Arabidopsis 피토크롬 돌연변이체에서 ethylene 생합성 조절 작용

Abstract

식물생장과 발달에 중요한 역할을 하는 phytochrome이 ethylene 생합성에 미치는 영향을 조사하기 위하여 여러 빛 조건에서 키운 phyA, phyB, phyAB에서 ethylene 생합성과 생합성에 관여하는 enzyme activity를 측정하였다. White light에서 키웠을 때 모든 mutant에서 ethylene 생합성이 감소되었다. 특히 double mutant에서는 wild type과 비교하여 37%가 감소하였다. Dark에서 키웠을 때에는 wild type만 감소하였고, mutant에서는 감소효과가 나타나지 않았다. Red light에서 키웠을 때 double mutant에서 급격한 감소가 일어났다. Far-red light 에서 키웠을 때는 phyB만 감소가 일어나지 않았다. Ethylene 생합성에 관여하는 enzyme인 ACO 활성 패턴과는 달리ACS 활성 패턴은 ethylene 생성 패턴과 유사하게 나타났다. 이 결과를 바탕으로 ethylene 생합성에는 phytochrome A와 B 모두 중요한 작용을 하며 특히 <TEX>$P_r$</TEX> 형태의 phytochrome이 ethylene 생성량을 조절한다는 것을 제시한다. 또한 phytochrome은 ethylene 생합성 단계에서 AdoMet가 ACC로 전환되는 단계에서 조절하는 것을 제시한다. In order to investigate the effect of phytochromes on the regulation of ethylene biosynthesis, we measured the ethylene production and the activities of enzymes involved in ethylene biosynthesis using phytochrome mutants such as <TEX>$phyA$</TEX>, <TEX>$phyB$</TEX>, and <TEX>$phyAB$</TEX> of Arabidopsis. The ethylene production was decreased in mutants grown in white light. In particular, double mutants showed a 37% decrease compared to the wild type in ethylene production. When Arabidopsis roots were grown in the dark, mutants did not show a decrease in ethylene production; however, production was significantly decreased in the double mutant grown in red light. Only <TEX>$phyB$</TEX> did not show the decrease in the ethylene production in far-red light. Unlike the ACO activities, the ACS activities of mutants showed the same pattern as the ethylene production under several light conditions. The results of ACS activities confirmed the expression of the ACS gene by RT-PCR analysis. The decrease of ethylene production in mutants was due to the lower activity of ACC synthase, which converts the S-adenosyl-L-methionine (AdoMet) to 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene. These results suggested that both phytochrome A and B play an important role in the regulation of ethylene biosynthesis in Arabidopsis roots in the conversion step of AdoMet to ACC, which is regulated by ACS.