HISTOCHEMICAL ANALYSES OF SILICON-INDUCED RESISTANCE IN
THE INTERACTION OF TOMATO (SOLANUM LYCOPERSICUM L.) AND
RALSTONIA SOLANACEARUM. T. Schacht and K. Wydra.
Leibniz
Universität Hannover, Institute of Plant Diseases and Plant Protection,
Herrenhäuser Str. 2. 30149 Hannover, Germany. wydra@ipp.unihannover.de
Abstract: Silicon-induced resistance has been studied on molecular genetic and
immuno-histochemical level and revealed an increase in expression of genes
involved in the basal resistance reaction and of signalling genes belonging
mainly to the jasmonic acid pathway. To further characterize and localize the
reaction on histochemical level, various biochemical parameters linked to
resistance in different pathosystems, such as tylosis formation, hydrogen
peroxide accumulation, lignification and callose deposition were studied
microscopically at different times after inoculation. Tomato genotype King
Kong 2 showed significantly increased tylosis formation in vessels of the
midstem in silicon-treated and R. solanacearum-inoculated plants compared
to non-inoculated plants of the same treatment at eight days post inoculation
(dpi), and an elevated tylosis formation compared to inoculated and noninoculated
plants of the non-silicon treatment. At 12 dpi an increased tylosis
formation was additionally observed in silicon-treated inoculated plants
compared to all other treatments. Further investigations for differences in
lignification, hydrogenperoxide accumulation and callose deposition revealed
that these mechanisms are apparently not involved in the silicon-induced
resistance of tomato to R. solanacearum.