ABA and GA metabolism during incubation rather than hormone contents in dry seeds is the key to understanding secondary dormancy and germination of Syngonanthus verticillatus seeds. The mechanism of seed dormancy cycle, although very important for preventing germination during unfavorable periods for seedling establishment, is poorly understood in tropical species. Here, we used a perennial tropical species of the Brazilian campo rupestre, Syngonanthus verticillatus (Eriocaulaceae), to investigate the involvement of ABA and GA in modulating secondary dormancy of seeds buried in situ over time and the dynamic of these hormones during the incubation of dormant and non-dormant seeds. Hormone analyses were carried out with freshly harvested seeds and on buried seeds exhumed after 3, 6 and 9 months. Dynamics of ABA and GAs in dormant and non-dormant seeds during incubation (0, 12, 24 and 36 h) under favorable conditions for germination (at 20 °C in the presence of light) were also investigated. In addition, the effects of GA4 and fluridone were evaluated for overcoming secondary dormancy. Our results showed that changes in the contents of both ABA and GA4 occurred after burial, suggesting they may be related to the modulation of secondary dormancy/germination of S. verticillatus seeds. The application of fluridone was more effective than GA4 at overcoming secondary dormancy. We conclude that during incubation, de novo ABA synthesis and its consequent maintenance at high contents regulate the inhibition of germination in dormant seeds, while GA4 synthesis and ABA catabolism modulate the germination of non-dormant seeds. ABA and GA metabolism during incubation of both dormant and non-dormant seeds rather than hormone contents of dry seeds in the field is thought to be the key to understanding secondary dormancy and germination.

中文翻译：

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ABA 和 GA4 动态调节 Syngonanthus verticillatus 种子的次生休眠和萌发

孵化过程中的 ABA 和 GA 代谢而不是干种子中的激素含量是理解轮枝莲种子次生休眠和萌发的关键。种子休眠周期的机制虽然对于在幼苗建立的不利时期防止发芽非常重要，但在热带物种中却知之甚少。在这里，我们使用巴西 campo rupestre 的多年生热带物种 Syngonanthus verticillatus (Eriocaulaceae) 来研究 ABA 和 GA 在调节原位埋藏种子随时间的二次休眠以及这些激素在休眠孵化过程中的动态和非休眠种子。对新鲜收获的种子和在 3、6 和 9 个月后挖出的埋藏种子进行激素分析。还研究了在有利于萌发的条件下（20°C 光照）下孵化（0、12、24 和 36 小时）休眠和非休眠种子中 ABA 和 GAs 的动态。此外，还评估了 GA4 和氟啶酮对克服继发性休眠的影响。我们的研究结果表明，埋藏后ABA和GA4的含量都发生了变化，这表明它们可能与轮枝菌种子二次休眠/萌发的调节有关。在克服二次休眠方面，氟利酮的应用比GA4更有效。我们得出结论，在孵化过程中，从头 ABA 合成及其随后的高含量维持调节了休眠种子萌发的抑制，而 GA4 合成和 ABA 分解代谢调节了非休眠种子的萌发。