title: Synergistic interaction of physcion and chrysophanol on plant powdery mildew.
abstract: The extract of the plant Rheum officinale Baill, mainly containing the anthraquinones physcion and chrysophanol, is highly active against plant powdery mildew. Experiments were conducted in the laboratory and greenhouse to determine the interaction of the two compounds on cucumber powdery mildew [Sphaerotheca fuliginea (Schlecht.) Poll] and on wheat powdery mildew [Blumeria graminis (DC.) Speer f. sp. tritici Marchal]. Physcion was much more bioactive than chrysophanol against these powdery mildews. There was a significant synergistic interaction between the two compounds on the diseases when the ratios of physcion to chrysophanol ranged from 1:9 to 5:5. The synergistic degree increased with increase in the chrysophanol proportion in the combination. The findings indicate that, in order to ensure constant efficacy of the extract on the disease, both the contents and the proportion of the main active ingredients physcion and chrysophanol have to be determined.
authors.affiliation: Agronomy and Biotechnology College, China Agricultural University, Beijing 10094, PR China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Yang
authors.forename: Lijun
authors.initials: L
authors.lastname: Yang
authors.forename: Shaonan
authors.initials: S
authors.lastname: Wang
authors.forename: Dazhao
authors.initials: D
authors.lastname: Yu
authors.forename: Hanwen
authors.initials: H
authors.lastname: Ni
mesh_terms: D000880:Anthraquinones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001203:Ascomycota / Q000187:drug effects*; D018553:Cucumis sativus / Q000187:drug effects / Q000382:microbiology*; D004642:Emodin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D012250:Rheum / Q000737:chemistry; D027343:Rhizome / Q000737:chemistry; D014908:Triticum / Q000187:drug effects / Q000382:microbiology*
chemical_list: D000880:Anthraquinones; D000935:Antifungal Agents; C008905:physcione; D004642:Emodin; C027113:chrysophanic acid