Cytokinins are plant hormones with biological functions ranging from coordination of plant growth to the regulation of biotic and abiotic stress-related responses and senescence. The components of the plant immune system can learn from past elicitations by microbial pathogens and herbivores and adapt to new threats. It is known that plants can enter the primed state of enhanced defense induced by either natural or synthetic compounds. While the involvement of cytokinins in defense priming has been documented, no comprehensive model of their action has been provided to date. Here, we report the functional characterization of two aromatic cytokinin derivatives, 6-benzylaminopurine-9-arabinosides (BAPAs), 3-methoxy-BAPA and 3-hydroxy-BAPA, that proved to be effective in delaying senescence in detached leaves while having low interactions with the cytokinin pathway. An RNA-seq profiling study on Arabidopsis leaves treated with 3-methoxy-BAPA revealed that short and extended treatments with this compound shifted the transcriptional response markedly toward defense. Both treatments revealed upregulation of genes involved in processes associated with plant innate immunity such as cell wall remodeling and upregulation of specific MAP kinases, most importantly MPK11, which is a MAPK module involved in stress-related signaling during the pathogen-associated molecular patterns (PAMPs) response. In addition, elevated levels of JA and its metabolites, jasmonate/ethylene-driven upregulation of PLANT DEFENSIN 1.2 (PDF1.2) and other defensins, and also temporarily elevated levels of reactive oxygen species marked the plant response to 3-methoxy-BAPA treatment. Synergistic interactions were observed when plants were cotreated with 3-hydroxy-BAPA and the flagellin-derived bacterial PAMP peptide (flg22), leading to the enhanced expression of the PAMP-triggered immunity (PTI) marker gene FRK1. Our data collectively show that some BAPAs can sensitively prime the PTI responses in a low micromolar range of concentrations while having no observable negative effects on the overall fitness of the plant.
- MeSH
- Arabidopsis chemie metabolismus MeSH
- arabinonukleosidy chemie farmakologie MeSH
- cytokininy chemie farmakologie MeSH
- imunita rostlin účinky léků MeSH
- listy rostlin účinky léků MeSH
- MAP kinasový signální systém účinky léků MeSH
- mitogenem aktivované proteinkinasy genetika metabolismus MeSH
- molekulární struktura MeSH
- PAMP struktury farmakologie MeSH
- proteiny huseníčku genetika metabolismus MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- arabinonukleosidy MeSH
- cytokininy MeSH
- mitogenem aktivované proteinkinasy MeSH
- PAMP struktury MeSH
- proteiny huseníčku MeSH
BACKGROUND: Ozonated water (O3 wat) soil drench and/or foliar spray applications were evaluated for their potential to control the root-knot nematode Meloidogyne incognita (RKN) and the airborne pathogen Tomato spotted wilt virus (TSWV) in tomato. We investigated how O3 wat modulates the salicylic acid/jasmonic acid/ethylene (SA/JA/ET) signalling network in the host, locally and systemically, to induce resistance to nematode and virus. RESULTS: The application as soil drench was effective in reducing the number of galls and egg masses, but did not reduce the incidence and severity of TSWV infection. Conversely, O3 wat applied by foliar spray decreased TSWV disease incidence and severity (-20%), but was not able to control M. incognita infection. SA-related genes were generally upregulated in both locally treated and systemically reached tissues, showing a positive action of the O3 wat treatment on SA signalling. Neither O3 wat application method significantly altered JA-related gene expression in either direction. ET-related genes were differentially regulated by root or leaf treatments, indicating that O3 wat may have different effects on ET-mediated signalling in different organs. JA/ET/SA related pathways were differentially modulated by O3 wat in the presence of either RKN or TSWV. CONCLUSION: O3 wat had a higher efficacy when applied directly to organs challenged by the pathogens, although it was potentially able to stimulate defence responses through the activation of SA signalling. Owing to its safety and effectiveness in controlling nematode and virus infections, O3 wat can be considered as a possible alternative tool for sustainable disease management practices. © 2019 Society of Chemical Industry.
- Klíčová slova
- Meloidogyne incognita, Solanum lycopersicum, TSWV, defence responses, hormones, ozonated water,
- MeSH
- imunita rostlin * účinky léků MeSH
- nemoci rostlin parazitologie prevence a kontrola virologie MeSH
- ozon aplikace a dávkování MeSH
- regulátory růstu rostlin fyziologie MeSH
- signální transdukce účinky léků MeSH
- Solanum lycopersicum účinky léků fyziologie MeSH
- Tospovirus fyziologie MeSH
- Tylenchoidea fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ozon MeSH
- regulátory růstu rostlin MeSH
Recognition of pathogen-associated molecular patterns (PAMPs) is crucial for plant defence against pathogen attack. The best characterized PAMP is flg22, a 22 amino acid conserved peptide from flagellin protein. In Arabidopsis thaliana, flg22 is recognized by the flagellin sensing 2 (FLS2) receptor. In this study, we focused on biotic stress responses triggered by flg22 after exposure to temporary heat stress (HS). It is important to study the reactions of plants to multiple stress conditions because plants are often exposed simultaneously to a combination of both abiotic and biotic stresses. Transient early production of reactive oxygen species (ROS) is a well-characterized response to PAMP recognition. We demonstrate the strong reduction of flg22-induced ROS production in A. thaliana after HS treatment. In addition, a decrease in FLS2 transcription and a decrease of the FLS2 presence at the plasma membrane are shown after HS. In summary, our data show the strong inhibitory effect of HS on flg22-triggered events in A. thaliana. Subsequently, temporary HS strongly decreases the resistance of A. thaliana to Pseudomonas syringae. We propose that short exposure to high temperature is a crucial abiotic stress factor that suppresses PAMP-triggered immunity, which subsequently leads to the higher susceptibility of plants to pathogens.
