An ectomycorrhizal fungus alters sensitivity to jasmonate, salicylate, gibberellin, and ethylene in host roots
Veronica Basso, Annegret Kohler, Shingo Miyauchi, Vasanth Singan, Frédéric Guinet, Jan Šimura, Ondřej Novák, Kerrie W. Barry, Mojgan Amirebrahimi, Jonathan Block, Yohann Daguerre, Hyunsoo Na, Igor V. Grigoriev, Francis Martin and Claire Veneault-Fourrey
13 December 2019, Plant, Cell & Environment; doi: 10.1111/pce.13702
The phytohormones jasmonate, gibberellin, salicylate, and ethylene regulate an interconnected reprogramming network integrating root development with plant responses against microbes. The establishment of mutualistic ectomycorrhizal symbiosis requires the suppression of plant defense responses against fungi as well as the modification of root architecture and cortical cell wall properties. Here, we investigated the contribution of phytohormones and their crosstalk to the ontogenesis of ectomycorrhizae (ECM) between grey poplar (Populus tremula x alba) roots and the fungus Laccaria bicolor. To obtain the hormonal blueprint of developing ECM, we quantified the concentrations of jasmonates, gibberellins, and salicylate via liquid chromatography‐tandem mass spectrometry. Subsequently, we assessed root architecture, mycorrhizal morphology, and gene expression levels (RNA‐sequencing) in phytohormone‐treated poplar lateral roots in the presence or absence of L. bicolor. Salicylic acid accumulated in mid‐stage ECM. Exogenous phytohormone treatment affected the fungal colonization rate and/or frequency of Hartig net formation. Colonized lateral roots displayed diminished responsiveness to jasmonate but regulated some genes, implicated in defense and cell wall remodeling, that were specifically differentially expressed after jasmonate treatment. Responses to salicylate, gibberellin, and ethylene were enhanced in ECM. The dynamics of phytohormone accumulation and response suggest that jasmonate, gibberellin, salicylate, and ethylene signaling play multifaceted roles in poplar‐L. bicolor ectomycorrhizal development.
Basso, V., Kohler, A., Miyauchi, S., Singan, V., Guinet, F., Šimura, J., Novák, O., Barry, K.W., Amirebrahimi, M., Block, J., Daguerre, Y., Na, H., Grigoriev, I.V., Martin, F. and Veneault‐Fourrey, C. (2019), An ectomycorrhizal fungus alters sensitivity to jasmonate, salicylate, gibberellin, and ethylene in host roots. Plant Cell Environ. Accepted Author Manuscript. doi:10.1111/pce.13702