ABA及其信号元件对姜花萜类花香物质的代谢调控

The flower fragrance is a very significant ornamental floral trait. Hedychium coronarium is important cut flower in South China market, which have rich floral fragrance. Abscisic acid (ABA) is one of the important plant hormones to regulate multiple physiological processes, but there is less report of its regulation on the biosynthesis of flower scent. Our initial research proved that exogenous ABA regulates the synthesis and release of ginger flower fragrance and the ABA content differ greatly among ginger specis with different fragrances. This project is to explore the molecular mechanism of ABA regulation on the biosynthesis and release of flower fragranct by using different fragrant ginger specis as research materials, in their different flowering process and treated with exogenous ABA and its inhibitor, through content analysis of various types of active and inactive ABA and floral composition and expression of terpene synthases, the physiological effects of ABA regulation on ginger flower fragrance synthesis and release will be acquired. Furtherly by analysis of transcriptome sequencing and expression profiling in different flowering periods the candidate regulatory genes in ABA signal conponents can be selected out. By petals viruse-induced gene silencing, sense transient expression and agrobacterium-mediated transformation methods the functions of these key candidate genes obtained will be identified. Through this research it is expected to get critical genes that regulate the synthesis of flower fragrance and new knowledge for regulatory networks of terpene metabolism, and supply new genes for genetic engineer technology to cultivate new varieties for improvement of flower fragrant trait in ornamental plant.

花香是花卉的重要观赏性状，姜花(Hedychium coronarium)是南方重要的香型切花。脱落酸（ABA）是重要的植物激素之一，调控植物许多生理过程，但在调控植物花香上鲜见报道。我们先期的研究已发现外源ABA对姜花花香物质代谢有较大的影响，不同花香味姜花品种释香过程中ABA含量差异显著。本项目以浓香、淡香和无香的姜花为材料，通过其不同开花进程和ABA及抑制剂处理，获得ABA含量变化以及花香成分和萜类花香合成酶关键基因TPS表达的变化信息，明确ABA对姜花花香物质合成和释放的生理作用并找出ABA信号元件中与萜类花香合成释放相关的候选基因，进行花瓣病毒瞬时沉默和正义瞬时表达及姜花中进行稳定遗传转化，研究其对姜花萜类花香合成物质和挥发的影响。通过项目的研究，可望获得调控姜花花香物质合成的关键基因，为萜类物质代谢调控网络通过新知识，并为利用基因工程技术创制香花新品种提供有效新基因。

花香是花卉的重要观赏性状，姜花（Hedychium coronarium）是南方重要的香型切花。脱落酸（ABA）是重要的植物激素，调控植物许多生理过程，但在调控植物花香上鲜见报道。课题组前期已发现外源ABA对姜花花香物质代谢有较大的影响，不同香味姜花品种释香过程中ABA含量差异显著。本项目进一步测定了姜花花朵从青蕾期至盛开后期6个时期的内源ABA含量，发现变化ABA含量与姜花花香释放趋势基本一致。基于基因组、转录组和qPCR分析鉴定了ABA信号核心传导通路三大基因家族（PP2C、SnRK、bZIP）中与花香释放规律一致的基因，通过启动子元件分析、酵母单杂交、双荧光素酶和凝胶阻滞分析实验（EMSA）发现HcbZIP80与HcbZIP114能转录激活多个花香关键合成酶基因，通过酵母双杂交、双分子荧光互补（Bi-FC）、免疫共沉淀（Co-IP）、GSTpull-down、Phos-tag SDS-PAGE磷酸化分析和双荧光素酶等实验证明HcbZIP80与HcMYC2-1在细胞核中互作，且外源ABA与JA分别能增强HcbZIP80与HcMYC2-1对HcTPS1基因启动子的转录活性，HcSnRK2.1/2.2蛋白激酶能够直接磷酸化HcbZIP80转录因子，并增强HcbZIP80对花香物质合成关键基因的转录激活效应。HcPP2C17/31能够抑制HcSnRK2.1对HcbZIP80的激活效应，而HcPYL能够解除或部分解除HcPP2C17/31的抑制作用。瞬时沉默HcbZIP80/114、HcSnRK2.1/2.2后姜花花瓣的花香释放显著下降，瞬时沉默HcPP2C17/31后姜花花瓣的花香释放显著上升。遗传转化实验表明HcBZIP80过表达烟草的盛开花朵的能释放单萜类挥发性化合物沉香醇，而对照野生型烟草盛开花朵中未检测到沉香醇的释放。这些调控姜花花香物质合成的关键因子的分子调控机理丰富了我们对植物花香代谢调控网络认识，并为利用基因工程技术创制香花新品种提供有效新基因。