Annals of Botany

Small is beautiful when plants are on the pull

Richard Fleischer’s film Fantastic Voyage tells of a surgical team who were miniaturized in order to travel in a tiny submarine through a patient’s bloodstream. The purpose of this voyage was to locate and disperse a blood clot in the brain. Although it is impossible to shrink humans, sending therapeutic agents to specific places in the body has become possible through nanotechnology. Tiny particles on a nanometre scale may be directed, for example, to deliver cytotoxic drugs to cancer cells. But what about plants? In the late 1980s, methods were developed for shooting DNA-coated gold or tungsten particles into plant cells, methods now known as biolistics. Questions arise as to whether, in addition to genetic modification via biolistics, nanotechnology has any other applications, including applications with whole plants. The work of a Spanish research team, González-Melendi et al. (pp. 187–195), suggests that the answer may soon be ‘yes’. The authors suspended carbon-coated iron nanoparticles in surfactant solution that was thoroughly mixed into a commercially available succinated gel to give a ‘biocompatible magnetic fluid’. This was injected into the petioles of whole Cucurbita pepo plants, facilitating entry into and transport through the vascular system. Furthermore, the transport could be directed by placing magnets adjacent to parts of the plant. Analysis of plant organs and tissues by microscopy, confocal microscopy and EM showed that the particles became concentrated in relation to the magnetic field. Thus particles accumulated, both inside and outside cells, in regions of the roots and of petioles adjacent to a magnet. The way is therefore opened for the delivery of particular cargoes coated onto the nanoparticles to specific parts of the plant. The use of magnets to generate particle distribution in individual plants is not readily applicable to large crop stands, but certainly could be used with individual plants such as olive and other fruit trees, as suggested by the authors.