Yin Ruohe, Han Kerstin, Heller Werner, Albert Andreas, Dobrev Petre I, Zažímalová Eva, Schäffner Anton R
Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
Research Unit Environmental Simulation, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
New Phytol. 2014 Jan;201(2):466-475. doi: 10.1111/nph.12558. Epub 2013 Oct 25.
Polar auxin transport (PAT) plays key roles in the regulation of plant growth and development. Flavonoids have been implicated in the inhibition of PAT. However, the active flavonoid derivative(s) involved in this process in vivo has not yet been identified. Here, we provide evidence that a specific flavonol bis-glycoside is correlated with shorter plant stature and reduced PAT. Specific flavonoid-biosynthetic or flavonoid-glycosylating steps were genetically blocked in Arabidopsis thaliana. The differential flavonol patterns established were analyzed by high-performance liquid chromatography (HPLC) and related to altered plant stature. PAT was monitored in stem segments using a radioactive [(3)H]-indole-3-acetic acid tracer. The flavonoid 3-O-glucosyltransferase mutant ugt78d2 exhibited a dwarf stature in addition to its altered flavonol glycoside pattern. This was accompanied by reduced PAT in ugt78d2 shoots. The ugt78d2-dependent growth defects were flavonoid dependent, as they were rescued by genetic blocking of flavonoid biosynthesis. Phenotypic and metabolic analyses of a series of mutants defective at various steps of flavonoid formation narrowed down the potentially active moiety to kaempferol 3-O-rhamnoside-7-O-rhamnoside. Moreover, the level of this compound was negatively correlated with basipetal auxin transport. These results indicate that kaempferol 3-O-rhamnoside-7-O-rhamnoside acts as an endogenous PAT inhibitor in Arabidopsis shoots.
极性生长素运输（PAT）在植物生长和发育的调控中起着关键作用。黄酮类化合物与PAT的抑制有关。然而，体内参与这一过程的活性黄酮类衍生物尚未被确定。在此，我们提供证据表明一种特定的黄酮醇双糖苷与植株矮小和PAT降低相关。在拟南芥中对特定的黄酮类生物合成或黄酮类糖基化步骤进行了基因阻断。通过高效液相色谱（HPLC）分析所建立的不同黄酮醇模式，并将其与植株高度的改变相关联。使用放射性[（3）H] - 吲哚 - 3 - 乙酸示踪剂监测茎段中的PAT。黄酮类3 - O - 葡萄糖基转移酶突变体ugt78d2除了其黄酮醇糖苷模式改变外，还表现出矮小的株型。这伴随着ugt78d2茎中PAT的降低。ugt78d2依赖性生长缺陷是黄酮类依赖性的，因为它们通过黄酮类生物合成的基因阻断得以挽救。对一系列在黄酮类形成的各个步骤有缺陷的突变体进行的表型和代谢分析将潜在的活性部分缩小到山奈酚3 - O - 鼠李糖苷 - 7 - O - 鼠李糖苷。此外，该化合物的水平与生长素的向基运输呈负相关。这些结果表明山奈酚3 - O - 鼠李糖苷 - 7 - O - 鼠李糖苷在拟南芥茎中作为一种内源性PAT抑制剂发挥作用。
