Since the isolation of the first cytokinin almost 60 yr ago, cytokinins have become critically important for ornamental and agricultural crops in plant tissue culture. Despite the extensive research on this class of compounds, little information is available on the chemical stability of cytokinins in solution or following an autoclave cycle with Murashige and Skoog (MS) basal medium. This work describes the stability in aqueous solutions of five widely used adenine-based cytokinins: trans-zeatin (tZ), 6-(γ,γ-dimethylallylamino) purine (2iP), kinetin, benzyladenine (BA), and m-topolin. High pressure liquid chromatography (HPLC) and electrospray ionization-mass spectrometry (ESI-MS) were used to quantify and identify their degradation. BA, kinetin, 2iP, and m-topolin were stable at 1.0 mg mL-1 in 0.05 N KOH, with no statistically significant concentration changes (p > 0.05) after 90 d of storage at temperatures of -20°C, 2-6°C, or 25°C. The cytokinin tZ was used as a model compound to evaluate stability under alkaline and acid conditions as well as after repeated freeze-thaw cycles. Trans-zeatin retained >90% of the initial concentration of 1.0 mg mL-1 when dissolved in 0.01 N KOH and stored at -20°C and 2-6°C for 90 d, with only the 2-6°C temperature treatment showing a statistical significant concentration change (p = 0.03). The 1.0 mg mL-1 tZ solution in 0.01 N KOH was stable through six repeated freeze-thaw cycles over 90 d without any significant change in concentration compared to the initial freeze-thaw. Yet, tZ showed highly significant concentration changes when dissolved at 50 mg mL-1 and 0.5 N KOH. All of these adenine-based cytokinins showed exceptional stability following an autoclave cycle at 121°C, 110 kPa for 30 min when in solutions of 1.0 mg mL-1 in 0.05 N KOH, with no significant degradation detected. Trans-zeatin was also found to be stable after one autoclave cycle with 1× MS-basal salts.

中文翻译：

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水溶液中基于腺嘌呤的细胞分裂素的稳定性。

自从大约60年前分离出第一种细胞分裂素以来，细胞分裂素对于植物组织培养中的观赏和农作物已变得至关重要。尽管对这类化合物进行了广泛的研究，但是关于细胞分裂素在溶液中或在Murashige和Skoog（MS）基础培养基的高压灭菌循环后的化学稳定性方面的信息很少。这项工作描述了五种广泛使用的基于腺嘌呤的细胞分裂素在水溶液中的稳定性：反式玉米素（tZ），6-（γ，γ-二甲基烯丙基氨基）嘌呤（2iP），激动素，苄基腺嘌呤（BA）和间-topolin。高压液相色谱（HPLC）和电喷雾电离质谱（ESI-MS）用于定量和鉴定其降解。BA，激动素，2iP和间拓扑蛋白在0.05 N KOH中在1.0 mg mL-1时稳定，在-20°C，2-6°C或25°C的温度下存放90天后，浓度没有统计学上的显着变化（p> 0.05）。细胞分裂素tZ用作模型化合物，以评估在碱性和酸性条件下以及反复冻融循环后的稳定性。当溶于0.01 N KOH中时，反式玉米蛋白保留了1.0 mg mL-1初始浓度的90％以上，并且仅在2-6°C的温度处理下在-20°C和2-6°C储存90天显示出统计学上显着的浓度变化（p = 0.03）。在90天内，经过六个重复的冻融循环，在0.01 N KOH中的1.0 mg mL-1 tZ溶液是稳定的，与最初的冻融相比，浓度没有任何显着变化。然而，当溶解于50 mg mL-1和0.5 N KOH时，tZ表现出非常显着的浓度变化。当在1.0 mg mL-1的0.05 N KOH溶液中于121°C，110 kPa高压灭菌循环30分钟后，所有这些基于腺嘌呤的细胞分裂素均显示出卓越的稳定性。在用1x MS基础盐进行一个高压灭菌循环后，反玉米蛋白也被发现是稳定的。