Aska Goverse,1 and
1Laboratory of Nematology, Department of Plant Sciences, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, The Netherlands; 2Molecular Cytology, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Kruislaan 316, 1098 SM Amsterdam, The Netherlands; 3Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, Building 37, 02-776 Warsaw, Poland
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Accepted 15 February 2008.
For the proliferation of their feeding sites (syncytia), the potato cyst nematode Globodera rostochiensis is thought to recruit plant endo-β-1,4-glucanases (EGases, EC. 184.108.40.206). Reverse-transcription polymerase chain reaction experiments on tomato (Solanum lycopersicum) indicated that the expression of two out of the at least eight EGases, namely Sl-cel7 and Sl-cel9C1, is specifically upregulated during syncytium formation. In situ hybridization and immunodetection studies demonstrated that both EGases are specifically expressed inside and adjacent to proliferating syncytia. To assess the importance of Sl-cel7 and Sl-cel9C1 for nematode development, we decided to knock them out individually. Sl-cel9C1 probably is the only class C EGase in tomato, and we were unable to regenerate Sl-cel9C1--silenced plants. Potato (S. tuberosum), a close relative of tomato, harbors at least two class C EGases, and St-cel7-or St-cel9C1--silenced potato plants showed no obvious aberrant phenotype. Infection with potato cyst nematodes resulted in a severe reduction of the number of adult females (up to 60%) and a sharp increase in the fraction of females without eggs (up to 89%). Hence, the recruitment of CEL7, an enzyme that uses xyloglucan and noncrystalline cellulose as natural substrates, and CEL9C1, an enzyme that uses crystalline cellulose, is essential for growth and development of potato cyst nematodes.
Additional keywords:cellulase, cell wall, plant-parasitic nematode, plant resistance.
© 2008 The American Phytopathological Society