- Klíčová slova
- Arabidopsis thaliana, Pseudomonas syringae, PAMP-triggered immunity, flagellin sensing 2 receptor, flg22, heat stress, reactive oxygen species,
- MeSH
- alarminy metabolismus MeSH
- Arabidopsis účinky léků genetika imunologie mikrobiologie MeSH
- flagelin farmakologie MeSH
- genetická transkripce účinky léků MeSH
- imunita rostlin * účinky léků MeSH
- nemoci rostlin imunologie mikrobiologie MeSH
- odolnost vůči nemocem imunologie MeSH
- proteiny huseníčku genetika metabolismus MeSH
- Pseudomonas syringae účinky léků fyziologie MeSH
- reakce na tepelný šok * účinky léků MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- respirační vzplanutí účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- alarminy MeSH
- flagelin MeSH
- proteiny huseníčku MeSH
An increasing demand for environmentally acceptable alternative for traditional pesticides provides an impetus to conceive new bio-based strategies in crop protection. Employing induced resistance is one such strategy, consisting of boosting the natural plant immunity. Upon infections, plants defend themselves by activating their immune mechanisms. These are initiated after the recognition of an invading pathogen via the microbe-associated molecular patterns (MAMPs) or other microbe-derived molecules. Triggered responses inhibit pathogen spread from the infected site. Systemic signal transport even enables to prepare, i.e. prime, distal uninfected tissues for more rapid and enhanced response upon the consequent pathogen attack. Similar defense mechanisms can be triggered by purified MAMPs, pathogen-derived molecules, signal molecules involved in plant resistance to pathogens, such as salicylic and jasmonic acid, or a wide range of other chemical compounds. Induced resistance can be also conferred by plant-associated microorganisms, including beneficial bacteria or fungi. Treatment with resistance inducers or beneficial microorganisms provides long-lasting resistance for plants to a wide range of pathogens. This study surveys current knowledge on resistance and its mechanisms provided by microbe-, algae- and plant-derived elicitors in different crops. The main scope deals with bacterial substances and fungus-derived molecules chitin and chitosan and algae elicitors, including naturally sulphated polysaccharides such as ulvans, fucans or carageenans. Recent advances in the utilization of this strategy in practical crop protection are also discussed.
- Klíčová slova
- Algae polysaccharides, Biochar, Chitosan, Compost, Elicitor, Induced resistance, Plant extracts,
- MeSH
- dřevěné a živočišné uhlí farmakologie MeSH
- imunita rostlin * účinky léků MeSH
- nemoci rostlin mikrobiologie MeSH
- odolnost vůči nemocem * účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- biochar MeSH Prohlížeč
- dřevěné a živočišné uhlí MeSH
Heterodera schachtii, a plant-parasitic cyst nematode, invades host roots and induces a specific syncytial feeding structure, from which it withdraws all required nutrients, causing severe yield losses. The system H. schachtii-Arabidopsis is an excellent research model for investigating plant defence mechanisms. Such responses are suppressed in well-established syncytia, whereas they are induced during early parasitism. However, the mechanisms by which the defence responses are modulated and the role of phytohormones are largely unknown. The aim of this study was to elucidate the role of hormone-based defence responses at the onset of nematode infection. First, concentrations of main phytohormones were quantified and the expression of several hormone-related genes was analysed using quantitative real-time (qRT)-PCR or GeneChip. Further, the effects of individual hormones were evaluated via nematode attraction and infection assays using plants with altered endogenous hormone concentrations. Our results suggest a pivotal and positive role for ethylene during nematode attraction, whereas jasmonic acid triggers early defence responses against H. schachtii. Salicylic acid seems to be a negative regulator during later syncytium and female development. We conclude that nematodes are able to impose specific changes in hormone pools, thus modulating hormone-based defence and signal transduction in strict dependence on their parasitism stage.
- Klíčová slova
- Heterodera schachtii, defence responses, early infection, ethylene, jasmonic acid, plant-parasitic nematodes, salicylic acid,
- MeSH
- Arabidopsis účinky léků genetika parazitologie fyziologie MeSH
- biotest MeSH
- cyklopentany farmakologie MeSH
- fyziologický stres * účinky léků genetika MeSH
- genetická transkripce účinky léků MeSH
- hmotnostní spektrometrie MeSH
- imunita rostlin * účinky léků MeSH
- kořeny rostlin účinky léků parazitologie MeSH
- kyselina salicylová farmakologie MeSH
- nemoci rostlin parazitologie MeSH
- oxylipiny farmakologie MeSH
- paraziti fyziologie MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- regulátory růstu rostlin metabolismus MeSH
- rostlinné geny MeSH
- Tylenchoidea účinky léků fyziologie MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cyklopentany MeSH
- jasmonic acid MeSH Prohlížeč
- kyselina salicylová MeSH
- oxylipiny MeSH
- regulátory růstu rostlin MeSH
