The CYCLOPS Response Element in the NIN Promoter Is Important but Not Essential for Infection Thread Formation During Lotus japonicus-Rhizobia Symbiosis
The CYCLOPS Response Element in the NIN Promoter Is Important but Not Essential for Infection Thread Formation During Lotus japonicus-Rhizobia Symbiosis
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DOI：
10.1094/mpmi-10-21-0252-r
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发表时间：
2022-08-01
影响因子：
3.5
通讯作者：
Takeda, Naoya
中科院分区：
文献类型：
--
作者：
Akamatsu, Akira;Nagae, Miwa;Takeda, Naoya
豆科植物-根瘤菌共生关系的建立，称为根瘤共生关系（RNS），需要在分子水平上进行复杂的相互作用。已知来源于宿主植物的转录因子NIN对RNS至关重要，其调节相关过程，如根毛形态的改变、侵染丝的形成和细胞分裂。这强调了NIN表达的精确时空调控对于RNS建立的重要性;然而，NIN启动子序列在这一过程中的详细作用仍不清楚。daphne突变体是一个在NIN起始密码子上游7 kb处含有染色体易位的等位基因，它不形成结节，但形成侵染丝，表明NIN起始密码子上游7 kb内的区域在侵染丝形成过程中参与NIN的表达。CYCLOPS与NIN启动子中的CYCLOPS反应元件（CYC-RE）结合，并且剑水蚤突变体在感染线形成方面有缺陷。在这里，我们使用NIN启动子的各种截短形式对nin突变体进行了互补分析，发现CYC-RE对于感染丝的形成很重要。此外，通过CRISPR/Cas9技术产生的CYC-RE缺失突变体显示出感染线形成的显著减少，表明CYC-RE对于在该过程中微调NIN表达很重要。然而，事实上，感染线的形成是不完全废除CYC-RE缺失突变体表明，顺式和反式因子以外的CYCLOPS和CYC-RE可能协同调节NIN的表达诱导感染线的形成。
The establishment of the legume-rhizobia symbiosis, termed the root-nodule symbiosis (RNS), requires elaborate interactions at the molecular level. The host plant-derived transcription factor NODULE INCEPTION (NIN) is known to be crucial for RNS, regulating associated processes such as alteration of root hair morphology, infection thread formation, and cell division dur-ing nodulation. This emphasizes the importance of the precise spatiotemporal regulation of NIN expression for the establish-ment of RNS; however, the detailed role of NIN promoter se-quences in this process remains unclear. The daphne mutant, a nin mutant allele containing a chromosomal translocation ap-proximately 7 kb upstream of the start codon, does not form nodules but does form infection threads, indicating that the re-gion within 7 kb of the NIN start codon contributes to NIN ex-pression during infection thread formation. CYCLOPS binds to a CYCLOPS response element (CYC-RE) in the NIN promoter, and cyclops mutants are defective in infection thread formation. Here, we performed complementation analysis in nin mutants, using various truncated forms of the NIN promoter, and found that the CYC-RE is important for infection thread formation. Additionally, the CYC-RE deletion mutant, generated through CRISPR/Cas9 technology, displayed a significant reduction in infection thread formation, indicating that the CYC-RE is im-portant for the fine-tuning of NIN expression during this pro-cess. However, the fact that infection thread formation is not completely abolished in the CYC-RE deletion mutant suggests that cis and trans factors other than CYCLOPS and the CYC-RE may cooperatively regulate NIN expression for the induction of infection thread formation.