Identification of Ice Plant (Mesembryanthemum crystallinum L.) MicroRNAs Using RNA-Seq and Their Putative Roles in High Salinity Responses in Seedlings.
Identification of Ice Plant (Mesembryanthemum crystallinum L.) MicroRNAs Using RNA-Seq and Their Putative Roles in High Salinity Responses in Seedlings.
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DOI：
10.3389/fpls.2016.01143
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发表时间：
2016
影响因子：
5.6
通讯作者：
Yen HE
中科院分区：
文献类型：
--
作者：
Chiang CP;Yim WC;Sun YH;Ohnishi M;Mimura T;Cushman JC;Yen HE
盐生植物晶体冰（Mesembryanthemum crystinum）是研究耐盐分子机制的一个有用模型。对冰植物的形态、生理、代谢和基因表达进行了研究，并通过大规模的基因表达谱分析勾勒出冰植物耐盐性的轮廓。在冰植物幼苗中观察到，随着盐度的突然增加，根系生长迅速。使用荧光染料检测Na+，我们发现冰植物的根通过分泌或在专门的细胞中储存Na+来响应Na+通量的增加。采用高通量测序技术鉴定了200 mM NaCl处理或不处理3 d龄幼苗的小RNA谱。共发现21个科的135个保守mirna。鉴定出19个保守的mcr- mirna和12个新的mcr- mirna的发夹前体。盐胁迫6 h后，大多数mcr- mirna的表达相对丰度降低，而其对应靶基因的表达相对丰度升高。同源靶基因参与了广泛的生物学过程：调节生长发育的转录因子，最保守的mcr-miRNA催化miRNA生物发生的酶，以及一些新型mcr-miRNA参与离子稳态和干旱胁迫反应的蛋白质。靶基因的功能分析表明，盐胁迫下根系的细胞过程，包括生长发育、代谢和离子运输活性可能会增强。盐胁迫后数小时内，11个保守mirna和2个新mirna的表达与预测靶标呈负相关。已知一些保守的mirna调节根伸长、根尖分生组织活性和侧根形成。根据miRNA和靶基因的表达模式，结合对Na+分布的观察，冰植物可能是利用Na+作为细胞扩张和保卫细胞开放的渗透剂来应对盐度升高。过量的Na+可能通过根表皮分泌，也可能储存在专门的叶表皮细胞中。这些反应在一定程度上受mirna介导的转录后水平调控。
The halophyte Mesembryanthemum crystallinum (common or crystalline ice plant) is a useful model for studying molecular mechanisms of salt tolerance. The morphology, physiology, metabolism, and gene expression of ice plant have been studied and large-scale analyses of gene expression profiling have drawn an outline of salt tolerance in ice plant. A rapid root growth to a sudden increase in salinity was observed in ice plant seedlings. Using a fluorescent dye to detect Na+, we found that ice plant roots respond to an increased flux of Na+ by either secreting or storing Na+ in specialized cells. High-throughput sequencing was used to identify small RNA profiles in 3-day-old seedlings treated with or without 200 mM NaCl. In total, 135 conserved miRNAs belonging to 21 families were found. The hairpin precursor of 19 conserved mcr-miRNAs and 12 novel mcr-miRNAs were identified. After 6 h of salt stress, the expression of most mcr-miRNAs showed decreased relative abundance, whereas the expression of their corresponding target genes showed increased mRNA relative abundance. The cognate target genes are involved in a broad range of biological processes: transcription factors that regulate growth and development, enzymes that catalyze miRNA biogenesis for the most conserved mcr-miRNA, and proteins that are involved in ion homeostasis and drought-stress responses for some novel mcr-miRNAs. Analyses of the functions of target genes revealed that cellular processes, including growth and development, metabolism, and ion transport activity are likely to be enhanced in roots under salt stress. The expression of eleven conserved miRNAs and two novel miRNAs were correlated reciprocally with predicted targets within hours after salt stress exposure. Several conserved miRNAs have been known to regulate root elongation, root apical meristem activity, and lateral root formation. Based upon the expression pattern of miRNA and target genes in combination with the observation of Na+ distribution, ice plant likely responds to increased salinity by using Na+ as an osmoticum for cell expansion and guard cell opening. Excessive Na+ could either be secreted through the root epidermis or stored in specialized leaf epidermal cells. These responses are regulated in part at the miRNA-mediated post-transcriptional level.