Early chloroplastic alterations analysed by optical coherence tomography during a harpin‐induced hypersensitive response

Boccara, Martine; Schwartz, Wilfrid; Guiot, Elvire; Vidal, Guillaume; Paepe, Rosine De; Dubois, Arnaud; Boccara, Albert‐Claude

doi:10.1111/j.1365-313x.2007.03051.x

Cited by 43 publications

(25 citation statements)

References 31 publications

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“…It has been shown that Ca 2 + regulates FBPase 42,43 , and the stability of the photosystem II and thylakoid O 2 evolving complexes 44 . Th e stromal Ca 2 + transients coincide with the stress-induced rapid downregulation of photosynthesis 39,45,46 . Importantly, photosynthesis collapse may lead to photo-induced production of ROS including 1 O 2 (ref.…”

Section: Days After Inoculation ( D ) Ion Leakage At 3 Days After Inmentioning

confidence: 90%

Chloroplast-mediated activation of plant immune signalling in Arabidopsis

et al. 2012

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Chloroplasts have a critical role in plant immunity as a site for the production for salicylic acid and jasmonic acid, important mediators of plant immunity. However, the molecular link between chloroplasts and the cytoplasmic-nuclear immune system remains largely unknown. Here we show that pathogen-associated molecular pattern (PAMP) signals are quickly relayed to chloroplasts and evoke specifi c Ca 2 + signatures in the stroma. We further demonstrate that a chloroplast-localized protein, named calcium-sensing receptor (CAS), is involved in stromal Ca 2 + transients and responsible for both PAMP-induced basal resistance and R gene-mediated hypersensitive cell death. CAS acts upstream of salicylic acid accumulation. Transcriptome analysis demonstrates that CAS is involved in PAMP-induced expression of defence genes and suppression of chloroplast gene expression possibly through 1 O 2 -mediated retrograde signalling, allowing chloroplast-mediated transcriptional reprogramming during plant immune responses. The present study reveals a previously unknown chloroplast-mediated signalling pathway linking chloroplasts to cytoplasmic-nuclear immune responses.

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Section: Days After Inoculation ( D ) Ion Leakage At 3 Days After Inmentioning

confidence: 90%

Chloroplast-mediated activation of plant immune signalling in Arabidopsis

et al. 2012

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“…This is suggested by the harpin-induced modifications in the reflective index of the membranes observed by optical coherence tomography (53). Stress-induced changes in the organization of thylakoid structure and composition can decrease PSII and photosystem I activities (54).…”

Section: Harpin Elicitation Inactivates Psii and Induces Ros Accumulamentioning

confidence: 99%

Light and Oxygen Are Not Required for Harpin-induced Cell Death

Garmier

Priault²,

Vidal³

et al. 2007

Journal of Biological Chemistry

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Nicotiana sylvestris leaves challenged by the bacterial elicitor harpin N Ea were used as a model system in which to determine the respective roles of light, oxygen, photosynthesis, and respiration in the programmed cell death response in plants. The appearance of cell death markers, such as membrane damage, nuclear fragmentation, and induction of the stress-responsive element Tnt1, was observed in all conditions. However, the cell death process was delayed in the dark compared with the light, despite a similar accumulation of superoxide and hydrogen peroxide in the chloroplasts. In contrast, harpin-induced cell death was accelerated under very low oxygen (<0.1% O 2 ) compared with air. Oxygen deprivation impaired accumulation of chloroplastic reactive oxygen species (ROS) and the induction of cytosolic antioxidant genes in both the light and the dark. It also attenuates the collapse of photosynthetic capacity and the respiratory burst driven by mitochondrial alternative oxidase activity observed in air. Since alternative oxidase is known to limit overreduction of the respiratory chain, these results strongly suggest that mitochondrial ROS accumulate in leaves elicited under low oxygen. We conclude that the harpin-induced cell death does not require ROS accumulation in the apoplast or in the chloroplasts but that mitochondrial ROS could be important in the orchestration of the cell suicide program.Light and oxygen are generally considered to be important in the responses of plants to environmental stress, principally because they are involved in the generation of reactive oxygen species (ROS) 4 and associated molecular and biochemical changes. ROS are central to redox sensing during biotic and abiotic stress responses, and they act as second messengers in the activation of signal transduction pathways. ROS activate mitogen-activated protein kinase cascades that phosphorylate a variety of proteins involved in plant growth and development as well as death responses (1). High ROS levels can trigger the appearance of programmed cell death (PCD) and the induction of caspase activation in animals (2) and the activation of the ubiquitin/26 S proteasome system in plants (3). The cellular compartmentation of ROS production in PCD responses has been extensively investigated. For example, it has been established that ROS are generated in the apoplast during the oxidative burst that often accompanies plant PCD responses (4). It is widely accepted that this oxidative burst is caused by activation of DPI-sensitive NADPH oxidase-like enzymes (5) and/or the activation of various extracellular oxidases and peroxidases (6) linked to the spontaneous or enzyme-catalyzed dismutation of superoxide to H 2 O 2 . However, clear cause and effect relationships between apoplastic ROS production and the execution of cell death have never been established, and ROS have been suggested to be involved in the spread of cell death rather than in the death process per se (7).Other possible sites of ROS production are the chloroplasts and mitochond...

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“…Cellular-level resolution images of various ophthalmic tissues [51], embryos and plants [24,25,52,53] have been published. A few other examples obtained with the FF-OCM technique described in this chapter are presented in this section.…”

Section: Illustration Of Imaging Capabilitiesmentioning

confidence: 99%