3种石斛PEPC羧化酶活力比较

Comparative Study on PEPC Activity in Three Dendrobia Leaves

石斛属植物具有兼性景天酸代谢植物特征,磷酸烯醇式丙酮酸羧化酶是该类植物碳代谢的关键酶。本研究选用3种石斛为材料,测定了其磷酸烯醇式丙酮酸羧化酶活性。结果表明,报春石斛晚间黑暗条件下酶活性较强,凌晨高达25μmolCO2/(m2.s),而在中午光照最充足时,酶的活性相对较弱;金钗石斛酶活性日变化特点与报春石斛相似,但是活性比较弱;鼓槌石斛的酶活性很弱,通常在8μmolCO2/(m2.s)以下,昼夜变化幅度很小,表现为黑暗状态下比光下更强。

The species within the genus of Dendrobium exhibited the characteristics of facultative Crassulacean acid metabolism plants. Aiming at clarifying carbon assimilation pathway of dendrobium, three Dendrobia were employed in this study, and measurement of PEPC activity was conducted by the means of ultraviolet spectrophotometer. The results indicated that PEPC activity of D. primulinum from dark leaves was as strong as 25 txmolCO2/ （m2 ~ s） early morning, whilst it was relatively weak at noon when sun light was bright, which to some certain concluded that D. primulinum showed the characteristics of CAM plant. In terms of diurnal fluctuation of PEPC activity in D. nobile was resembled to D. primulinum. The PEPC activity in D. chrysotoxum was very weak as below 8 μmol CO2/ （ m2·s）, and the magnitude of diurnal fluctuation was small as comparing to other two objects; anyway, its activity from dark leaves was stronger than one from illuminated leaves, the data from the trials means that D. chrysotoxum is inclined to acting via C3 pathway.