低温诱导烟草早花的分子机理研究

Low temperature (cold stress) can induce early flowering in plants; affecting plant growth, development, and geographical distribution; result in the death of plants and reduction of agricultural production. Currently, the studies of cold-regulated plant flowering time are mainly carried out in the model plant Arabidopsis thaliana. However, few studies on the molecular mechanisms of cold-induced early flowering have been found in the thermophilic plants, such as cultivated tobacco (Nicotiana tabacum). Studying the molecular mechanisms of cold-induced early flowering in tobacco can enrich the existing plant flowering induction pathways, and is of great significance to understand the molecular and genetic mechanisms of flowering induction in higher plants as well. In this project, a stable and repeatable experimental method for cold-induced early flowering in tobacco has been established. The transcriptome and phtyohormone (GAs, IAA, JA, JA-Ile) data from tobacco leaves during cold stress treatment was also obtained. Our results showed that the peak of GA1 contents appears earlier, and the transcript levels of some MADS-box gene have been changed. This project will characterize the functions of candidate MADS-box genes, and GA during cold-induced early flowering in tobacco. The results of project will provide not only the knowledge of molecular mechanisms of cold-induced early flowering, but also the basis of regulating flower formation at molecular level in tobacco.

低温胁迫促进植物早花、影响植物的生长发育及地理分布，严重时会导致植物的死亡，造成农业减产危害。目前，多利用喜凉的模式植物拟南芥开展低温胁迫影响植物开花时间的研究，而在喜温植物如栽培烟草中还未见低温胁迫如何使开花时间提前的分子机理研究。对低温胁迫诱导烟草早花的分子机制研究，可丰富现有植物开花诱导途径，对解析高等植物成花诱导调控的分子遗传机制具有重要意义。项目组建立了能稳定重复的低温诱导烟草早花实验方法，获得了低温诱导早花的转录组及GAs、IAA、JA、JA-Ile等激素含量数据。前期结果表明低温诱导使GA1峰值提前，部分MADS-box基因转录水平发生变化。本项目拟在低温胁迫诱导烟草早花的生理过程中，验证MADS-box候选基因的功能，明确GA在这一过程中的作用，为解析低温胁迫诱导烟草早花的分子机理及从分子水平调控烟草成花诱导奠定基础。

烟草是重要的经济作物，能够极大地改善边远地区农民收入。烟草会受到低温胁迫的影响，低温胁迫会导致烟草提早开花，这极大地影响烟草的产量及品质。本项目聚焦低温胁迫可诱导烟草早花的生理现象，通过分析MADS-box候选基因的功能，明确赤霉素在这种生理过程中的作用，解析低温胁迫诱导烟草早花的分子机理，为从分子水平调控烟草开花奠定基础。本项目获得以下研究结果。.1）本研究表明低温胁迫使烟草中赤霉素含量增加，外施赤霉素可使烟草提早开花，而外施赤霉素抑制剂PCA可使烟草延迟开花。同时发现赤霉素处理可上调烟草部分内源MADS基因的表达。这表明赤霉素可能是低温诱导烟草提早开花的关键原因。.2）我们通过转基因检测了关键基因对烟草开花的影响。NtDELLA是赤霉素调控路径的核心基因，过表达NtDELLA基因会抑制赤霉素路径会使烟草延迟开花；抑制该基因表达会促进赤霉素路径烟草会提早开花。抑制烟草NtDELLA基因表达时NtAGL3（MADS基因）表达上调。过表达NtAGL3基因能够使烟草提早开花。NtAGL3表达数据结合转基因数据揭示赤霉素可能通过NtDELLA基因调控NtAGL3的表达进而调控烟草开花的时期。研究表明在烟草中抑制另一个MADS基因NtSOC1表达也会使烟草在低温胁迫条件下延迟开花10天左右。在烟草中抑制NtMYB15的表达能够使烟草在低温胁迫条件下延迟开花5天左右。.3）此外，我们分析烟草不同组织器官的芯片数据，发现NtbHLH137基因与NtAGL3基因在表达上呈现相反的趋势，在花中NtAGL3的表达高而NtbHLH137基因的表达低，在其它器官呈现NtbHLH137基因的表达高而NtAGL3基因的表达低。转基因表明过表达NtbHLH137基因能够使烟草显著晚花，而抑制该基因的表达能够使烟草提早开花。栽培烟草具有开花周期长的缺点，因此本项目探索采用VIGS技术在本氏烟中筛选与烟草开花时期相关的基因，经过筛选最终确定8个基因参与调控烟草开花时期。本项目为最终培育出抗低温胁迫早花的烟草品种奠定基础。.本项目发表SCI文章4篇，获授权发明专利3项，两人晋升副研究员，一人入选云南省两类人才计划。