Bevan M, Shufflebottom D, Edwards K, Jefferson R, Schuch W
Institute of Plant Science Research, Cambridge Laboratory, UK.
EMBO J. 1989 Jul;8(7):1899-906. doi: 10.1002/j.1460-2075.1989.tb03592.x.
Phenylalanine ammonia-lyase (PAL) catalyses the first step in the biosynthesis of phenylpropanoids, which form a wide variety of plant secondary products. The transcription of PAL is regulated in response to various factors that induce the accumulation of flavonoids, lignin and compounds thought to be involved in plant defence reactions. The 5' upstream sequence of a PAL gene from Phaseolus vulgaris was fused to the coding region of the reporter gene encoding beta-glucuronidase (GUS), and transformed into potato and tobacco plants. Histochemical analysis of GUS expression showed that the PAL promoter was active in specific cell types that accumulated phenylpropanoid derivatives in response to mechanical wounding, and also during normal development of the xylem and flower. In xylem that had undergone secondary thickening, GUS activity occurred in rays of cells thought to be the xylem parenchyma. It was postulated that PAL activity in these cells could provide intermediates for lignin synthesis in xylem vessels that had terminally differentiated.
苯丙氨酸解氨酶（PAL）催化苯丙烷类生物合成的第一步，苯丙烷类可形成多种植物次生产物。PAL的转录受多种因素调控，这些因素会诱导黄酮类、木质素以及被认为参与植物防御反应的化合物的积累。菜豆PAL基因的5'上游序列与编码β-葡萄糖醛酸酶（GUS）的报告基因的编码区融合，并转化到马铃薯和烟草植株中。对GUS表达的组织化学分析表明，PAL启动子在特定细胞类型中具有活性，这些细胞类型会因机械损伤而积累苯丙烷类衍生物，并且在木质部和花的正常发育过程中也有活性。在经历次生加厚的木质部中，GUS活性出现在被认为是木质部薄壁组织的细胞射线中。据推测，这些细胞中的PAL活性可为终末分化的木质部导管中的木质素合成提供中间体。
