Bassil Elias, Hu Hening, Brown Patrick H
Pomology Department, University of California, Davis, California 95616, USA.
Plant Physiol. 2004 Oct;136(2):3383-95. doi: 10.1104/pp.104.040527. Epub 2004 Oct 1.
The only defined physiological role of boron in plants is as a cross-linking molecule involving reversible covalent bonds with cis-diols on either side of borate. Boronic acids, which form the same reversible bonds with cis-diols but cannot cross-link two molecules, were used to selectively disrupt boron function in plants. In cultured tobacco (Nicotiana tabacum cv BY-2) cells, addition of boronic acids caused the disruption of cytoplasmic strands and cell-to-cell wall detachment. The effect of the boronic acids could be relieved by the addition of boron-complexing sugars and was proportional to the boronic acid-binding strength of the sugar. Experiments with germinating petunia (Petunia hybrida) pollen and boronate-affinity chromatography showed that boronic acids and boron compete for the same binding sites. The boronic acids appear to specifically disrupt or prevent borate-dependent cross-links important for the structural integrity of the cell, including the organization of transvacuolar cytoplasmic strands. Boron likely plays a structural role in the plant cytoskeleton. We conclude that boronic acids can be used to rapidly and reversibly induce boron deficiency-like responses and therefore are useful tools for investigating boron function in plants.
硼在植物中唯一明确的生理作用是作为一种交联分子，与硼酸盐两侧的顺式二醇形成可逆的共价键。硼酸能与顺式二醇形成相同的可逆键，但不能交联两个分子，被用于选择性地破坏植物中的硼功能。在培养的烟草（烟草品种BY-2）细胞中，添加硼酸会导致细胞质丝的破坏和细胞间细胞壁的分离。硼酸的这种作用可以通过添加与硼络合的糖来缓解，且与糖的硼酸结合强度成正比。对矮牵牛（矮牵牛杂交种）花粉萌发和硼酸亲和色谱的实验表明，硼酸和硼竞争相同的结合位点。硼酸似乎特异性地破坏或阻止了对细胞结构完整性很重要的硼酸盐依赖性交联，包括液泡间细胞质丝的组织。硼可能在植物细胞骨架中起结构作用。我们得出结论，硼酸可用于快速、可逆地诱导类似硼缺乏的反应，因此是研究硼在植物中功能的有用工具。
