Veselov Stanislav Yu, Timergalina Leila N, Akhiyarova Guzel R, Kudoyarova Guzel R, Korobova Alla V, Ivanov Igor, Arkhipova Tatiana N, Prinsen Els
Bashkir State University, Zaki-Validi st. 32, Ufa, 450076, Russia.
Ufa Institute of Biology, Ufa Research Centre, Russian Academy of Sciences, pr. Oktyabrya 69, Ufa, 450054, Russia.
Protoplasma. 2018 Sep;255(5):1581-1594. doi: 10.1007/s00709-018-1248-7. Epub 2018 Apr 10.
The aim of the present report was to demonstrate how a novel approach for immunohistochemical localization of cytokinins in the leaf and particularly in the phloem may complement to the study of their long-distance transport. Different procedures of fixation were used to conjugate either cytokinin bases or their ribosides to proteins of cytoplasm to enable visualization and differential localization of these cytokinins in the leaf cells of wheat plants. In parallel to immunolocalization of cytokinins in the leaf cells, we immunoassayed distribution of free bases of cytokinins, their nucleotides and ribosides between roots and shoots of wheat plants as well as their presence in phloem sap after incubation of leaves in a solution supplemented with either trans-zeatin or isopentenyladenine. The obtained data show ribosylation of the zeatin applied to the leaves and its elevated level in the phloem sap supported by in vivo localization showing the presence of ribosylated forms of zeatin in leaf vessels. This suggests that conversion of zeatin to its riboside is important for the shoot-to-root transport of zeatin-type cytokinins in wheat. Exogenous isopentenyladenine was not modified, but diffused from the leaves as free base. These metabolic differences may not be universal and may depend on the plant species and age. Although the measurements of cytokinins in the phloem sap and root tissue is the most defining for determining cytokinin transport, study of immunolocalization of either free cytokinin bases or their ribosylated forms may be a valuable source of information for predicting their transport in the phloem and to the roots.
本报告的目的是展示一种用于细胞分裂素在叶片尤其是韧皮部免疫组织化学定位的新方法如何补充其长距离运输的研究。使用不同的固定程序将细胞分裂素碱基或其核糖苷与细胞质蛋白结合，以便在小麦植株的叶片细胞中可视化并区分这些细胞分裂素的定位。在对叶片细胞中的细胞分裂素进行免疫定位的同时，我们对小麦植株根和地上部分之间细胞分裂素的游离碱基、其核苷酸和核糖苷的分布以及在添加了反式玉米素或异戊烯腺嘌呤的溶液中孵育叶片后其在韧皮部汁液中的存在情况进行了免疫测定。获得的数据显示，施加到叶片上的玉米素发生了核糖基化，并且其在韧皮部汁液中的水平升高，体内定位表明叶片导管中存在核糖基化形式的玉米素。这表明玉米素向其核糖苷的转化对于小麦中玉米素型细胞分裂素的地上部向根部运输很重要。外源异戊烯腺嘌呤未被修饰，而是以游离碱基的形式从叶片中扩散出来。这些代谢差异可能并不普遍，可能取决于植物物种和年龄。虽然对韧皮部汁液和根组织中细胞分裂素的测量对于确定细胞分裂素的运输最为关键，但对游离细胞分裂素碱基或其核糖基化形式的免疫定位研究可能是预测其在韧皮部和向根部运输的有价值信息来源。
