Zook M
Department of Botany and Plant Pathology, Michigan State University, East Lansing, Michigan 48824, USA.
Plant Physiol. 1998 Dec;118(4):1389-93. doi: 10.1104/pp.118.4.1389.
Camalexin (3-thiazol-2'-yl-indole) is the principal phytoalexin that accumulates in Arabidopsis after infection by fungi or bacteria. Camalexin accumulation was detectable in Arabidopsis cell-suspension cultures 3 to 5 h after inoculation with Cochliobolus carbonum (Race 1), and then increased rapidly from 7 to 24 h after inoculation. Levels of radioactivity incorporated into camalexin during a 1.5-h pulse labeling with [14C]anthranilate also increased with time after fungal inoculation. The levels of radioactive incorporation into camalexin increased rapidly between 7 and 18 h after inoculation, and then decreased along with camalexin accumulation. Relatively low levels of radioactivity from [14C]anthranilate incorporated into camalexin in the noninoculated controls. Autoradiographic analysis of the accumulation of chloroform-extractable metabolites labeled with [14C]anthranilate revealed a transient increase in the incorporation of radioactivity into indole in fungus-inoculated Arabidopsis cell cultures. The time-course measurement of radioactive incorporation into camalexin during a 1.5-h pulse labeling with [14C]indole was similar to that with [14C]anthranilate. These data suggest that indole destined for camalexin synthesis is produced by a separate enzymatic reaction that does not involve tryptophan synthase.
植保菌素（3-噻唑-2'-基吲哚）是拟南芥在受到真菌或细菌感染后积累的主要植物抗毒素。在用玉米小斑病菌（小种1）接种后3至5小时，在拟南芥细胞悬浮培养物中可检测到植保菌素的积累，然后在接种后7至24小时迅速增加。在用[14C]邻氨基苯甲酸进行1.5小时脉冲标记期间，掺入植保菌素中的放射性水平也随着真菌接种后的时间而增加。接种后7至18小时，植保菌素中放射性掺入水平迅速增加，然后随着植保菌素积累而下降。在未接种的对照中，[14C]邻氨基苯甲酸掺入植保菌素中的放射性水平相对较低。对用[14C]邻氨基苯甲酸标记的氯仿可提取代谢物积累的放射自显影分析表明，在真菌接种的拟南芥细胞培养物中，放射性掺入吲哚的量有短暂增加。在用[14C]吲哚进行1.5小时脉冲标记期间，对植保菌素中放射性掺入的时间进程测量与用[14C]邻氨基苯甲酸的测量相似。这些数据表明，用于植保菌素合成的吲哚是由一个不涉及色氨酸合酶的独立酶促反应产生的。
