SVP-like调控鸢尾季节性生长暂停与生态休眠诱导的分子机制

Iris spp. are one of the most widely used perennial flowers in gardens and landscaping, and most of them have long dormancy periods in winter. Notably, there are two closely related iris species with obvious differences in the time of seasonal growth cessation and dormancy induction in the Yangtze River Delta, which performs deciduous and evergreen, respectively. Previous studies have confirmed that there is only eco-dormancy in these two iris species. To date, the dormancy regulation mechanism of monocotyledonous plants, especially the one with only eco-dormancy is still unclear. SVP-like genes were significantly differentially expressed and exhibited different expression patterns in these two iris species by transcriptome analysis during dormancy induction. Therefore, this study intends to determine the type, sequence characteristics, subcellular localization and transcriptional activation activity by the full-length cloning and comparative analysis of the SVP-like genes in Iris tectorum and I. japonica. The expression patterns of SVP-like genes will be analyzed under natural and artificial dormancy induction conditions in these two species. Phenotypic analysis and functional identification will be performed on transgenic and wild type irises. The downstream target genes will be screened by DEGs getting from RNA-Seq on transgenic and wild type irises, and the information of the binding domain of SVP-like will be used for further screening. Also, SVP-like promoter sequence will be cloned and upstream transcription factors will be analyzed by key cis-acting elements. Finally, the binding of the transcription factor to the promoter of the target gene of interest will be verified using the Y1H and LUC assays. So far, we could explore the molecular mechanism of iris seasonal growth cessation and ecological dormancy induction regulated by SVP-like. This study not only enriches the existing research theory of plant dormancy but also lays a foundation for revealing the regulation of evergreen and deciduous traits in perennial flowers.

鸢尾是园林应用最广泛的宿根花卉之一，大多冬季休眠期长。但江南地区分布有秋季生长暂停早晚存在显著差异的鸢尾近缘种，分别表现为落叶和常绿，后证实两种鸢尾仅有生态休眠。迄今尚无针对单子叶植物、特别是仅有生态休眠类型的休眠调控机理研究。SVP-like在休眠差异种质鸢尾和蝴蝶花不同阶段显著差异表达且模式不同。因此本研究拟对二者SVP-like全长克隆、特征和表达分析；获得二者转基因植株，分析休眠诱导前后其与野生型表型相关生理和基因变化并利用RNA-Seq获得DEG；根据SVP-like结合序列筛选DEG获得靶基因；克隆SVP-like启动子，通过关键顺式作用元件分析上游转录因子；利用Y1H和LUC assay验证转录因子与目的靶基因启动子结合作用。综上，探讨SVP-like调控鸢尾季节性生长暂停和生态休眠诱导分子机制。该研究不仅能丰富现有休眠研究理论，也为揭示宿根花卉常绿与落叶性状调控奠定基础。

越冬休眠是植物应对冬季不良环境的最关键策略，以鸢尾属植物为代表的部分多年生单子叶植物具有特殊越冬休眠特性，即不需低温积累打破休眠，因此，揭示其越冬休眠机制具有重要的生物学意义和经济价值。本项目围绕SVP-like基因在鸢尾季节性生长暂停与生态休眠诱导中的功能和转录调控机制开展研究。根据转录组信息和同源性分析，克隆获得3个SVP-like基因全长cDNA序列，证实其为核定位转录因子，并且表达模式与越冬休眠诱导过程密切相关。基于转录组数据挖掘和基因沉默技术，证实SVP-like基因可正调控鸢尾生态休眠诱导。其次，克隆获得SVP-like基因启动子序列并通过关键顺式作用元件分析预测其上游转录因子。结合酵母单杂交一对一验证和LUC试验，证实MYC2在休眠诱导过程中负调控SVP-like表达，而CBF则正调控SVP-like表达，这表明了茉莉酸和低温信号可能是调控鸢尾生态休眠诱导的关键因子。最后，在下游基因筛选中发现NCED，LOX1等激素合成相关基因可能受SVP-like调控，这表明SVP-like作为转录因子，可能通过调控脱落酸和茉莉酸合成相关基因的表达影响其内源激素水平，进而调控鸢尾生态休眠诱导。这些研究结果表明，SVP-like作为休眠调控网络的核心，其表达变化可能受到茉莉酸等激素的精密调控来影响鸢尾生态休眠诱导过程。以上结果既丰富了SVP-like的休眠调控网络，也为茉莉酸在多年生单子叶植物生态休眠过程中发挥调控作用提供了理论依据。此外，为通过基因工程改良植物越冬休眠特性奠定了基础。