Synchrotron X-ray CT of rose peduncles – evaluation of tissue damage by radiation*

"Bent-neck" syndrome, an important postharvest problem of cut roses, is probably caused by water supply limitations and/or the structural weakness of vascular bundles of the peduncle tissue. For this reason, advanced knowledge about the microstructures of rose peduncles and their cultivar specific variations may lead to a better understanding of the underlying mechanisms. Synchrotron X-ray computed tomography (SXCT), especially phase-based CT, is a highly suitable technique to nondestructively investigate plants' micro anatomy. SXCT with monochromatic X-ray beams of 30, 40 and 50 keV photon energy was used to evaluate the three-dimensional inner structures of the peduncles of 3 rose cultivars that differ greatly in their bent-neck susceptibility. Results indicated that this technique achieves sufficiently high spatial resolution to investigate complex tissues. However, further investigations with chlorophyll fluorescence analysis (CFA) and optical microscope imagery reveal different kinds of heavy damage of the irradiated regions induced by synchrotron X-rays; in a cultivar-specific manner, partial destruction of cell walls occurred a few hours after X-ray irradiation. Furthermore, a delayed inhibition of photosynthesis accompanied by the degradation of chlorophyll was obvious from CFA within hours and days after the end of CT measurements. Although SXCT is certainly well suited for three-dimensional anatomical analysis of rose peduncles, the applied technique is not nondestructive

3D-analysis of plant microstructures: advantages and limitations of synchrotron X-ray microtomography

Synchrotron X-ray computer microtomography was used to analyze the microstructure of rose peduncles. Samples from three rose cultivars, differing in anatomy, were scanned to study the relation between tissue structure and peduncles mechanical strength. Additionally, chlorophyll fluorescence imaging and conventional light microscopy was applied to quantify possible irradiation-induced damage to plant physiology and tissue structure. The spatial resolution of synchrotron X-ray computer microtomography was sufficiently high to investigate the complex tissues of intact rose peduncles without the necessity of any preparation. However, synchrotron X-radiation induces two different types of damage on irradiated tissues. First, within a few hours after first X-ray exposure, there is a direct physical destruction of cell walls. In addition, a slow and delayed destruction of chlorophyll and, consequently, of photosynthetic activity occurred within hours/ days after the exposure. The results indicate that synchrotron X-ray computer microtomography is well suited for three-dimensional visualization of the microstructure of rose peduncles. However, in its current technique, synchrotron X-ray computer microtomography is not really non-destructive but induce tissue damage. Hence, this technique needs further optimization before it can be applied for time-series investigations of living plant materials

Calcium oxalate crystals distribution in rose peduncles Non invasive analysis by synchrotron X ray micro tomography

Comprehensive knowledge of plant microstructures and their variations is essential to understanding the mechanisms underlying postharvest quality changes of horticultural products. In this study, phase contrast computed microtomography CT using synchrotron X radiation was applied to non invasively investigate the inner structure of peduncles of samples of three rose cultivars that differ greatly in their shelf life. Due to its high resolution, synchrotron x ray tomography can be used to study tissues and even individual cells without physically interfering with the product. In 3 D CT images of peduncle samples of all cultivars, numbers of small spherical particles with x ray attenuation much higher than that of cell cytoplasm were observed. These particles were smaller than parenchyma cells and vessel elements, and were mainly scattered in the cortex tissue but were also present less abundantly between vascular bundles . The X ray attenuation patterns reflect the high density of these crystalline, biomineral particles. Microscopic evaluation of concomitantly prepared fresh cut slices clearly indentified these particles as calcium oxalate crystals, which, due to their shape and sizes, can be determined as calcium oxalate druses. To the best of our knowledge, this is the first report on the in situ distribution of calcium oxalate crystals in rose peduncles

3D analysis of plant microstructures advantages and limitations of synchrotron X ray microtomography

Synchrotron X ray computer microtomography was used to analyze the microstructure of rose peduncles. Samples from three rose cultivars, differing in anatomy, were scanned to study the relation between tissue structure and peduncles mechanical strength. Additionally, chlorophyll fluorescence imaging and conventional light microscopy was applied to quantify possible irradiation induced damage to plant physiology and tissue structure. The spatial resolution of synchrotron X ray computer microtomography was sufficiently high to investigate the complex tissues of intact rose peduncles without the necessity of any preparation. However, synchrotron X radiation induces two different types of damage on irradiated tissues. First, within a few hours after first X ray exposure, there is a direct physical destruction of cell walls. In addition, a slow and delayed destruction of chlorophyll and, consequently, of photosynthetic activity occurred within hours days after the exposure. The results indicate that synchrotron X ray computer microtomography is well suited for three dimensional visualization of the microstructure of rose peduncles. However, in its current technique, synchrotron X ray computer microtomography is not really non destructive but induce tissue damage. Hence, this technique needs further optimization before it can be applied for time series investigations of living plant materials. K e y w o r d s plant microstructure, chlorophyll fluorescence imaging, image analysis, mechanical strength, tissue damag

Hochortsauflösendes, gro flächiges Neutronen Detektorsystem für die Brennstoffzellenforschung

Kurzfassung Die speziellen Eigenschaften von Neutronen, insbesondere die hohe Sensitivität für Wasser sowie die Fähigkeit, viele metallische Komponenten zu durchdringen, macht die Neutronenradiografie zum attraktiven Werkzeug für die Brennstoffzellenforschung. Die detaillierte Untersuchung des Wasserhaushalts erfordert eine hohe Ortsauflösung des Detektors sowie ein flexibles und großes Abbildungsfeld. Bislang schränkte die geringe räumliche Ortsauflösung konventioneller Detektorsysteme die Detailtiefe bei der Wiedergabe von Wasserverteilungen in Zellen stark ein. Spezielle hochauflösende Detektorsysteme hingegen ermöglichen nur die Abbildung kleinster Teilbereiche der Zelle. Am Helmholtz-Zentrum Berlin wurde ein Detektorsystem entwickelt, das beide Grundforderungen erfüllt: Ein neuartiger Gadox-Szintillator ermöglicht eine deutlich verbesserte Ortsauflösung von max. 25 μm. Das verwendete Kamerasystem mit einem 4096×4097-Pixel-CCD-Sensor ermöglicht ein großes und flexibles Abbildungsfeld, z.B. 61,44×61,44 mm2 beim 1:1-Abbildungsmaßstab. Mit diesem System lassen sich Brennstoffzellen großflächig und mit hoher Auflösung untersuchen.</jats:p