Bai Bin, Bian Hongwu, Zeng Zhanghui, Hou Ning, Shi Bo, Wang Junhui, Zhu Muyuan, Han Ning
Laboratory of Plant-Animal Interactions, College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, China.
Yunnan Forestry Technological College, Kunming, China.
Plant Cell Physiol. 2017 Mar 1;58(3):426-439. doi: 10.1093/pcp/pcw211.
High-throughput small RNA sequencing has identified several potential aluminum (Al)-responsive microRNAs (miRNAs); however, their regulatory role remains unknown. Here, we identified two miR393 family members in barley, and confirmed two target genes-HvTIR1 and HvAFB-through a modified form of 5'-RACE (rapid amplification of cDNA ends) as well as degradome data analysis. Furthermore, we investigated the biological function of the miR393/target module in root development and its Al stress response. The investigation showed that miR393 affected root growth and adventitious root number by altering auxin sensitivity. Al3+ exposure suppressed miR393 expression in root apex, while overexpression of miR393 counteracted Al-induced inhibition of root elongation and alleviated reactive oxygen species (ROS)-induced cell death. Target mimic (MIM393)-mediated inhibition of miR393's activity enhanced root sensitivity to Al toxicity. We also confirmed that auxin enhanced Al-induced root growth inhibition in barley via application of exogenous 1-naphthaleneacetic acid (NAA), and the expression of auxin-responsive genes in the root apex was induced upon Al treatment. Overexpression of miR393 attenuated the effect of exogenous NAA on Al-induced root growth inhibition, and down-regulated the expression of auxin-responsive genes under Al stress, implying that miR393 regulates root sensitivity to Al through the alteration of auxin signaling output in barley. Therefore, these data indicate that miR393 acts as an integrator of environmental cues in auxin signaling, and suggest a new strategy to improve plant resistance to Al toxicity.
高通量小RNA测序已鉴定出几种潜在的铝（Al）响应性微小RNA（miRNA）；然而，它们的调控作用仍不清楚。在此，我们在大麦中鉴定出两个miR393家族成员，并通过改进的5'-RACE（cDNA末端快速扩增）形式以及降解组数据分析确认了两个靶基因——HvTIR1和HvAFB。此外，我们研究了miR393/靶标模块在根系发育及其铝胁迫响应中的生物学功能。研究表明，miR393通过改变生长素敏感性影响根生长和不定根数。Al3+暴露抑制了根尖中miR393的表达，而miR393的过表达抵消了铝诱导的根伸长抑制，并减轻了活性氧（ROS）诱导的细胞死亡。靶标模拟物（MIM393）介导的miR393活性抑制增强了根对铝毒性的敏感性。我们还通过施用外源1-萘乙酸（NAA）证实了生长素增强了铝诱导的大麦根生长抑制，并且在铝处理后根尖中生长素响应基因的表达被诱导。miR393的过表达减弱了外源NAA对铝诱导的根生长抑制的影响，并下调了铝胁迫下生长素响应基因的表达，这意味着miR393通过改变大麦中生长素信号输出调节根对铝的敏感性。因此，这些数据表明miR393在生长素信号传导中作为环境信号的整合者，并提出了一种提高植物对铝毒性抗性的新策略。
