Induction of Haustorium Development by Sphaeropsidones in Radicles of the Parasitic Weeds Striga and Orobanche. A Structure-Activity Relationship Study.
Crop attack by parasitic weeds such as Striga and Orobanche occurs through developmental processes triggered by host chemodetection. Seeds of those weed species remain dormant in the soil until germination is triggered by host root exudates. The development of haustorium, a parasitic plant organ that invades the host to withdraw its nutrients, is also initiated in Orobanchaceae by host molecular cues. The induction of haustorium development by exogenous signals has previously been reported for Striga but not for Orobanche species. In this work, we demonstrate that sphaeropsidone and epi-sphaeropsidone, two phytotoxic cyclohexene oxides isolated from the fungus Diplodia cupressi, a causal agent of cypress canker, induce haustorium development in radicles of the parasitic weeds Striga hermonthica, Orobanche crenata, and Orobanche cumana. This is the first report of chemical stimulation of haustorium development in radicles of Orobanche in the absence of host. In addition, SAR studies were carried out by testing the haustorium-inducing activity of the natural cyclohexene oxides, seven already known and four new hemisynthetic derivatives, in O. cumana, O. crenata, and S. hermonthica, to find a molecular specificity model required for haustorium induction. The results suggested that the haustorium-inducing activity is due to the possibility to convert the natural sphaeropsidone and natural and hemisynthetic derivatives in the corresponding 3-methoxyquinone and that the stereochemistry at C-5 also seems to affect this activity.
UMR 1347 Agroécologie, INRA , BP 86510, F-21000 Dijon, France.
Mónica
M
Fernández-Aparicio
Dipartimento di Scienze Chimiche, Università di Napoli Federico II , Complesso Universitario Monte Sant'Angelo, Via Cintia 4, 80126, Napoli, Italy.
Marco
M
Masi
Dipartimento di Agraria, Sezione di Patologia Vegetale ed Entomologia, Università degli Studi di Sassari , Viale Italia 39, 07100, Sassari, Italy.
Lucia
L
Maddau
Dipartimento di Scienze Chimiche, Università di Napoli Federico II , Complesso Universitario Monte Sant'Angelo, Via Cintia 4, 80126, Napoli, Italy.
Alessio
A
Cimmino
Dipartimento di Scienze Chimiche, Università di Napoli Federico II , Complesso Universitario Monte Sant'Angelo, Via Cintia 4, 80126, Napoli, Italy.
Marco
M
Evidente
Institute for Sustainable Agriculture, CSIC , Apdo. 4084, 14080 Córdoba, Spain.
Diego
D
Rubiales
Dipartimento di Scienze Chimiche, Università di Napoli Federico II , Complesso Universitario Monte Sant'Angelo, Via Cintia 4, 80126, Napoli, Italy.
Antonio
A
Evidente
D001203:Ascomycota / Q000737:chemistry; D004224:Diterpenes / Q000737:chemistry* / Q000494:pharmacology*; D018525:Germination / Q000187:drug effects; D031672:Orobanche / Q000187:drug effects* / Q000254:growth & development; D057685:Plant Weeds / Q000187:drug effects* / Q000254:growth & development; D012639:Seeds / Q000187:drug effects; D034362:Striga / Q000187:drug effects* / Q000254:growth & development; D013329:Structure-Activity Relationship
D004224:Diterpenes; C523395:sphaeropsidone
Orobanche crenata; Orobanche cumana; Striga hermonthica; attachment organ; cyclohexene oxides; haustorium-inducing factor