Conserved mechanisms in nodulation and arbuscular mycorrhization in the non-legume Parasponia andersonii

Summary

The most well-known symbiosis is the relationship between plants with arbuscular mycorrhiza fungi (AMF) and nitrogen-fixing rhizobia. AMF can associate with almost 80% of all land plants, whereas nitrogen-fixing rhizobia are restricted to the legumes plant. Parasponiais the only non-legume plant that can establish nitrogen-fixing endosymbiosis with rhizobium. In this thesis, I investigated conserved mechanisms in nodulation and mycorrhization in Parasponia. The main aim in nitrogen-fixing nodulation research is to engineer the nodulation capacity in non-nodulating crops. To this end, it is important to identify critical genetic adaptations underlying the nodulation trait. Using reverse genetic approaches, we showed that PanNFP2 and PanSYMRK function in nodulation, and mycorrhization is conserved in Parasponia, similar as found in legumes. Furthermore, we discovered that PanGAT1, which is nodule specific, is not essential for nodulation. Overall, this thesis suggests that PanNFP2 is an essential engineering candidate for nodule organogenesis in non-nodulating plants.