Kansal Shivani, Mutum Roseeta Devi, Balyan Sonia C, Arora Mukesh K, Singh Ashok Kumar, Mathur Saloni, Raghuvanshi Saurabh
Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Marg, New Delhi, 110021, India.
Planta. 2015 Jun;241(6):1543-59. doi: 10.1007/s00425-015-2279-3. Epub 2015 Mar 26.
Drought-tolerant rice variety, Nagina 22 (N22), has a unique spikelet miRNome during anthesis stage drought as well as transition from heading to anthesis. Molecular characterization of genetic diversity of rice is essential to understand the evolution and molecular basis of various agronomically important traits such as drought tolerance. miRNAs play an important role in regulating plant development as well as stress response such as drought. In this study, we characterized the yet unexplored dynamics of the spikelet miRNA population during developmental transition from 'heading' to 'anthesis' as well as anthesis stage drought stress in a drought-tolerant indica rice variety, N22. A significant proportion of miRNA population (~20 %) in N22 spikelets is modulated during transition from heading to anthesis indicating a unique miRNome at anthesis, a developmental stage highly sensitive to stress (drought/heat). Based on the analysis of degradome data, majority of differentially regulated miRNAs appear to regulate transcription factors, some of which are implicated in regulation of development and fertilization. Similarly, drought during anthesis leads to a global change in miRNA expression pattern including those which regulate ROS homeostasis. It was possible to identify several miRNAs that were not reported to be drought responsive in earlier studies. Interestingly, a significant proportion of the drought-regulated miRNAs co-localize within QTLs related to drought tolerance and associated traits. Comparison of the expression profiles between N22 and Pusa Basmati 1 (drought sensitive) identified miRNAs with variety-specific expression patterns during phase transition (miR164, miR396, miR812, and miR1881) as well as drought stress (miR1881) indicating an evolution of a distinct and variety-specific regulatory mechanism. The promoters of these miRNAs contain LREs (light-responsive elements) and are induced by dark treatment. It was also possible to identify 4 novel miRNAs including an intronic miRNA that was conserved in both rice varieties.
耐旱水稻品种Nagina 22（N22）在花期干旱以及从抽穗到花期的过渡阶段具有独特的小穗miRNA组。对水稻遗传多样性进行分子特征分析对于理解各种重要农艺性状（如耐旱性）的进化和分子基础至关重要。miRNA在调节植物发育以及干旱等胁迫反应中发挥着重要作用。在本研究中，我们对耐旱籼稻品种N22在从“抽穗”到“花期”的发育转变以及花期干旱胁迫期间小穗miRNA群体尚未被探索的动态变化进行了特征分析。在N22小穗中，约20%的miRNA群体在从抽穗到花期的过渡阶段受到调控，这表明在花期这个对胁迫（干旱/高温）高度敏感的发育阶段存在独特的miRNA组。基于降解组数据分析，大多数差异调节的miRNA似乎调控转录因子，其中一些转录因子与发育和受精的调控有关。同样，花期干旱会导致miRNA表达模式的全局变化，包括那些调节活性氧稳态的miRNA。有可能鉴定出一些在早期研究中未被报道对干旱有响应的miRNA。有趣的是，相当一部分受干旱调控的miRNA共定位于与耐旱性及相关性状相关的QTL内。比较N22和Pusa Basmati 1（干旱敏感型）之间的表达谱，鉴定出在阶段转变（miR164、miR396、miR812和miR1881）以及干旱胁迫（miR1881）期间具有品种特异性表达模式的miRNA，这表明存在一种独特的、品种特异性的调控机制。这些miRNA的启动子包含光响应元件（LRE），并受黑暗处理诱导。还可能鉴定出4个新的miRNA，包括一个在两个水稻品种中都保守的内含子miRNA。
