Mitteilungen der Gesellschaft für Pflanzenbauwissenschaften Band 23

Mitt. Ges. Pflanzenbauwiss. 23: 243 (2011)
Sulfur nutrition of tomato (Solanum lycopersicum)
in relation to its resistance against pathogens
Katharina Bollig, Marc Zahn and Walter J. Horst
Institute for Plant Nutrition, Faculty of Natural Science, Leibniz University Hannover. E-Mail:
bollig@pflern.uni-hannover.de
Introduction
The soil borne fungus Verticillium dahliae (V. dahliae) causes vascular wilt disease
and drastically limits crop yield worldwide (Fradin and Thomma, 2006). Since no
effective fungicide preventing an infection is available current research focuses on
the elucidation of possible resistance promoting mechanisms. One strategy seems to
be the synthesis and deposition of the sulfur (S)-containing defense compound
(SDC) elemental S (S 0 ) in infected vascular plant tissue. S 0 was detected 21 days
past V. dahliae infection in a tolerant tomato (Solanum lycopersicum) genotype,
whereas sensitive plants produced considerably lower amounts (Williams et al.,
2002). We investigate the influence of externally applied S to tomato on S-enhanced
defense mechanisms potentially limiting fungal growth in colonized vascular tissue.
Material and Methods
Absolute and relative quantifications were performed in a CFX96 Real-Time
System (BioRad Laboratories, Hercules, CA) including total genomic DNA from
tomato hypocotyl tissue and fungal mycelium or tomato cDNA. Tolerant tomato tissue
was fixed, embedded and microtome sectioned for the isolation of cell structures
using the PALM MicroBeam microscope (Zeiss MicroImaging GmbH, 07740 Jena).
Results and DiscussionThe influence of S nutrition on V. dahliae infection within
vasculature of two tomato genotypes with different susceptibility levels was analyzed
by absolute quantitative Real-Time PCR (qRT-PCR). Excess S supply reduced the
fungus in infected vascular stem tissue of both tomato genotypes. This reflects an in
planta fungicidal impact of supra-optimal S nutrition. A spatial identification of genes
connected to S assimilation, which might play a role in the generation of S 0 , was
performed. Laser Microdissection was applied with relative qRT-PCR to identify
candidates in the xylem of tomato plants. Tissue-specific expression-patterns for
genes of the S metabolism as affected by genotype and S nutrition were identified.
Future work is on Agrobacterium-mediated transformation with genes possibly
relevant for synthesis of S 0 exhibiting a distinct spatial expression pattern within
tomato vasculature.
References
Fradin, E.F., Thomma, B.P.H.J. 2006: Physiology and molecular aspects of Verticillium wilt diseases
caused by V. dahliae and V. albo-atrum. Mol Plant Pathol. 7:71-86.
Williams, J. S., Hall S.A., Hawkesford M.J., Beale, M.H., Cooper R.M. 2002: Elemental Sulfur and
Thiol Accumulation in Tomato and Defense against a Fungal Vascular Pathogen. Plant Physiol.
128:150-159.