Hirsche Jörg, García Fernández José M, Stabentheiner Edith, Großkinsky Dominik K, Roitsch Thomas
Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg, Würzburg, Germany.
Instituto de Investigaciones Químicas, CSIC, Universidad de Sevilla, Américo Vespucio, Isla de la Cartuja, Sevilla, Spain.
Plant Cell Physiol. 2017 Apr 1;58(4):691-701. doi: 10.1093/pcp/pcx020.
Pollen germination as a crucial process in plant development strongly depends on the accessibility of carbon as energy source. Carbohydrates, however, function not only as a primary energy source, but also as important signaling components. In a comprehensive study, we analyzed various aspects of the impact of 32 different sugars on in vitro germination of Arabidopsis pollen comprising about 150 variations of individual sugars and combinations. Twenty-six structurally different mono-, di- and oligosaccharides, and sugar analogs were initially tested for their ability to support pollen germination. Whereas several di- and oligosaccharides supported pollen germination, hexoses such as glucose, fructose and mannose did not support and even considerably inhibited pollen germination when added to germination-supporting medium. Complementary experiments using glucose analogs with varying functional features, the hexokinase inhibitor mannoheptulose and the glucose-insensitive hexokinase-deficient Arabidopsis mutant gin2-1 suggested that mannose- and glucose-mediated inhibition of sucrose-supported pollen germination depends partially on hexokinase signaling. The results suggest that, in addition to their role as energy source, sugars act as signaling molecules differentially regulating the complex process of pollen germination depending on their structural properties. Thus, a sugar-dependent multilayer regulation of Arabidopsis pollen germination is supported, which makes this approach a valuable experimental system for future studies addressing sugar sensing and signaling.
花粉萌发作为植物发育中的一个关键过程，强烈依赖于碳作为能源的可及性。然而，碳水化合物不仅作为主要能源发挥作用，还作为重要的信号成分。在一项全面研究中，我们分析了32种不同糖类对拟南芥花粉体外萌发的影响的各个方面，这些糖类包括约150种单个糖类及其组合的变体。最初测试了26种结构不同的单糖、双糖和寡糖以及糖类似物支持花粉萌发的能力。虽然几种双糖和寡糖支持花粉萌发，但己糖如葡萄糖、果糖和甘露糖在添加到支持萌发的培养基中时，不支持甚至显著抑制花粉萌发。使用具有不同功能特性的葡萄糖类似物、己糖激酶抑制剂甘露庚酮糖以及葡萄糖不敏感的己糖激酶缺陷型拟南芥突变体gin2-1进行的补充实验表明，甘露糖和葡萄糖介导的对蔗糖支持的花粉萌发的抑制部分取决于己糖激酶信号传导。结果表明，除了作为能源的作用外，糖类还作为信号分子，根据其结构特性差异调节花粉萌发的复杂过程。因此，支持了拟南芥花粉萌发的糖依赖性多层调节，这使得该方法成为未来研究糖感知和信号传导的有价值的实验系统。
