Unraveling new molecular players involved in the autoregulation of nodulation in Medicago truncatula
Unraveling new molecular players involved in the autoregulation of nodulation in Medicago truncatula
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DOI：
10.1093/jxb/ery465
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发表时间：
2019-02-01
影响因子：
6.9
通讯作者：
Goormachtig, Sofie
中科院分区：
文献类型：
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作者：
Gautrat, Pierre;Mortier, Virginie;Goormachtig, Sofie
与根瘤菌共生产生的豆科植物根瘤的数量受到植物的严格控制。CLAVATA 3/胚胎周围区（CLE）肽家族的某些成员，特别是蒺藜苜蓿中的MtCLE 12和MtCLE 13，在系统性自动调节结节形成（AON）途径中起作用，该途径负调节结节的数量。关于AON相关CLE肽下游的分子途径知之甚少。在这里，通过转录组分析，我们发现异位表达MtCLE 13的根只下调了有限数量的基因，包括三个下调的编码溶素基序受体样激酶的基因（LysM-RLKs），其中包括促凝因子（NF）受体NF感知基因（NFP）和两个上调基因MtTML 1和MtTML 2，编码太多的爱（TML）相关的Kelch重复包含F盒蛋白。所观察到的失调是特异性的结瘤相关的MtCLE基因的异位表达，并依赖于超数值结节（SUNN）AON RLK。此外，这两个MtTML基因的过表达和沉默表明，它们在根瘤数量的负调控中发挥作用。因此，所鉴定的MtTML基因是显示为AON途径中的中心的Lotus MtTML基因的功能对应物。此外，我们提出，LysM-RLK编码基因的一个子集的下调，其中是NFP，可能有助于进一步的限制，一旦第一个结节已经形成。
The number of legume root nodules resulting from a symbiosis with rhizobia is tightly controlled by the plant. Certain members of the CLAVATA3/Embryo Surrounding Region (CLE) peptide family, specifically MtCLE12 and MtCLE13 in Medicago truncatula, act in the systemic autoregulation of nodulation (AON) pathway that negatively regulates the number of nodules. Little is known about the molecular pathways that operate downstream of the AON-related CLE peptides. Here, by means of a transcriptome analysis, we show that roots ectopically expressing MtCLE13 deregulate only a limited number of genes, including three down-regulated genes encoding lysin motif receptor-like kinases (LysM-RLKs), among which are the nodulation factor (NF) receptor NF Perception gene (NFP) and two up-regulated genes, MtTML1 and MtTML2, encoding Too Much Love (TML)-related Kelch-repeat containing F-box proteins. The observed deregulation was specific for the ectopic expression of nodulation-related MtCLE genes and depended on the Super Numeric Nodules (SUNN) AON RLK. Moreover, overexpression and silencing of these two MtTML genes demonstrated that they play a role in the negative regulation of nodule numbers. Hence, the identified MtTML genes are the functional counterpart of the Lotus japonicus TML gene shown to be central in the AON pathway. Additionally, we propose that the down-regulation of a subset of LysM-RLK-encoding genes, among which is NFP, might contribute to the restriction of further nodulation once the first nodules have been formed.