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1.
  总被引:1,自引:0,他引:1  
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2.
Reversible hormone conjugations in plants may represent physiologically and biochemically essential pathways in the regulation of endogenous levels of biologically active pools of phytohormones. Conjugates of auxins, gibberellins, and cytokinins are now widely recognized as serving a storage function for rapid (im)mobilization of these phytohormones, depending on a variety of environmental, developmental, and physiological factors. The significance of conjugates of other phytohormones (abscisic acid, ethylene, jasmonic acid, and salicylic acid) is less well understood. Recent developments in studies on phytohormone conjugation, involving both biochemical and molecular biology approaches, are presented here. The nature and possible functions of the conjugates are discussed. Conjugates of other compounds (e.g., anthranilate-glucosides) are also known (for review, see Hösel, 1981). However, it is not known whether these compounds have a signaling function.  相似文献   

3.
    
The role of salicylic acid (SA) in plant responses to pathogens has been well documented, but its direct and indirect effects on plant responses to insects are not so well understood. We examined the effects of SA, alone and in combination with jasmonic acid (JA), on the performance of the generalist herbivore, Spodoptera exigua, in wild-type and mutant Arabidopsis thaliana genotypes that varied genetically in their ability to mount SA- and JA-mediated defence responses. In one experiment, growth of S. exigua larvae was highest on the Wassilewskija wild-type, intermediate on the Columbia wild-type and the JA-deficient fad mutant, and lowest on the nim1-1 and jar1-mutants, which are defective in the SA and JA pathways, respectively. Activity of guaiacol peroxidase, polyphenoloxidase, n-acetylglucosaminidase, and trypsin inhibitor varied by genotype but did not correlate with insect performance. SA treatment increased growth of S. exigua larvae by approximately 35% over all genotypes, but had no discernable effect on activities of the four defence proteins. In a second experiment, growth of S. exigua was highest across treatments on the cep1 mutant, a constitutive expressor of high SA levels and systemic acquired resistance, and lowest on the fad mutant, which is JA-deficient. JA treatment generally increased activity of all four defence proteins, increased total glucosinolate levels and reduced insect growth by approximately 25% over all genotypes. SA generally inhibited expression of JA-induced resistance to S. exigua when both hormones were applied simultaneously. Across genotypes and treatments, larval mass was negatively correlated with the activity of trypsin inhibitor and polyphenoloxidase and with total glucosinolate levels, and insect damage was negatively correlated with the activity of polyphenoloxidase. SA had little effect on the induction of defence protein activity by JA. However, SA attenuated the induction of glucosinolates by JA and therefore may explain better the interactive effects of SA and JA on insect performance. This study illustrates that direct and indirect cross-effects of SA on resistance to S. exigua can occur in A. thaliana. Effects of SA may be mediated through effects on plant defence chemistry or other aspects of the suitability of foliage for insect feeding and growth.  相似文献   

4.
    
Jasmonic acid (JA) and salicylic acid (SA) regulate stomatal closure, preventing pathogen invasion into plants. However, to what extent abscisic acid (ABA), SA and JA interact, and what the roles of SA and JA are in stomatal responses to environmental cues, remains unclear. Here, by using intact plant gas-exchange measurements in JA and SA single and double mutants, we show that stomatal responsiveness to CO2, light intensity, ABA, high vapor pressure deficit and ozone either did not or, for some stimuli only, very slightly depended upon JA and SA biosynthesis and signaling mutants, including dde2, sid2, coi1, jai1, myc2 and npr1 alleles. Although the stomata in the mutants studied clearly responded to ABA, CO2, light and ozone, ABA-triggered stomatal closure in npr1-1 was slightly accelerated compared with the wild type. Stomatal reopening after ozone pulses was quicker in the coi1-16 mutant than in the wild type. In intact Arabidopsis plants, spraying with methyl-JA led to only a modest reduction in stomatal conductance 80 min after treatment, whereas ABA and CO2 induced pronounced stomatal closure within minutes. We could not document a reduction of stomatal conductance after spraying with SA. Coronatine-induced stomatal opening was initiated slowly after 1.5–2.0 h, and reached a maximum by 3 h after spraying intact plants. Our results suggest that ABA, CO2 and light are major regulators of rapid guard cell signaling, whereas JA and SA could play only minor roles in the whole-plant stomatal response to environmental cues in Arabidopsis and Solanum lycopersicum (tomato).  相似文献   

5.
    
