浙贝母FtGGPS功能验证及其对鳞茎发育的影响

Functions of FtGGPS and its role in the bulb development of Fritillaria thunbergii

摘要:

本研究旨在基于繁殖系数和单鳞茎重量存在差异的‘浙贝1号’与‘浙贝3号’成熟期转录组数据，挖掘调控鳞茎发育的关键基因，并通过功能验证阐明其作用机制。利用生物信息学分析、原核表达、烟草过表达及亚细胞定位等技术，对关键基因进行功能验证并解析其上游调控序列；结合相关理化数据，探讨关键基因对鳞茎发育的影响。结果表明，差异基因FtGGPS编码蛋白属于GGPS1家族，参与赤霉素(gibberellin, GA)、脱落酸(abscisic acid, ABA)、叶绿醌(phylloquinone, VK1)合成及叶绿体形成。其上游调控序列中含有GARE-motif等响应元件及ERF等转录因子结合位点，可响应GA信号调控FtGGPS表达。结合相关性分析发现，在FtGGPS低水平表达时，GA和ABA维持较低水平合成；而高水平表达时，GA的快速积累反馈抑制FtGGPS表达，这种抑制效应随GA代谢而解除，从而维持鳞茎中GA和ABA的高水平合成。综上，FtGGPS调控GA和ABA水平，以不同表达模式影响浙贝母鳞茎发育。本研究有助于完善浙贝母鳞茎发育的激素调控网络理论，并为分子育种提供理论依据。

Abstract:

This study aimed to identify key genes regulating the bulb development of Fritillaria thunbergii by utilizing transcriptome data from the mature stage of ‘Zhebei No.1’ and ‘Zhebei No.3’ cultivars, which exhibited differences in propagation coefficient and single bulb weight. Furthermore, functional validation was performed to elucidate the mechanisms underlying their effects. Key candidate genes were functionally validated via bioinformatics analysis, prokaryotic expression, tobacco overexpression, and subcellular localization techniques, and their upstream regulatory sequences were analyzed. Relevant physicochemical data were integrated to investigate the impacts of these key genes on bulb development. The differentially expressed gene FtGGPS encoded a GGPS1 family member involved in gibberellin (GA), abscisic acid (ABA), and phylloquinone (VK1) biosynthesis, as well as chloroplast formation. Its upstream regulatory sequence contained GA-responsive elements such as the GARE-motif and transcription factor binding sites such as ERF, enabling GA signal-responsive regulation of FtGGPS expression. Correlation analysis indicated that under low FtGGPS expression levels, GA and ABA synthesis remained at low levels. Conversely, under high FtGGPS expression levels, rapid GA accumulation triggered feedback inhibition of FtGGPS expression. This inhibitory effect was alleviated with GA metabolism, which thereby maintained high-level synthesis of GA and ABA within the bulb. FtGGPS modulates the bulb development of F. thunbergii by regulating GA and ABA levels through distinct expression patterns. Elucidating the function of FtGGPS will help refine the hormonal regulatory network of bulb development in F. thunbergii and provide a theoretical basis for molecular breeding.