TABLE CONTENTS

SESSION TWENTY – COMPATIBLE HOST-PARASITE INTERACTIONS
CONVENORS: FLORIAN GRUNDLER & EL-SHAWADFY MOUSA
Supply and Processing of Assimilates in Nematode-induced Syncytia
Grundler, F.M.W.
Institute of Plant Protection, University of Natural Resources and Applied Life Sciences, Vienna
The cyst nematode Heterodera schachtii induces specific syncytial feeding sites in the roots
of its host, from where it withdraws its nutrients. Syncytia generate strong sinks in the host
plant’s transport system. In roots of Arabidopsis thaliana syncytia are symplasmically
isolated during the first days of nematode development and solute supply relies on the
activity of syncytial plasma membrane-bound transport proteins. Only later, plasmodesmata
are formed connecting syncytia with the phloem. The expression of all sugar transporter
genes annotated in the Arabidopsis Membrane Protein Library in young and fully developed
syncytia was compared to non-infected A. thaliana roots by Affymetrix gene chip analysis.
Three genes STP12 (At4g21480), ERD (At3g05400) and ANTR2 (At4g00370) were selected
for in depth studies using qRT-PCR and in situ-RT-PCR. T-DNA insertion lines of STP12
and ERD both significantly affected nematode development. Further, the expression of
STP12 and ERD in syncytia of male juveniles was compared to their expression in syncytia
of female juveniles. In order to prove sugar transporter activity in syncytia fluorescencelabelled
glucose was loaded into the phloem of leaves and readily translocated into syncytia.
Although the nematodes withdraw high amounts of nutrients, we found accumulation starch
accumulation of starch in syncytia using high-performance liquid chromatography and
microscopic analyses. Further, we monitored the expression of genes involved in the starch
metabolic pathway by gene chip analysis and quantitative reverse transcription-PCR. Starch
seems to serve as a carbohydrate buffer to compensate changing solute uptake by the
nematode and as long-term storage during juvenile development.
5 th International Congress of Nematology, 2008 76