MicroRNAs (miRNAs) have been reported to be correlated with various stress responses in soybean, but only a few miRNAs have been demonstrated to respond to low phosphorus (LP) stress. To unravel the response mechanisms of miRNAs to low-P stress, the roots of two representative soybean genotypes with different P efficiency, Nannong94-156 (a LP-tolerant genotype) and Bogao (a LP-sensitive genotype), were used for the construction of RNA sequencing (RNA-seq) libraries under low/normal-P treatment by high-throughput sequencing. In total, 603 existing miRNAs and 1699 novel miRNAs belonging to 248 and 1582 families in all samples were identified, respectively. Among these miRNAs, 777 miRNAs were differentially expressed (DE) across different P levels and genotypes. Furthermore, putative targets of DE miRNAs were predicted, and these miRNAs mainly targeted ERF (ethylene responsive factor), auxin response factors (ARF), zinc finger protein, MYB, and NAC domain transcription factors. Gene ontology (GO) analysis showed that targets of DE miRNAs were significantly enriched in binding, metabolic processes, biological regulation, response to stress, and phosphorus metabolic processes. In addition, the expression profiles of chosen P-responsive miRNAs and target genes were validated by quantitative real-time PCR (qRT-PCR). Our study focused on genome-wide miRNA identification in two representative soybean genotypes under low-P stress. Overall, the DE miRNAs across different P levels and genotypes and their putative target genes will provide useful information for further study of miRNAs mediating low-P response and facilitate improvements in soybean breeding.

据报道，MicroRNA (miRNA) 与大豆的各种胁迫反应相关，但只有少数 miRNA 被证明能够响应低磷 (LP) 胁迫。为了揭示miRNA对低磷胁迫的响应机制，以具有不同磷效率的两个代表性大豆基因型Nannong94-156（耐LP基因型）和Bogao（LP敏感基因型）的根为基础构建通过高通量测序分析低/正常磷处理下的 RNA 测序 (RNA-seq) 文库。总共，在所有样本中鉴定出了 603 个现有 miRNA 和 1699 个新 miRNA，分别属于 248 个和 1582 个家族。在这些 miRNA 中，777 个 miRNA 在不同的 P 水平和基因型中存在差异表达 (DE)。此外，预测了DE miRNA的假定靶点，这些miRNA主要靶向ERF（乙烯反应因子）、生长素反应因子（ARF）、锌指蛋白、MYB和NAC域转录因子。基因本体（GO）分析表明，DE miRNA 的靶标在结合、代谢过程、生物调节、应激反应和磷代谢过程方面显着富集。此外，所选 P 响应 miRNA 和靶基因的表达谱通过定量实时 PCR (qRT-PCR) 进行了验证。我们的研究重点是低磷胁迫下两种代表性大豆基因型的全基因组 miRNA 鉴定。总体而言，不同磷水平和基因型的 DE miRNA 及其假定的靶基因将为进一步研究介导低磷响应的 miRNA 提供有用的信息，并促进大豆育种的改进。