Polymorphic ITS as a tool to identify hybrids and their parents in cultivated genisteae (Fabaceae)
Résumé
Internal Transcribed Spacer (ITS) of ribosomal DNA is a classical sequence used for phylogenetic analyses. Usually, concerted evolution homogenizes the numerous ITS of an organism in such a way that a single sequence is amplified. However, for vegetatively propagated plants of hybrid origin, several ITS sequences can be obtained from a single individual. By cloning ITS sequences of various taxa assigned to tribe Genisteae within Fabaceae, we have been able to show such ITS polymorphism in Cytisus x kewensis, C. x dallimorei, C. x praecox, Genista x spachiana and G. 'Porlock' among others. For these taxa, the distinct ITS sequences can be compared with sequences of putative parents found in literature. We have then confirmed that Cytisus x kewensis is a C. ardoinoi x C. multiflorus cross. We have also confirmed that Genista 'Porlock' is a cross between G.monspessulana and G. x spachiana. Genista x spachiana, commonly presented as G. canariensis x G. stenopetala cross may in fact be a more complex hybrid involving also G. monspessulana.