Plant Cell Environ. | 茎源miR2111调控豆科植物根和根瘤的发育
豆科植物通过结节自动调节（AON）控制其结节数量。 根瘤菌感染会刺激根源性CLE肽激素的产生，这些激素会转移到植物地上部分中，从而作为新的调节信号。
我们用大豆证明了这种芽来源的信号是miR2111，它通过韧皮部转运到根部，它的靶标是结瘤的负调控因子Too Much Love（TML）的转录本。根瘤菌诱导的CLE肽抑制了miR2111的表达，导致TML在根中积累，并随后抑制了结节器官的发生。
通过叶柄饲喂合成的成熟miR2111可以增加了每株植物的根瘤数。
同样，通过过表达来提高miR2111的可用性可促进结瘤，而TML的靶模拟对野生型植物的根瘤发育产生相反的影响，并减轻了AON缺陷突变体的超结瘤和发育不良的根生长表型。
此外，在非结瘤野生型植物中，miR2111的异位表达显着增强了侧根的出苗，同时降低了侧根的长度和平均根的直径。
相反，组成性表达靶模拟物构建体的毛状根表现出降低的侧根密度。
总体而言，这些发现表明，miR2111既是积极调控根瘤发育的关键地上部分到地下因子，又可以塑造根系体系结构。
Legumes control their nodule numbers through the Autoregulation Of Nodulation (AON). Rhizobia infection stimulates the production of root‐derived CLE peptide hormones that are translocated to the shoot where they regulate a new signal. We used soybean to demonstrate that this shoot‐derived signal is miR2111, which is transported via phloem to the root where it targets transcripts of Too Much Love (TML), a negative regulator of nodulation. Shoot perception of rhizobia‐induced CLE peptides suppresses miR2111 expression, resulting in TML accumulation in roots and subsequent inhibition of nodule organogenesis. Feeding synthetic mature miR2111 via the petiole increased nodule numbers per plant. Likewise, elevating miR2111 availability by over‐expression promoted nodulation, while target mimicry of TML induced the opposite effect on nodule development in wild‐type plants and alleviated the supernodulating and stunted root growth phenotypes of AON‐defective mutants. Additionally, in non‐nodulating wild‐type plants, ectopic expression of miR2111 significantly enhanced lateral root emergence with a decrease in lateral root length and average root diameter. In contrast, hairy roots constitutively expressing the target mimic construct exhibited reduced lateral root density. Overall, these findings demonstrate that miR2111 is both the critical shoot‐to‐root factor that positively regulates root nodule development, and also acts to shape root system architecture.
https://onlinelibrary.wiley.com/journal/13653040
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