Genome-wide identification of nodule-specific transcripts in the model legume Medicago truncatula
Genome-wide identification of nodule-specific transcripts in the model legume Medicago truncatula
复制标题
DOI：
10.1104/pp.006833
复制
发表时间：
2002-10-01
期刊：
影响因子：
7.4
通讯作者：
Vance, CP
中科院分区：
文献类型：
--
作者：
Fedorova, M;van de Mortel, J;Vance, CP
蒺藜苜蓿表达序列标签（EST）数据库（Gene Index）包含来自30个cDNA文库的超过140，000个序列。该资源提供了识别以前未表征的基因并评估其在计算机中表达的频率和组织特异性的可能性。因为M.与拟南芥不同，蒺藜形成共生根瘤，这是研究豆科植物根瘤发育和功能特异性基因的一个特别重要的方法。我们的分析揭示了340个假定的基因产物或暂定的共有序列（TC），仅在根瘤中表达。这些TC由2至379个EST代表。在这些TC中，3%似乎编码新的蛋白质，57%编码与GenBank登录的弱相似性的蛋白质，40%编码与已知蛋白质强相似性的蛋白质。根据预测的蛋白质产物功能，将结节特异性TC分为9类。除了以前的特点nodulins，其他的例子高度丰富的结节特异性转录包括plantacyanin，凝集素，胚胎特异性蛋白质，嘌呤通透酶。六个结节特异性TC编码钙调素样蛋白，其具有独特的可裂解转运序列，可能将蛋白质靶向至类细菌周围空间。令人惊讶的是，114个结节特异性TC编码小Cys簇蛋白与可切割的转运肽。为了确定计算机分析的有效性，通过宏阵列和RNA印迹杂交分析了91个推定的结节特异性TC的表达。结节增强表达实验证实的TC组成的五个或更多的EST，而那些TC含有较少的EST的结果是可变的。
The Medicago truncatula expressed sequence tag (EST) database (Gene Index) contains over 140,000 sequences from 30 cDNA libraries. This resource offers the possibility of identifying previously uncharacterized genes and assessing the frequency and tissue specificity of their expression in silico. Because M. truncatula forms symbiotic root nodules, unlike Arabidopsis, this is a particularly important approach in investigating genes specific to nodule development and function in legumes. Our analyses have revealed 340 putative gene products or tentative consensus sequences (TCs), expressed solely in root nodules. These TCs were represented by two to 379 ESTs. Of these TCs, 3% appear to encode novel proteins, 57% encode proteins with a weak similarity to the GenBank accessions, and 40% encode proteins with strong similarity to the known proteins. Nodule-specific TCs were grouped into nine categories based on the predicted function of their protein products. Besides previously characterized nodulins, other examples of highly abundant nodule-specific transcripts include plantacyanin, agglutinin, embryo-specific protein, and purine permease. Six nodule-specific TCs encode calmodulin-like proteins that possess a unique cleavable transit sequence potentially targeting the protein into the peribacteroid space. Surprisingly, 114 nodule-specific TCs encode small Cys cluster proteins with a cleavable transit peptide. To determine the validity of the in silico analysis, expression of 91 putative nodule-specific TCs was analyzed by macroarray and RNA-blot hybridizations. Nodule-enhanced expression was confirmed experimentally for the TCs composed of five or more ESTs, whereas the results for those TCs containing fewer ESTs were variable.