Arabidopsis thaliana has proven to be an extremely useful model organism in studies of plant biology and an extensive base of knowledge has been amassed of the diverse molecular processes in this plant. The next step is to apply this knowledge to other plant species and gain broader insights into agricultural and environmental phenomena. Of special interest is the developmental process of abscission, a cell separation event where plants lose their organs. In A. thaliana this process has been shown to be regulated by the peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) which signals through the receptor-like kinases HAESA (HAE) and HAESA-LIKE 2 (HSL2), and induces cell separation during floral organ abscission and lateral root emergence. Orthologs of IDA, HAE and HSL2 are found throughout the angiosperm lineage and are hypothesized to be involved in abscission processes as a conserved signaling system. The process of seed abscission has not been addressed to any large extent in A. thaliana despite the agronomic value of controlling seed abscission in crop plants. The closely related plant Brassica rapa represents a suitable candidate for the step from model species to an agriculturally important species for studies of seed abscission. B. rapa which shares many characteristics with A. thaliana and has a sequenced genome will be suitable for the application of A. thaliana knowledge to a new species. In this study we wanted to apply the available knowledge of the A. thaliana IDA, HAE and HSL2 signaling system to B. rapa. Through in silico approaches we show that orthologs of this system are present in B. rapa. By using promoter:reporter transgenic lines we show a similar spatial expression of IDA and HSL2 in A. thaliana and B. rapa, indicating a conserved functional role. We also studied the expression of HAE and HSL2 during abscission in B.rapa.