Presentation Information
[3GteX-09]Control of chloroplast biogenesis by oxygen- and sulfur-based redox
○Takayuki Shimizu1 (1. Nara Women's University (Japan))
Keywords:
Chloroplast biogenesis,Redox regulation,Polysulfidation,Photosynthesis gene expression,Chlorophyll biosynthesis
[Purpose]
Chloroplast biogenesis is tightly regulated by light and redox signals to optimize photosynthetic activity under changing environmental conditions. Oxygen-dependent redox regulation is well established in chloroplast development, whereas the role of sulfur-based redox processes remains unclear. Polysulfide regulates physiological functions through covalent cysteine modification (polysulfidation). Here, we report that polysulfide participates in chloroplast biogenesis and investigate their effects on the expression of nuclear-encoded photosynthesis genes (PhANGs) and chlorophyll biosynthesis.
[Method]
Arabidopsis thaliana seedlings were analyzed during the dark-to-light transition in the presence or absence of polysulfide to evaluate the establishment of photosynthesis. Chlorophyll accumulation and the expression of PhANGs were examined to assess photosynthetic initiation. In addition, the effects of redox state and polysulfide on chlorophyll biosynthesis under high light, where photosynthesis is suppressed, were investigated to evaluate regulatory mechanisms. This approach enabled analysis of polysulfide function from the perspectives of both the initiation and regulation of photosynthesis.
[Results]
Polysulfide treatment during the dark-to-light transition reduced chlorophyll accumulation and attenuated light-induced PhANG expression, indicating impaired establishment of photosynthesis. Transcriptome profiling revealed coordinated repression of genes associated with photosynthetic function and chloroplast organization, highlighting the importance of factors involved in PhANG transcriptional regulation and light-responsive signaling.Chlorophyll biosynthesis was redox-responsive, and polysulfides further influenced this process. Effects were observed in chlorophyll biosynthetic intermediates in darkness and in the suppression of chlorophyll accumulation under high light.
[Consideration]
These findings suggest that sulfur-based redox processes interact with established light- and oxygen-dependent pathways to modulate chloroplast biogenesis. While redox regulation is typically mediated by electrons from the photosynthetic electron transport chain and associated reactive oxygen species, sulfur metabolism may also function as an intermediate electron sink, giving rise to sulfur-based redox regulation through protein polysulfidation. This redox layer may regulate photosynthesis and help prevent photooxidative stress.
[Conclusion]
Our results reveal polysulfide-mediated regulation as a previously unrecognized sulfur-based redox mechanism influencing chloroplast biogenesis through effects on PhANG expression and chlorophyll biosynthesis. This finding suggests a new redox regulatory layer in photosynthetic control and points to future strategies for enhancing photosynthetic function through sulfur-based redox modulation.
Chloroplast biogenesis is tightly regulated by light and redox signals to optimize photosynthetic activity under changing environmental conditions. Oxygen-dependent redox regulation is well established in chloroplast development, whereas the role of sulfur-based redox processes remains unclear. Polysulfide regulates physiological functions through covalent cysteine modification (polysulfidation). Here, we report that polysulfide participates in chloroplast biogenesis and investigate their effects on the expression of nuclear-encoded photosynthesis genes (PhANGs) and chlorophyll biosynthesis.
[Method]
Arabidopsis thaliana seedlings were analyzed during the dark-to-light transition in the presence or absence of polysulfide to evaluate the establishment of photosynthesis. Chlorophyll accumulation and the expression of PhANGs were examined to assess photosynthetic initiation. In addition, the effects of redox state and polysulfide on chlorophyll biosynthesis under high light, where photosynthesis is suppressed, were investigated to evaluate regulatory mechanisms. This approach enabled analysis of polysulfide function from the perspectives of both the initiation and regulation of photosynthesis.
[Results]
Polysulfide treatment during the dark-to-light transition reduced chlorophyll accumulation and attenuated light-induced PhANG expression, indicating impaired establishment of photosynthesis. Transcriptome profiling revealed coordinated repression of genes associated with photosynthetic function and chloroplast organization, highlighting the importance of factors involved in PhANG transcriptional regulation and light-responsive signaling.Chlorophyll biosynthesis was redox-responsive, and polysulfides further influenced this process. Effects were observed in chlorophyll biosynthetic intermediates in darkness and in the suppression of chlorophyll accumulation under high light.
[Consideration]
These findings suggest that sulfur-based redox processes interact with established light- and oxygen-dependent pathways to modulate chloroplast biogenesis. While redox regulation is typically mediated by electrons from the photosynthetic electron transport chain and associated reactive oxygen species, sulfur metabolism may also function as an intermediate electron sink, giving rise to sulfur-based redox regulation through protein polysulfidation. This redox layer may regulate photosynthesis and help prevent photooxidative stress.
[Conclusion]
Our results reveal polysulfide-mediated regulation as a previously unrecognized sulfur-based redox mechanism influencing chloroplast biogenesis through effects on PhANG expression and chlorophyll biosynthesis. This finding suggests a new redox regulatory layer in photosynthetic control and points to future strategies for enhancing photosynthetic function through sulfur-based redox modulation.
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