荒漠孑遗植物沙冬青属特异性miRNA的鉴定和功能研究

The tertiary relic genus Ammopiptanthus is the only genus with evergreen broadleaf habit and an endemic shrub genus in the desert and arid regions of Central-Asia. Plants in genus Ammopiptanthus have high level of tolerance to drought and low temperature stress, and some unique genes might exist in genomes of Ammopiptanthus species, which closely related to their biological characteristic, thus are regarded as an important resource plant for mining stress-tolerant genes. miRNAs play key roles in development and abiotic stress response in plant. Extensive studies have been conducted on conserved miRNAs, while less attention have been paid to the non-conserved lineage-specific miRNAs. We speculate that the non-conserved, genus-specific miRNA might contribute greatly to the unique biological characteristic of Ammopiptanthus species, including their extremely high level of tolerance to abiotic stress. The applicants have systematically identified the miRNAs in A. mongolicus and found several Ammopiptanthus genus-specific miRNAs targeting genes involved in important biological process. Based on these results, the applicants plan to identify the miRNAs and their targets in A. nanus systematically, and then identify the genus-specific miRNAs in the two Ammopiptanthus species and analyze the spatio-temporal expression pattern of these miRNAs and their targets. Finally, the functions of these genus-specific miRNA will be further investigated by using plant transgenic technology. The study will provide important data for elucidation of the molecular mechanism underlying the biological characteristic of genus Ammopiptanthus, advance our understanding on the biological functions of non-conserved miRNAs.

孑遗植物沙冬青属是中亚荒漠唯一和特有的常绿阔叶灌木，具有耐旱、耐寒等特性，是植物耐逆基因挖掘的理想材料。沙冬青属基因组中可能存在一些独特的基因资源，与沙冬青属植物的生物学特征密切相关。miRNA在植物发育和环境胁迫应答中发挥重要的调控作用，目前对保守的miRNA研究较多，对非保守的种系特异性miRNA研究很少。推测沙冬青属特有的非保守RNA——沙冬青属特异miRNA可能与其耐逆性等生物学特征有关。本研究在系统鉴定蒙古沙冬青miRNA，发现部分沙冬青属特异miRNA靶向重要基因的基础上，拟系统鉴定新疆沙冬青miRNA及其靶基因；确定沙冬青属特异性miRNA，分析这些miRNA和靶基因的时空与诱导表达模式；并通过转基因研究揭示沙冬青属特异miRNA的生物学功能。本研究将为阐明荒漠孑遗植物沙冬青属的生物学特征的分子基础提供miRNA水平的证据，促进对于植物非保守miRNA的生物学功能的理解。

荒漠孑遗植物沙冬青属仅有新疆沙冬青和蒙古沙冬青2个种，是中亚荒漠唯一和特有的常绿阔叶灌木，具有耐旱、耐寒等特性，其基因组中可能存在一些独特的基因资源，决定了沙冬青属植物的生物学特征，因此，沙冬青属是植物耐逆基因挖掘的理想材料。miRNA在植物发育和逆境胁迫应答中发挥重要的调控作用。本项目获得了高质量的染色体水平的新疆沙冬青和蒙古沙冬青基因组，系统鉴定了新疆沙冬青miRNA及其靶基因和低温应答miRNA。综合对miRNA基因家族的分析研究，鉴定了沙冬青中存在的种系特异性miRNA及其靶基因。选择了miR1507、miR1515和miR4415进行低温应答及靶基因功能研究，可分别通过形成 miR1507-(NB-ARC-TIR)-(NBS-LRR)/ miR1507-(NB-ARC)-CSDP1、miR1515-RNA16S-DCL2、miR4415-(L-AO)-ASA/DHA调控模块参与新疆沙冬青低温胁迫应答。本项目的研究结果可为深入理解小RNA在参与沙冬青逆境适应调控中的作用奠定了基础，构建的基因组数据库为小RNA鉴定、比较基因组分析等研究提供了有价值的数据支撑，研究结果为了解豆科植物的系统发育关系及植物物种对于青藏高原隆升的演化响应都具有重要意义。