The Identification of Maize and Arabidopsis Type I FLAVONE SYNTHASEs Links Flavones with Hormones and Biotic Interactions
The Identification of Maize and Arabidopsis Type I FLAVONE SYNTHASEs Links Flavones with Hormones and Biotic Interactions
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DOI：
10.1104/pp.15.00515
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发表时间：
2015-10-01
期刊：
影响因子：
7.4
通讯作者：
Casati, Paula
中科院分区：
文献类型：
--
作者：
Falcone Ferreyra, Maria Lorena;Emiliani, Julia;Casati, Paula
黄酮是黄酮类化合物的一大类，具有多种功能，广泛分布于陆地植物中。有两类不同类别的黄酮合成酶 (FNS) 可以催化黄烷酮转化为黄酮。 FNSI 类包括可溶性 Fe(2+/)2-酮戊二酸依赖性双加氧酶，FNSII 酶是氧和 NADPH 依赖性细胞色素 P450 膜结合单加氧酶。在这里，我们描述了玉米 (Zea mays) 和拟南芥 (Arabidopsis thaliana) 中 FNSI 酶的鉴定和表征。在玉米中，ZmFNSI-1 在表达 3-脱氧类黄酮 R2R3-MYB 调节因子 P1 的穗丝和果皮中以显着较高的水平表达，表明 ZmFNSI-1 可能是合成黄酮 O-糖苷的主要酶。我们还在此表明，与 ZmFNSI-1 相似的拟南芥酶 DOWNY MILDEW RESISTANT6 (AtDMR6) 具有 FNSI 活性。虽然 dmr6 突变体显示出对丁香假单胞菌的敏感性丧失，但表达 ZmFNSI-1 的转基因 dmr6 植物显示出与野生型植物相似的敏感性，表明 ZmFNSI-1 可以补充突变体表型。 AtDMR6 表达分析显示出组织和发育阶段依赖性模式，在茎生叶和衰老叶中高表达。最后，我们发现拟南芥茎叶和衰老叶子积累芹菜素，证明拟南芥植物具有参与黄酮生物合成的 FNSI 活性。这里提出的结果还表明拟南芥中黄酮和水杨酸途径之间存在交叉对话。通过这种方式，病原体会诱导黄酮减少水杨酸，从而增加易感性。
Flavones are a major group of flavonoids with diverse functions and are extensively distributed in land plants. There are two different classes of FLAVONE SYNTHASE (FNS) enzymes that catalyze the conversion of the flavanones into flavones. The FNSI class comprises soluble Fe(2+/)2-oxoglutarate-dependent dioxygenases, and FNSII enzymes are oxygen- and NADPH-dependent cytochrome P450 membrane-bound monooxygenases. Here, we describe the identification and characterization of FNSI enzymes from maize (Zea mays) and Arabidopsis (Arabidopsis thaliana). In maize, ZmFNSI-1 is expressed at significantly higher levels in silks and pericarps expressing the 3-deoxy flavonoid R2R3-MYB regulator P1, suggesting that ZmFNSI-1 could be the main enzyme for the synthesis of flavone O-glycosides. We also show here that DOWNY MILDEW RESISTANT6 (AtDMR6), the Arabidopsis homologous enzyme to ZmFNSI-1, has FNSI activity. While dmr6 mutants show loss of susceptibility to Pseudomonas syringae, transgenic dmr6 plants expressing ZmFNSI-1 show similar susceptibility to wild-type plants, demonstrating that ZmFNSI-1 can complement the mutant phenotype. AtDMR6 expression analysis showed a tissue- and developmental stage-dependent pattern, with high expression in cauline and senescing leaves. Finally, we show that Arabidopsis cauline and senescing leaves accumulate apigenin, demonstrating that Arabidopsis plants have an FNSI activity involved in the biosynthesis of flavones. The results presented here also suggest cross talk between the flavone and salicylic acid pathways in Arabidopsis; in this way, pathogens would induce flavones to decrease salicylic acid and, hence, increase susceptibility.