Abstract
Plants make use of “two-component systems” (TCSs) for signal transduction, and these are involved in a number of vital cellular responses, such as responses to cytokinins, ethylene, red light, and osmosensing (Schaller et al., 2011). The TCS as found in plants incorporates three signaling elements: His kinases, His-containing phosphotransfer proteins, and response regulators (Heyl and Schmülling, 2003; Kakimoto, 2003; Schaller et al., 2008). Advances in high-throughput sequencing technologies have led to a dramatic increase in the number of sequenced genomes and ESTs and, concomitantly, an increase in the TCS elements identified in different plant species (Hellmann et al., 2010). As there is no common agreement for the nomenclature of TCS elements in plants, this has led to a confusing and in part contradictory naming of newly identified genes of this pathway. Thus, at the recent cytokinin meeting (Cytokinin Metabolism, Signaling, and Function, July 8–10, 2012, in Berlin), researchers discussed general guidelines that could be applied to the nomenclature of TCS members from all plant species. However, as the gene names for TCS members of the model systems Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) have been grown historically and are well established (Schaller et al., 2007, 2008), the authors suggest applying the following guidelines to all other plant species only.