Šimura Jan, Spíchal Lukáš, Adamec Lubomír, Pěnčík Aleš, Rolčík Jakub, Novák Ondřej, Strnad Miroslav
Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany AS CR and Faculty of Science of Palacký University, Šlechtitelů 27, CZ-78371 Olomouc, Czech Republic Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science of Palacký University, Šlechtitelů 27, CZ-78371 Olomouc, Czech Republic.
Institute of Botany of the Czech Academy of Sciences, Section of Plant Ecology, Dukelská 135, CZ-37982 Třeboň, Czech Republic.
Ann Bot. 2016 May;117(6):1037-44. doi: 10.1093/aob/mcw020. Epub 2016 Apr 20.
The typical rootless linear shoots of aquatic carnivorous plants exhibit clear, steep polarity associated with very rapid apical shoot growth. The aim of this study was to determine how auxin and cytokinin contents are related to polarity and shoot growth in such plants.
The main auxin and cytokinin metabolites in separated shoot segments and turions of two carnivorous plants, Aldrovanda vesiculosa and Utricularia australis, were analysed using ultra-high-performance liquid chromatography coupled with triple quad mass spectrometry.
In both species, only isoprenoid cytokinins were identified. Zeatin cytokinins predominated in the apical parts, with their concentrations decreasing basipetally, and the trans isomer predominated in A. vesiculosa whereas the cis form was more abundant in U australis. Isopentenyladenine-type cytokinins, in contrast, increased basipetally. Conjugated cytokinin metabolites, the O-glucosides, were present at high concentrations in A. vesiculosa but only in minute amounts in U. australis. N(9)-glucoside forms were detected only in U. australis, with isopentenyladenine-9-glucoside (iP9G) being most abundant. In addition to free indole-3-acetic acid (IAA), indole-3-acetamide (IAM), IAA-aspartate (IAAsp), IAA-glutamate (IAGlu) and IAA-glycine (IAGly) conjugates were identified.
Both species show common trends in auxin and cytokinin levels, the apical localization of the cytokinin biosynthesis and basipetal change in the ratio of active cytokinins to auxin, in favour of auxin. However, our detailed study of cytokinin metabolic profiles also revealed that both species developed different regulatory mechanisms of active cytokinin content; on the level of their degradation, in U. australis, or in the biosynthesis itself, in the case of A. vesiculosa Results indicate that the rapid turnover of these signalling molecules along the shoots is essential for maintaining the dynamic balance between the rapid polar growth and development of the apical parts and senescence of the older, basal parts of the shoots.
水生食虫植物典型的无根线性茎表现出明显、陡峭的极性，且茎尖生长非常迅速。本研究的目的是确定生长素和细胞分裂素含量与这类植物的极性及茎生长之间的关系。
利用超高效液相色谱-三重四极杆质谱联用技术分析了两种食虫植物——轮叶黑藻和南方狸藻离体茎段及鳞芽中的主要生长素和细胞分裂素代谢物。
在这两个物种中，仅鉴定出类异戊二烯细胞分裂素。玉米素类细胞分裂素在茎尖部分占主导，其浓度向基部递减，反式异构体在轮叶黑藻中占主导，而顺式形式在南方狸藻中更为丰富。相比之下，异戊烯腺嘌呤型细胞分裂素向基部增加。结合型细胞分裂素代谢物，即O-葡萄糖苷，在轮叶黑藻中含量很高，但在南方狸藻中含量极少。仅在南方狸藻中检测到N(9)-葡萄糖苷形式，其中异戊烯腺嘌呤-9-葡萄糖苷（iP9G）最为丰富。除了游离的吲哚-3-乙酸（IAA）外，还鉴定出吲哚-3-乙酰胺（IAM）、IAA-天冬氨酸（IAAsp）、IAA-谷氨酸（IAGlu）和IAA-甘氨酸（IAGly）结合物。
这两个物种在生长素和细胞分裂素水平、细胞分裂素生物合成的顶端定位以及活性细胞分裂素与生长素比值的向基部变化方面都表现出共同趋势，有利于生长素。然而，我们对细胞分裂素代谢谱的详细研究还表明，这两个物种发展出了不同的活性细胞分裂素含量调节机制；在南方狸藻中是在降解水平，而在轮叶黑藻中是在生物合成本身。结果表明，这些信号分子沿茎的快速周转对于维持茎尖快速极性生长发育与老的基部部分衰老之间的动态平衡至关重要。
