Charnikhova Tatsiana V, Gaus Katharina, Lumbroso Alexandre, Sanders Mark, Vincken Jean-Paul, De Mesmaeker Alain, Ruyter-Spira Carolien P, Screpanti Claudio, Bouwmeester Harro J
Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
Syngenta Crop Protection AG Research Chemistry, Schaffhauserstr. 101, 4332 Stein, Switzerland.
Phytochemistry. 2017 May;137:123-131. doi: 10.1016/j.phytochem.2017.02.010. Epub 2017 Feb 16.
In the root exudate and root extracts of maize hybrid cv NK Falkone seven putative strigolactones were detected using UPLC-TQ-MS-MS. All seven compounds displayed MS-MS-fragmentation common for strigolactones and particularly the presence of a fragment of m/z 97 Da, which may indicate the presence of the so-called D-ring, suggests they are strigolactones. The levels of all these putative strigolactones increased upon phosphate starvation and decreased upon fluridone (carotenoid biosynthesis inhibitor) treatment, both of which are a common response for strigolactones. All seven compounds were subsequently isolated with prep-HPLC-MS. They all exhibited Striga hermonthica seed germination inducing activity just as the synthetic strigolactone analog GR24. The structure of two of the seven compounds was elucidated by NMR spectroscopy as: methyl (2E,3E)-4-(3,3-dimethyl-5-oxo-2-(prop-1-en-2-yl)tetrahydrofuran-2-yl)-2-(((4-methyl-5-oxo-2,5-dihydrofuran-2-yl)oxy)methylene)but-3-enoate (two diastereomers 1a and 1b). Strigolactones (1a/b) are closely related to the methyl ester of carlactonoic acid (MeCLA) and heliolactone. However, they contain a unique 4,4-dimethyltetrahydrofuran-2-one motif as the "A-ring" instead of the classical (di)methylcyclohexene. Because these compounds were isolated from maize (Zea mays) we called them "zealactone 1a and 1b". The implications of this discovery for our view on strigolactones and their biosynthesis are discussed.
利用超高效液相色谱-串联四极杆质谱联用仪（UPLC-TQ-MS-MS）在玉米杂交种cv NK Falkone的根系分泌物和根提取物中检测到7种假定的独脚金内酯。所有这7种化合物均显示出独脚金内酯常见的质谱-质谱碎片化特征，特别是存在质荷比为97 Da的碎片，这可能表明存在所谓的D环，表明它们是独脚金内酯。所有这些假定的独脚金内酯的水平在磷饥饿时升高，在氟啶酮（类胡萝卜素生物合成抑制剂）处理时降低，这两者都是独脚金内酯的常见反应。随后通过制备型高效液相色谱-质谱联用仪分离出所有7种化合物。它们都表现出与合成独脚金内酯类似物GR24一样的诱导独脚金种子萌发的活性。通过核磁共振光谱法阐明了这7种化合物中两种的结构为：(2E,3E)-4-(3,3-二甲基-5-氧代-2-(丙-1-烯-2-基)四氢呋喃-2-基)-2-(((4-甲基-5-氧代-2,5-二氢呋喃-2-基)氧基)亚甲基)丁酸甲酯（两种非对映异构体1a和1b）。独脚金内酯（1a/b）与独脚金烯酸甲酯（MeCLA）和向日葵内酯密切相关。然而，它们含有一个独特的4,4-二甲基四氢呋喃-2-酮基序作为“A环”，而不是经典的（二）甲基环己烯。由于这些化合物是从玉米（Zea mays）中分离出来的，我们将它们称为“玉米独脚金内酯1a和1b”。讨论了这一发现对我们关于独脚金内酯及其生物合成观点的影响。
