We show that DCN1 binds ubiquitin and RUB/NEDD8, associates with cullin, and is functionally conserved. DCN1 activity is required for pollen development transitions and embryogenesis, and for pollen tube growth. Plant proteomes show remarkable plasticity in reaction to environmental challenges and during developmental transitions. Some of this adaptability comes from ubiquitin-mediated protein degradation regulated by cullin-RING E3 ubiquitin ligases (CRLs). CRLs are activated through modification of the cullin subunit with the ubiquitin-like protein RUB/NEDD8 by an E3 ligase called defective in cullin neddylation 1 (DCN1). Here we show that tobacco DCN1 binds ubiquitin and RUB/NEDD8 and associates with cullin. When knocked down by RNAi, tobacco pollen formation was affected and zygotic embryogenesis was blocked around the globular stage. Additionally, we found that RNAi of DCN1 inhibited the stress-triggered reprogramming of cultured microspores from their intrinsic gametophytic mode of development to an embryogenic state. This stress-induced developmental switch is a known feature in many important crops and leads ultimately to the formation of haploid embryos and plants. Compensating the RNAi effect by re-transformation with a promoter-silencing construct restored pollen development and zygotic embryogenesis, as well as the ability for stress-induced formation of embryogenic microspores. Overexpression of DCN1 accelerated pollen tube growth and increased the potential for microspore reprogramming. These results demonstrate that the biochemical function of DCN1 is conserved in plants and that its activity is involved in transitions during pollen development and embryogenesis, and for pollen tube growth.

中文翻译：

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DCN1 的烟草同源物参与花粉发育和胚胎发生。

我们表明 DCN1 结合泛素和 RUB/NEDD8，与 cullin 相关联，并且在功能上是保守的。DCN1 活性是花粉发育转变和胚胎发生以及花粉管生长所必需的。植物蛋白质组在应对环境挑战和发育转变过程中表现出显着的可塑性。这种适应性部分来自于由 cullin-RING E3 泛素连接酶 (CRL) 调节的泛素介导的蛋白质降解。CRL 是通过一种称为 cullin neddylation 1 (DCN1) 缺陷的 E3 连接酶用泛素样蛋白 RUB/NEDD8 修饰 cullin 亚基来激活的。在这里我们显示烟草 DCN1 结合泛素和 RUB/NEDD8 并与 cullin 相关联。当被 RNAi 击倒时，烟草花粉的形成受到影响，合子胚胎发生在球状阶段附近被阻止。此外，我们发现 DCN1 的 RNAi 抑制了压力触发的培养小孢子从其内在配子体发育模式到胚胎发生状态的重编程。这种应激诱导的发育转换是许多重要作物的已知特征，并最终导致单倍体胚胎和植物的形成。通过用启动子沉默构建体重新转化来补偿 RNAi 效应，恢复了花粉发育和合子胚胎发生，以及压力诱导形成胚性小孢子的能力。DCN1 的过表达加速了花粉管的生长并增加了小孢子重编程的潜力。这些结果表明，DCN1 的生化功能在植物中是保守的，其活性参与花粉发育和胚胎发生过程中的转变，