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The Tomato Aux/IAA Transcription Factor IAA9 Is Involved in Fruit Development and Leaf Morphogenesis

Wang, Hua and Jones, Brian and Li, Zhengguo and Frasse, Pierre and Delalande, Corinne and Regad, Farid and Chaabouni, Salma and Latché, Alain and Pech, Jean-Claude and Bouzayen, Mondher The Tomato Aux/IAA Transcription Factor IAA9 Is Involved in Fruit Development and Leaf Morphogenesis. (2005) The Plant Cell, 1. 2676-2692. ISSN 1040-4651

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Official URL: http://dx.doi.org//10.1105/tpc.105.033415


Auxin/indole-3-acetic acid (Aux/IAA) proteins are transcriptional regulators that mediate many aspects of plant responses to auxin. While functions of most Aux/IAAs have been defined mainly by gain-of-function mutant alleles in Arabidopsis thaliana, phenotypes associated with loss-of-function mutations have been scarce and subtle. We report here that the downregulation of IAA9, a tomato (Solanum lycopersicum) gene from a distinct subfamily of Aux/IAA genes, results in a pleiotropic phenotype, consistent with its ubiquitous expression pattern. IAA9-inhibited lines have simple leaves instead of wild-type compound leaves, and fruit development is triggered before fertilization, giving rise to parthenocarpy. This indicates that IAA9 is a key mediator of leaf morphogenesis and fruit set. In addition, antisense plants displayed auxin-related growth alterations, including enhanced hypocotyl/stem elongation, increased leaf vascularization, and reduced apical dominance. Auxin dose–response assays revealed that IAA9 downregulated lines were hypersensitive to auxin, although the only early auxin-responsive gene that was found to be upregulated in the antisense lines was IAA3. The activity of the IAA3 promoter was stimulated in the IAA9 antisense genetic background, indicating that IAA9 acts in planta as a transcriptional repressor of auxin signaling. While no mutation in any member of subfamily IV has been reported to date, the phenotypes associated with the downregulation of IAA9 reveal distinct and novel roles for members of the Aux/IAA gene family.

Item Type:Article
Additional Information:The original PDF of the article can be found at The Plant Cell website : http://www.plantcell.org/cgi/content/abstract/17/10/2676
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Other partners > Chongqing University (CHINA)
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Deposited On:12 Nov 2008 08:25

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