Wulf Anne, Manthey Katja, Doll Jasmin, Perlick Andreas M, Linke Burkhard, Bekel Thomas, Meyer Folker, Franken Philipp, Küster Helge, Krajinski Franziska
Department of Molecular Genetics, University Hannover, Herrenhaeuser Str. 2, 30419 Hannover, Germany.
Mol Plant Microbe Interact. 2003 Apr;16(4):306-14. doi: 10.1094/MPMI.2003.16.4.306.
Significant changes in root morphology and physiology during arbuscular mycorrhiza (AM) development are likely to be controlled by specific gene expression pattern in the host plant. Until now, little was known about transcriptional changes which occur AM-exclusively; that is, they do not occur during other root-microbe associations, nor are they induced by improved phosphate nutrition. In order to identify such AM-exclusive gene inductions of Medicago truncatula, we used a pool of different RNA samples as subtractor population in a suppressive subtractive hybridization (SSH) experiment. This approach resulted in the identification of a number of new AM-regulated genes. None of these genes were expressed in nonmycorrhiza roots or leaves. Electronic data obtained by comparison of the cDNA sequences to expressed sequence tag (EST) sequences from a wide range of cDNA libraries in the M. truncatula EST database (Gene Index, MtGI) support the mycorrhiza specificity of the corresponding genes, because sequences in the MtGI that were found to match the identified SSH-cDNA sequences originated exclusively from AM cDNA libraries. The promoter of one of those genes, MtGst1, showing similarities to plant glutathione-S-transferase (GST) encoding genes, was cloned and used in reporter gene studies. In contrast to studies with the potato GST gene PRP, MtGst 1 promoter activity was detected in all zones of the root cortex colonized by Glomus intraradices, but nowhere else.
丛枝菌根（AM）发育过程中根系形态和生理的显著变化可能受宿主植物特定基因表达模式的控制。到目前为止，关于仅在AM过程中发生的转录变化知之甚少；也就是说，这些变化在其他根-微生物互作过程中不会发生，也不会因改善磷营养而诱导产生。为了鉴定蒺藜苜蓿中这种仅在AM过程中被诱导的基因，我们在抑制性消减杂交（SSH）实验中使用了一组不同的RNA样本作为消减群体。这种方法鉴定出了许多新的受AM调控的基因。这些基因在非菌根化的根或叶中均未表达。通过将cDNA序列与蒺藜苜蓿EST数据库（基因索引，MtGI）中来自广泛cDNA文库的表达序列标签（EST）序列进行比较获得的电子数据支持了相应基因的菌根特异性，因为在MtGI中发现与鉴定出的SSH-cDNA序列匹配的序列仅来自AM cDNA文库。其中一个基因MtGst1的启动子与植物谷胱甘肽-S-转移酶（GST）编码基因具有相似性，已被克隆并用于报告基因研究。与马铃薯GST基因PRP的研究不同，在被根内球囊霉定殖的根皮层的所有区域都检测到了MtGst 1启动子活性，但在其他地方均未检测到。
