Preliminary Study On The Mode Of Action Of Carabrone

Carabrone is a sesquiterpenoid lactone compound from C.macrocephalum. Previous study indicated it has good antifungal activity, and has excellent activity on wheat powdery mildew, wheat take–all, wheat stripe rust, pot culture experiment indicated that Carabrone has a systemic action in wheat, physiological and biochemical test showed that Carabrone may have a certain effect on both biosynthesis and bio-oxidation of pathogen. In order to clear the mode of action and the mechanism of Carabrone to pathogen. In this paper, we study the conduction of Carabrone in wheat and take Gaeumannomyces graminis as test object in order to study the effects of Carabrone on bio-oxidation process of Gaeumannomyces graminis. The main results are as follows:1 The inhibition of Carabrone on Blumeria graminis mainly by inhibiting the expansion of colonyThe results of Carabrone on spore germination and colony expansion of Blumeria graminis by leave fragment method in vitro indicated that there is no significant inhibitory effect on spore germination by Carabrone. But it has significant effect on colony growth and showed some concentration-dependent, EC50 is 105.4314mg/L.2 There is a conduction of Carabrone from down to up in wheatPot culture experiment indicated that Carabrone could control Blumeria graminis by irrigation, the protective effect and the curative effect is 61.18% and 60.77% .Using HPLC method to detect the absorption of Carabrone by wheat roots in soil and in solution. The results showed that after 24h the content is the highest by in soil, reached to 26.825μg/g, and the absorption test of wheat roots in solution showed that the content of Carabrone increased gradually as the time went by.Comprehensive analysis of the results of activity tests and instrumental analysis can be inferred that Carabrone has apparent systemic action and a conduction from down to up in wheat.At the test dose, HPLC assay showed that there is not a significant conduction of Carabrone from up to down in wheat. 3 Carabrone has effect on the bio-oxidation process of Gaeumannomyces graminis(1) The results of Co-toxicity test of Carabrone and SHAM to Gaeumannomyces graminis showed that SHAM has significant synergism to Carabrone. The increment mulliple is 1.86, indicating that Carabrone can affect the generation of ATP by interfere with respiratory electron transport chain process obviously.(2) Carabrone has different effect on the activity of mitochondrial complexes in Gaeum- annomyces graminis by in vitro.The results show that as the concentration of Carabrone gradually increased, the activity of complex I showed overall decreasing trend. When the concentration reached to 32mg/L, the activity of complex II were significantly increased. Only when the concentration is 1 mg/L, the activity of complex III were 1.4 times lower than the control.Complex IV have no significant effect by Carabrone.(3) Carabrone has effect on all the four kinds of mitochondrial complexes in Gaeuman- nomyces graminis by in vivo.The results showed that when the concentration of Carabrone is low, there is no significant difference compared with the control, with the concentration increased, all the four kinds of complexes decreased.Through the results we can conclude that Carabrone has certain effect on bio-oxidation of Gaeumannomyces graminis, Carabrone may decreased the synthesis of ATP by interfere with complexes on respiratory electron transport chain , resulting in insufficient supply of biomass energy, leading to slow the growth of mycelium.