Centre for Carbohydrate Recognition and Signalling, MBI, Aarhus University, Aarhus C, Denmark.
PLoS One. 2009 Aug 7;4(8):e6556. doi: 10.1371/journal.pone.0006556.
Genetic analyses of plant symbiotic mutants has led to the identification of key genes involved in Rhizobium-legume communication as well as in development and function of nitrogen fixing root nodules. However, the impact of these genes in coordinating the transcriptional programs of nodule development has only been studied in limited and isolated studies. Here, we present an integrated genome-wide analysis of transcriptome landscapes in Lotus japonicus wild-type and symbiotic mutant plants. Encompassing five different organs, five stages of the sequentially developed determinate Lotus root nodules, and eight mutants impaired at different stages of the symbiotic interaction, our data set integrates an unprecedented combination of organ- or tissue-specific profiles with mutant transcript profiles. In total, 38 different conditions sampled under the same well-defined growth regimes were included. This comprehensive analysis unravelled new and unexpected patterns of transcriptional regulation during symbiosis and organ development. Contrary to expectations, none of the previously characterized nodulins were among the 37 genes specifically expressed in nodules. Another surprise was the extensive transcriptional response in whole root compared to the susceptible root zone where the cellular response is most pronounced. A large number of transcripts predicted to encode transcriptional regulators, receptors and proteins involved in signal transduction, as well as many genes with unknown function, were found to be regulated during nodule organogenesis and rhizobial infection. Combining wild type and mutant profiles of these transcripts demonstrates the activation of a complex genetic program that delineates symbiotic nitrogen fixation. The complete data set was organized into an indexed expression directory that is accessible from a resource database, and here we present selected examples of biological questions that can be addressed with this comprehensive and powerful gene expression data set.
对植物共生突变体的遗传分析导致了参与根瘤菌-豆科植物通讯以及固氮根瘤发育和功能的关键基因的鉴定。然而，这些基因在协调根瘤发育的转录程序中的作用仅在有限和孤立的研究中进行了研究。在这里，我们展示了对野生型和共生突变体豌豆植物的全基因组转录组图谱的综合分析。涵盖五个不同的器官，五个连续发育的定态豌豆根瘤的阶段，以及八个在共生相互作用的不同阶段受损的突变体，我们的数据集中整合了前所未有的器官或组织特异性图谱与突变体转录图谱的组合。总共包含在相同明确定义的生长条件下采样的 38 种不同条件。这种综合分析揭示了共生和器官发育过程中全新的和意想不到的转录调控模式。与预期相反，在根瘤中特异性表达的 37 个基因中没有一个是以前表征的结瘤素。另一个惊喜是整个根中的广泛转录反应与易感根区相比，易感根区中的细胞反应最为明显。大量预测编码转录调节剂、受体和参与信号转导的蛋白质的转录本，以及许多具有未知功能的基因，在根瘤器官发生和根瘤菌感染期间被发现受到调节。将这些转录本的野生型和突变型图谱结合起来，证明了激活了一个复杂的遗传程序，该程序划定了共生固氮作用。完整的数据集被组织到一个可从资源数据库访问的索引表达目录中，在这里我们展示了可以使用这个综合和强大的基因表达数据集解决的一些生物学问题的示例。
