Frenzel André, Manthey Katja, Perlick Andreas M, Meyer Folker, Pühler Alfred, Küster Helge, Krajinski Franziska
Lehrgebiet Molekulargenetik, Universität Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany.
Mol Plant Microbe Interact. 2005 Aug;18(8):771-82. doi: 10.1094/MPMI-18-0771.
The large majority of plants are capable of undergoing a tight symbiosis with arbuscular mycorrhizal (AM) fungi. During this symbiosis, highly specialized new structures called arbuscules are formed within the host cells, indicating that, during interaction with AM fungi, plants express AM-specific genetic programs. Despite increasing efforts, the number of genes known to be induced in the AM symbiosis is still low. In order to identify novel AM-induced genes which have not been listed before, 5,646 expressed sequence tags (ESTs) were generated from two Medicago truncatula cDNA libraries: a random cDNA library (MtAmp) and a suppression subtractive hybridization (SSH) library (MtGim), the latter being designed to enhance the cloning of mycorrhiza-upregulated genes. In silico expression analysis was applied to identify those tentative consensus sequences (TCs) of The Institute for Genomic Research M. truncatula gene index (MtGI) that are composed exclusively of ESTs deriving from the MtGim or MtAmp library, but not from any other cDNA library of the MtGI. This search revealed 115 MtAmp- or MTGim-specific TCs. For the majority of these TCs with sequence similarities to plant genes, the AM-specific expression was verified by quantitative reverse-transcription polymerase chain reaction. Annotation of the novel genes induced in mycorrhizal roots suggested their involvement in different transport as well as signaling processes and revealed a novel family of AM-specific lectin genes. The expression of reporter gene fusions in transgenic roots revealed an arbuscule-related expression of two members of the lectin gene family, indicating a role for AM-specific lectins during arbuscule formation or functioning.
绝大多数植物能够与丛枝菌根（AM）真菌形成紧密的共生关系。在这种共生过程中，宿主细胞内会形成一种名为丛枝的高度特化新结构，这表明在与AM真菌相互作用时，植物会表达AM特异性遗传程序。尽管人们付出了越来越多的努力，但已知在AM共生中被诱导的基因数量仍然很少。为了鉴定以前未列出的新的AM诱导基因，从两个蒺藜苜蓿cDNA文库中生成了5646个表达序列标签（EST）：一个随机cDNA文库（MtAmp）和一个抑制性消减杂交（SSH）文库（MtGim），后者旨在增强菌根上调基因的克隆。通过电子表达分析来鉴定那些仅由来自MtGim或MtAmp文库的EST组成，而不是来自MtGI的任何其他cDNA文库的蒺藜苜蓿基因索引（MtGI）的初步一致性序列（TC）。该搜索揭示了115个MtAmp或MTGim特异性TC。对于这些与植物基因具有序列相似性的大多数TC，通过定量逆转录聚合酶链反应验证了其AM特异性表达。对菌根根中诱导的新基因的注释表明它们参与了不同的转运以及信号传导过程，并揭示了一个新的AM特异性凝集素基因家族。报告基因融合体在转基因根中的表达揭示了凝集素基因家族两个成员与丛枝相关的表达，表明AM特异性凝集素在丛枝形成或功能发挥过程中发挥作用。
