University of Cologne - Center of Excellence for plant Sciences CEPLAS
Fungal microbiota of Arabis alpina
Most land plants rely on the ancient arbuscular mycorhizal symbiosis to acquire Phosphorus. Arabis alpina, as all Brassicaceae plants, is unable to form this symbiosis, yet it can grow under extremely P limited soils. We studied the root microbiota of wild-growing A. alpina from the french Alps and discovered that this plant lives in association with Helotiales fungi which can provide them with P. We have refered to these fungi as 'mycorhiza-like fungi' because although they do not belong to the classic mycorhizal lineages, they also can transfer P to their host.
A. alpina root fungal microbiota. Juliana Almario, Ganga Jeena, Jörg Wunder, Gregor Langen, AlgaZuccaro, George Coupland, Marcel Bucher. 2017. Proceedings of the National Academy of Sciences Oct 2017, 114 (44) E9403-E9412.
This work received a lot of attention and was featured in a commentary in PNAS: Fungal root microbiota and plant nutrition. Marcel G. A. van der Heijden, Nina Dombrowski, Klaus Schlaeppi. 2017. Proceedings of the National Academy of Sciences, 114 (44) 11574-11576
This work was supported by CEPLAS and a Plant Fellows fellowship http://www.plantfellows.org to J.A., and was done in collaboration with the groups of Alga Zuccaro (University of Cologne) and George Coupland (Max-Planck Cologne).
Impact of P-starvation on the root fungal microbiota
The aim of this project was to understant to what extent the response of plants to Phosphorus scarcity (Phosphate Starvation Response) remodels the composition of the root microbiota. Izabela Fabianska conducted the study using Arabidopsis thaliana (WT and PSR mutants) and different soil P amendments. She showed that the amounts of P in the soil and in the plant indeed predispose the plant to interact more with some fungi (e.g. root pathogens from the Olpidiales) and less with other fungi (e.g. Helotiales).
Fabiańska, I., Gerlach, N., Almario, J. and Bucher, M. (2019), Plant-mediated effects of soil phosphorus on the root-associated fungal microbiota in Arabidopsis thaliana. New Phytol, 221: 2123-2137.
PhD of Izabela Fabianska, co-supervision by Juliana Almario and Marcel Bucher. Photos by Izabela Fabianska.
Photo by Li Xue.
How does the establishment of the AM symbiosis impact root microbiota assembly?
The establishment of the arbuscular mycorrhizal (AM) symbiosis triggers many changes in plant roots, including changes in morphology, metabolism and defences. Moreover, AM fungi produce antimicrobial compounds which can suppress the growth of neighboring microbes. Along with Li and Izabela, we studied the impact of the establishment of the AM symbiosis on root-microbiota formation in Lotus japonicus. We analysed the root microbiota of ten L. japonicus mutants, impaired at different stages of AM formation, and saw that symbiosis-deficient plants (unable to form arbuscules) had a different root microbiota and were havily colonized by Dactylonectria fungi. We could experimentally show that AM fungi are actually able to suppress root colonisation by Dactylonectria saprophytes, both directly AND via the plant, suggesting AM fungi could be acting as root gatekeepers.
Xue, L., Almario, J., Fabiańska, I., Saridis, G. and Bucher, M. (2019). Dysfunction in the arbuscular mycorrhizal symbiosis has consistent but small effects on the establishment of the fungal microbiota in Lotus japonicus. New Phytol, 224: 409-420.
Max Planck Institute for Plant Breeding Cologne / University of Tübingen
Temporal dynamics of the leaf microbiota in wild Arabidopsis populations
This project was started by Eric Kemen and Matthew Agler and aims at understanding the temporal dynamics of the A. thaliana leaf microbiota. Six natural populations have been followed for the last 9 years and changes in their leaf microbiota has been recorded. This data has already been used to show that pathogenic Pseudomonas viridiflava are systematically present at high abundance in Arabidopsis leaves (Karasov et al., 2018), prompting the question of how wild plants remain healthy while being under pathogen attack. Our hypothesis is that other microbes might be helping the plant...