Project description:Plants experience dynamic light daily, with light conditions varying on a second-by-second basis. Little is understood about the mechanisms that allow plants to survive such variable conditions. Here, we have exposed Arabidopsis thaliana plants to naturally fluctuating light regimes alongside traditional square light regimes. The response was highly consistent across experiments, leading us to believe there is an epigenetic mechanism involved. We show significant alterations in DNA methylation between fluctuating light acclimated plants, and square light acclimated plants, demonstrating the frequency of fluctuations impacts the plant methylation. This was accompanied by significant changes in gene expression, some of which correlated with altered DNA methylation. Interestingly, several transposable elements which displayed differential methylation were found to be differentially expressed between light regimes. This data suggests DNA methylation may have a role in acclimation to natural light which may directly regulate gene expression and impact transposable element activation.
Project description:Plants experience dynamic light daily, with light conditions varying on a second-by-second basis. Little is understood about the mechanisms that allow plants to survive such variable conditions. Here, we have exposed Arabidopsis thaliana plants to naturally fluctuating light regimes alongside traditional square light regimes. The response was highly consistent across experiments, leading us to believe there is an epigenetic mechanism involved. We show significant alterations in DNA methylation between fluctuating light acclimated plants, and square light acclimated plants, demonstrating the frequency of fluctuations impacts the plant methylation. This was accompanied by significant changes in gene expression, some of which correlated with altered DNA methylation. Interestingly, several transposable elements which displayed differential methylation were found to be differentially expressed between light regimes. This data suggests DNA methylation may have a role in acclimation to natural light which may directly regulate gene expression and impact transposable element activation.
Project description:Plants in the natural environment experience continuous dynamic changes in light intensity. Here, we exposed Arabidopsis thaliana plants to naturally fluctuating light regimes alongside traditional square light regimes such as those often found in control environment growth chambers. The physiological response was highly consistent across experiments in sibling plants, indicating the possibility of an epigenetic mechanism, leading us to investigated differences in DNA methylation. Our results identified a large number of changes in DNA methylation patterns between fluctuating light acclimated plants and square light acclimated plants, demonstrating natural fluctuations in light impacts plant epigenetic mechanisms. Most importantly, there are more differences in DNA methylation patterns between different light pattern regimes than between different light intensities. These differences in DNA methylation were accompanied by significant changes in gene expression, some of which correlated with altered DNA methylation. One of these genes, MCCA, was found to significantly impact photosynthetic efficiency when knocked out. Thousands of transposable elements copies were differentially methylated between light regimes. Interestingly, up to 30% of these TEs are linked to nearby differentially expressed genes. Our data suggests DNA methylation plays a role in acclimation to natural light which may directly regulate gene expression and impact transposable element activation.
Project description:Plants are subjected to perpetual fluctuations of light intensity and spectral composition in their natural growth environment, particularly due to movement of clouds and upper canopy leaves. Sudden exposure to intense light is accompanied by absorption of excess light energy, which results in an overload of photosynthetic electron transport chain and generation of reactive oxygen species in and around thylakoid membranes. To cope with this photooxidative stress and to prevent chronic photoinhibition under dynamically changing light intensities, plants have evolved various short- and long-term photoprotective mechanisms. We used quantitative mass spectrometry to investigate long-term acclimation of Arabidopsis thaliana leaf proteome to fluctuating light (FL) which induces photooxidative stress. After three days of FL exposure the proteomes of young and mature leaves were analyzed separately in the morning and at the end of day to examine possible interaction between FL acclimation and leaf development or time of day.
Project description:Fluctuating light affects photosynthesis in chloroplasts, resulting changes of a series of redox reactions and accumulation of reactive oxygen species (ROS). Chloroplast redox regulation have been considered as “a fine regulation of protein function which is crucial for efficient photosynthesis”. However, the role of redox regulation in acclimation to fluctuating light for plants is still unclear. In this study, we performed global quantitative mapping of the Arabidopsis thaliana (wild-type and pgr5 mutant) cysteine thiol switching using the latest iodoTMT-based redox proteomics technology, systematically revealing a high-quality landscape of fluctuating light-responsive redox-modified proteins for the first time. Notably, photosynthesis-related pathway, especially PSI-related proteins, are operational thiol-switching hotspots.
Project description:PROTON GRADIENT REGULATION 5 (PGR5) plays a critical role in generating proton motive force across thylakoid membranes and supporting photoprotection under fluctuating light in C3 plants. It is proposed that this function is achieved by regulating cyclic electron flow around Photosystem I. During the evolutionary transition from C3 to C4 photosynthesis, PGR5 abundance in leaves has increased, coinciding with an enhancement in cyclic electron flow rate. To investigate the role of PGR5 in C4 photosynthesis and photoprotection, we generated Setaria viridis (a model C4 monocot) lines with null PGR5 alleles. We demonstrate that loss of PGR5 severely impairs the establishment of proton motive force, photosynthetic control, and energy-dependent non-photochemical quenching at high irradiances, leading to a loss of Photosystem I activity under light stress. Furthermore, plants lacking PGR5 exhibit drastically reduced growth and photosynthesis when grown under fluctuating daylight; however, they are less severely affected than C3 pgr5 mutants. This relative tolerance arises from the ability of S. viridis lacking PGR5 to maintain significant levels of photosynthetic control, in contrast to C3 mutants. Additionally, in the absence of PGR5 and qE, a slower-relaxing, zeaxanthin-dependent form of non-photochemical quenching supports survival under fluctuating light, albeit at the cost of reduced photochemical efficiency and assimilation. Our findings highlight the essential role of PGR5 in enabling efficient C4 photosynthesis under fluctuating light by regulating photosynthetic control and energy-dependent non-photochemical quenching. This study also uncovers the interplay between multiple photoprotective mechanisms safeguarding C4 photosynthesis under light stress.