Zhang Xiaoming, Lin Hua-Ming, Hu Hong, Hu Xiangyang, Hu Liwei
Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Plant Divers. 2016 May 20;38(1):53-58. doi: 10.1016/j.pld.2016.05.004. eCollection 2016 Feb.
Gamma-aminobutyric acid (GABA) is a four-carbon non-protein amino acid conserved from bacteria to plants and vertebrates. Increasing evidence supports a regulatory role for GABA in plant development and the plant's response to environmental stress. The biosynthesis of nicotine, the main economically important metabolite in tobacco, is tightly regulated. GABA has not hitherto been reported to function in nicotine biosynthesis. Here we report that water flooding treatment (hypoxia) markedly induced the accumulation of GABA and stimulated nicotine biosynthesis. Suppressing GABA accumulation by treatment with glutamate decarboxylase inhibitor impaired flooding-induced nicotine biosynthesis, while exogenous GABA application directly induced nicotine biosynthesis. Based on these results, we propose that GABA triggers nicotine biosynthesis in tobacco seedlings subjected to flooding. Our results provide insight into the molecular mechanism of nicotine biosynthesis in tobacco plants exposed to environmental stress.
γ-氨基丁酸（GABA）是一种四碳非蛋白质氨基酸，从细菌到植物和脊椎动物都有保守性。越来越多的证据支持GABA在植物发育和植物对环境胁迫的反应中起调节作用。烟草中主要的经济重要代谢产物尼古丁的生物合成受到严格调控。迄今为止，尚未报道GABA在尼古丁生物合成中发挥作用。在此我们报道，水淹处理（缺氧）显著诱导了GABA的积累并刺激了尼古丁的生物合成。用谷氨酸脱羧酶抑制剂处理抑制GABA积累会损害水淹诱导的尼古丁生物合成，而外源施加GABA则直接诱导尼古丁生物合成。基于这些结果，我们提出GABA触发了遭受水淹的烟草幼苗中的尼古丁生物合成。我们的结果为暴露于环境胁迫下的烟草植物中尼古丁生物合成的分子机制提供了见解。
