Gibberellins (GAs) play a pivotal role in the induction of somatic embryogenesis from in vitro root apices of spinach plants. With the aim to understand the role of GAs in this process and to improve somatic embryo (SE) regeneration efficiency, the impact of light and GAs on SE initiation from the in vitro root apices was studied. The root sections were isolated from in vitro-grown SE-derived plants and placed on medium containing 20 µM α-naphthaleneacetic acid (NAA) and 0–10 µM GA₃ or GA₁, and cultivated under light conditions or in darkness. The most efficient SE regeneration response (100% regenerating SEs and 40.73 SEs per root apices) was achieved only in the presence of both light and GAs, with GA₃ always exhibiting much stronger effect than GA₁. Considering that light enhances GAs biosynthesis and the necessity of GAs for SE initiation, the expression levels of genes encoding the key enzymes involved in the final steps of GAs synthesis (SoGA20-ox1 and SoGA3-ox1) and deactivation (SoGA2-ox1, SoGA2-ox2 and SoGA2-ox3) were analyzed. Light enhanced the expression of all five GA-ox genes, while exogenously supplied NAA + GA₃ provoked downregulation of SoGA20-ox1 and SoGA3-ox1 and upregulation of SoGA2ox-2 and SoGA2ox-3 expression. The expression of SoGA2ox-1 only slightly decreased. The results indicated the capability of isolated spinach roots to perceive the light and autonomously produce GAs. The expression levels of genes encoding key enzymes involved in GA biosynthesis suggest that lower levels of GAs favor SE initiation.

赤霉素（GAs）在从菠菜植物的体外根尖诱导体细胞胚发生中起关键作用。为了了解GA在此过程中的作用并提高体细胞胚（SE）的再生效率，研究了光和GA对体外根尖SE引发的影响。从体外生长的SE来源的植物中分离出根部，并置于含有20 µMα-萘乙酸（NAA）和0–10 µM GA ₃或GA _1的培养基上，并在明亮或黑暗的条件下培养。仅在有光和GA的情况下，才能实现最有效的SE再生响应（100％再生SE和40.73 SE /根），GA ₃始终表现出比GA强得多的效果₁。考虑到光增强了GAs的生物合成和SE引发GA的必要性，因此编码参与GAs合成（SoGA20-ox1和SoGA3-ox1）和失活（SoGA2-ox1，SoGA2-的最终步骤的关键酶的基因的表达水平ox2和SoGA2-ox3）进行了分析。光增强了所有五个GA-ox基因的表达，而外源提供的NAA + GA ₃引起SoGA20-ox1和SoGA3-ox1的下调以及SoGA2ox-2和SoGA2ox-3的上调。SoGA2ox-1的表达仅略有下降。结果表明，分离出的菠菜根具有感知光和自主产生GA的能力。编码参与GA生物合成的关键酶的基因的表达水平表明，较低水平的GA有利于SE的起始。