Semenova Maria G, Petina Alekandra N, Fedorova Elena E
Timiryazev Institute of Plant Physiology, Russian Academy of Science, 127276 Moscow, Russia.
Int J Mol Sci. 2024 Mar 2;25(5):2918. doi: 10.3390/ijms25052918.
The interaction of plants and soil bacteria rhizobia leads to the formation of root nodule symbiosis. The intracellular form of rhizobia, the symbiosomes, are able to perform the nitrogen fixation by converting atmospheric dinitrogen into ammonia, which is available for plants. The symbiosis involves the resource sharing between two partners, but this exchange does not include equivalence, which can lead to resource scarcity and stress responses of one of the partners. In this review, we analyze the possible involvement of the autophagy pathway in the process of the maintenance of the nitrogen-fixing bacteria intracellular colony and the changes in the endomembrane system of the host cell. According to in silico expression analysis, ATG genes of all groups were expressed in the root nodule, and the expression was developmental zone dependent. The analysis of expression of genes involved in the response to carbon or nitrogen deficiency has shown a suboptimal access to sugars and nitrogen in the nodule tissue. The upregulation of several ER stress genes was also detected. Hence, the root nodule cells are under heavy bacterial infection, carbon deprivation, and insufficient nitrogen supply, making nodule cells prone to autophagy. We speculate that the membrane formation around the intracellular rhizobia may be quite similar to the phagophore formation, and the induction of autophagy and ER stress are essential to the success of this process.
植物与土壤细菌根瘤菌的相互作用导致根瘤共生的形成。根瘤菌的细胞内形式，即共生体，能够通过将大气中的双氮转化为植物可利用的氨来进行固氮。这种共生涉及两个伙伴之间的资源共享，但这种交换并不对等，这可能导致其中一个伙伴出现资源短缺和应激反应。在这篇综述中，我们分析了自噬途径在维持固氮细菌细胞内群体过程以及宿主细胞内膜系统变化中可能发挥的作用。根据电子表达分析，所有组的ATG基因在根瘤中均有表达，且表达具有发育区依赖性。对参与碳或氮缺乏反应的基因表达分析表明，根瘤组织中糖类和氮的获取并不理想。还检测到几个内质网应激基因的上调。因此，根瘤细胞受到严重的细菌感染、碳剥夺和氮供应不足的影响，使根瘤细胞易于发生自噬。我们推测，细胞内根瘤菌周围的膜形成可能与吞噬泡的形成非常相似，自噬和内质网应激的诱导对这一过程的成功至关重要。
