Vascularization and loading of amino acids into nematode-induced feeding sites

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Two different groups of plant-parasitic sedentary nematodes, the cyst nematodes and the root-knot nematodes, withdraw nutrients from their host’s roots from highly specialized cellular feeding structures. In the case of cyst nematodes nutrients enter the so-called syncytium symplastically, via plasmodesmata. In the case of root-knot nematodes the feeding structure consist of giant cells which are symplastically isolated and, therefore, depend on transport proteins for nutrient import. Both feeding sites are connected to a highly specialized type of unloading phloem, which, in case of root-knot nematodes consist exclusively of sieve elements. The mechanisms that control vascularization of feeding sites and transport proteins that play a role in nutrient import into giant cells are largely unknown. One aim of this proposal is to elucidate the events that control vascularization of feeding sites. Particularly the role of the phytohormone auxin will be addressed. Furthermore the role of a sieve element marker and the role of plasmodesmata localized receptors will be investigated. The other part of the proposal aims to characterize the role of an amino acid transporter in sink tissues, especially in giant cells. The changes of its localization in response to nutrient status and nematode infestation will be investigated.