Main conclusion

The dormancy release by KAR₁ is associated with a reduction of coleorhiza and radicle sensitivity to ABA as well as with reduction the ABA/GA_s ratio in the coleorhiza, by a decrease content of ABA, and in the radicle, by a decrease the ABA and an increase of the GA_s contents.

Abstract

Both, karrikin 1 (KAR₁) and gibberellin A₃ (GA₃), release dormancy in Avena fatua caryopses, resulting in the emergence of coleorhiza (CE) and radicle (RE). Moreover, KAR₁ and GA₃ stimulate CE and RE in the presence of abscisic acid (ABA), the stimulation being more effective in CE. The stimulatory effects of KAR₁ and GA₃ involve also the CE and RE rates. A similar effect was observed at KAR₁ concentrations much lower than those of GA₃. KAR₁ increased the levels of bioactive GA₅ and GA₆ in embryos and the levels of GA₁, GA₅, GA_3, GA₆ and GA₄ in radicles. The stimulatory effect of KAR₁ on germination, associated with increased levels of gibberellins (GA_s) and reduced levels of ABA in embryos, was counteracted by paclobutrazol (PAC), commonly regarded as a GA_s biosynthesis inhibitor. Consequently, KAR₁ decreased the ABA/GA_s ratio, whereas PAC, used alone or in combination with KAR₁, increased it. The ABA/GA_s ratio was reduced by KAR₁ in both coleorhiza and radicle, the effect being stronger in the latter. We present the first evidence that KAR₁-induced dormancy release requires a decreased ABA/GA_s ratio in coleorhiza and radicle. It is concluded that the dormancy-releasing effect of KAR₁ in A. fatua caryopses includes (i) a reduction of the coleorhiza and radicle sensitivity to ABA, and (2) a reduction of the ABA/GA_s ratio (i) in the coleorhiza, by decreasing the ABA content, and (ii) in the radicle, by decreasing the ABA and increasing the content GA_s, particularly GA₁. The results may suggest different mechanisms of dormancy release by KAR₁ in monocot and dicot seeds.

中文翻译：

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KAR1 诱导的燕麦颖果休眠释放涉及降低颖果对 ABA 的敏感性以及椰根和胚根中 ABA/GAs 的比率

主要结论

_{KAR 1}解除休眠与降低菜根和胚根对 ABA 的敏感性以及降低菜根中 ABA/GA_的比例（通过减少 ABA 含量）和在菜根中（通过减少 ABA）相关。以及GA_含量的增加。

抽象的

karrikin 1 (KAR ₁ ) 和赤霉素 A ₃ (GA ₃ ) 均可解除燕麦的休眠状态，导致胚根 (CE) 和胚根 (RE) 的出现。此外，KAR ₁和GA ₃在脱落酸(ABA) 存在下刺激CE 和RE，该刺激在CE 中更有效。 KAR ₁和 GA ₃的刺激作用还涉及 CE 和 RE 率。在远低于 GA _{3浓度的 KAR 1}浓度下观察到类似的效果。 KAR _{1增加了胚胎中生物活性GA 5}和GA ₆的水平以及胚根中GA ₁、GA ₅、GA _{3 、} GA ₆和GA ₄的水平。 KAR ₁对发芽的刺激作用与胚胎中赤霉素 (GA _s )水平的增加和 ABA 水平的降低有关，而多效唑 (PAC) 可以抵消这种作用，多效唑 (PAC) 通常被视为 GA _s生物合成抑制剂。因此，KAR ₁降低了ABA/GA _s比率，而单独使用或与KAR ₁组合使用的PAC则增加了该比率。 KAR ₁降低了胚根和胚根中的ABA/GA _s比值，后者的作用更强。我们提出了第一个证据，证明 KAR ₁诱导的休眠释放需要降低鞘根和胚根中ABA/GA_的比率。结论是，KAR ₁在A. fatua caryopses 中的休眠释放作用包括 (i) 降低胚根和胚根对 ABA 的敏感性，以及 (2) 降低 ABA/GA _s比率 (i) (ii)在胚根中，通过减少 ABA 并增加 GA _s (特别是 GA _{1 )}的含量。这些结果可能表明 KAR ₁在单子叶植物和双子叶植物种子中释放休眠的不同机制。