Calcium oxalate crystal 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 cut roses, bent-neck syndrome is a widespread problem damaging millions of flowers well before the end of inherent vase life. Besides water status, structure and function of peduncles, and as a result, tissue strength, may determine bent-neck susceptibility. In this study, phase-contrast X-ray computed microtomography (sXMT) was applied to investigate non-invasively the inner structure of peduncles of samples of three rose cultivars that have been shown to differ greatly in their bent-neck susceptibility. Due to its high resolution, sXMT can be used to three-dimensionally study tissues, and even individual cells, without physically interfering with the product. In 3D sXMT images of peduncle samples of all cultivars, spherical, crystalline, biomineral, high X-ray attenuation particles were observed. These calcium oxalate (CaOx) druses, as clearly identified due to their shape and sizes by microscopic evaluation of concomitantly prepared fresh-cut slices, were mainly scattered in the cortex tissue but were also present less abundantly between vascular bundles. Because CaOx crystals are assumed to serve as structural support, high crystal densities may increase tissue strength. Although the CaOx crystal distribution pattern, the relative radial druse density and the CaOx crystal size differed greatly between samples of the three rose cultivars, these variations do not match the mechanical tissue strength, and hence the bent-neck susceptibility of cultivars as determined in earlier experiments. To the best of our knowledge, this is the first report on the in situ distribution of calcium oxalate crystals in rose peduncles.

[1]  N. Lersten,et al.  Calcium oxalate crystal macropattern development during Prunus virginiana (Rosaceae) leaf growth , 2004 .

[2]  B. Libert,et al.  Oxalate in crop plants , 1987 .

[3]  S. Wilkins,et al.  Simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object , 2002, Journal of microscopy.

[4]  V. Franceschi,et al.  Distribution of calcium oxalate crystals in the secondary phloem of conifers: a constitutive defense mechanism? , 2003, The New phytologist.

[5]  John Banhart,et al.  X-ray and neutron imaging – Complementary techniques for materials science and engineering , 2010 .

[6]  N. Lersten,et al.  Calcium oxalate crystal types and trends in their distribution patterns in leaves ofPrunus (Rosaceae: Prunoideae) , 2000, Plant Systematics and Evolution.

[7]  V. Franceschi,et al.  Calcium oxalate in plants: formation and function. , 2005, Annual review of plant biology.

[8]  H. K. Mebatsion,et al.  Three-dimensional pore space quantification of apple tissue using X-ray computed microtomography , 2007, Planta.

[9]  Su-Hwa Chen,et al.  Ultrastructural study on the formation of sclereids in the floating leaves of Nymphoides coreana and Nuphar schimadai , 2000 .

[10]  G. Coté,et al.  Diversity and distribution of idioblasts producing calcium oxalate crystals in Dieffenbachia seguine (Araceae). , 2009, American journal of botany.

[11]  H. K. Mebatsion,et al.  Three-Dimensional Gas Exchange Pathways in Pome Fruit Characterized by Synchrotron X-Ray Computed Tomography1[C][W][OA] , 2008, Plant Physiology.

[12]  D. Inzé,et al.  Plant structure visualization by high-resolution X-ray computed tomography. , 2010, Trends in plant science.

[13]  P. Rudall,et al.  Calcium Oxalate Crystals in Monocotyledons: A Review of their Structure and Systematics , 1999 .

[14]  P. Nakata.  Advances in our understanding of calcium oxalate crystal formation and function in plants , 2003 .

[15]  H. Horner,et al.  Calcium oxalate crystals in plants , 1980, The Botanical Review.

[16]  Masaru Kobayashi,et al.  Boron and calcium, essential inorganic constituents of pectic polysaccharides in higher plant cell walls , 1998, Journal of Plant Research.

[17]  Atsushi Momose,et al.  Phase–contrast X–ray computed tomography for observing biological soft tissues , 1996, Nature Medicine.

[18]  S. Gudin.  Effect of preharvest growing temperatures on the development of cut roses , 1992 .

[19]  P. Rudall,et al.  Cellular ultrastructure and crystal development in Amorphophallus (Araceae). , 2008, Annals of botany.

[20]  Sang-Joon Lee,et al.  In vivo visualization of the water-refilling process in xylem vessels using X-ray micro-imaging. , 2008, Annals of botany.

[21]  B. Molano-Flores,et al.  Herbivory and Calcium Concentrations Affect Calcium Oxalate Crystal Formation in Leaves ofSida (Malvaceae) , 2001 .

[22]  J. Faragher,et al.  Physical stem-end treatment effects on cut rose and acacia vase life and water relations , 2011 .

[23]  Marco Stampanoni,et al.  Virtual taphonomy using synchrotron tomographic microscopy reveals cryptic features and internal structure of modern and fossil plants , 2009, Proceedings of the National Academy of Sciences.

[24]  Michael D. Abràmoff,et al.  Image processing with ImageJ , 2004 .

[25]  Ws. Rasband.  ImageJ, U.S. National Institutes of Health, Bethesda, Maryland, USA , 2011 .

[26]  N. Lersten,et al.  Development of the calcium oxalate crystal macropattern in pomegranate (Punica granatum, Punicaceae). , 2005, American journal of botany.

[27]  N. Lersten,et al.  Crystal macropattern development in Prunus serotina (Rosaceae, Prunoideae) leaves. , 2006, Annals of botany.

[28]  P. Cloetens,et al.  Phase objects in synchrotron radiation hard x-ray imaging , 1996 .

[29]  E. Christiansen,et al.  Anatomical and chemical defenses of conifer bark against bark beetles and other pests. , 2005, The New phytologist.

[30]  A. Momose.  Phase-sensitive imaging and phase tomography using X-ray interferometers. , 2003, Optics express.

[31]  M. A. Webb.  Cell-Mediated Crystallization of Calcium Oxalate in Plants , 1999, Plant Cell.

[32]  S. Zabler,et al.  High resolution synchrotron-based radiography and tomography using hard X-rays at the BAMline (BESSY II) , 2008 .

[33]  P. Cloetens,et al.  Quantitative phase tomography of Arabidopsis seeds reveals intercellular void network , 2006, Proceedings of the National Academy of Sciences.