Changes in mRNA abundance within Heterodera schachtii-infected roots of Arabidopsis thaliana

Gene expression changes in plant roots infected by plant-parasitic cyst nem atodes are involved in the formation of nematode feeding sites. We analyzed mRNA abundance changes within roots of Arabidopsis thaliana during the ear ly compatible interaction with Heterodera schachtii, the sugarbeet cyst nem atode, Approximately 1,600 root sections, each containing a single parasiti c nematode and its feeding site, and 1,600 adjacent, nematode-free root sec tions were excised from aseptic A, thaliana cultures 3 to 4 days after inoc ulation with H, schachtii, These tissue samples were termed infected and un infected, respectively. Preparasitic nematodes were added to the uninfected tissue sample to maintain the nematode to plant tissue proportion, mRNA ex tracted from these two tissue samples was subjected to differential display analysis. Thirty-six cDNA clones corresponding to mRNA species with differ ent abundance between both tissue samples were isolated. Of these clones, 2 4 were of A, thaliana origin and 12 were from H, schachtii, Differential di splay data predicted that the A, thaliana cDNA clones corresponded to 13 tr anscripts that were more abundant in the infected root sections and II tran scripts that were more abundant in the uninfected root sections. H, schacht ii cDNA clones were predicted to correspond to four transcripts that were m ore abundant in parasitic nematodes and to eight transcripts that were more abundant in preparasitic nematodes, In situ hybridization experiments conf irmed the mRNA abundance changes in A. thaliana roots predicted by the diff erential display analyses for two A. thaliana clones.