Molecular tools for the identification of Pseudo-nitzschia calliantha and P. delicatissima in the Ebre Delta, Spain

Abstract

Six non-axenic clonal cultures of Pseudo nitzschia from Alfacs and Fangar Bay in the Ebre delta in the NW Mediterranean were characterised in terms of morphology and rRNA sequences. Based on scanning and transmission electron microscopy, the isolates were identified as P. delicatissima (Cleve) Heiden and P. calliantha Lundholm, Moestrup et Hasle. The identity of the species was supported by analyses of the ITS1, 5.8S and ITS2 of the nuclear-encoded rRNA sequences. We report the initial results in the development of P. calliantha- and P. delicatissima-specific probes targeting the rRNA for the identification of Pseudo-nitzschia spp. by fluorescent in situ hybridisation (FISH) techniques. The P. delicatissima-specific probe was shown to react with three out of the four clones of P. delicatissima tested whereas P. calliantha-specific probe reacted with only one out of the two P. calliantha clones tested