Land plants use diverse hormones to coordinate their growth, development and responses against biotic and abiotic stresses. Salicylic acid (SA) is an essential hormone in plant immunity, with its levels and signaling tightly regulated to ensure a balanced immune output. Over the past three decades, molecular genetic analyses performed primarily in Arabidopsis have elucidated the biosynthesis and signal transduction pathways of key plant hormones, including abscisic acid, jasmonic acid, ethylene, auxin, cytokinin, brassinosteroids, and gibberellin. Crosstalk between different hormones has become a major focus in plant biology with the goal of obtaining a full picture of the plant hormone signaling network. This review highlights the roles of SA in plant immunity and summarizes our current understanding of the pairwise interactions of SA with other major plant hormones. The complexity of these interactions is discussed, with the hope of stimulating research to address existing knowledge gaps in hormone crosstalk, particularly in the context of balancing plant growth and defense.  相似文献   

6.
  总被引:13,自引:0,他引:13  
Experiments with Arabidopsis mutants and sensitive and tolerant pairs in several other species have elucidated the molecular basis of plant ozone sensitivity and ozone lesion development. They have indicated an important role for hormonal signalling in determining the outcome of ozone challenge at the cellular level. The reactive oxygen species (ROS) from ozone degradation can cause either direct necrotic damage or induce the process of programmed cell death. Perception of ozone or ROS from its degradation in the apoplast activates several signal transduction pathways that regulate the responses of the cells to the increased oxidative load. Plant hormones salicylic acid, jasmonic acid, ethylene and abscisic acid are involved in determining the duration and extent of ozone-induced cell death and its propagation. Salicylic acid is required for the programmed cell death, ethylene promotes endogenous ROS formation and lesion propagation, and jasmonic acid is involved in limiting the lesion spreading. Abscisic acid is most likely involved through the regulation of stomata and thus is expected to affect lesion initiation. The roles and interactions of perception of ozone, the immediate downstream responses, hormone biosynthesis and signalling during ozone lesion initiation and formation are reviewed.  相似文献   

7.
    
The salicylic acid (SA)-induction deficient (sid) mutants of Arabidopsis, eds5 and sid2 accumulate normal amounts of camalexin after inoculation with Pseudomonas syringae pv. tomato (Pst), while transgenic NahG plants expressing an SA hydroxylase that degrades SA have reduced levels of camalexin and exhibit a higher susceptibility to different pathogens compared to the sid mutants. SID2 encodes an isochorismate synthase necessary for the synthesis of SA. NahG was shown to act epistatically to the sid mutant phenotype regarding accumulation of camalexin after inoculation with Pst in eds5NahG and sid2NahG plants. The effect of the pad4 mutation on the sid mutant phenotype was furthermore tested in eds5pad4 and sid2pad4 double mutants, and it was demonstrated that PAD4 acts epistatically to EDS5 and SID2 regarding the production of camalexin after inoculation with Pst. NahG plants and pad4 mutants were also found to produce less ethylene (ET) after infection with Pst in comparison to the wild type (WT) and sid mutants. Both PAD4 and NahG acted epistatically to SID regarding the Pst-dependent production of ET that was found to be necessary for the accumulation of camalexin. Early production of jasmonic acid (JA) 12 h after inoculation with Pst/avrRpt2 was absent in all plants expressing NahG compared to the other mutants tested here. These genetic studies unravel pleiotropic changes in defence signalling of NahG plants that are unlikely to result from their low SA content. This adds unexpected difficulties in the interpretation of earlier findings based solely on NahG plants.  相似文献   

8.
9.
20℃下后熟果实的LOX活性增加先于自由基产生和乙烯生成;JA处理对果实后熟软化启动期(采后1d)和果实快速软化期(采后5d)果实切片中的LOX活性、自由基产生和乙烯生物合成有促进作用,至果实软化后期(采后7d)这种效应消失;亚油酸只在采后1d果实切片中促使LOX活性和乙烯生成;SA处理抑制了果实后熟进程中组织切片的LOX活性、自由基产生和乙烯的生物合成;SA和JA对LOX活性和乙烯生物合成具有明显的拮抗作用。  相似文献   

