BACKGROUND Seed dormancy is a prevailing condition in which seeds are unable to germinate, even under favorable environmental conditions. Harvested Brassica oleracea (Chinese cabbage) seeds are dormant and normally germinate (poorly) at 21 °C. This study investigated the connections between ethylene, nitric oxide (NO), and karrikin 1 (KAR1) in the dormancy release of secondary dormant Brassica oleracea seeds. RESULTS NO and KAR1 were found to induce seed germination, and stimulated the production of ethylene and 1-aminocyclopropane-1-carboxylic acid (ACC), and both ethylene biosynthesis enzyme ACC oxidase (ACO) [1] and ACC synthase (ACS) [2]. In the presence of NO and KAR1, ACS and ACO activity reached maximum levels after 36 and 48 h, respectively. The inhibitor of ethylene 2,5-norbornadiene (NBD) had an adverse effect on Brassica oleracea seed germination (inhibiting nearly 50% of germination) in the presence of NO and KAR1. The benefits from NO and KAR1 in the germination of secondary dormant Brassica oleracea seeds were also associated with a marked increase in reactive oxygen species (ROS) (H2O2 and O2˙-) and antioxidant enzyme activity at early germination stages. Catalase (CAT) and glutathione reductase (GR) activity increased 2 d and 4 d, respectively, after treatment, while no significant changes were observed in superoxide dismutase (SOD) activity under NO and KAR1 applications. An increase in H2O2 and O2˙- levels were observed during the entire incubation period, which increasing ethylene production in the presence of NO and KAR1. Abscisic acid (ABA) contents decreased and glutathione reductase (GA) contents increased in the presence of NO and KAR1. Gene expression studies were carried out with seven ethylene biosynthesis ACC synthases (ACS) genes, two ethylene receptors (ETR) genes and one ACO gene. Our results provide more evidence for the involvement of ethylene in inducing seed germination in the presence of NO and KAR1. Three out of seven ethylene biosynthesis genes (BOACS7, BOACS9 and BOACS11), two ethylene receptors (BOETR1 and BOETR2) and one ACO gene (BOACO1) were up-regulated in the presence of NO and KAR1. CONCLUSION Consequently, ACS activity, ACO activity and the expression of different ethylene related genes increased, modified the ROS level, antioxidant enzyme activity, and ethylene biosynthesis pathway and successfully removed (nearly 98%) of the seed dormancy of secondary dormant Brassica olereace seeds after 7 days of NO and KAR1 application.

中文翻译：

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使用带有乙烯生物合成途径，ROS和抗氧化酶修饰的NO和KAR1减轻甘蓝种子的休眠。

背景技术种子休眠是普遍的条件，其中即使在有利的环境条件下种子也不能发芽。收获的芸苔种子（大白菜）处于休眠状态，通常在21°C时发芽（较差）。这项研究调查了二级休眠甘蓝种子的休眠释放中乙烯，一氧化氮（NO）和karrikin 1（KAR1）之间的关系。结果NO和KAR1被发现诱导种子萌发，并刺激了乙烯和1-氨基环丙烷-1-羧酸（ACC）的产生，并刺激了乙烯生物合成酶ACC氧化酶（ACO）[1]和ACC合酶（ACS）[ 2]。在存在NO和KAR1的情况下，ACS和ACO活性分别在36和48小时后达到最高水平。乙烯2的抑制剂 在没有NO和KAR1的情况下，5-降冰片二烯（NBD）对甘蓝型油菜种子发芽有不利影响（抑制了近50％的发芽）。NO和KAR1在次生休眠甘蓝种子萌发中的益处还与发芽初期的活性氧（ROS）（H2O2和O2 +-）和抗氧化酶活性的显着增加有关。处理后，过氧化氢酶（CAT）和谷胱甘肽还原酶（GR）活性分别增加了2 d和4 d，而在NO和KAR1施用下，超氧化物歧化酶（SOD）活性未见明显变化。在整个孵育过程中，观察到H2O2和O2 +的增加，这在存在NO和KAR1的情况下增加了乙烯的产量。在存在NO和KAR1的情况下，脱落酸（ABA）含量降低，而谷胱甘肽还原酶（GA）含量升高。使用七个乙烯生物合成ACC合成酶（ACS）基因，两个乙烯受体（ETR）基因和一个ACO基因进行了基因表达研究。我们的结果为存在NO和KAR1的乙烯参与种子萌发提供了更多证据。在存在NO和KAR1的情况下，七个乙烯生物合成基因中的三个（BOACS7，BOACS9和BOACS11），两个乙烯受体（BOETR1和BOETR2）和一个ACO基因（BOACO1）被上调。结论因此，ACS活性，ACO活性和不同乙烯相关基因的表达增加，修饰了ROS水平，抗氧化酶活性，