Conserved Functions of Arabidopsis and Rice CC-Type Glutaredoxins in Flower Development and Pathogen Response
a Max Planck Institute for Plant Breeding Research, Plant Molecular Genetics, 50829 Cologne, Germany
b School of Biological Sciences/Plant Science Initiative, University of Nebraska–Lincoln, Nebraska 68588, USA
c Botany Department, University of Osnabrück, 40969 Osnabrück, Germany
d Max Planck Institute for Plant Breeding Research, Plant Microbe Interactions, 50829 Cologne, Germany
1 To whom correspondence should be addressed. E-mail zachgo{at}biologie.uni-osnabrueck.de, fax +49 541 9692245, tel. +49 541 9692860.
Glutaredoxins (GRXs) are ubiquitous oxidoreductases that play a crucial role in response to oxidative stress by reducing disulfides in various organisms. In planta, three different GRX classes have been identified according to their active site motifs. CPYC and CGFS classes are found in all organisms, whereas the CC-type class is specific for higher land plants. Recently, two Arabidopsis CC-type GRXs, ROXY1 and ROXY2, were shown to exert crucial functions in petal and anther initiation and differentiation. To analyze the function of CC-type GRXs in the distantly related monocots, we isolated and characterized OsROXY1 and OsROXY2—two rice homologs of ROXY1. Both genes are expressed in vegetative and reproductive stages. Although rice flower morphology is distinct from eudicots, OsROXY1/2 floral expression patterns are similar to their Arabidopsis counterparts ROXY1/2. Complementation experiments demonstrate that OsROXY1 and OsROXY2 can fully rescue the roxy1 floral mutant phenotype. Overexpression of OsROXY1, OsROXY2, and ROXY1 in Arabidopsis causes similar vegetative and reproductive plant developmental defects. ROXY1 and its rice homologs thus exert a conserved function during eudicot and monocot flower development. Strikingly, overexpression of these CC-type GRXs also leads to an increased accumulation of hydrogen peroxide levels and hyper-susceptibility to infection from the necrotrophic pathogen Botrytis cinerea, revealing the importance of balanced redox processes in flower organ development and pathogen defence.
Key Words: ROXY1 • glutaredoxin • Arabidopsis • rice • flower development • pathogen defence • Botrytis cinerea
2 These authors contributed equally to this work.
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  M. Ziemann, M. Bhave, and S. Zachgo Origin and Diversification of Land Plant CC-Type Glutaredoxins Gen Biol Evol, August 21, 2009; 2009(0): 265 - 277. [Abstract] [Full Text] [PDF]
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