Institute of Botany of the Czech Academy of Sciences, CZ-379 01 Třeboň, Czech Republic.
Laboratory of Growth Regulators, Faculty of Science, Palacký University & Institute of Experimental Botany AS CR, CZ-783 71 Olomouc, Czech Republic.
Ann Bot. 2024 Jul 9;134(2):219-232. doi: 10.1093/aob/mcae059.
Turions are vegetative, dormant overwintering organs formed in aquatic plants in response to unfavourable ecological conditions. Contents of cytokinin (CK), auxin metabolites and abscisic acid (ABA) as main growth and development regulators were compared in innately dormant autumnal turions of 22 aquatic plant species of different functional ecological or taxonomic groups with those in non-dormant winter apices in three aquatic species and with those in spring turions of four species after their overwintering.
The hormones were analysed in miniature turion samples using ultraperformance liquid chromatography coupled with triple quadrupole mass spectrometry.
In innately dormant turions, the total contents of each of the four main CK types, biologically active forms and total CKs differed by two to three orders of magnitude across 22 species; the proportion of active CK forms was 0.18-67 %. Similarly, the content of four auxin forms was extremely variable and the IAA proportion as the active form was 0.014-99 %. The ABA content varied from almost zero to 54 µmol kg-1 dry weight and after overwintering it usually significantly decreased. Of all functional traits studied, hormone profiles depended most on the place of turion sprouting (surface vs bottom) and we suggest that this trait is crucial for turion ecophysiology.
The key role of ABA in regulating turion dormancy was confirmed. However, the highly variable pattern of the ABA content in innately dormant and in overwintered turions indicates that the hormonal mechanism regulating the innate dormancy and its breaking in turions is not uniform within aquatic plants.
芽球是水生植物在不利生态条件下形成的营养、休眠越冬器官。本研究比较了 22 种不同功能生态或分类群的水生植物先天休眠秋芽球与 3 种水生植物非休眠冬季顶芽和 4 种植物越冬后春季芽球中细胞分裂素（CK）、生长素代谢物和脱落酸（ABA）等主要生长发育调节剂的含量。
采用超高效液相色谱-三重四极杆质谱联用技术分析微型芽球样本中的激素。
在先天休眠的芽球中，22 种植物的 4 种主要 CK 类型、生物活性形式和总 CK 的总含量差异达两个数量级以上；活性 CK 形式的比例为 0.18-67%。同样，4 种生长素形式的含量变化非常大，IAA 作为活性形式的比例为 0.014-99%。ABA 含量从几乎为零到 54 µmol kg-1 干重不等，越冬后通常会显著降低。在所研究的所有功能特性中，激素谱最依赖于芽球萌发的位置（水面或水底），我们认为这一特性对芽球生态生理学至关重要。
本研究证实了 ABA 在调控芽球休眠中的关键作用。然而，先天休眠和越冬芽球中 ABA 含量的高度可变模式表明，调控芽球先天休眠及其打破的激素机制在水生植物中并不统一。
