The Plant Journal (2010) 62, 911-924

Shuta Asai, Keisuke Mase and Hirofumi Yoshioka (2010)
A key enzyme for flavin synthesis is required for nitric oxide and reactive oxygen species production in disease resistance
The Plant Journal 62 (6), 911-924
Abstract: 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 (NbMEK2^DD), 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.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Hirofumi Yoshioka

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora infestans
	Colletotrichum orbiculare