Using the glowing properties of plant cells, scientists have captured stunning images and explained the importance of specimen staining by tapping into the natural autofluorescence of tissues in a new study published in the journal Applications in Plant Sciences.
While we have come a long way into using microscopes to study architecture of cells, organelles, proteins, and even molecules of plants and trees there have been barriers towards comprehensively mapping the microscopic world. The new study is a cost-effective, generalized protocol for plant sample preparation and visualization that is equally applicable to large research institutions and smaller plant science groups, researchers claim.
Autofluorescence hasn’t always been viewed as a good thing. In cases where researchers have to use stains to visualize specific structures, the light-emitting properties of nearby tissues can interfere by decreasing the contrast between different cell types.
Autofluorescence is equally useful in plants, where it shows up in everything from the hard tissues that give woody plants their stability, to the water-wicking residue covering spores and pollen, to the diverse arsenal of toxic compounds plants produce to ward off would-be predators.
When the researchers looked through the microscope, the miniature world of plant cells and organelles was brought into sharp focus. The rigid lines of cell walls stood out in bas-relief from the tightly packed chlorophyll inside. By honing in on particular wavelengths of light emitted by proteins, they could distinguish between the dense features of nuclei and the water- and sugar-conducting tissue snaking their way between cells.
Most fixatives performed well in the representative plants, with striking results, but algae proved to be an exception. Most land plants have thick, buttressing cell walls that help prevent water loss while providing structural support, qualities that algae lack. Due to their flimsier cellular scaffolding, ethanol and alcohol fixatives quickly penetrated the cell walls of algae and the sole liverwort (a plant closely related to mosses) used in the study, causing the organelles to wrinkle and deform. For these specimens, Pegg recommends sticking to aldehyde fixatives or reducing the amount of time used in the specimen preparation stages.
Most research labs also don’t own the high-powered confocal microscopes required to view cellular structures at fine scales, instead paying hourly rates to use the equipment provided by their institution, an issue which Pegg and his colleagues hope their protocol can address.