title: Abutilon theophrasti's defense against the allelochemical benzoxazolin-2(3H)-one: support by Actinomucor elegans.
abstract: Abutilon theophrasti Medik., previously found to be rather insensitive to benzoxazinoid containing rye mulch and the allelochemical benzoxazolin-2(3H)-one (BOA), can be associated with the zygomycete Actinomucor elegans, whereby the fungus colonizes the root relatively superficially and mainly in the maturation zone. The fungus mitigates necrosis of the cotyledons when seedlings are incubated with 2 mM BOA, in contrast to those that lack the fungus. In liquid cultures of the fungus, tryptophan was identified. The accumulation of tryptophan is increased in presence of BOA. This amino acid seems to be important in protecting Abutilon against BOA and its derivatives since it suppressed the accumulation of BOA derived, highly toxic 2-aminophen-oxazin-3-one (APO) in the medium and on the root surface during BOA incubations of Abutilon seedlings. Although A. elegans is insensitive to BOA and APO, the fungus is not able to protect the plant against harmful effects of APO, when seedlings are treated with the compound. Abutilon can detoxify BOA via BOA-6-OH glucosylation probably by a cell wall associated glucosyltransferase, but only low amounts of the product accumulate. Low tryptophan concentrations can contribute to a degradation of the toxic intermediate BOA-6-OH by Fenton reactions, whereby the amino acid is oxidized. One of the oxidation products was identified as 4(1H)-quinolinone, which is the core substructure of the quorum sensing molecule 2-heptyl-3-hydroxy-4-quinolone. The mutualistic association of Abutilon theophrasti with Actinomucor elegans is considered as opportunistic and facultative. Such plant-fungus associations depend rather likely on environmental conditions, such as the mode of fertilization.
authors.affiliation: IMBIO Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Karlrobert-Kreiten Str. 13, 53115, Bonn, Germany.
authors.forename: Sevda Haghi
authors.initials: SH
authors.lastname: Kia
authors.forename: Margot
authors.initials: M
authors.lastname: Schulz
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Ayah
authors.forename: Alexander
authors.initials: A
authors.lastname: Schouten
authors.forename: Carmen
authors.initials: C
authors.lastname: Müllenborn
authors.forename: Christian
authors.initials: C
authors.lastname: Paetz
authors.forename: Bernd
authors.initials: B
authors.lastname: Schneider
authors.forename: Diana
authors.initials: D
authors.lastname: Hofmann
authors.forename: Ulrich
authors.initials: U
authors.lastname: Disko
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Tabaglio
authors.forename: Adriano
authors.initials: A
authors.lastname: Marocco
mesh_terms: D001583:Benzoxazoles / Q000378:metabolism*; D019660:Malvaceae / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D008969:Molecular Sequence Data; D009090:Mucorales / Q000502:physiology*; D010675:Pheromones / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D017422:Sequence Analysis, DNA
chemical_list: D001583:Benzoxazoles; D010675:Pheromones; C017057:benzoxazolone