Primed plants do not forget
TL;DR: An overview of the latest insights about defence priming is provided, ranging from early responses controlled by adjustments in hormone-dependent signalling pathways and availability of signal transduction proteins, to longer lasting mechanisms that involve possible regulation chromatin modification or DNA methylation.
About: This article is published in Environmental and Experimental Botany.The article was published on 2013-10-01. It has received 298 citations till now.
Citations
More filters
TL;DR: This review focuses on molecular processes at the interface between plant roots and ISR-eliciting mutualists, and on the progress in the understanding of ISR signaling and systemic defense priming.
Abstract: Beneficial microbes in the microbiome of plant roots improve plant health. Induced systemic resistance (ISR) emerged as an important mechanism by which selected plant growth–promoting bacteria and fungi in the rhizosphere prime the whole plant body for enhanced defense against a broad range of pathogens and insect herbivores. A wide variety of root-associated mutualists, including Pseudomonas, Bacillus, Trichoderma, and mycorrhiza species sensitize the plant immune system for enhanced defense without directly activating costly defenses. This review focuses on molecular processes at the interface between plant roots and ISR-eliciting mutualists, and on the progress in our understanding of ISR signaling and systemic defense priming. The central role of the root-specific transcription factor MYB72 in the onset of ISR and the role of phytohormones and defense regulatory proteins in the expression of ISR in aboveground plant parts are highlighted. Finally, the ecological function of ISR-inducing microbes in the root microbiome is discussed.
1,856 citations
Cites background from "Primed plants do not forget"
...Several excellent reviews have been published on the molecular mechanisms underlying defense priming (27, 47, 104), so we only highlight the most relevant issues below....
[...]
...Hence, plants seem to have the capacity to memorize a stressful situation and subsequently immunize not only themselves but also their offspring against future attacks (104)....
[...]
TL;DR: An overview of the impact on interactions between mycorrhizal plants and pathogens, herbivores, and parasitic plants, and the current knowledge of the underlying mechanisms is given, focusing on the priming of jasmonate-regulated plant defense mechanisms that play a central role in the induction of resistance by arbuscularmycorrhiza.
Abstract: Symbioses between plants and beneficial soil microorganisms like arbuscular-mycorrhizal fungi (AMF) are known to promote plant growth and help plants to cope with biotic and abiotic stresses. Profound physiological changes take place in the host plant upon root colonization by AMF affecting the interactions with a wide range of organisms below- and above-ground. Protective effects of the symbiosis against pathogens, pests, and parasitic plants have been described for many plant species, including agriculturally important crop varieties. Besides mechanisms such as improved plant nutrition and competition, experimental evidence supports a major role of plant defenses in the observed protection. During mycorrhiza establishment, modulation of plant defense responses occurs thus achieving a functional symbiosis. As a consequence of this modulation, a mild, but effective activation of the plant immune responses seems to occur, not only locally but also systemically. This activation leads to a primed state of the plant that allows a more efficient activation of defense mechanisms in response to attack by potential enemies. Here, we give an overview of the impact on interactions between mycorrhizal plants and pathogens, herbivores, and parasitic plants, and we summarize the current knowledge of the underlying mechanisms. We focus on the priming of jasmonate-regulated plant defense mechanisms that play a central role in the induction of resistance by arbuscular mycorrhizas.
727 citations
Cites background from "Primed plants do not forget"
...The molecular mechanisms behind priming of plant defenses and its biological relevance in plant resistance are now being uncovered (reviewed in Pastor et al., 2012), and evidence for trans-generational effects of priming have been a major advance in plant research (Luna et al., 2012; Rasmann et…...
[...]
TL;DR: This review covers recent advances in disclosing molecular mechanisms of priming, which include elevated levels of pattern-recognition receptors and dormant signaling enzymes, transcription factor HsfB1 activity, and alterations in chromatin state.
Abstract: When plants recognize potential opponents, invading pathogens, wound signals, or abiotic stress, they often switch to a primed state of enhanced defense. However, defense priming can also be induced by some natural or synthetic chemicals. In the primed state, plants respond to biotic and abiotic stress with faster and stronger activation of defense, and this is often linked to immunity and abiotic stress tolerance. This review covers recent advances in disclosing molecular mechanisms of priming. These include elevated levels of pattern-recognition receptors and dormant signaling enzymes, transcription factor HsfB1 activity, and alterations in chromatin state. They also comprise the identification of aspartyl-tRNA synthetase as a receptor of the priming activator β-aminobutyric acid. The article also illustrates the inheritance of priming, exemplifies the role of recently identified priming activators azelaic and pipecolic acid, elaborates on the similarity to defense priming in mammals, and discusses the ...
634 citations
TL;DR: Priming is an adaptive strategy that improves the defensive capacity of plants and can be durable and maintained throughout the plant's life cycle and can even be transmitted to subsequent generations, therefore representing a type of plant immunological memory.
