Nitric oxide (NO) has been recognized as a major player in the regulation of plant physiology and development. NO regulates cell cycle progression and cell elongation in flowering plants and green algae, although the information about NO function in non-vascular plants is scarce. Here, we analyze the effect of exogenous NO on Physcomitrella patens protonema growth. We find that increasing concentrations of the NO donor sodium nitroprusside (SNP) inhibit protonema relative growth rate and cell length. To further comprehend the effect of NO on moss development, we analyze the effect of SNP 5 and 10 µM on protoplast regeneration and, furthermore, protonema formation compared with untreated plants (control). Isolated protoplasts were left to regenerate for 24 h before starting the SNP treatments that lasted five days. The results show that SNP restrains the protoplast regeneration process and the formation of new protonema cells. When SNP treatments started five days after protoplast isolation, a decrease in cell number per protonema filament was observed, indicating an inhibition of cell cycle progression. Our results show that in non-vascular plants, NO negatively regulates plant regeneration, cell cycle and cell elongation.

中文翻译：

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外源性一氧化氮延缓了草丛小孢子中原生质体和原生质体发育的植物再生。

一氧化氮（NO）被认为是调节植物生理和发育的主要参与者。NO调节开花植物和绿藻中的细胞周期进程和细胞伸长，尽管关于非维管植物中NO功能的信息很少。在这里，我们分析了外源NO对小立碗藓的影响原生质生长。我们发现增加的NO供体硝普钠（SNP）的浓度会抑制质子的相对生长速率和细胞长度。为了进一步了解NO对苔藓发育的影响，我们分析了SNP 5和10 µM对原生质体再生的影响，此外，与未经处理的植物（对照）相比，原生质的形成。在开始持续五天的SNP处理之前，将分离的原生质体再生24小时。结果表明，SNP抑制了原生质体的再生过程和新的原生质细胞的形成。当原生质体分离后五天开始SNP处理时，观察到每条原生质体细丝的细胞数量减少，表明细胞周期进程受到抑制。我们的结果表明，在非维管植物中，