Flavonols modulate lateral root emergence by scavenging reactive oxygen species in Arabidopsis thaliana.
Flavonols modulate lateral root emergence by scavenging reactive oxygen species in Arabidopsis thaliana.
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DOI：
10.1074/jbc.ra120.014543
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发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Muday GK
中科院分区：
文献类型：
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作者：
Chapman JM;Muday GK
黄酮类化合物是一类特殊的代谢产物，其亚类包括黄酮醇和花青素，其具有独特的抗氧化剂性质。黄曲霉素调节植物的发育，但它们是否以及如何影响侧根的发育尚不清楚。我们研究了黄酮醇在这一过程中的潜在作用，利用拟南芥突变体与类黄酮生物合成的关键酶编码基因的缺陷。我们观察到tt 4和fls 1突变体，不产生黄酮醇，增加了侧根的出现。tt 4根表型通过遗传和化学互补被逆转。为了更具体地定义所涉及的类黄酮，我们测试了一系列类黄酮生物合成突变体，消除了花青素和黄酮醇类槲皮素和异鼠李素在调节侧根发育中的作用。相反，两个tt 7突变等位基因，在分支点酶的缺陷，阻止槲皮素的生物合成，形成侧根的数量减少和tt 7 -2山萘酚水平升高。使用黄酮醇特异性染料，我们观察到，在tt 7 -2突变体中，山奈酚积累侧根原基在更高的水平比野生型。这些数据与山奈酚或下游衍生物作为侧根出现的负调节剂是一致的。我们研究了ROS的积累，使用ROS响应探针，并发现减少荧光的超氧化物选择性探针内的tt 7 -2的原基与野生型相比，但不是在tt 4突变体，与这些突变体对侧根出现相反的影响一致。这些结果支持了一个模型，其中增加的山奈酚水平的tt 7 -2的侧根原基减少超氧化物浓度和ROS刺激的侧根出现。
Flavonoids are a class of specialized metabolites with subclasses including flavonols and anthocyanins, which have unique properties as antioxidants. Flavonoids modulate plant development, but whether and how they impact lateral root development is unclear. We examined potential roles for flavonols in this process using Arabidopsis thaliana mutants with defects in genes encoding key enzymes in flavonoid biosynthesis. We observed the tt4 and fls1 mutants, which produce no flavonols, have increased lateral root emergence. The tt4 root phenotype was reversed by genetic and chemical complementation. To more specifically define the flavonoids involved, we tested an array of flavonoid biosynthetic mutants, eliminating roles for anthocyanins and the flavonols quercetin and isorhamnetin in modulating lateral root development. Instead, two tt7 mutant alleles, with defects in a branchpoint enzyme blocking quercetin biosynthesis, formed reduced numbers of lateral roots and tt7-2 had elevated levels of kaempferol. Using a flavonol-specific dye, we observed that in the tt7-2 mutant, kaempferol accumulated within lateral root primordia at higher levels than wild-type. These data are consistent with kaempferol, or downstream derivatives, acting as a negative regulator of lateral root emergence. We examined ROS accumulation using ROS-responsive probes and found reduced fluorescence of a superoxide-selective probe within the primordia of tt7-2 compared with wild-type, but not in the tt4 mutant, consistent with opposite effects of these mutants on lateral root emergence. These results support a model in which increased level of kaempferol in the lateral root primordia of tt7-2 reduces superoxide concentration and ROS-stimulated lateral root emergence.