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キーワード:
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要旨:
Heterodera schachtii second-stage juveniles invade the root of their host and move intracellularly towards the vascular cylinder, where they induce the formation of a plant-derived syncytium and become sedentary. The hypertrophic and hypermetabolic syncytium serves as the sole nutritional source for the developing juveniles. Due to this dependency, it is crucial for H. schachtii to successfully initiate and maintain the syncytium in order to complete its lifecycle and produce progeny. Transcriptome data of Arabidopsis thaliana-derived syncytia compared to uninfected root tissues revealed an increase in the expression of genes involved in metabolic processes, including the biosynthetic pathways of several vitamins. These metabolites are essential nutrients, as they cannot be stored or synthesized by humans and, presumably, all other animals. A. thaliana lines over-expressing single or multiple steps of the biosynthesis of vitamin B1 (VB1) and vitamin B7 (VB7) were differently susceptible to infection by H. schachtii, confirming their important function during cyst nematode parasitism. Notably, our work has identified homologs of VB1 and VB7 biosynthetic genes, and their high expression during feeding stages, in H. schachtii. Using RNAi to down-regulate these genes, we observed defects in the nematode’s development. We assume that H. schachtii can perform the full or partial biosynthesis of VB1 and VB7, which serves as an evolutionary benefit for its parasitism by ensuring a continuous supply of these vitamins. Nevertheless, the simultaneous up-regulation of the host homologs during infection implies a highly sophisticated adaptation of host and parasite metabolism to ensure successful biotrophic parasitism without starving the host.
