Expression of the cell death protein CED-4 of Caenorhabditis elegans in transgenic tobacco plants confers resistance to Meloidogyne incognita

Abstract

Plant parasitic nematodes are devastating to agricultural production. Recent estimates indicate that losses due to nematode infestation can reach US$ 125 billion per year worldwide. Further aggravating the problem is the use of chemicals, such as methyl bromide. Even though methyl bromide is still the best tool currently available to combat nematode infestation, it has been targeted by international treaties for elimination from worldwide agriculture due to its deleterious impact on the environment. Therefore, alternatives are urgently needed to eliminate the threat of both parasitic nematodes and hazardous pesticides. In an attempt to develop novel strategies for nematode control, we produced and characterized transgenic tobacco plants constitutively expressing the ced-4 gene from Caenorhabditis elegans and exposed homozygous lines to the plant parasitic nematode Meloidogyne incognita. Five transgenic lines tested showed a significant reduction in the number of nematode-induced galls formed. These tolerant tobacco lines displayed high levels of ced-4 expression (determined via a competitive reverse transcription-PCR assay) and the presence of CED-4 (determined by Western blot analysis with anti-CED-4 antibodies). In addition, protein extracts from transgenic ced-4 plants restored CED-3 activity of the ced-4 mutant C. elegans protein extracts to wild-type levels, indicating that the CED-4 protein produced in these transgenic plants is functional. We suggest that programmed cell death genes may provide an alternative to control plant parasitic nematodes.