Circular spectropolarimetric sensing of chiral photosystems in decaying leaves

Abstract

Circular polarization spectroscopy has proven to be an indispensable tool in photosynthesis research and (bio)-molecular research in general. Oxygenic photosystems typically display an asymmetric Cotton effect around the chlorophyll absorbance maximum with a signal $\le 1\%$. In vegetation, these signals are the direct result of the chirality of the supramolecular aggregates. The circular polarization is thus directly influenced by the composition and architecture of the photosynthetic macrodomains, and is thereby linked to photosynthetic functioning. Although ordinarily measured only on a molecular level, we have developed a new spectropolarimetric instrument, TreePol, that allows for both laboratory and in-the-field measurements. Through spectral multiplexing, TreePol is capable of fast measurements with a sensitivity of $\sim 1\ast 10^{-4}$ and is therefore suitable of non-destructively probing the molecular architecture of whole plant leaves. We have measured the chiroptical evolution of \textit{Hedera helix} leaves for a period of 22 days. Spectrally resolved circular polarization measurements (450-900 nm) on whole leaves in transmission exhibit a strong decrease in the polarization signal over time after plucking, which we accredit to the deterioration of chiral macro-aggregates. Chlorophyll \textit{a} levels measured over the same period by means of UV-Vis absorption and fluorescence spectroscopy showed a much smaller decrease. With these results we are able to distinguish healthy from deteriorating leaves. Hereby we indicate the potency of circular polarization spectroscopy on whole and intact leaves as a nondestructive tool for structural and plant stress assessment. Additionally, we underline the establishment of circular polarization signals as remotely accessible means of detecting the presence of extraterrestrial life.

arXiv comment29 pages, 6 figures

References in corpus (12)

• Vegetation's Red Edge: A Possible Spectroscopic Biosignature of Extraterrestrial Plants
• Spectral signatures of photosynthesis I: Review of Earth organisms
• Discovery of the Interstellar Chiral Molecule Propylene Oxide (CH${}_3$CHCH${}_2$O)
• Spectral Evolution of an Earth-Like Planet
• Abiotic oxygen-dominated atmospheres on terrestrial habitable zone planets
• Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic Earth
• Abiotic O${}_2$ Levels on Planets around F, G, K, and M Stars: Possible False Positives for Life?
• Detection of circular polarization in light scattered from photosynthetic microbes
• Identifying Planetary Biosignature Impostors: Spectral Features of CO and O4 Resulting from Abiotic O2/O3 Production
• A noise-induced mechanism for biological homochirality of early life self-replicators
• Nonphotosynthetic Pigments as Potential Biosignatures
• A high-sensitivity polarimeter using a ferro-electric liquid crystal modulator

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• The O2 A-band in fluxes and polarization of starlight reflected by Earth-like exoplanets
• Biosignatures of the Earth I. Airborne spectropolarimetric detection of photosynthetic life
• Classical polarimetry with a twist: a compact, geometric approach
• Spectropolarimetry of primitive phototrophs as global surface biosignatures
• Surface and Temporal Biosignatures
• Directional aspects of vegetation linear and circular polarization biosignatures
• Anthropics of Aluminum-26 Decay and Biological Homochirality
• A snapshot full-Stokes spectropolarimeter for detecting life on Earth
• Design of the Life Signature Detection Polarimeter LSDpol
• Spatial polarization modulators: distinguishing diffraction effects from spatial polarization modulation