title: Strigolactone biosynthesis is evolutionarily conserved, regulated by phosphate starvation and contributes to resistance against phytopathogenic fungi in a moss, Physcomitrella patens.
abstract: In seed plants, strigolactones (SLs) regulate architecture and induce mycorrhizal symbiosis in response to environmental cues. SLs are formed by combined activity of the carotenoid cleavage dioxygenases (CCDs) 7 and 8 from 9-cis-β-carotene, leading to carlactone that is converted by cytochromes P450 (clade 711; MAX1 in Arabidopsis) into various SLs. As Physcomitrella patens possesses CCD7 and CCD8 homologs but lacks MAX1, we investigated if PpCCD7 together with PpCCD8 form carlactone and how deletion of these enzymes influences growth and interactions with the environment. We investigated the enzymatic activity of PpCCD7 and PpCCD8 in vitro, identified the formed products by high performance liquid chromatography (HPLC) and LC-MS, and generated and analysed ΔCCD7 and ΔCCD8 mutants. We defined enzymatic activity of PpCCD7 as a stereospecific 9-cis-CCD and PpCCD8 as a carlactone synthase. ΔCCD7 and ΔCCD8 lines showed enhanced caulonema growth, which was revertible by adding the SL analogue GR24 or carlactone. Wild-type (WT) exudates induced seed germination in Orobanche ramosa. This activity was increased upon phosphate starvation and abolished in exudates of both mutants. Furthermore, both mutants showed increased susceptibility to phytopathogenic fungi. Our study reveals the deep evolutionary conservation of SL biosynthesis, SL function, and its regulation by biotic and abiotic cues.
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Eva L
authors.initials: EL
authors.lastname: Decker
authors.affiliation: Cell Biology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Adrian
authors.initials: A
authors.lastname: Alder
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hunn
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Jenny
authors.initials: J
authors.lastname: Ferguson
authors.affiliation: Department of Agricultural Sciences, University of Helsinki, Latokartanonkaari 7, Helsinki, FIN-00014, Finland.
authors.forename: Mikko T
authors.initials: MT
authors.lastname: Lehtonen
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Bjoern
authors.initials: B
authors.lastname: Scheler
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Klaus L
authors.initials: KL
authors.lastname: Kerres
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Gertrud
authors.initials: G
authors.lastname: Wiedemann
authors.affiliation: Cell Biology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.
authors.forename: Vajiheh
authors.initials: V
authors.lastname: Safavi-Rizi
authors.affiliation: Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, E-41080, Spain.
authors.forename: Steffen
authors.initials: S
authors.lastname: Nordzieke
authors.affiliation: BESE Division, Plant Science Program, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
authors.forename: Aparna
authors.initials: A
authors.lastname: Balakrishna
authors.affiliation: BESE Division, Plant Science Program, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
authors.forename: Lina
authors.initials: L
authors.lastname: Baz
authors.affiliation: Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, E-41080, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Avalos
authors.affiliation: Department of Agricultural Sciences, University of Helsinki, Latokartanonkaari 7, Helsinki, FIN-00014, Finland.
authors.forename: Jari P T
authors.initials: JPT
authors.lastname: Valkonen
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.|FRIAS - Freiburg Institute for Advanced Studies, University of Freiburg, Freiburg, 79104, Germany.|BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Freiburg, 79104, Germany.
authors.forename: Ralf
authors.identifier: http://orcid.org/0000-0002-5496-6711
authors.initials: R
authors.lastname: Reski
authors.affiliation: Cell Biology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, Freiburg, 79104, Germany.|BESE Division, Plant Science Program, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
authors.forename: Salim
authors.initials: S
authors.lastname: Al-Babili
mesh_terms: D005075:Biological Evolution; D019068:Bryopsida / Q000382:microbiology* / Q000502:physiology*; D002338:Carotenoids / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D049308:Dioxygenases / Q000378:metabolism; D060467:Disease Resistance; D004198:Disease Susceptibility; D055786:Gene Knockout Techniques; D018525:Germination; D006575:Heterocyclic Compounds, 3-Ring / Q000378:metabolism; D007783:Lactones / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010710:Phosphates / Q000172:deficiency*; D010935:Plant Diseases / Q000382:microbiology*; D010940:Plant Proteins / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: C000591191:GR24 strigolactone; D006575:Heterocyclic Compounds, 3-Ring; D007783:Lactones; D010710:Phosphates; D010940:Plant Proteins; D002338:Carotenoids; D049308:Dioxygenases
keywords: 
  Orobanche ramosa
  ; 
  Physcomitrella patens
  ; 
  Sclerotinia sclerotiorum
  ; carlactone; carotenoid cleavage dioxygenase; carotenoids; phosphate starvation; strigolactones