Expression of a novel tobacco gene, NgCDM1, is preferentially associated with pathogen-induced cell death

The nucleotide sequence for NgCDM1 was deposited in GenBank database under the accession number AF208022. Incompatible plant-pathogen interactions result in rapid cell death known as the hypersensitive response (HR) and activation of host defense-related genes. To understand cellular mechanisms controlling HR against pathogen attack, we previously isolated a pool of tobacco genes that are induced or repressed by infection of TMV. In this study, expression of a TMV-induced gene, NgCDM1, which has low sequence homology to known genes was investigated. NgCDM1 mRNA accumulated not only during HR by inoculation of the avirulent pathogen Pseudomonas syringae pv. syringae 61, but also in necrotic cell death caused by infiltration of the virulent pathogen P. s. pv. tabaci. However, induction of the NgCDM1 transcripts was not triggered by cell death caused by senescence or freezing stress. Expression of NgCDM1 mRNA was independent of the plant defense signaling pathways induced by salicylic acid, methyl jasmonate, or H2O2 and also not associated with systemic acquired resistance. Immunoblot analysis revealed that NgCDM1 protein coincidently accumulated with induction of NgCDM1 transcript and was localized primarily in the vicinity of HR-lesion. These results indicate that expression of NgCDM1 gene is preferentially associated with pathogen-induced cell death. (C) 2003 Elsevier Ltd. All rights reserved.