Phytophthora × pelgrandis, a new natural hybrid pathogenic to Pelargonium grandiflorum hort.

Abstract

A new Phytophthora hybrid of Ph. cactorum (Leb. & Cohn) Schroet. and Ph. nicotianae van Breda de Haan pathogenic to cultivars of Pelargonium grandiflorum hort. is described as Phytophthora × pelgrandis and its morphological features are documented. Morphological, physiological (e.g. temperature requirements) and molecular data (DNA sequencing, random amplified polymorphic DNA-PCR) are presented for isolates of the Phytophthora hybrid. Pathogenicity was tested on cultivars of P. grandiflorum and Nicotiana tabacum. For comparison cultures of the parental species and additional Phytophthora taxa also were examined.

• hybrid
• ITS and Cox I sequence phylogeny
• morphology
• Nicotiana tabacum
• pathogenicity tests
• Pelargonium grandiflorum
• Phytophthora cactorum
• Ph. nicotianae
• Ph. ×pelgrandis
• RAPD-PCR
• taxonomy

For the conscientious preservation of the cultures and the preparation of the media we thank Mrs Karin Zinn and Mrs Monika Krüger. Our special thanks to Mrs Verena Ristau for the precise generation of the technical data and to Mr Gregg Robideau for providing us with Cox I sequences. We also are grateful for the help of Dr Andre Levesque, who offered valuable suggestions during the preparation of the manuscript. In addition we thank the companies DNA SCAN GmbH (formerly Gillersheim, Germany) and Elsner pac Jungpflanzen (Dresden, Germany) for the free of charge services.