A Legume TOR Protein Kinase Regulates Rhizobium Symbiosis and Is Essential for Infection and Nodule Development
A Legume TOR Protein Kinase Regulates Rhizobium Symbiosis and Is Essential for Infection and Nodule Development
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DOI：
10.1104/pp.16.00844
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发表时间：
2016-11-01
期刊：
影响因子：
7.4
通讯作者：
Lara, Miguel
中科院分区：
文献类型：
--
作者：
Nanjareddy, Kalpana;Blanco, Lourdes;Lara, Miguel
雷帕霉素（TOR）蛋白激酶的靶点调节酵母、动物和植物的代谢、生长和寿命，与营养状态和环境条件协调。TOR功能的营养依赖性使得该激酶成为涉及营养获取的共生协会的假定调节剂。然而，职权范围在这些进程中的作用仍有待了解。在这里，我们揭示了TOR在菜豆（菜豆）-热带根瘤菌（根瘤菌）共生相互作用中的作用。TOR在所有测试的菜豆组织中表达，在根分生组织和衰老的根瘤中具有较高的转录水平。我们发现TOR启动子沿着进行性感染线和在成熟结节的感染细胞中表达。使用RNA干扰（RNAi）的TOR的转录后基因沉默表明，该基因参与侧根伸长和根细胞组织，也改变根毛的密度，大小和数量。TOR转录物的抑制也影响了感染线的进展和相关的皮质细胞分裂，导致结节数量急剧减少。TOR-RNAi导致活性氧积累减少，CyclinD 1和CyclinD 3表达改变，这是感染线进展和结节器官形成的关键因素。TOR调控的ATG基因在TOR-RNAi根中的增强表达表明TOR在识别根瘤菌作为共生体中起作用。总之，这些数据表明TOR在菜豆根瘤共生的建立中起着至关重要的作用。
The target of rapamycin (TOR) protein kinase regulates metabolism, growth, and life span in yeast, animals, and plants in coordination with nutrient status and environmental conditions. The nutrient-dependent nature of TOR functionality makes this kinase a putative regulator of symbiotic associations involving nutrient acquisition. However, TOR's role in these processes remains to be understood. Here, we uncovered the role of TOR during the bean (Phaseolus vulgaris)-Rhizobium tropici (Rhizobium) symbiotic interaction. TOR was expressed in all tested bean tissues, with higher transcript levels in the root meristems and senesced nodules. We showed TOR promoter expression along the progressing infection thread and in the infected cells of mature nodules. Posttranscriptional gene silencing of TOR using RNA interference (RNAi) showed that this gene is involved in lateral root elongation and root cell organization and also alters the density, size, and number of root hairs. The suppression of TOR transcripts also affected infection thread progression and associated cortical cell divisions, resulting in a drastic reduction of nodule numbers. TOR-RNAi resulted in reduced reactive oxygen species accumulation and altered CyclinD1 and CyclinD3 expression, which are crucial factors for infection thread progression and nodule organogenesis. Enhanced expression of TOR-regulated ATG genes in TOR-RNAi roots suggested that TOR plays a role in the recognition of Rhizobium as a symbiont. Together, these data suggest that TOR plays a vital role in the establishment of root nodule symbiosis in the common bean.