Identification and Characterization of Terpene Synthase Genes Accounting for the Volatile Terpene Emissions in Flowers of Freesia hybrida

First author: Fengzhan Gao; Affiliations: Northeast Normal University (东北师范大学): Changchun, China

Corresponding author: Xiang Gao (高翔)

The origin of flower scents (气味) is a crucial event in biological evolution, which provides olfactory (嗅觉的) signals to attract pollinators. In this study, bioinformatic, metabolomics, biochemical and molecular methodologies were integrated to investigate the candidate genes involved in the biosynthesis of volatile components (VOCs; 挥发性成分) in two cultivars of Freesia hybrida(小苍兰), Red River®and Ambiance, which released different categories of compounds. We found that terpene synthase (TPS) genes were the pivotal genes determining spatiotemporal (时空的) release of the VOCs in both cultivars. Eight FhTPS genes were isolated and six were found to be functional: FhTPS1 was a single product enzyme catalyzing the formation of linalool (芳樟醇), whereas the other four FhTPS proteins were multi-product enzymes, in which FhTPS4, FhTPS6 and FhTPS7 could recognize GPP and FPP simultaneously. In brief, FhTPS enzymatic products closely matched the volatile terpenes emitted (放出) from flowers, and significant correlations were found between VOCs release and FhTPS gene expression. Based on these results, graphical models were proposed to summarize the biosynthesis of Freesia floral volatile terpenes. The characterization of FhTPS genes paves the way to decipher their roles in speciation and fitness of the Freesia species, and this knowledge could also be used to introduce or enhance scent in other plants.

植物花的气味是生物氧化过程中的一个至关重要的事件，其提供了嗅觉信号以吸引授粉者。本文整合了生物信息学、代谢组学、生物化学以及分子试验等方法研究了参与两种释放不同化合物的小苍兰栽培品种（Red River和Ambiance）中挥发性成分VOC的生物合成。作者发现萜类合酶TPS基因是这两个栽培种中决定VOC时空释放的关键调控基因。作者分离出了8个FhTPS基因，其中6个具有功能。FhTPS1催化反应，参与芳樟醇的形成，另外4个FhTPS蛋白参与多个酶促反应，其中FhTPS4、FhTPS6和FhTPS7能够同时识别GPP和FPP。此外，FhTPS的酶促产物十分匹配花的挥发性萜类物质，且VOC的释放与FhTPS基因的表达显著相关。基于这些结果，作者总结并构建了小苍兰挥发性萜类生物合成的示图。本文关于FhTPS基因的功能鉴定为进一步阐述其在小苍兰属物种形成及适应性方面的作用提供了基础，同时也可被用作其它植物增强花气味的参考。

通讯：高翔 (http://js.nenu.edu.cn/teacher/index.php?zgh=2010900062)

研究方向：1、解析观赏花卉香雪兰花朵多种重要农艺性状的转录调控网络，建立香雪兰瞬时及稳定遗传转化体系；2、揭示MBW复合物中MYB转录因子在被子植物进化过程中的进化机制；3、筛选控制大豆和番茄异黄酮、花色苷和原花青素等次生代谢物质合成的MYB和MADS-box等转录因子基因，解析它们参与的转录调控网络；4、探究花色和花香等花朵性状影响植物传粉者选择行为的分子机制，揭示花色和花香性状的生态和进化意义。

doi: https://doi.org/10.1093/jxb/ery224

Journal: Journal of Experimental Botany

Published date: 12 June, 2018

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