Ni W, Fahrendorf T, Ballance G M, Lamb C J, Dixon R A
Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73402, USA.
Plant Mol Biol. 1996 Feb;30(3):427-38. doi: 10.1007/BF00049322.
Nuclear transcript run-on analysis was used to investigate++ the relative transcription rates of genes encoding enzymes of isoflavonoid phytoalexin biosynthesis and related pathways in elicitor-treated alfalfa (Medicago sativa L.) cell suspension cultures. Genes encoding L-phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and chalcone reductase (CHR) were most rapidly activated, with increases in transcription measurable within 10-20 min after elicitation. Cinnamic acid 4-hydroxylase (C4H), chalcone isomerase (CHI), isoflavone reductase (IFR) and caffeic acid 3-0-methyltransferase (COMT) genes were also rapidly activated, but at a slower initial rate. Transcription of chalcone 2'-O-methyltransferase (CHOMT), and 1,3-beta-D-glucanase genes was less rapid, with lag periods of 60 and 30 min post-elicitation, respectively. Treatment of cells with a PAL inhibitor L-alpha-aminooxy-beta-phenylpropionic acid (AOPP) resulted in increased transcription of PAL, CHS and CHR, but reduced transcription of CHOMT, indicating a role for phenylpropanoid products as both negative and positive regulators of gene expression within the phenylpropanoid pathway.
采用核转录延伸分析来研究在激发子处理的苜蓿（紫花苜蓿）细胞悬浮培养物中，编码异黄酮植保素生物合成及相关途径中酶的基因的相对转录速率。编码L-苯丙氨酸解氨酶（PAL）、查尔酮合酶（CHS）和查尔酮还原酶（CHR）的基因被最快速激活，在激发后10 - 20分钟内转录增加即可检测到。肉桂酸4-羟化酶（C4H）、查尔酮异构酶（CHI）、异黄酮还原酶（IFR）和咖啡酸3-O-甲基转移酶（COMT）基因也被快速激活，但初始速率较慢。查尔酮2'-O-甲基转移酶（CHOMT）和1,3-β-D-葡聚糖酶基因的转录较慢，激发后延迟期分别为60分钟和30分钟。用PAL抑制剂L-α-氨基氧基-β-苯丙酸（AOPP）处理细胞导致PAL、CHS和CHR的转录增加，但CHOMT的转录减少，表明苯丙烷类产物在苯丙烷途径内作为基因表达的负调控因子和正调控因子均发挥作用。
