Abstract
This experiment was conducted to investigate the protoporphyrin Ⅸ (PPIX)accumulation, activity of antioxidative enzymes and contents of antioxidant in tolerant-wheat and susceptible-barley to protoporphyrinogen oxidase (Protox) inhibiting-herbicides [oxyfluorfen(2-chloro-l-(3-ethoxy-nitrophenoxy-4-(trifluoromethyl) benzene, acifluorfen (5-[2-chloro-4-(trifl-uoromethyl) phenoxy]-2-nitrobenzoic acid), bifenox(methyl-5-(2, 4-dichlorophenoxy) 2-nitroben-zoate), and oxadiazon (5-tert-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2-one)]. The tolerant-wheat and susceptible-barley were soaked in these compounds at 10$^{-6}$ M for 2hrs and exposed to light for 2,4,6 or 8hrs to investigate change of the activity of antioxidative enzymes. The activities of monodehydroascorbate reductase(MDAR), catalase(CAL) and superoxide dismutase(SOD) were lower in the barley than in the wheat after the treatement of these compounds. The activity of peroxidase(POX) was lower in the barley than in the wheat at 8hrs after the treatment of oxyfluorfen but other compounds showed no difference in activity in wheat and barley. The activity of glutathione reductase(GR) was increased in wheat and barley according as hours of treatment of these compounds became increased but its activity was no difference between wheat and barley. In the case of the content of vitamin C due to the treatment of these compounds, the wheat decreased less than the barley. After the treatment of oxyfluorfen the content of vitamin E in the wheat was higher than in the barley but other compounds didn't have any difference between wheat and barley. And after the treatment of acifluorfen the content of carotenoid was greater in the wheat than in the barley but other compounds didn't have any difference between wheat and barley. The content of glutathione (GSH, GSSG) was greater in the barley than in the wheat. The content of protoporphyrin Ⅸ (PPIX) accumulation by the treatments of these compounds was more in the barley than in the wheat. Especially, the treatment of oxyfluorfen and acifluorfen were more accumulated 2.3 and 1.3 fold in the barley than in the wheat, respectively.
Protoporphyrinogen oxidase(Protox) 저해형 제초제로 알려진 oxyfluorfen(OF), acifluorfen(AF), bifenox(BF) 및 oxadiazon(OD)에 대해 밀이 보리보다 특이적으로 내성을 보인 요인이 이들 제초제 처리로 인하여 발생된 singlet oxygen을 무독화할 수 있는 항산화효소 및 항산화제의 능력 차이와 Protox 저해에 의한 protoporphyrin Ⅸ(PPIX)의 축적량에 기인하는지를 알아 보고자 하였다. 내성을 보인 밀과 감수성을 보인 보리에 OF, AF, BF 및 OD을 $10^{-6}$ M로 침지처리후 광에 2, 4, 6 및 8시간 경과후에 항산화효소 활성 변화를 본 결과, 이들 네 가지 약제 처리 후 monodehy-droascorbate reductase(MDAR), catalase(CAL) 및 superoxide dismutase(SOD)의 활성은 밀보다 보리에서 활성의 감소폭이 컸다. POX 활성은 OF 처리후 단지 8시간에만 밀보다 보리에서 활성이 적었을 뿐, 그밖의 AF, BF 및 OD 처리에서는 차이가 없었다. GR활성은 4약제 처리후 시간이 경과될수록 활성이 증가하였으나, 밀과 보리간에 활성의 차이는 없었다. 네 가지 약제 처리 후 항산화제인 vitamin C 함량은 밀보다 보리에서 함량 감소가 컸었다. Vitamin E는 OF처리에서만 밀이 보리보다 함량 감소가 적었을 뿐 그 밖의 약제에 대해서는 차이가 없었다. 그리고 carotenoid 함량은 AF처리에서만 밀이 보리보다 함량 감소가 적었을 뿐 그 밖의 약제에 대해서는 차이가 없었다 Glutathione(GSH, GSSG) 함량은 네 가지 약제처리 모두 밀보다 보리에서 함량이 많았다. 이들 약제 처리후 PPIX 축적량은 밀보다 보리에서 많았고, 특히 OF및 AF 처리에서는 각각 밀보다 보리에서 2.3배 및 1.3배가 더 많이 축적되었다.
