The architecture of plant vasculature and transport as seen with magnetic resonance microscopy

Abstract

Water and photosynthate transport through plants has been studied extensively for the past three centuries. Few techniques are available that are capable of providing both physiological and anatomical information, and most are destructive in nature. We report the use of high resolution magnetic resonance microscopy (MRM) for the study of intact plant vasculature. Both two- (2-D) and three-dimensional (3-D) image acquisition protocols are employed wherein the plant vasculature can be readily distinguished from surrounding parenchymal tissue. In the 3-D image sets, the vasculature has been digitally segmented, allowing isolation of only the intact vascular architecture. The paths of water and photosynthate transport into several plant specimens have been visualized in this manner. Images of sugar beets, plants that store high concentrations of sucrose within the parenchyma, show contrast patterns between vasculature and parenchyma that are opposite to those seen in images acquired of an apple, fig, okra pod, kiwi fruit, and potato, plants that do not store high concentrations of sucrose. This suggests that transport and accumulation of photosynthates may be partially responsible for contrasts seen within images acquired of these plant specimens. Key words: transport, transpiration, sugar, MRI, magnetic resonance imaging, plants.