Yang Qian, Trinh Hoat Xuan, Imai Satoshi, Ishihara Atsushi, Zhang Liqun, Nakayashiki Hitoshi, Tosa Yukio, Mayama Shigeyuki
Laboratory of Plant Pathology, Graduate School of Science and Technology, Kobe University, Kobe 657-8501, Japan.
Mol Plant Microbe Interact. 2004 Jan;17(1):81-9. doi: 10.1094/MPMI.2004.17.1.81.
Two oat genes encoding hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyltransferase (HHT) and S-adenosyl-L-methionine:trans-caffeoyl-CoA 3-O-methyltransferase (CCoAOMT), both of which are possibly involved in the biosynthesis of oat avenanthramide phytoalexins, were cloned and their expression profiles in response to biological stress were studied. Four distinct cDNAs of oat HHT (AsHHT1-4) were isolated with the degenerative polymerase chain reaction method. The enzymatic activity of AsHHT1 expressed in E. coli was found using hydroxyanthranilate and hydroxycinnamoyl-CoAs as cosubstrates. Cloned oat CCoAOMT (AsCCoAOMT) encoded a polypeptide of 130 amino acid residues with 77.7 to 80.8% identities to the CCoAOMT sequences from other plant species. The accumulation of AsHHT1 and AsCCoAOMT transcripts increased concomitantly with phytoalexin accumulation by the treatment of victorin, a specific elicitor in oat lines carrying the Pc-2/Vb gene. Pharmacological approaches indicated the involvement of Ca2+, NO, and protein kinases in the signaling pathways of AsHHT1 and AsCCoAOMT mRNA induction. When oat leaves were inoculated with Puccinia coronata, the mRNA expression of AsHHT1 and AsCCOAOMT increased in both incompatible and compatible interactions but more rapidly in incompatible interaction. Interestingly, however, significant phytoalexin accumulation was observed only in incompatible interaction during the experimental period, suggesting that phytoalexin accumulation may be inhibited in one or more posttranscriptional processes in the compatible interaction.
克隆了两个燕麦基因，它们分别编码羟基肉桂酰辅酶A：羟基邻氨基苯甲酸N - 羟基肉桂酰转移酶（HHT）和S - 腺苷 - L - 甲硫氨酸：反式咖啡酰辅酶A 3 - O - 甲基转移酶（CCoAOMT），这两种酶可能都参与燕麦抗毒素燕麦酰胺的生物合成，并研究了它们在生物胁迫下的表达谱。采用简并聚合酶链反应方法分离出4个不同的燕麦HHT cDNA（AsHHT1 - 4）。以羟基邻氨基苯甲酸和羟基肉桂酰辅酶A作为共底物，测定了在大肠杆菌中表达的AsHHT1的酶活性。克隆的燕麦CCoAOMT（AsCCoAOMT）编码一个由130个氨基酸残基组成的多肽，与其他植物物种的CCoAOMT序列具有77.7%至80.8%的同源性。通过用维克托菌素（一种携带Pc - 2/Vb基因的燕麦品系中的特异性激发子）处理，AsHHT1和AsCCoAOMT转录本的积累与植物抗毒素的积累同时增加。药理学方法表明，Ca2 +、NO和蛋白激酶参与了AsHHT1和AsCCoAOMT mRNA诱导的信号通路。当燕麦叶片接种冠锈菌时，AsHHT1和AsCCOAOMT的mRNA表达在不亲和和亲和互作中均增加，但在不亲和互作中增加得更快。然而，有趣的是，在实验期间仅在不亲和互作中观察到显著的植物抗毒素积累，这表明在亲和互作中，植物抗毒素的积累可能在一个或多个转录后过程中受到抑制。
