Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, St. Lucia, Brisbane, Qld, Australia.
Plant Biotechnol J. 2012 Oct;10(8):995-1010. doi: 10.1111/j.1467-7652.2012.00729.x. Epub 2012 Aug 2.
All lateral organ development in plants, such as nodulation in legumes, requires the temporal and spatial regulation of genes and gene networks. A total mRNA profiling approach using RNA-seq to target the specific soybean (Glycine max) root tissues responding to compatible rhizobia [i.e. the Zone Of Nodulation (ZON)] revealed a large number of novel, often transient, mRNA changes occurring during the early stages of nodulation. Focusing on the ZON enabled us to discard the majority of root tissues and their developmentally diverse gene transcripts, thereby highlighting the lowly and transiently expressed nodulation-specific genes. It also enabled us to concentrate on a precise moment in early nodule development at each sampling time. We focused on discovering genes regulated specifically by the Bradyrhizobium-produced Nod factor signal, by inoculating roots with either a competent wild-type or incompetent mutant (nodC(-) ) strain of Bradyrhizobium japonicum. Collectively, 2915 genes were identified as being differentially expressed, including many known soybean nodulation genes. A number of unknown nodulation gene candidates and soybean orthologues of nodulation genes previously reported in other legume species were also identified. The differential expression of several candidates was confirmed and further characterized via inoculation time-course studies and qRT-PCR. The expression of many genes, including an endo-1,4-β-glucanase, a cytochrome P450 and a TIR-LRR-NBS receptor kinase, was transient, peaking quickly during the initiation of nodule ontogeny. Additional genes were found to be down-regulated. Significantly, a set of differentially regulated genes acting in the gibberellic acid (GA) biosynthesis pathway was discovered, suggesting a novel role of GAs in nodulation.
植物所有侧生器官的发育，如豆科植物的结瘤，都需要基因和基因网络的时空调节。使用 RNA-seq 靶向特定大豆（Glycine max）根组织（即结瘤区（ZON））来进行总 mRNA 谱分析，以响应相容的根瘤菌，揭示了大量在结瘤早期发生的新的、通常是短暂的 mRNA 变化。专注于 ZON 使我们能够丢弃大多数根组织及其发育上多样化的基因转录本，从而突出低表达和短暂表达的结瘤特异性基因。它还使我们能够专注于每个采样时间早期结瘤发育的精确时刻。我们专注于发现受 Bradyrhizobium 产生的 Nod 因子信号特异性调节的基因，通过用有竞争力的野生型或无能力突变体（nodC(-)）菌株接种根，接种根。共鉴定出 2915 个差异表达的基因，包括许多已知的大豆结瘤基因。还鉴定出一些未知的结瘤基因候选基因和以前在其他豆科植物中报道的结瘤基因的大豆同源物。通过接种时间进程研究和 qRT-PCR 进一步证实和表征了几个候选基因的差异表达。许多基因的表达，包括内切 1,4-β-葡聚糖酶、细胞色素 P450 和 TIR-LRR-NBS 受体激酶，是短暂的，在结瘤原基发生的起始阶段迅速达到峰值。还发现了一些基因下调。值得注意的是，发现了一组在赤霉素（GA）生物合成途径中作用的差异调节基因，表明 GA 在结瘤中具有新的作用。