10.
  总被引:5,自引:0,他引:5  
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11.
Hormone-Virus Interactions in Plants   总被引:1,自引:0,他引:1  
Symptoms of virus infection may be simplistically ascribed to a change in quantity of a particular plant hormone, and frequently virus-induced symptoms can be mimicked by application or removal of a plant hormone. In this review, we look critically at the information available concerning changes in the biosynthesis and metabolism of plant hormones following virus infection. In addition, we briefly review the effects of virus infection on endogenous jasmonates and salicylic acid. We also briefly assess the involvement of the classical plant hormones, jasmonic acid and salicylic acid in the induction of defense-related genes.  相似文献   

12.
  总被引:2,自引:0,他引:2  
Ethylene and salicylic acid (SA) are key intermediates in a host's response to pathogens. Previously, we have shown using a tomato compatible interaction that ethylene and SA act sequentially and are essential for disease symptom production. Here, we have examined the relationship between the two signals in the Arabidopsis-Xanthomonas campestris pv. campestris (Xcc) compatible interaction. Preventing SA accumulation by expression of the nahG gene reduced subsequent ethylene production and altered the development of disease symptoms, with plants showing no visible chlorosis. The ethylene insensitive lines, etr1-1 and etr2-1, on the other hand, accumulated SA and exhibited normal but precocious symptom development. Therefore, Arabidopsis, like tomato, was found to exhibit co-operative ethylene and SA action for the production of disease symptoms. However, in Arabidopsis, SA was found to act upstream of ethylene. Jasmonic acid and indole-3-acetic acid levels were also found to increase in response to Xcc. In contrast to ethylene, accumulation of these hormones was not found to be dependent on SA action. These results indicate that the plants response to a virulent pathogen is a composite of multiple signaling pathways.  相似文献   

13.
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。  相似文献   

14.
    
Plants activate direct and indirect defences in response to insect egg deposition. However, whether eggs can manipulate plant defence is unknown. In Arabidopsis thaliana, oviposition by the butterfly Pieris brassicae triggers cellular and molecular changes that are similar to the changes caused by biotrophic pathogens. In the present study, we found that the plant defence signal salicylic acid (SA) accumulates at the site of oviposition. This is unexpected, as the SA pathway controls defence against fungal and bacterial pathogens and negatively interacts with the jasmonic acid (JA) pathway, which is crucial for the defence against herbivores. Application of P. brassicae or Spodoptera littoralis egg extract onto leaves reduced the induction of insect‐responsive genes after challenge with caterpillars, suggesting that egg‐derived elicitors suppress plant defence. Consequently, larval growth of the generalist herbivore S. littoralis, but not of the specialist P. brassicae, was significantly higher on plants treated with egg extract than on control plants. In contrast, suppression of gene induction and enhanced S. littoralis performance were not seen in the SA‐deficient mutant sid2‐1, indicating that it is SA that mediates this phenomenon. These data reveal an intriguing facet of the cross‐talk between SA and JA signalling pathways, and suggest that insects have evolved a way to suppress the induction of defence genes by laying eggs that release elicitors. We show here that egg‐induced SA accumulation negatively interferes with the JA pathway, and provides an advantage for generalist herbivores.  相似文献   

15.
    
The evolutionarily recent transfer of the gene for cytochrome c oxidase subunit 2 (cox2) from the mitochondrion to the nucleus in legumes is shown to have involved novel gene-activation steps. The acquired mitochondrial targeting presequence is bordered by two introns. Characterization of the import of soybean Cox2 indicates that the presequence is cleaved in a three-step process which is independent of assembly. The final processing step takes place only in the mitochondria of legume species, and not in several non-legume plants. The unusually long presequence of 136 amino acids consists of three regions: the first 20 amino acids are required for mitochondrial targeting and can be replaced by another presequence; the central portion of the presequence is required for efficient import of the Cox2 protein into mitochondria; and the last 12 amino acids, derived from the mitochondrially encoded protein, are required for correct maturation of the imported protein. The acquisition of a unique presequence, and the capacity for legume mitochondria to remove this presequence post-import, are considered to be essential adaptations for targeting of Cox2 to the mitochondrion and therefore activation of the transferred gene in the nucleus.  相似文献   

