Flavonoids are plant-specific antioxidant compounds that modulate plant development, which include flavonols and anthocyanins subclasses. In Arabidopsis thaliana, mutants in genes encoding each step in the flavonoid biosynthetic pathway have been isolated. We used these mutants to examine the role of flavonols in initiation and emergence of lateral roots and asked whether this regulation occurs through scavenging ROS. The tt4 mutants have a defect in the first committed step of flavonoid biosynthesis and have increased lateral root emergence. This phenotype was reversed by both genetic and chemical complementation. Using these flavonoid biosynthetic mutants, we eliminated roles for anthocyanins and the flavonols, quercetin and isorhamnetin, in controlling lateral root development. The tt7-2 mutant has a defect in a branchpoint enzyme blocking quercetin biosynthesis that led to elevated levels of kaempferol and reduced lateral roots. Kaempferol accumulated within lateral root primordia and was significantly increased in tt7-2. Thee data are consistent with kaempferol acting as a negative regulator of lateral root emergence. We examined ROS accumulation above and within the primordia using a general ROS sensor and identified increased signal above the primordia of the tt4 and tt7-2 mutants compared to wild type. Using a superoxide specific sensor, we detected a decrease in signal within the primordia of tt7-2, but not the tt4 mutant, compared to wild type. Together, these results support a model in which increased level of kaempferol in tt7-2 leads to a reduction in superoxide concentration in the lateral root primordia thereby reducing ROS-stimulated lateral root emergence.

中文翻译：

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黄酮醇通过清除拟南芥中的活性氧来调节侧根的出苗。

黄酮类化合物是植物特有的抗氧化剂化合物，可调节植物发育，其中包括黄酮醇和花青素亚类。在拟南芥中，已分离出编码类黄酮生物合成途径每个步骤的基因突变体。我们使用这些突变体检查了黄酮醇在侧根的萌芽和萌发中的作用，并询问这种调节是否通过清除ROS发生。tt4突变体在类黄酮生物合成的第一步中存在缺陷，并增加了侧根的出苗。这种表型被遗传和化学互补所逆转。使用这些类黄酮生物合成突变体，我们消除了花色素苷和黄酮醇，槲皮素和异鼠李素在控制侧根发育中的作用。tt7-2突变体在阻断槲皮素生物合成的分支点酶中存在缺陷，从而导致山fer酚水平升高和侧根减少。山emp酚在侧根原基中积累，并在tt7-2中显着增加。您的数据与山emp酚作为侧根出苗的负向调节剂是一致的。我们使用通用的ROS传感器检查了原基上方和内部的ROS积累，并确定了与野生型相比tt4和tt7-2突变体的原基上方信号增加。与野生型相比，使用超氧化物歧化酶特异性传感器，我们在tt7-2的原基内检测到信号减少，但未检测到tt4突变体。一起，