Brassinosteroids Antagonize Gibberellin- and Salicylate-Mediated Root Immunity in Rice
Brassinosteroids (BRs) are a unique class of plant steroid hormones that orchestrate myriad growth and developmental processes. Although BRs have long been known to protect plants from a suite of biotic and abiotic stresses, our understanding of the underlying molecular mechanisms is still rudimenta...
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| Vydané v: | Plant physiology (Bethesda) Ročník 158; číslo 4; s. 1833 - 1846 |
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| Hlavní autori: | , , , , , , , , |
| Médium: | Journal Article |
| Jazyk: | English |
| Vydavateľské údaje: |
Rockville, MD
American Society of Plant Biologists
01.04.2012
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| Predmet: | |
| ISSN: | 0032-0889, 1532-2548, 1532-2548 |
| On-line prístup: | Získať plný text |
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| Shrnutí: | Brassinosteroids (BRs) are a unique class of plant steroid hormones that orchestrate myriad growth and developmental processes. Although BRs have long been known to protect plants from a suite of biotic and abiotic stresses, our understanding of the underlying molecular mechanisms is still rudimentary. Aiming to further decipher the molecular logic of BR-modulated immunity, we have examined the dynamics and impact of BRs during infection of rice (Oryza sativa) with the root oomycete Pythium graminicola. Challenging the prevailing view that BRs positively regulate plant innate immunity, we show that P. graminicola exploits BRs as virulence factors and hijacks the rice BR machinery to inflict disease. Moreover, we demonstrate that this immunesuppressive effect of BRs is due, at least in part, to negative cross talk with salicylic acid (SA) and gibberellic acid (GA) pathways. BR-mediated suppression of SA defenses occurred downstream of SA biosynthesis, but upstream of the master defense regulators NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 and OsWRKY45. In contrast, BR alleviated GA-directed immune responses by interfering at multiple levels with GA metabolism, resulting in indirect stabilization of the DELLA protein and central GA repressor SLENDER RICE1 (SLR1). Collectively, these data favor a model whereby P. graminicola coopts the plant BR pathway as a decoy to antagonize effectual SA-and GA-mediated defenses. Our results highlight the importance of BRs in modulating plant immunity and uncover pathogen-mediated manipulation of plant steroid homeostasis as a core virulence strategy. |
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| Bibliografia: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 Some figures in this article are displayed in color online but in black and white in the print edition. This work was supported by grants from the Special Research Fund of Ghent University, by a specialization fellowship of the Flemish Institute for the stimulation of scientific-technological research in industry (to E.V.B.), and by a postdoctoral fellowship of the Research Foundation–Flanders (to D.D.V.). Present address: Ronald Lab, Department of Plant Pathology, University of California, Davis, CA 95616. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Monica Höfte (monica.hofte@ugent.be). The online version of this article contains Web-only data. www.plantphysiol.org/cgi/doi/10.1104/pp.112.193672 Open Access articles can be viewed online without a subscription. |
| ISSN: | 0032-0889 1532-2548 1532-2548 |
| DOI: | 10.1104/pp.112.193672 |