A key enzyme for flavin synthesis is required for nitric oxide and reactive oxygen species production in disease resistance
A key enzyme for flavin synthesis is required for nitric oxide and reactive oxygen species production in disease resistance
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DOI：
10.1111/j.1365-313x.2010.04206.x
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发表时间：
2010-06-01
期刊：
影响因子：
7.2
通讯作者：
Yoshioka, Hirofumi
中科院分区：
文献类型：
--
作者：
Asai, Shuta;Mase, Keisuke;Yoshioka, Hirofumi
一氧化氮(NO)和活性氧(ROS)在植物免疫中起着关键作用。然而，对这些自由基产生的调控机制还没有完全了解。超敏反应(HR)细胞死亡需要同时平衡地产生NO和ROS。在这项研究中，我们通过病毒诱导的基因沉默，通过筛选与丝裂原活化蛋白激酶介导的细胞死亡相关的基因，鉴定了编码参与黄素生物合成的双功能酶鸟苷三磷酸环水解酶II/3，4-二羟基-2-丁酮-4-磷酸合成酶的NbRibA。在NbRibA沉默的本氏烟草中，内源核黄素及其衍生物黄素单核苷酸(FMN)和黄素腺嘌呤二核苷酸(FAD)的水平降低，这是参与氧化还原反应的几种酶的重要辅基。沉默NbRibA不仅可以抑制HR细胞的死亡，还可以抑制INF1 elicitin和NbMEK2(NbMEK2DD)诱导的NO和ROS的产生，并诱导对致病疫霉和子囊菌的高度敏感性。加入核黄素、FMN或FAD可逆转INF1诱导的NbRibA沉默叶片的自由基产生和HR细胞死亡。这些结果表明，黄素的生物合成参与调节NO和ROS的产生，以及HR细胞的死亡。
P>Nitric oxide (NO) and reactive oxygen species (ROS) play key roles in plant immunity. However, the regulatory mechanisms of the production of these radicals are not fully understood. Hypersensitive response (HR) cell death requires the simultaneous and balanced production of NO and ROS. In this study we indentified NbRibA encoding a bifunctional enzyme, guanosine triphosphate cyclohydrolase II/3,4-dihydroxy-2-butanone-4-phosphate synthase, which participates in the biosynthesis of flavin, by screening genes related to mitogen-activated protein kinase-mediated cell death, using virus-induced gene silencing. Levels of endogenous riboflavin and its derivatives, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are important prosthetic groups for several enzymes participating in redox reactions, decreased in NbRibA-silenced Nicotiana benthamiana. Silencing NbRibA compromised not only HR cell death, but also the NO and ROS production induced by INF1 elicitin and a constitutively active form of NbMEK2 (NbMEK2DD), and also induced high susceptibility to oomycete Phytophthora infestans and ascomycete Colletotrichum orbiculare. Compromised radical production and HR cell death induced by INF1 in NbRibA-silenced leaves were rescued by adding riboflavin, FMN or FAD. These results indicate that flavin biosynthesis participates in regulating NO and ROS production, and HR cell death.