Legumes develop root nodules in which bacteria fix nitrogen for plants. The phytohormones auxin and cytokinin regulate nodule organogenesis by recruiting various genes to effect symbiosis. Moreover, these genes are regulated by the action of microRNAs also. To understand the complex regulatory network involving miRNAs in response to phytohormones and rhizobial interactions in chickpea roots, a miRNA expression profiling was performed. Indole acetic acid and 6-benzylaminopurine at concentrations of 0.1, 1 and 10 µM were used for auxin and cytokinin exogenous treatment and Mesorhizobium ciceri to study rhizobial interaction with chickpea root. Expression profiling of a set of 11 miRNAs was performed. Further, the targets of the candidate miRNAs were identified, followed by functional annotation. This analysis revealed that cat-miR160, cat-miR164, cat-miR396 and cat-miR398 were responsive to auxin and cytokinin. cat-miR319 was found to be only auxin responsive and is known to regulate auxin signalling by targeting TEOSINTE BRANCHED/CYCLOIDEA/PCF (TCP) which interacts with auxin inducible genes. Further, cytokinin elicited a response at very low concentration of 0.1 µM, and most of the miRNAs investigated were responsive to cytokinin. Interactome analysis revealed that cat-miR164 and cat-miR168 work in conjunction to regulate auxin signalling. Interestingly, cat-miR169 and cat-miR482 were low expressing during auxin treatment and M. ciceri infection but their expression spiked during cytokinin treatment, indicating a cytokinin mediated mode of action. The miRNA expression profiling in response to phytohormones and rhizobia and the reported function of their target genes suggested a crosstalk among the phytohormonal responses during chickpea nodulation.

中文翻译：

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miRNA的表达谱表明鹰嘴豆的植物激素反应与根瘤菌感染之间存在串扰

豆类产生根瘤，细菌在其中固氮为植物。植物激素生长素和细胞分裂素通过募集各种影响共生的基因来调节结节器官的发生。此外，这些基因也受microRNA的作用调节。为了了解鹰嘴豆根中涉及植物激素和根瘤菌相互作用的涉及miRNA的复杂调控网络，进行了miRNA表达谱分析。浓度分别为0.1、1和10 µM的吲哚乙酸和6-苄基氨基嘌呤用于生长素和细胞分裂素的外源治疗和中生根瘤菌研究与鹰嘴豆根的根瘤菌相互作用。进行了一组11种miRNA的表达谱分析。此外，鉴定了候选miRNA的靶标，随后进行功能注释。该分析表明，cat-miR160，cat-miR164，cat-miR396和cat-miR398对生长素和细胞分裂素有反应。发现cat-miR319仅对植物生长素有反应，并且已知它通过靶向与植物生长素诱导基因相互作用的TEOSINTE BRANCHED / CYCLOIDEA / PCF（TCP）来调节植物生长素信号传导。此外，细胞分裂素在0.1 µM的极低浓度下即可引起反应，并且所研究的大多数miRNA对细胞分裂素均具有反应。相互作用分析表明，cat-miR164和cat-miR168协同调节生长素信号传导。有趣的是，在生长素治疗期间cat-miR169和cat-miR482的表达较低，西西里支原体感染，但是在细胞分裂素治疗期间它们的表达达到峰值，表明细胞分裂素介导的作用方式。响应植物激素和根瘤菌的miRNA表达谱及其报道的靶基因功能表明鹰嘴豆结节过程中植物激素反应之间存在串扰。