Krause A, Lan V T, Broughton W J
L.B.M.P.S., Université de Genève, Chambésy, Switzerland.
Mol Plant Microbe Interact. 1997 Apr;10(3):388-93. doi: 10.1094/MPMI.1997.10.3.388.
Chalcone synthase (CHS) of Vigna unguiculata is encoded by a gene family that is abundantly transcribed in leaves and nodules. Inoculation with Rhizobium sp. NGR234, which nodulates V. unguiculata, or with NGR delta nodABC, a mutant deficient in Nod factor production, induced rapid accumulation of CHS mRNAs in roots and root hairs. As both Nod+ and Nod- bacteria provoke responses, induction of CHS gene expression may involve symbiotic or defense responses. Four days after inoculation with the wild-type Rhizobium sp., the transcript levels increased in roots but decreased in root hairs. Use of a region unique to the 5' end of a specific CHS gene (VuCHS1) showed that increases of transcript levels in root hairs 24 h after inoculation with both rhizobia were specific to this gene. Transcripts of this gene in roots were only detectable 4 days after treatment with NGR234. It is possible therefore that accumulation of VuCHS1 follows the infection pathway of rhizobia entering legume roots. Purified Nod factors induced accumulation of transcripts, showing that they might be part of the signal transduction pathway leading to CHS expression.
豇豆的查尔酮合酶（CHS）由一个基因家族编码，该基因家族在叶片和根瘤中大量转录。用能使豇豆结瘤的根瘤菌NGR234或用缺乏结瘤因子产生的突变体NGR delta nodABC接种，可诱导根和根毛中CHS mRNA的快速积累。由于结瘤型和非结瘤型细菌都会引发反应，CHS基因表达的诱导可能涉及共生或防御反应。用野生型根瘤菌接种四天后，根中的转录水平升高，但根毛中的转录水平降低。使用特定CHS基因（VuCHS1）5'端独特的区域表明，接种两种根瘤菌24小时后根毛中转录水平的增加是该基因特有的。该基因在根中的转录本仅在NGR234处理四天后才可检测到。因此，VuCHS1的积累可能遵循根瘤菌进入豆科植物根的感染途径。纯化的结瘤因子诱导转录本积累，表明它们可能是导致CHS表达的信号转导途径的一部分。
