LACK OF SYMBIONT ACCOMMODATION controls intracellular symbiont accommodation in root nodule and arbuscular mycorrhizal symbiosis in Lotus japonicus
LACK OF SYMBIONT ACCOMMODATION controls intracellular symbiont accommodation in root nodule and arbuscular mycorrhizal symbiosis in Lotus japonicus
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DOI：
10.1371/journal.pgen.1007865
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发表时间：
2019-01
期刊：
影响因子：
4.5
通讯作者：
Takuya Suzaki;N. Takeda;Hanna Nishida;Motomi Hoshino;Momoyo Ito;Fumika Misawa;Y. Handa;K. Miura;M. Kawaguchi
中科院分区：
文献类型：
--
作者：
Takuya Suzaki;N. Takeda;Hanna Nishida;Motomi Hoshino;Momoyo Ito;Fumika Misawa;Y. Handa;K. Miura;M. Kawaguchi
固氮根瘤菌和丛枝菌根真菌（AMF）与植物根系形成共生体，这些共生体是通过精确调节宿主植物细胞内共生体的适应性而建立的。在模式豆科植物如百脉根和蒺藜苜蓿中，根瘤菌通过细胞内入侵系统进入根部，该系统依赖于根毛感染线（IT）的形成。虽然IT介导的细胞内根瘤菌入侵被认为是最进化衍生的入侵系统，但一些研究表明，当一些结瘤相关因子经过基因修饰时，基础细胞间入侵系统可以取代它。此外，细胞内根瘤菌的住宿建议有一个类似的机制AMF住宿。然而，我们对潜在的遗传机制的理解是不完整的。在这里，我们确定一个L。根瘤形成缺陷突变体，在缺乏共生适应（LAN）基因中发生突变，根毛IT形成强烈减少，但细胞间根瘤菌入侵最终导致功能性根瘤形成。LjLAN编码与拟南芥介体2/29/32同源的蛋白质，可能作为介体复合物的亚基，介体复合物是基因转录所需的多蛋白复合物。我们还表明，LjLAN的行为与信号通路，包括LjCYCLOPS平行。此外，lan突变大大降低了AMF的定殖水平。综上所述，我们的数据提供了一个新的因素，在根瘤和AM共生过程中的共生体适应过程中具有共同的作用。
Nitrogen-fixing rhizobia and arbuscular mycorrhizal fungi (AMF) form symbioses with plant roots and these are established by precise regulation of symbiont accommodation within host plant cells. In model legumes such as Lotus japonicus and Medicago truncatula, rhizobia enter into roots through an intracellular invasion system that depends on the formation of a root-hair infection thread (IT). While IT-mediated intracellular rhizobia invasion is thought to be the most evolutionarily derived invasion system, some studies have indicated that a basal intercellular invasion system can replace it when some nodulation-related factors are genetically modified. In addition, intracellular rhizobia accommodation is suggested to have a similar mechanism as AMF accommodation. Nevertheless, our understanding of the underlying genetic mechanisms is incomplete. Here we identify a L. japonicus nodulation-deficient mutant, with a mutation in the LACK OF SYMBIONT ACCOMMODATION (LAN) gene, in which root-hair IT formation is strongly reduced, but intercellular rhizobial invasion eventually results in functional nodule formation. LjLAN encodes a protein that is homologous to Arabidopsis MEDIATOR 2/29/32 possibly acting as a subunit of a Mediator complex, a multiprotein complex required for gene transcription. We also show that LjLAN acts in parallel with a signaling pathway including LjCYCLOPS. In addition, the lan mutation drastically reduces the colonization levels of AMF. Taken together, our data provide a new factor that has a common role in symbiont accommodation process during root nodule and AM symbiosis.