Abstract
Eight days grown barley seedlings were treated with dimethipin for 72 hours and then the content of chlorophyll and photosynthetic electron activities of isolated chloroplasts were investigated. At the treatment of 10/sup -5/ M dimethipin the content of chlorophyll was decreased to 33% at 72 hours. Seven days etiolated barley seedlings were exposed to the light while dimethipin was added. At the time of 48 hours' greening chlorophyll content was reduced to 43% at 10/sup -4/M dimethipin and the chlorophyll a/b ratio was increased. In photosynthetic electron transport the activity of PSⅡ+PSⅠ was decreased to 10% at 48 hours and 25% at 72 hours at 10/sup -4/ M dimethipin. In the treatment of 10/sup -4/ M dimethipin the activity of PSⅡ+PSⅠ, except water splitting system was inhibited to 16% at 48 hours and 27% at 72 hours. The activity of PSⅡ was inhibited to 8% at 24 hours, 13% at 48 hours and 18% at 72 hours at 10/sup -4/ M dimethipin. The activity of PSⅠ was inhibited to 4% at 24 hours, 8% at 48 hours and 10% at 72 hours at 10/sup -4/ M dimethipin. In the times of greening of 7 days etiolated barley seedlings the activities of PSⅡ+PSⅠ were reduced to 5, 10, 10 and 11 % at 6, 12, 24, and 48 hours, respectively, at 10/sup -4/ M dimethipin. On the other hand, the activity of PSⅡ+PSⅠ except water splitting system, was not inhibited at all incubated hours in 10/sup -4/M dimethipin and there were no clear changes of the activities of PSⅡ and PSⅠ as compared to the control. Therefore, it could be concluded that dimethipin inhibited the photosynthetic electron activity by affecting the function of chloroplast rather than the synthesis of chloroplast and the inhibited function of chloroplast seems to come from the severe decrease of chlorophyll content.
8일간 생장한 보리 유식물에 72시간 동안 dimethipin을 처리하면서 엽록소 함량의 변화와 광합성적 전자전달 활성을 측정하였다. 10/sup -3/M dimethipin을 72시간 처리한 경우 엽록소 함량이 33% 감소하였다. 이에 비해 7일간 암소에서 생장시킨 후 dimethipin을 처리한 보리 유식물은 녹화 48시간에 10/sup -4/M에서 대조구에 비해 43% 엽록소 함량이 감소하였으며, 엽록소 a/b 비율이 증가하였다. 24시간의 dimethipin처리는 PSⅡ+PSⅠ활성에 거의 영향을 미치지 않았다. 10/sup -4/M dimethipin처리는 48시간 배양시 10% 그리고 72시간에는 25%의 PSⅡ+PSⅠ 활성을 억제하였다. Water splitting system을 제외한 PSⅡ+PSⅠ 활성은 10/sup -4/M dimethipin을 48시간 처리할 경우 16% 그리고 72시간에는 27% 억제되었다. 10/sup -4/M dimethipin을 24시간 처리할 경우 PSⅡ활성은 8%, 48시간에서는 13% 그리고 72시간에서는 18% 억제되었다. 10/sup -4/M dimethipin을 24시간 처리할 경우 PSⅠ활성은 4%, 48시간에서는 8% 그리고 72시간에서는 10% 억제되었다. 7일간 암소에서 자란 황백화된 보리 유식물을 녹화시간 6, 12, 24와 48시간에 dimethipin을 처리할 경우 PSⅡ+PSⅠ 활성은 5, 10, 10 그리고 11% 억제되었다. 반면에 water splitting system을 제외한 PSⅡ+PSⅠ 활성은 모든 처리시간에서 그 효과가 없었다. 또한 PSⅡ와 PSⅠ의 활성도 대조구와 큰 차이가 없었다. 이와 같이 dimethipin에 의해 야기된 광합성적 전자전달활성의 억제는 엽록체 합성과정에서의 영향보다는 엽록체의 기능에 영향을 주는 것으로 사료되며, 이러한 엽록체 기능의 감소는 dimethipin에 의해 야기되는 30∼40%의 엽록소 함량감소에 의한 것으로 사료된다.