Altered Disease Development in the eui Mutants and Eui Overexpressors Indicates that Gibberellins Negatively Regulate Rice Basal Disease Resistance

Gibberellins (GAs) form a group of important plant tetracyclic diterpenoid hormones that are involved in many aspects of plant growth and development. Emerging evidence implicates that GAs also play roles in stress responses. However, the role of GAs in biotic stress is largely unknown. Here, we rep...

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Bibliographic Details
Published in:Molecular plant 2008-05, Vol.1 (3), p.528-537
Main Authors: Yang, Dong-Lei, Li, Qun, Deng, Yi-Wen, Lou, Yong-Gen, Wang, Mu-Yang, Zhou, Guo-Xing, Zhang, Ying-Ying, He, Zu-Hua
Format: Article
Language:English
Subjects:
Cyclopentanes - metabolism
Gene Expression Regulation, Fungal
Gibberellins - pharmacology
Immunity, Innate - drug effects
Magnaporthe - genetics
Magnaporthe - growth & development
Magnaporthe - pathogenicity
Mutation
Oryza - drug effects
Oryza - immunology
Oryza - microbiology
Oryza - physiology
Oxylipins - metabolism
Plant Diseases - genetics
Plant Diseases - immunology
Plant Diseases - microbiology
Plant Growth Regulators - metabolism
Plant Leaves - microbiology
Salicylic Acid - metabolism
Seedlings - metabolism
Triazoles - pharmacology
Xanthomonas - genetics
Xanthomonas - growth & development
Xanthomonas - pathogenicity
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Summary:Gibberellins (GAs) form a group of important plant tetracyclic diterpenoid hormones that are involved in many aspects of plant growth and development. Emerging evidence implicates that GAs also play roles in stress responses. However, the role of GAs in biotic stress is largely unknown. Here, we report that knockout or overexpression of the Elongated uppermost internode (Eui) gene encoding a GA deactivating enzyme compromises or increases, respectively, disease resistance to bacterial blight (Xanthomonas oryzae pv. oyrzae) and rice blast (Magnaporthe oryzae). Exogenous application of GA3 and the inhibitor of GA synthesis (uniconazol) could increase disease susceptibility and resistance, respectively, to bacterial blight. Similarly, uniconazol restored disease resistance of the eui mutant and GA3 decreased disease resistance of the Eui overexpressors to bacterial blight. Therefore, the change of resistance attributes to GA levels. In consistency with this, the GA metabolism genes OsGA20ox2 and OsGA2ox1 were down-regulated during pathogen challenge. We also found that PR1a induction was enhanced but the SA level was decreased in the Eui overexpressor, while the JA level was reduced in the eui mutant. Together, our current study indicates that GAs play a negative role in rice basal disease resistance, with EUI as a positive modulator through regulating the level of bioactive GAs.
ISSN:1674-2052
1752-9867
DOI:10.1093/mp/ssn021