Physcomitrella patens MAX2 characterization suggests an ancient role for this F-box protein in photomorphogenesis rather than strigolactone signalling

Mauricio Lopez-Obando (1) , Ruan de Villiers , Beate Hoffmann (1) , Linnan Ma , Alexandre A. de Saint Germain (1) , Jens Kossmann , Yoan Coudert (2) , C. Jill Harrison (2) , Catherine Rameau (1) , Paul Hills , Sandrine Bonhomme (3)

1 IJPB - Institut Jean-Pierre Bourgin
2 University of Bristol [Bristol]
3 UR254 - Unité de Recherche en Génétique et Amélioration des Plantes

Strigolactones (SLs) are key hormonal regulators of flowering plant development and are widely distributed amongst streptophytes. In Arabidopsis, SLs signal via the F-box protein MORE AXILLARY GROWTH2 (MAX2), affecting multiple aspects of development including shoot branching, root architecture and drought tolerance. Previous characterization of a Physcomitrella patens moss mutant with defective SL synthesis supports an ancient role for SLs in land plants, but the origin and evolution of signalling pathway components are unknown. Here we investigate the function of a moss homologue of MAX2, PpMAX2, and characterize its role in SL signalling pathway evolution by genetic analysis. We report that the moss Ppmax2 mutant shows very distinct phenotypes from the moss SL-deficient mutant. In addition, the Ppmax2 mutant remains sensitive to SLs, showing a clear transcriptional SL response in dark conditions, and the response to red light is also altered. These data suggest divergent evolutionary trajectories for SL signalling pathway evolution in mosses and vascular plants. In P.patens, the primary roles for MAX2 are in photomorphogenesis and moss early development rather than in SL response, which may require other, as yet unidentified, factors.

Mots clés: bryophyte; F-box protein; hormone signalling; moss; photomorphogenesis; strigolactone

Domaines: Sciences du Vivant [q-bio]

Mauricio Lopez-Obando, Ruan de Villiers, Beate Hoffmann, Linnan Ma, Alexandre A. de Saint Germain, et al.. Physcomitrella patens MAX2 characterization suggests an ancient role for this F-box protein in photomorphogenesis rather than strigolactone signalling. New Phytologist, 2018, 219 (2), pp.743-756. ⟨10.1111/nph.15214⟩. ⟨hal-02352220⟩