16.
  总被引:6,自引:0,他引:6  
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17.
【目的】探明朱砂叶螨Tetranychus cinnabarinus持续为害对玉米Zea mays叶片内茉莉酸(jasmonic acid,JA)、水杨酸(salicylic acid,SA)、乙烯(ethylene,ET)、一氧化氮(nitricoxide,NO)、脱落酸(abscisic acid,ABA)和过氧化氢(hydrogen peroxide,H2O2)6个防御信号分子的诱导作用。【方法】室内人工接螨(10,20和30头/叶),采用分光光度法(SP)、高效液相色谱法(HPLC)和酶联免疫法(ELISA),测定了朱砂叶螨持续为害0,24,48,72和96 h后,玉米幼苗叶片内6个信号分子的含量。【结果】朱砂叶螨持续刺吸为害玉米幼苗叶片后,JA,ABA和H2O23个信号分子含量在叶螨刺吸为害24 h内迅速上升,在24 h时达高峰值,叶螨密度为30头/叶时其含量分别为同期未接螨对照的4.13,3.84和3.20倍,24-48 h内迅速下降;此后,ABA和H2O2含量维持在较低水平,而JA含量在48-96 h内又上升至次高峰值。NO含量则在24-48 h内上升较快,48 h时达最高,叶螨密度为30头/叶时其含量为同期未接螨对照的5.09倍。SA和ET含量在96 h内均随刺吸时间的延长而增大,96 h时最高,叶螨密度为30头/叶时其含量分别为同期未接螨对照的5.17和2.99倍。叶螨密度为30头/叶时,6个信号分子含量均显著高于同期未接螨对照(P0.05)。【结论】朱砂叶螨为害对玉米叶片内JA,SA,ET,NO,ABA和H2O2均具有诱导作用,且6个信号分子在叶螨持续为害玉米叶片后循序被诱导。  相似文献   

18.
    
Systemic resistance is induced by necrotizing pathogenic microbes and non-pathogenic rhizobacteria and confers protection against a broad range of pathogens. Here we show that Arabidopsis GDSL LIPASE-LIKE 1 (GLIP1) plays an important role in plant immunity, eliciting both local and systemic resistance in plants. GLIP1 functions independently of salicylic acid but requires ethylene signaling. Enhancement of GLIP1 expression in plants increases resistance to pathogens including Alternaria brassicicola , Erwinia carotovora and Pseudomonas syringae , and limits their growth at the infection site. Furthermore, local treatment with GLIP1 proteins is sufficient for the activation of systemic resistance, inducing both resistance gene expression and pathogen resistance in systemic leaves. The PDF1.2 -inducing activity accumulates in petiole exudates in a GLIP1-dependent manner and is fractionated in the size range of less than 10 kDa as determined by size exclusion chromatography. Our results demonstrate that GLIP1-elicited systemic resistance is dependent on ethylene signaling and provide evidence that GLIP1 may mediate the production of a systemic signaling molecule(s).  相似文献   

19.
Ozone: a tool for probing programmed cell death in plants   总被引:27,自引:0,他引:27  
  相似文献   

20.
以蚕豆下表皮为材料研究了水杨酸、(±)茉莉酸和乙烯对气孔运动的影响及其相互关系。结果表明,在一定范围内,水杨酸和乙烯利都可诱导气孔关闭,并且二者能够相互增强其作用强度;(±)茉莉酸能够促进气孔开度增大,加入(±)茉莉酸减弱了乙烯利对气孔运动的影响,(±)茉莉酸和乙烯利存在拮抗效应。降低内源乙烯的水平可以增强(±)茉莉酸促进气孔张开的作用、降低水杨酸的诱导气孔关闭效应。而水杨酸和(±)茉莉酸之间的关系比较复杂。  相似文献   

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