D. REINHARDT - Positive and negative regulators of arbuscular mycorrhiza

Abstract

Most plants improve their mineral nutrition by hosting in their roots arbuscular mycorrhizal (AM) fungi, which provide them with phosphate in exchange for reduced carbon. To identify regulatory components involved in AM development, we have conducted forward mutant screens in the transposon line W138 of petunia. A first component identified by this strategy is VAPYRIN, an ankyrin-related protein that localizes to an unknown subcellular compartment (Feddermann et al., 2010). VAPYRIN consists of two protein:protein-interaction domains. We are pursuing different biochemical approaches to identify interacting partner proteins of VAPYRIN.

A second component, ATYPICAL ARBUSCULE1 (ATA1), that was recently identified by transposon mutagenesis, encodes a transcription factor of the GRAS family (Rich et al., 2015). ATA1 is required for the development of the fungal arbuscules, which mediate nutrient transfer between the symbiotic partners, and for the induction of symbiosis genes in the host. Several of these genes encode homologs of the cutin biosynthetic machinery, indicating that secreted lipids could represent an important element in AM symbiosis.

References

N. Feddermann, R.R. Duvvuru Muni, T. Zeier, J. Stuurman, F. Ercolin, M. Schorderet, D. Reinhardt. (2010). The PAM1 gene of petunia, required for intracellular accommodation and morphogenesis of arbuscular mycorrhizal fungi, encodes a homologue of VAPYRIN. Plant J. 64, 470-481.

M. K. Rich, M. Schorderet, L. Bapaume, L. Falquet, P. Morel, M. Vandenbussche, D. Reinhardt. (2015). A petunia transcription factor controls symbiotic gene expression and fungal morphogenesis in arbuscular mycorrhiza. Plant Phys. 168, 788-797.

Contact: Benoit Lefebvre, LIPM