Tissue-Printing Methods for Localization of RNA and Proteins that Control Seed Dormancy and Germination

A number of genes and proteins are expressed in a tissue- or cell layer-specific manner. Spatial patterns of gene expression are critical to understanding gene function. Tissue printing provides a simple and rapid method to analyze localization of mRNA and protein at the tissue and cellular levels. This is especially convenient for gene expression analysis in hard tissues, such as seeds that are often difficult to section. Seed RNA or protein can be transferred onto a suitable membrane by printing the cut surface of a bisected seed. This method has been used successfully to determine mRNA and protein localization in seed research. The resolution of printed seed images and RNA and protein signals in tissue printing is sufficient to identify embryo- or endosperm-specific expression of various genes and proteins. In some cases, these studies have contributed to elucidating the spatial characteristics of hydrolytic enzymes putatively involved in the completion of germination and/or early postgerminative growth. By the same principle, tissue-printing methods could also be valuable for elucidating the spatial characteristics of genes/proteins that control the inception, maintenance, and termination of seed dormancy.