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Comprehensive Genome-Wide Analysis of the Aux/IAA Gene Family in Eucalyptus: Evidence for the Role of EgrIAA4 in Wood Formation

Yu, Hong and Soler, Marçal and San Clemente, Hélène and Mila, Isabelle and Paiva, Jorge A. P. and Myburg, Alexander A. and Bouzayen, Mondher and Grima-Pettenati, Jacqueline and Cassan-Wang, Hua Comprehensive Genome-Wide Analysis of the Aux/IAA Gene Family in Eucalyptus: Evidence for the Role of EgrIAA4 in Wood Formation. (2015) Plant and Cell Physiology, 56 (4). 700-714. ISSN 0032-0781

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Official URL: http://dx.doi.org/10.1093/pcp/pcu215

Abstract

Auxin plays a pivotal role in various plant growth and development processes, including vascular differentiation. The modulation of auxin responsiveness through the auxin perception and signaling machinery is believed to be a major regulatory mechanism controlling cambium activity and wood formation. To gain more insights into the roles of key Aux/IAA gene regulators of the auxin response in these processes, we identified and characterized members of the Aux/IAA family in the genome of Eucalyptus grandis, a tree of worldwide economic importance. We found that the gene family in Eucalyptus is slightly smaller than that in Populus and Arabidopsis, but all phylogenetic groups are represented. High-throughput expression profiling of different organs and tissues highlighted several Aux/IAA genes expressed in vascular cambium and/or developing xylem, some showing differential expression in response to developmental (juvenile vs. mature) and/or to environmental (tension stress) cues. Based on the expression profiles, we selected a promising candidate gene, EgrIAA4, for functional characterization. We showed that EgrIAA4 protein is localized in the nucleus and functions as an auxin-responsive repressor. Overexpressing a stabilized version of EgrIAA4 in Arabidopsis dramatically impeded plant growth and fertility and induced auxin-insensitive phenotypes such as inhibition of primary root elongation, lateral root emergence and agravitropism. Interestingly, the lignified secondary walls of the interfascicular fibers appeared very late, whereas those of the xylary fibers were virtually undetectable, suggesting that EgrIAA4 may play crucial roles in fiber development and secondary cell wall deposition.

Item Type:Article
HAL Id:hal-01142476
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Instituto de Biologia Experimental e Tecnológica - iBET (PORTUGAL)
Other partners > University of Pretoria (SOUTH AFRICA)
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Deposited On:15 Apr 2015 10:32

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