Transcriptomics of Actinorhizal Symbioses Reveals Homologs of the Whole Common Symbiotic Signaling Cascade1[W]
Transcriptomics of Actinorhizal Symbioses Reveals Homologs of the Whole Common Symbiotic Signaling Cascade1[W]
复制标题
放线菌共生体的转录组学揭示了整个常见共生信号级联的同源物1[W]
作者：
V. Hocher;N. Alloisio;F. Auguy;P. Fournier;Patrick Doumas;P. Pujić;H. Gherbi;Clothilde Queiroux;C. da Silva;P. Wincker;P. Normand;D. Bogusz
利用比较转录组学方法研究了两种放线菌共生植物木麻黄和赤杨与固氮放线菌Frankia接触后的共生过程。在这两个物种的根和3周龄的结节中回收了大约14，000个unigenes。设计了一个转录组阵列来监测根和结节之间表达水平的变化，从而能够识别上调和下调的基因以及根和结节特异性基因。通过定量聚合酶链反应证实了象征共生的几个基因的表达水平。正如预期的那样，一些与碳和氮交换，防御病原体，或胁迫抗性相关的基因受到强烈调控。此外，同源基因的共同和根瘤特异性信号转导途径已知的豆科植物中确定的两个放线菌共生植物。宿主植物信号通路的保守性在其细菌共生体Frankia的基因组中缺乏典型的nod基因的情况下更加令人惊讶。从这些研究中出现的进化模式加强了假设的一个共同的遗传祖先的Fabid（Eurosid I）的sperulating分支的遗传倾向sperulation。
Comparative transcriptomics of two actinorhizal symbiotic plants, Casuarina glauca and Alnus glutinosa, was used to gain insight into their symbiotic programs triggered following contact with the nitrogen-fixing actinobacterium Frankia. Approximately 14,000 unigenes were recovered in roots and 3-week-old nodules of each of the two species. A transcriptomic array was designed to monitor changes in expression levels between roots and nodules, enabling the identification of up- and down-regulated genes as well as root- and nodule-specific genes. The expression levels of several genes emblematic of symbiosis were confirmed by quantitative polymerase chain reaction. As expected, several genes related to carbon and nitrogen exchange, defense against pathogens, or stress resistance were strongly regulated. Furthermore, homolog genes of the common and nodule-specific signaling pathways known in legumes were identified in the two actinorhizal symbiotic plants. The conservation of the host plant signaling pathway is all the more surprising in light of the lack of canonical nod genes in the genomes of its bacterial symbiont, Frankia. The evolutionary pattern emerging from these studies reinforces the hypothesis of a common genetic ancestor of the Fabid (Eurosid I) nodulating clade with a genetic predisposition for nodulation.