Root growth is modulated by different factors, including phytohormones, transcription factors, and microRNAs (miRNAs). MicroRNA156 and its targets, the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes, define an age-dependent pathway that controls several developmental processes, including lateral root emergence. However, it remains unclear whether miR156-regulated SPLs control root meristem activity and root-derived de novo shoot regeneration. Here, we show that MIR156 and SPL genes have opposing expression patterns during the progression of primary root (PR) growth in Arabidopsis, suggesting that age cues may modulate root development. Plants with high miR156 levels display reduced meristem size, resulting in shorter primary root (PRs). Conversely, plants with reduced miR156 levels show higher meristem activity. Importantly, loss of function of SPL10 decreases meristem activity, while SPL10 de-repression increases it. Meristem activity is regulated by SPL10 probably through the reduction of cytokinin responses, via the modulation of type-B ARABIDOPSIS RESPONSE REGULATOR1(ARR1) expression. We also show that SPL10 de-repression in the PRs abolishes de novo shoot regenerative capacity by attenuating cytokinin responses. Our results reveal a cooperative regulation of root meristem activity and root-derived de novo shoot regeneration by integrating age cues with cytokinin responses via miR156-targeted SPL10.

中文翻译：

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靶向miR156的SPL10通过细胞分裂素反应控制拟南芥的根分生组织活性和根衍生的新芽再生。

根的生长受不同因素的调节，包括植物激素，转录因子和microRNA（miRNA）。MicroRNA156及其靶标SQUAMOSA PROPERTER BINDING PROTEIN LIKE（SPL）基因，定义了一种年龄依赖性途径，该途径可控制多个发育过程，包括侧根出现。但是，尚不清楚miR156调节的SPL是否控制根分生组织活性和根衍生的新芽再生。在这里，我们显示，MIR156和SPL基因在拟南芥的初生根（PR）生长过程中具有相反的表达模式，表明年龄提示可能会调节根的发育。miR156水平高的植物显示出分生组织的大小减少，从而导致较短的初生根（PRs）。相反，miR156水平降低的植物表现出更高的分生组织活性。重要的，SPL10的功能丧失会降低分生组织活性，而SPL10的去阻遏作用会增强分生组织的活性。SPL10可能通过减少细胞分裂素反应，通过调节B型ARABIDOPSIS RESPONSE REGULATOR1（ARR1）表达来调节分生组织的活性。我们还显示，PRS中的SPL10抑制可通过减弱细胞分裂素应答来消除新芽再生能力。我们的研究结果表明，通过将年龄线索与针对miR156的SPL10的细胞分裂素反应相结合，可以对根分生组织活性和根衍生的新芽再生进行协同调控。我们还显示，PRS中的SPL10抑制可通过减弱细胞分裂素应答来消除新芽再生能力。我们的研究结果表明，通过将年龄线索与针对miR156的SPL10的细胞分裂素反应相结合，可以对根分生组织活性和根衍生的新芽再生进行协同调控。我们还显示，PRS中的SPL10抑制可通过减弱细胞分裂素应答来消除新芽再生能力。我们的研究结果表明，通过将年龄线索与针对miR156的SPL10的细胞分裂素反应相结合，可以对根分生组织活性和根衍生的新芽再生进行协同调控。