One of the oldest crops, foxtail millet (Setaria italica), is regarded as a model plant for studying drought tolerance owing to its short life-cycle and small genome size. The miRNA member miR394 plays multifaceted roles in plants. In this study, we identified the Sit-miR394 target gene SiFBP6 using 5′ RLM-RACE (RNA ligase mediated rapid amplification of 5′ cDNA ends). An expression analysis in different tissues showed that Sit-miR394 was highly expressed in leaves and had a lower relative expression in roots, while the target gene SiFBP6 exhibited the opposite expression pattern, being strongly expressed in roots and relatively lowly expressed in leaves. Furthermore, Sit-miR394 was upregulated in foxtail millet under drought-stress conditions and by exogenous methyl jasmonate, ethephon, salicylic acid and abscisic acid treatments. The overexpression of Sit-miR394 in transgenic Arabidopsis thaliana increased its tolerance to drought stress. The germination rates and root lengths were significantly greater compared with the wild-type line, which suggested that Sit-miR394 plays a positive role in responding to drought conditions. Moreover, a transcription analysis indicated that the overexpression of Sit-miR394 affected the expression of a set of stress-related genes, thereby conferring an increased abiotic or biotic stress tolerance to transgenic Arabidopsis. Thus, Sit-miR394 functions in the positive modulation of abiotic or biotic stress tolerance and has potential applications in molecular breeding to enhance stress tolerance in crops.

谷子（Setaria italica）是最古老的作物之一，由于其生命周期短且基因组较小，因此被认为是研究耐旱性的典范植物。miRNA成员miR394在植物中起多方面的作用。在这项研究中，我们使用5'RLM -RACE（RNA连接酶介导的5'cDNA末端的快速扩增）鉴定了Sit-miR394目标基因SiFBP6。在不同组织中的表达分析表明，Sit-miR394在叶片中高表达，而在根中相对表达较低，而靶基因SiFBP6表现出相反的表达模式，在根部强烈表达而在叶中表达相对较低。此外，Sit-miR394在干旱胁迫条件下的谷子小米中以及通过外源茉莉酸甲酯，乙烯利，水杨酸和脱落酸处理而上调。Sit-miR394在转基因拟南芥中的过表达增加了其对干旱胁迫的耐受性。与野生型相比，发芽率和根长明显更大，这表明Sit-miR394在应对干旱条件中发挥了积极作用。此外，转录分析表明Sit-miR394的过表达影响了一组应激相关基因的表达，从而赋予转基因拟南芥非生物或生物胁迫耐受性增加。因此，Sit-miR394在非生物或生物胁迫耐受性的正调控中起作用，并且在分子育种中具有潜在的应用，以增强农作物的胁迫耐受性。