AUTHOR=Changenet Valentin , Macadré Catherine , Boutet-Mercey Stéphanie , Magne Kévin , Januario Mélanie , Dalmais Marion , Bendahmane Abdelhafid , Mouille Grégory , Dufresne Marie 

TITLE=Overexpression of a Cytochrome P450 Monooxygenase Involved in Orobanchol Biosynthesis Increases Susceptibility to Fusarium Head Blight

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.662025

DOI=10.3389/fpls.2021.662025

ISSN=1664-462X

ABSTRACT=<p>Fusarium Head Blight (FHB) is a cereal disease caused primarily by the ascomycete fungus <italic>Fusarium graminearum</italic> with public health issues due to the production of mycotoxins including deoxynivalenol (DON). Genetic resistance is an efficient protection means and numerous quantitative trait loci have been identified, some of them related to the production of resistance metabolites. In this study, we have functionally characterized the <italic>Brachypodium distachyon BdCYP711A29</italic> gene encoding a cytochrome P450 monooxygenase (CYP). We showed that <italic>BdCYP711A29</italic> belongs to an oligogenic family of five members. However, following infection by <italic>F. graminearum</italic>, <italic>BdCYP711A29</italic> is the only copy strongly transcriptionally induced in a DON-dependent manner. The BdCYP711A29 protein is homologous to the <italic>Arabidopsis thaliana</italic> MAX1 and <italic>Oryza sativa</italic> MAX1-like CYPs representing key components of the strigolactone biosynthesis. We show that BdCYP711A29 is likely involved in orobanchol biosynthesis. Alteration of the <italic>BdCYP711A29</italic> sequence or expression alone does not modify plant architecture, most likely because of functional redundancy with the other copies. <italic>B. distachyon</italic> lines overexpressing <italic>BdCYP711A29</italic> exhibit an increased susceptibility to <italic>F. graminearum</italic>, although no significant changes in defense gene expression were detected. We demonstrate that both orobanchol and exudates of <italic>Bd711A29</italic> overexpressing lines stimulate the germination of <italic>F. graminearum</italic> macroconidia. We therefore hypothesize that orobanchol is a susceptibility factor to FHB.</p>