细胞分裂素诱导檀香醇生物合成的分子调控机制研究

Santalum album is an evergreen tree in Santalaceae. Sandalwood oil extracted from heartwood is very expensive and its value is three times to gold, in which major constituents are santalol ( > 80%), known as “Liquid Gold”. S. album starts to form heartwood about six to ten years after planting at normal growth condition and gain economic benefits after planting thirty to forty years. Therefore, it is of important sigificance to induct heartwood formation of S. album. To date, little is known about the regulation mechanism of santalol biosynthesis. .In our preliminary study, we found that exogenous cytokinin could remarkablely induce heartwood formation in S. album. Transcription factors, MYB, bHLH or WRKY may play important roles in regulating expression of SaSSY, SaCYP736A167 and SaCYP76F39V1 that are key genes involved in santalol biosynthesis. This project proposal that developed based on our preliminary results aims to study: (1) transcriptional regulatory networks of santalol biosynthesis, (2) the mechanisms of sandalol biosynthesis induced by cytokinin; (3) molecular regulation mechanism of MYB, bHLH or WRKY on expression of SaSSY, SaCYP736A167 and SaCYP76F39V1 based on plant physiology and biochemistry, molecular biology, combined with transcriptomic methods..The result of this project will help to understand molecular regualtion mechanism of santalol bisynthesis, but also has important significance in developing a practical method or technology to induce heartwood formation and enhance economic benefits in sandalwood industry.

檀香（Santalum album L.）为檀香科常绿乔木，从其心材中提取的檀香精油价值是黄金的三倍，素有“液体黄金”之称，其主要成分为檀香醇，约占80%以上。在自然生长条件下檀香需6-8年才开始形成心材，30-40年获经济收益，因此，开展促成檀香心材形成具有重要意义。但目前对檀香醇生物合成的调控机制认识仍不清楚。我们的前期研究表明：外源细胞分裂素能显著促成檀香心材形成；MYB，bHLH或WRKY类转录因子可能在檀香醇生物合成关键基因SaSSY、SaCYP736A167和SaCYP76F39V1的表达中具重要的调控作用。本项目拟应用生理生化、转录组学、分子生物学等技术研究：檀香醇生物合成的转录调控网络；细胞分裂素诱导檀香醇合成的作用机制；转录因子调控檀香醇生物合成的分子机制。研究结果为檀香的育种改良提供分子生物学基础，为实现人工促成檀香心材形成和提高经济效益具有重要应用价值。

本项目研究了细胞分裂素（6-BA）调控檀香心材形成的作用机制，结果表明：施加6-BA对内源激素水平的变化影响较大，推测一种/多种激素水平的升高激活了檀香茎形成层分化与心材的形成以及精油的合成和累积；结合代谢物分析、转录网络调控和关键基因的表达阐明了6-BA诱导檀香精油生物合成的作用机制。本研究研发了一种切实可行的高效人工促成檀香心材形成和精油合成的技术。该技术通过调控心材形成导致精油累积打破常规用MeJA诱导植物萜烯化合物生物合成的技术手段，相信在未来，人工促成檀香提早结香新技术将得以应用。鉴定到SaMYB89和几个SabHLHs对檀香精油合成关键酶基因SaSSY和SaCYP736A167可能具有调控作用，进一步通过双荧光素酶实验、酵母单杂交实验、EMSA实验验证了转录因子对檀香醇合成的分子调控机制。本项目研究结果为檀香的育种改良提供理论基础，为研发切实可行的诱导檀香精油生物合成的方法提供理论依据，以实现人工促成檀香心材形成、缩短檀香人工林的种植周期及提高经济效益具有重要的实际应用价值。