Reactive oxygen species (ROS) are produced in the olive reproductive organs as the result of intense metabolism. ROS production and pattern of distribution depend on the developmental stage, supposedly playing a broad panel of functions, which include defense and signaling between pollen and pistil. Among ROS-producing mechanisms, plasma membrane NADPH-oxidase activity is being highlighted in plant tissues, and two enzymes of this type have been characterized in Arabidopsis thaliana pollen (RbohH and RbohJ), playing important roles in pollen physiology. Besides, pollen from different species has shown distinct ROS production mechanism and patterns of distribution. In the olive reproductive tissues, a significant production of superoxide has been described. However, the enzymes responsible for such generation are unknown. Here, we have identified an Rboh-type gene (OeRbohH), mainly expressed in olive pollen. OeRbohH possesses a high degree of identity with RbohH and RbohJ from Arabidopsis, sharing most structural features and motifs. Immunohistochemistry experiments allowed us to localize OeRbohH throughout pollen ontogeny as well as during pollen tube elongation. Furthermore, the balanced activity of tip-localized OeRbohH during pollen tube growth has been shown to be important for normal pollen physiology. This was evidenced by the fact that overexpression caused abnormal phenotypes, whereas incubation with specific NADPH oxidase inhibitor or gene knockdown lead to impaired ROS production and subsequent inhibition of pollen germination and pollen tube growth.

• Klíčová slova
• NADPH oxidase, NOX, Rboh, olive, pollen, sexual plant reproduction,
• Publikační typ
• časopisecké články MeSH

Reactive oxygen species (ROS) have been recognized as important signaling compoundsof major importance in a number of developmental and physiological processes in plants. Theexistence of cellular compartments enables efficient redox compartmentalization and ensuresproper functioning of ROS-dependent signaling pathways. Similar to other organisms, theproduction of individual ROS in plant cells is highly localized and regulated bycompartment-specific enzyme pathways on transcriptional and post-translational level. ROSmetabolism and signaling in specific compartments are greatly affected by their chemicalinteractions with other reactive radical species, ROS scavengers and antioxidant enzymes. Adysregulation of the redox status, as a consequence of induced ROS generation or decreasedcapacity of their removal, occurs in plants exposed to diverse stress conditions. During stresscondition, strong induction of ROS-generating systems or attenuated ROS scavenging can lead tooxidative or nitrosative stress conditions, associated with potential damaging modifications of cellbiomolecules. Here, we present an overview of compartment-specific pathways of ROS productionand degradation and mechanisms of ROS homeostasis control within plant cell compartments.

• Klíčová slova
• cell wall, chloroplasts, cytoplasmic membrane, cytosol, glyoxysomes, mitochondria, peroxisomes, plant cell, reactive oxygen species,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence.

• Klíčová slova
• Cryptogein mutants, elicitors, fluidity, membrane order, plant defence, plasma membrane, reactive oxygen species, signalling.,
• MeSH
• Arabidopsis fyziologie   MeSH
• buněčná membrána metabolismus   fyziologie   MeSH
• fluidita membrány fyziologie   MeSH
• fluorescenční mikroskopie MeSH
• fluorescenční spektrometrie MeSH
• konfokální mikroskopie MeSH
• nemoci rostlin MeSH
• odolnost vůči nemocem fyziologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• signální transdukce fyziologie   MeSH
• tabák fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• reaktivní formy kyslíku MeSH