The application of differential display as a gene profiling tool in Citrus.

Invited Mini-Review: Citrus (Citrus spp.) is one of the most important and widespread fruit crops, with great economic and health value. However, it is among the most difficult plants to improve through traditional breeding approaches. In this context, the recent advent of genomic technology and of powerful new tools, such as differential display (DD-PCR), serial analysis of gene expression (SAGE), and cDNA microarray, have greatly increased the study of biological processes relevant to citriculture, ranging from developmental biology, to biotic and abiotic stresses, and post-harvest processes. This mini-review deals with the application of the DD-PCR technique to investigate gene expression in Citrus. The findings of various research groups on the isolation and profiling of genes expressed in Citrus during physiological events, and biotic and abiotic stress conditions with this methodology are described. Even genes expressed at very low levels, such as transcriptional factors, membrane proteins, and rare enzymes have been successfully isolated using this approach. These results suggest that DD-PCR is a very suitable method for investigating rare genes involved in life cycle of plants, especially when genomic sequence information of the species is not available.