Abstract: Priming is an adaptive strategy that improves the defensive capacity of plants. This phenomenon is marked by an enhanced activation of induced defense mechanisms. Stimuli from pathogens, beneficial microbes, or arthropods, as well as chemicals and abiotic cues, can trigger the establishment of priming by acting as warning signals. Upon stimulus perception, changes may occur in the plant at the physiological, transcriptional, metabolic, and epigenetic levels. This phase is called the priming phase. Upon subsequent challenge, the plant effectively mounts a faster and/or stronger defense response that defines the postchallenge primed state and results in increased resistance and/or stress tolerance. Priming can be durable and maintained throughout the plant's life cycle and can even be transmitted to subsequent generations, therefore representing a type of plant immunological memory.
537 citations
Cites background from "Primed plants do not forget"
...BTH and BABA have been thoroughly studied as priming agents against pathogens and insects (8, 10, 101)....
[...]
...Long-Term Responses Within the Same Generation Initial epigenetic changes in chromatin structure via DNA methylation and posttranslational modifications provide long-term memory within a generation that allow the plant to keep defense mechanisms primed for future attacks (101)....
[...]
...On the basis of studies that have analyzed different priming stimuli (49, 100, 101), a common subset of shared compounds can be identified that are then referred to as the priming fingerprint (49)....
[...]
TL;DR: Promising chemical agents such as sodium nitroprusside, hydrogen peroxide, sodium hydrosulfide, melatonin, and polyamines that can potentially confer enhanced tolerance when plants are exposed to multiple abiotic stresses are reviewed.
430 citations
Cites background from "Primed plants do not forget"
...The use of chemical priming agents to achieve enhanced plant tolerance delivers a more consistent and less variable priming response, which renders the approach accessible to molecular and genetic studies [90]....
[...]
...It has been proposed that dormant signaling molecules, or the proteins involved in their synthesis, are accumulated during priming by pre-exposure to an abiotic or biotic stress factor; these molecules are then recruited upon subsequent stress exposure, resulting in a faster and stronger defense response compared to non-primed plants [90]....
[...]
...throughmodification of histones, including the shortening and fractionation of H3K27me3 (histone H3 trimethylated on lysine 27) islands, andDNAmethylation [90]....
[...]
References
More filters
TL;DR: A detailed understanding of plant immune function will underpin crop improvement for food, fibre and biofuels production and provide extraordinary insights into molecular recognition, cell biology and evolution across biological kingdoms.
Abstract: Many plant-associated microbes are pathogens that impair plant growth and reproduction. Plants respond to infection using a two-branched innate immune system. The first branch recognizes and responds to molecules common to many classes of microbes, including non-pathogens. The second responds to pathogen virulence factors, either directly or through their effects on host targets. These plant immune systems, and the pathogen molecules to which they respond, provide extraordinary insights into molecular recognition, cell biology and evolution across biological kingdoms. A detailed understanding of plant immune function will underpin crop improvement for food, fibre and biofuels production.
10,539 citations
TL;DR: The surface of nucleosomes is studded with a multiplicity of modifications that can dictate the higher-order chromatin structure in which DNA is packaged and can orchestrate the ordered recruitment of enzyme complexes to manipulate DNA.
10,046 citations
TL;DR: In Arabidopsis, a network of at least 152 genes is involved in managing the level of ROS, and this network is highly dynamic and redundant, and encodes ROS-scavenging and ROS-producing proteins.
4,902 citations
TL;DR: This review summarizes results from Arabidopsis-pathogen systems regarding the contributions of various defense responses to resistance to several biotrophic and necrotrophic pathogens.
Abstract: It has been suggested that effective defense against biotrophic pathogens is largely due to programmed cell death in the host, and to associated activation of defense responses regulated by the salicylic acid-dependent pathway. In contrast, necrotrophic pathogens benefit from host cell death, so they are not limited by cell death and salicylic acid-dependent defenses, but rather by a different set of defense responses activated by jasmonic acid and ethylene signaling. This review summarizes results from Arabidopsis-pathogen systems regarding the contributions of various defense responses to resistance to several biotrophic and necrotrophic pathogens. While the model above seems generally correct, there are exceptions and additional complexities.
3,721 citations
TL;DR: A model describing the sequence of events leading from initial infection to the induction of defense genes is presented and exciting new data suggest that the mobile signal for SAR might be a lipid molecule.
Abstract: Systemic acquired resistance (SAR) is a mechanism of induced defense that confers long-lasting protection against a broad spectrum of microorganisms. SAR requires the signal molecule salicylic acid (SA) and is associated with accumulation of pathogenesis-related proteins, which are thought to contribute to resistance. Much progress has been made recently in elucidating the mechanism of SAR. Using the model plant Arabidopsis, it was discovered that the isochorismate pathway is the major source of SA during SAR. In response to SA, the positive regulator protein NPR1 moves to the nucleus where it interacts with TGA transcription factors to induce defense gene expression, thus activating SAR. Exciting new data suggest that the mobile signal for SAR might be a lipid molecule. We discuss the molecular and genetic data that have contributed to our understanding of SAR and present a model describing the sequence of events leading from initial infection to the induction of defense genes.
2,744 citations