Continuous, high-resolution biospeckle imaging reveals a discrete zone of activity at the root apex that responds to contact with obstacles

• DOI: 10.1093/aob/mct271
• Publication Date: 2013-11-28T01:18:41Z
• Authors: K. M. Ribeiro; B. Barreto; M. Pasqual; P. J. White; R. A. Braga; L. X. Dupuy
• Keywords: Apex (geometry)

Shining a laser onto biological material produces light speckles termed biospeckles. Patterns of biospeckle activity reflect changes in cell biochemistry, developmental processes and responses to the environment. The aim this work was develop methods investigate roots characterize distribution its intensity response thigmostimuli. Biospeckle Zea mays, also Jatropha curcas Citrus limonia, imaged live situ using portable digital microscope with spatial resolution 10 μm per pixel ability capture images every 0·080 s. A procedure incorporating Fujii algorithm, image restoration median Gaussian filters, segmentation maximum-entropy threshold extraction features tracing algorithm followed by spline fitting were developed obtain quantitative information from activity. wavelet transform used for spectral decomposition generalized additive models attribute statistical significance patterns greatest close root apex. Higher frequencies (3–6 Hz) contributed most total When encountered an obstacle, decreased abruptly throughout system. became attenuated repeated data suggest that at least one component resulted process, which is located zone division responds However, neither individual events nor elongation likely be responsible