It is well established that every living organism spontaneously emits photons referred to as ultra-weak photon emission (synonym biophotons or low-level chemiluminescence) which inherently embodies information about the wellbeing of the source. In recent years, efforts have been made to use this feature as a non-invasive diagnostic tool related to the detection of food quality, agriculture and biomedicine. The current study deals with stress resulting from wounding (mechanical injury) on Arabidopsis thaliana and how it modifies the spontaneous ultra-weak photon emission. The ultra-weak photon emission from control (non-wounded) and stressed (wounded) plants was monitored using different modes of ultra-weak photon emission measurement sensors like charge-coupled device (CCD) cameras and photomultiplier tubes (PMT) and the collected data were analyzed to determine the level of stress generated, photon emission patterns, and underlying biochemical process. It is generally considered that electronically excited species formed during the oxidative metabolic processes are responsible for the ultra-weak photon emission. In the current study, a high-performance cryogenic full-frame CCD camera was employed for two-dimensional in-vivo imaging of ultra-weak photon emission (up to several counts/s) and the spectral analysis was done by using spectral system connected to a PMT. The results show that Arabidopsis subjected to mechanical injury enhances the photon emission and also leads to changes in the spectral pattern of ultra-weak photon emission. Thus, ultra-weak photon emission can be used as a tool for oxidative stress imaging and can pave its way into numerous plant application research.

• Klíčová slova
• Arabidopsis, mechanical injury, oxidative radical reaction, reactive oxygen species, spectral properties, ultra-weak photon emission, wounding,
• Publikační typ
• časopisecké články MeSH

Singlet oxygen produced from triplet excited chlorophylls in photosynthesis is a signal molecule that can induce programmed cell death (PCD) through the action of the OXIDATIVE STRESS INDUCIBLE 1 (OXI1) kinase. Here, we identify two negative regulators of light-induced PCD that modulate OXI1 expression: DAD1 and DAD2, homologs of the human antiapoptotic protein DEFENDER AGAINST CELL DEATH. Overexpressing OXI1 in Arabidopsis (Arabidopsis thaliana) increased plant sensitivity to high light and induced early senescence of mature leaves. Both phenomena rely on a marked accumulation of jasmonate and salicylate. DAD1 or DAD2 overexpression decreased OXI1 expression, jasmonate levels, and sensitivity to photooxidative stress. Knock-out mutants of DAD1 or DAD2 exhibited the opposite responses. Exogenous applications of jasmonate upregulated salicylate biosynthesis genes and caused leaf damage in wild-type plants but not in the salicylate biosynthesis mutant Salicylic acid induction-deficient2, indicating that salicylate plays a crucial role in PCD downstream of jasmonate. Treating plants with salicylate upregulated the DAD genes and downregulated OXI1 We conclude that OXI1 and DAD are antagonistic regulators of cell death through modulating jasmonate and salicylate levels. High light-induced PCD thus results from a tight control of the relative activities of these regulating proteins, with DAD exerting a negative feedback control on OXI1 expression.

• MeSH
• apoptóza genetika   účinky záření   MeSH
• Arabidopsis cytologie   genetika   metabolismus   MeSH
• biosyntetické dráhy účinky léků   genetika   účinky záření   MeSH
• cyklopentany metabolismus   farmakologie   MeSH
• fosfolipasy A1 genetika   metabolismus   MeSH
• kyselina salicylová metabolismus   farmakologie   MeSH
• listy rostlin cytologie   genetika   metabolismus   MeSH
• mutace MeSH
• oxylipiny metabolismus   farmakologie   MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• singletový kyslík metabolismus   MeSH
• stanovení celkové genové exprese metody   MeSH
• světlo MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cyklopentany MeSH
• DAD1 protein, Arabidopsis MeSH Prohlížeč
• fosfolipasy A1 MeSH
• jasmonic acid MeSH Prohlížeč
• kyselina salicylová MeSH
• OXI1 protein, Arabidopsis MeSH Prohlížeč
• oxylipiny MeSH
• protein-serin-threoninkinasy MeSH
• proteiny huseníčku MeSH
• regulátory růstu rostlin MeSH
• singletový kyslík MeSH

