P-295 - Tricky parasites: how nematodes take their vitamins from plants

Cyst nematodes like Heterodera schachtii are obligate plant parasites that rely on a host-derived syncytium as their sole nutrient source. The successful establishment and maintenance of this feeding site are crucial for nematode development. To elucidate the molecular mechanisms underlying this parasitic relationship, we analyzed the transcriptome of Arabidopsis thaliana-derived syncytia and identified a significant up-regulation of genes involved in metabolic processes, including the biosynthesis of vitamins B1 (VB1) and B7 (VB7). These essential nutrients cannot be synthesized by humans and, presumably, all other animals. Functional studies using transgenic A. thaliana lines with over-expressed or silenced VB1 and VB7 biosynthetic genes showed differential susceptibility to H. schachtii, confirming their importance during infection. Notably, in the recently published genome of H. schachtii homologous genes for VB1 and VB7 biosynthesis were found, with high expression during feeding stages. RNAi-mediated silencing of these genes in the nematodes led to developmental defects, suggesting that H. schachtii has evolved the ability to partially or fully synthesize these vitamins. This finding implies an evolutionary benefit for the nematode, ensuring a continuous supply of essential nutrients without starving the host. However, the simultaneous up-regulation of host homologs during infection highlights a highly sophisticated adaptation of host and parasite metabolism.