| Summary: | MicroRNAs (miRNAs) regulate plant growth and development and plant responses to biotic and abiotic stresses. Although extensive studies show that miR159 family members regulate leaf and flower development in <i>Arabidopsis thaliana</i>, the roles of miRNAs in soybean (<i>Glycine max</i>) are poorly understood. Here, we identified six <i>MIR159</i> genes in soybean, <i>MIR159a</i>–<i>MIR159f</i>, and investigate their expression patterns in plants under low-phosphorus (low-P), NaCl, or abscisic acid (ABA) treatments. In soybean leaves, <i>MIR159e</i> and <i>MIR159f</i> expression was induced by low-P treatment, while in roots, <i>MIR159b</i>, <i>MIR159c</i>, <i>MIR159e</i>, and <i>MIR159f</i> expression was upregulated. In flowers, low-P led to upregulation of <i>MIR159a</i>, <i>MIR159b</i>, <i>MIR159c</i>, and <i>MIR159f</i> but downregulation of <i>MIR159d</i> and <i>MIR159e</i>. In soybean nodules, <i>MIR159b</i> was upregulated but <i>MIR159a</i>, <i>MIR159c</i>, and <i>MIR159d</i> was downregulated under P deficiency. NaCl treatment induced <i>MIR159a</i>, <i>MIR159b</i>, <i>MIR159c</i>, and <i>MIR159e</i> expression in leaves and <i>MIR159a</i>–<i>MIR159f</i> expression in roots. ABA treatment upregulated <i>MIR159a</i>, <i>MIR159b</i>, and <i>MIR159c</i> but downregulated <i>MIR159d</i>, <i>MIR159e</i>, and <i>MIR159f</i> in leaves. These results suggest that miR159 family members function in plant abiotic stress responses. Moreover, total P content in leaves was significantly lower in plants overexpressing <i>MIR159e</i> than in the wild type, suggesting that miR159e may regulate P absorption and transport in soybean plants.
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