Wounding, one of the most intensive stresses influencing plants ontogeny and lifespan, can be induced by herbivory as well as by physical factors. Reactive oxygen species play indispensable role both in the local and systemic defense reactions which enable "reprogramming" of metabolic pathways to set new boundaries and physiological equilibrium suitable for survival. In our current study, we provide experimental evidence on the formation of singlet oxygen (1O2) after wounding of Arabidopsis leaves. It is shown that 1O2 is formed by triplet-triplet energy transfer from triplet carbonyls to molecular oxygen. Using lipoxygenase inhibitor catechol, it is demonstrated that lipid peroxidation is initiated by lipoxygenase. Suppression of 1O2 formation in lox2 mutant which lacks chloroplast lipoxygenase indicates that lipoxygenase localized in chloroplast is predominantly responsible for 1O2 formation. Interestingly, 1O2 formation is solely restricted to chloroplasts localized at the wounding site. Data presented in this study might provide novel insight into wound-induced signaling in the local defense reaction.

• MeSH
• Arabidopsis MeSH
• fenotyp MeSH
• fluorescenční protilátková technika MeSH
• konfokální mikroskopie MeSH
• lipoxygenasa metabolismus   MeSH
• lipoxygenasy genetika   MeSH
• mastné kyseliny metabolismus   MeSH
• molekulární zobrazování MeSH
• mutace MeSH
• proteiny huseníčku genetika   MeSH
• rány a poranění metabolismus   MeSH
• singletový kyslík metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• lipoxygenasa MeSH
• lipoxygenase 2, Arabidopsis MeSH Prohlížeč
• lipoxygenasy MeSH
• mastné kyseliny MeSH
• proteiny huseníčku MeSH
• singletový kyslík MeSH

Singlet oxygen (1O2) is formed by triplet-triplet energy transfer from triplet chlorophyll to O2 via Type II photosensitization reaction in photosystem II (PSII). Formation of triplet chlorophyll is associated with the change in spin state of the excited electron and recombination of triplet radical pair in the PSII antenna complex and reaction center, respectively. Here, we have provided evidence for the formation of 1O2 by decomposition of protein hydroperoxide in PSII membranes deprived of Mn4O5Ca complex. Protein hydroperoxide is formed by protein oxidation initiated by highly oxidizing chlorophyll cation radical and hydroxyl radical formed by Type I photosensitization reaction. Under highly oxidizing conditions, protein hydroperoxide is oxidized to protein peroxyl radical which either cyclizes to dioxetane or recombines with another protein peroxyl radical to tetroxide. These highly unstable intermediates decompose to triplet carbonyls which transfer energy to O2 forming 1O2. Data presented in this study show for the first time that 1O2 is formed by decomposition of protein hydroperoxide in PSII membranes deprived of Mn4O5Ca complex.

• MeSH
• chlorofyl metabolismus   MeSH
• elektronová paramagnetická rezonance metody   MeSH
• fotosystém II (proteinový komplex) metabolismus   MeSH
• kyslík metabolismus   MeSH
• oxidace-redukce MeSH
• peroxid vodíku metabolismus   MeSH
• peroxidy metabolismus   MeSH
• přenos energie fyziologie   MeSH
• singletový kyslík metabolismus   MeSH
• světlo MeSH
• světlosběrné proteinové komplexy metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chlorofyl MeSH
• fotosystém II (proteinový komplex) MeSH
• kyslík MeSH
• perhydroxyl radical MeSH Prohlížeč
• peroxid vodíku MeSH
• peroxidy MeSH
• singletový kyslík MeSH
• světlosběrné proteinové komplexy MeSH