Abstract
Leaf senescence is an integral part of plant development and is driven by endogenous cues such as leaf or plant age. Developmental senescence aims to maximize the usage of carbon, nitrogen and mineral resources for growth and/or for the sake of the next generation. This requires efficient reallocation of the resources out of the senescing tissue into developing parts of the plant such as new leaves, fruits and seeds. However, premature senescence can be induced by severe and long-lasting biotic or abiotic stress conditions. It serves as an exit strategy to guarantee offspring in an unfavorable environment but is often combined with a trade-off in seed number and quality. In order to coordinate the very complex process of developmental senescence with environmental signals, highly organized networks and regulatory cues have to be in place. Reactive oxygen species, especially hydrogen peroxide (H2O2), are involved in senescence as well as in stress signaling. Here, we want to summarize the role of H2O2 as a signaling molecule in leaf senescence and shed more light on how specificity in signaling might be achieved. Altered hydrogen peroxide contents in specific compartments revealed a differential impact of H2O2 produced in different compartments. Arabidopsis lines with lower H2O2 levels in chloroplasts and cytoplasm point to the possibility that not the actual contents but the ratio between the two different compartments is sensed by the plant cells.
Highlights
Senescence is a phase of plant development and becomes visible by the degreening of leaves, in which the photosynthetic apparatus is dismantled and chlorophyll is broken down, leading to light green and yellowish leaves [1]
Even though hydrogen peroxide appears to be used as a signaling molecule in many different plant species, we focus on the findings in the model plant Arabidopsis thaliana
Measurement of intracellular H2O2 contents in different leaves of a single Arabidopsis rosette indicated that the increase during onset of monocarpic senescence can be observed more prominently in the younger leaves (Fig. 1) [48], suggesting that sequential senescence might use different signals. This long-term intracellular H2O2 increase at the onset of monocarpic senescence in Arabidopsis and oilseed rape is predominately due to sophisticated regulation of the activities of the H 2O2 scavenging enzymes catalase (CAT) and ascorbate peroxidase (APX) [48, 49]
Summary
Senescence is a phase of plant development and becomes visible by the degreening of leaves, in which the photosynthetic apparatus is dismantled and chlorophyll is broken down, leading to light green and yellowish leaves [1]. Arabidopsis lines with lower H2O2 levels in chloroplasts and cytoplasm point to the possibility that not the actual contents but the ratio between the two different compartments is sensed by the plant cells.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
