Epiphytic bromeliads might experience drought after a few hours without water, which is especially critical during early life stages. Consequently, juvenile epiphytic bromeliads probably rely on short-term activation of drought tolerance strategies, although the biochemical processes involved are still poorly understood. In this study, we aimed to evaluate the short-term drought response of juvenile plants of the epiphytic bromeliad Acanthostachys strobilacea (Schult. & Schult. f.) Klotzsch. We hypothesized that short-term drought would induce the accumulation of abscisic acid (ABA) and secondary messengers such as reactive oxygen and nitrogen species (ROS and RNS, respectively) before the activation of defence mechanisms. Three-month-old plants were transferred from well-watered to dry substrates and stress markers were assessed at 0, 2, 5, 10, 24, 48, and 72 h. Drought caused a 27.3% decrease in relative water content compared to the well-watered control at 72 h. A nearly 5-fold increment in the ABA content occurred at 72 h of stress, which was about two days after the first detection of peaks in RNS levels and defence mechanisms activation. Indeed, ascorbate peroxidase (EC 1.11.1.11) activities and proline content increased after 10 h, whereas after 24 h a higher catalase (EC 1.11.1.6) activity and osmotic adjustment occurred. Oxidative stress markers and photochemical efficiency of photosystem II indicated no significant damage induced by drought. We concluded that defence mechanisms activation during early drought in juvenile A. strobilacea might be regulated initially by ABA-independent pathways and RNS, while ABA-induced responses are triggered at subsequent stages of stress.

附生凤梨科动物在缺水几个小时后可能会遭受干旱，这在生命的早期尤其重要。因此，尽管对附生的凤梨科动物的生化过程仍知之甚少，但其可能依赖于短期启动抗旱策略。在这项研究中，我们旨在评估附生的凤梨棘形棘轮龙科幼体植物的短期干旱响应（舒尔特＆舒尔特f。）我们假设短期干旱会在防御机制激活之前诱导脱落酸（ABA）和次级信使的积累，例如活性氧和氮（分别为ROS和RNS）。将三个月大的植物从水分充足的基质转移到干燥的基质上，并在0、2、5、10、24、48和72 h评估胁迫标记。与72小时的浇水良好的对照相比，干旱造成的相对含水量减少27.3％。ABA含量的近5倍增加发生在应激72小时，大约在第一次检测到RNS水平和防御机制激活后约两天。实际上，抗坏血酸过氧化物酶（EC 1.11.1.11）的活性和脯氨酸含量在10小时后增加，而过氧化氢酶（EC 1.11.1在24小时后）升高。6）活动和渗透调节发生。光系统II的氧化应激标记和光化学效率表明干旱没有引起明显的破坏。我们得出的结论是，少年早期干旱期间防御机制的激活球星菌最初可能受ABA独立途径和RNS的调节，而ABA诱导的反应则在随后的应激阶段触发。