PHENOTYPIC AND BIOCHEMICAL ANALYSES OF SILICON – INDUCED
RESISTANCE AGAINST RALSTONIA SOLANACEARUM IN POTATO
GENOTYPES. D. Sadikaj and K. Wydra Institute of Plant Diseases
and Plant Protection, Leibniz Universität Hannover, Herrenhäuser Str. 2,
30419 Hannover, Germany. wydra@ipp.uni-hannover.de
Abstract: Treatment of potato genotypes Desirée, moderately resistant, Saxon,
susceptible, and Estima, highly susceptible to bacterial wilt, with silicon
identified potato as Si-non-accumulator (less than 0.13% Si in roots). Silicon
treatment in form of monosilicic acid and silicon dioxide reduced disease
severity and incidence in genotype Desirée by 35% and 25%, respectively,
while for genotype Saxon the influence of silicon was variable, and no effect
was observed in Estima. Silicon amendment reduced the colonisation of
roots and stems in the three genotypes. No significant differences in PAL
activity and soluble phenols were found across treatments in genotypes
Desirée and Saxon. In genotype Saxon PAL activity was tendenciously
suppressed in the Rastonia solanacearum infected plants, regardless of the
Si amendment and plant organ tested, root or stem. No significant
differences were found between treatments and genotypes in PAL activity
and total soluble phenols. Probing cell walls of mid-stem xylem vessels with
the anti-arabinogalactan protein (AGP) antibody LM2 revealed higher
accumulation of AGPs due to R. solanacearum infection in genotype
Desirée. The induction was stronger in the R. solanacearum-infected, siliconamended
treatment, whereas un-inoculated treatments showed no increased
fluorescence. No differences were found in genotypes Saxon and Estima.
The results of this study indicate that Si nutrition can induce resistance
mechanism in a non-accumulator plant species, in a genotype-dependent
interaction, as we similarly observed in here not presented studies with
eggplant and geranium.