Are Histidine Kinases of Arbuscular Mycorrhizal Fungi Involved in the Response to Ethylene and Cytokinins?

0577905 - ÚEB 2024 RIV US eng J - Journal Article
Mongès, A. - Yaakoub, H. - Bidon, B. - Glévarec, G. - Héricourt, F. - Carpin, S. - Chauderon, L. - Drašarová, Lenka - Spíchal, L. - Binder, B. M. - Papon, N. - Rochange, S.
Are Histidine Kinases of Arbuscular Mycorrhizal Fungi Involved in the Response to Ethylene and Cytokinins?
Molecular Plant-Microbe Interactions. Roč. 36, č. 10 (2023), s. 656-665. ISSN 0894-0282. E-ISSN 1943-7706
R&D Projects: GA MŠMT(CZ) EF16_019/0000827
Institutional support: RVO:61389030
Keywords : cytokinin * ethylene * mycorrhiza * receptor * Rhizophagus * symbiosis
OECD category: Biochemistry and molecular biology
Impact factor: 3.5, year: 2022
Method of publishing: Open access
https://doi.org/10.1094/MPMI-05-23-0056-R

Signals are exchanged at all stages of the arbuscular mycorrhizal (AM) symbiosis between fungi and their host plants. Root-exuded strigolactones are well-known early symbiotic cues, but the role of other phytohormones as interkingdom signals has seldom been investigated. Here we focus on ethylene and cytokinins, for which candidate receptors have been identified in the genome of the AM fungus Rhizophagus irregularis. Ethylene is known from the literature to affect asymbiotic development of AM fungi, and in the present study, we found that three cytokinin forms could stimulate spore germination in R. irregularis. Heterologous complementation of a Saccharomyces cerevisiae mutant strain with the candidate ethylene receptor RiHHK6 suggested that this protein can sense and transduce an ethylene signal. Accordingly, its N-terminal domain expressed in Pichia pastoris displayed saturable binding to radiolabeled ethylene. Thus, RiHHK6 displays the expected characteristics of an ethylene receptor. In contrast, the candidate cytokinin receptor RiHHK7 did not complement the S. cerevisiae mutant strain or Medicago truncatula cytokinin receptor mutants and seemed unable to bind cytokinins, suggesting that another receptor is involved in the perception of these phytohormones. Taken together, our results support the hypothesis that AM fungi respond to a range of phytohormones and that these compounds bear multiple functions in the rhizosphere beyond their known roles as internal plant developmental regulators. Our analysis of two phytohormone receptor candidates also sheds new light on the possible perception mechanisms in AM fungi.
Permanent Link: https://hdl.handle.net/11104/0346989