In this study we compare the quantity and distribution of different elements in twisted and straight internodes of this liana species, and analyse elemental co-localization in these two types of internodes. The scattered bundles typical of monocotyledonous stems resemble the cable-like construction of many lianas, with vascular strands included in a soft parenchyma (Isnard et al., 2009 ). Monocotyledons lianas offer an interesting comparison with dicotyledonous lianas in terms of functional anatomy (Carlquist, 1991 ). Many wild Dioscorea species are a very important source of secondary metabolites (diosgenin and related steroidal saponins) used in the pharmaceutical industry and medicine (Furmanowa & Guzewska, 1988 Šavikin-Fodulović et al., 1998 ). This plant is a herbaceous monocotyledonous dioecious tuberous perennial liana, growing to a length of 2 m with a climbing stem. In this study we used statistical/image analysis of µSXRF data to describe elemental associations in Dioscorea balcanica Košanin stem sections as a model system.ĭioscorea balcanica (Dioscoreaceae) is an endemic species, a tertiary relict of the Balkan peninsula, and only wild Dioscorea species currently thrive in this area. However, the overall number of studies applying µSXRF analysis is still small in plant science (Lombi et al., 2011 ). This method may forward our knowledge of the changes in elemental distribution in plants grown under various external conditions (Punshon et al., 2009 ). In plant science, µSXRF may be used for obtaining spatially resolved data on the element distribution in tissues. X-ray fluorescence is particularly suited for quantifying trace elements in cells without the need for artificial dyes or fluorophores. The high penetration capability of X-rays combined with a high spatial resolution makes X-ray fluorescence an ideal tool for two- and three-dimensional structural visualization at the subcellular level (reviewed by Ice et al., 2011 ). Using X-ray microfluorescence, data on multiple elements can be collected simultaneously without sample destruction.

detection limit (Paunesku et al., 2009 ). Synchrotron-based X-ray microfluorescence (µSXRF) microscopy is well suited for in situ investigations of elemental distribution in whole or thick-sectioned unstained biological samples such as single cells or tissues, with a sub-p.p.m. These image analyses and statistical methods provided very similar outcomes and could be applied to various types of biological samples imaged by µSXRF. In addition, co-localization of micronutrient elements is much more prominent in twisted than in straight internodes. Micronutrient elements are mostly grouped in the vasculature and in the sclerenchyma cell layer. Macronutrient elements (K, P, Ca, Cl) are distributed homogeneously in both straight and twisted internodes. Three different statistical methods were employed to analyse the macronutrient and micronutrient distributions and co-localization. In this study the quantity, distribution and grouping/co-localization of various elements have been identified in straight and twisted internodes of the stems of the monocotyledonous climber D. Elements are mapped and quantified at sub-p.p.m. Synchrotron-based X-ray microfluorescence (µSXRF) is an analytical method suitable for in situ investigation of the distribution of micronutrient and macronutrient elements in several-micrometres-thick unstained biological samples, e.g.

Phototime in x ray a technique