims to detect the two signal events in the elicitation of plant defense responses and secondary metabolism in plant cell cultures by low-energy ultrasound (US), transient production of reactive oxygen species (ROS) or the oxidative burst and jasmonic acid (JA) biosynthesis, and examine their influence on secondary metabolism. Experiments were carried out in Taxus chinensis cell suspension culture which produces the anticancer diterpenoid Taxol (paclitaxel). The culture was exposed to low-frequency US for a short period of time (2 min). At sufficiently high US power levels the US exposure significantly enhanced the Taxol production and slightly depressed cell growth and viability. The US exposure induced transient production of O(2)*- and H(2)O(2) and an increase in the intracellular JA level as well as the activities of enzymes for JA synthesis, lipoxygenase (LOX), and allene oxide synthase (AOS). Inhibition of the ROS production by putative ROS scavengers or the JA accumulation by LOX inhibitors effectively suppressed the US-stimulated Taxol production. Inhibition of the ROS production also suppressed the US-induced JA accumulation. These results suggest that oxidative burst is an upstream event to JA accumulation, and both ROS from the oxidative burst and JA from the LOX pathway are key signal elements in the elicitation of Taxol production of T. chinensis cells by low-energy US.     

Triacontanol negatively modulates the jasmonic acid-stimulated proteinase inhibitors in tomato (Lycopersicon esculentum)

Triacontanol (TRIA), a long chain aliphatic alcohol (C30H61OH) reverses the effect of jasmonic acid (JA) in inducing proteinase inhibitors (PIs) in tomato leaves. Porcine pancreas trypsin and Spodoptera litura gut proteinases were inhibited in the presence of leaf proteins treated with JA, and TRIA partially reverses this effect. Spodoptera litura larvae fed with tomato leaves treated with JA were reduced in body weight and TRIA is able to partially reverse this JA-induced effect. These results reflect the partial reversal effect of TRIA in down regulating the JA-induced production of proteinase inhibitors.     

Systemic induction of a Phytolacca insularis antiviral protein gene by mechanical wounding, jasmonic acid, and abscisic acid

We have isolated a gene encoding a ribosome-inactivating protein (RIP) from Phytolacca insularis, designated as P. insularis antiviral protein 2 (PIP2). The PIP2 gene contained an open reading frame encoding a polypeptide of 315 amino acids. The deduced amino acid sequence of PIP2 was similar to those of other RIPs from Phytolacca plants. Recombinant PIP2 was expressed in Escherichia coli and was used to investigate its biological activities. Recombinant PIP2 inhibited protein synthesis in rabbit reticulocyte lysate by inactivating ribosomes through N-glycosidase activity. It also exhibited antiviral activity against tobacco mosaic virus (TMV). Expression of the PIP2 gene was developmentally regulated in leaves and roots of P. insularis. Furthermore, expression of the PIP2 gene was induced in leaves by mechanical wounding. The wound induction of the PIP2 gene was systemic. Expression of the PIP2 gene also increased in leaves in a systemic manner after treatment with jasmonic acid (JA) and abscisic acid (ABA), but not with salicylic acid (SA). These results imply that plants have employed the systemic synthesis of the defensive proteins to protect themselves more efficiently from infecting viruses.     

Control of Dioscorea alata microtuber dormancy and germination by jasmonic acid

Effects of appling exogenous jasmonic acid (JA) on the germination of Dioscorea alata L. microtubers were examined on Murashige and Skoog (MS) medium. Microtuber germination was promoted by JA (0.1 and 1 M) supplemented to the culture medium but higher concentrations (30 and 100 M) completely inhibited germination. When these inhibited microtubers were transferred to hormone-free medium, germination resumed.After transfer to greenhouse conditions, almost all plants (95%) from tubers previously cultivated on MS medium with 100 M JA survived and all acclimatized plants had produced tubers after 8 months. It is concluded that depending on JA concentration, both the germination and dormancy processes in D. alata microtubers were affected. The release from dormancy is easily obtained by transferring dormant microtubers to hormone-free medium.     

系统素、茉莉酸在番茄系统伤反应中的作用

当植物受到机械损伤或昆虫伤害时,植物体会在受伤部位产生伤信号分子启动防御基因的系统表达,蛋白酶抑制剂基因是防御基因的一典型代表.番茄是研究植物系统伤信号很好的模式植物,目前,三种类型的番茄系统伤信号突变体被鉴定出来,通过对番茄系统伤信号突变体进行功能分析并在它们之间进行相互嫁接实验,研究结果表明系统素和茉莉酸通过同一信号通路来激活防御基因的系统表达.系统素(或它的前体原系统素)在受伤部位激活茉莉酸的合成,使之达到系统反应的水平,应对外来伤害;茉莉酸或其衍生物是重要的系统伤信号分子,它诱导伤防御基因的系统表达.植物的系统伤反应可比做动物的炎症反应,它们之间有许多相似之处.     

Monitoring of methyl jasmonate-responsive genes in Arabidopsis by cDNA macroarray: self-activation of jasmonic acid biosynthesis and crosstalk with other phytohormone signaling pathways.

Jasmonates mediate various physiological events in plant cells such as defense responses, flowering, and senescence through intracellular and intercellular signaling pathways, and the expression of a large number of genes appears to be regulated by jasmonates. In order to obtain information on the regulatory network of jasmonate-responsive genes (JRGs) in Arabidopsis thaliana (Arabidopsis), we screened 2880 cDNA clones for jasmonate responsiveness by a cDNA macroarray procedure. Since many of the JRGs reported so far have been identified in leaf tissues, the cDNA clones used were chosen from a non-redundant EST library that was prepared from above-ground organs. Hybridization to the filters was achieved using alpha-33P-labeled single-strand DNAs synthesized from mRNAs obtained from methyl jasmonate (MeJA)-treated and untreated Arabidopsis seedlings. Data analysis identified 41 JRGs whose mRNA levels were changed by more than three fold in response to MeJA. This was confirmed by Northern blot analysis by using eight representatives. Among the 41 JRGs identified, 5 genes were JA biosynthesis genes and 3 genes were involved in other signaling pathways (ethylene, auxin, and salicylic acid). These results suggest the existence of a positive feedback regulatory system for JA biosynthesis and the possibility of crosstalk between JA signaling and other signaling pathways.