The auxin Sl-IAA17 transcriptional repressor controls fruit size via the regulation of the endoreduplication-related cell expansion

Liyan Su, Carole Bassa, Corinne Audran, Catherine Cheniclet, Christian Chevalier, Mondher Bouzayen, Jean-Paul Roustan and Christian Chervin

Résumé:

Auxin is known to regulate cell division and cell elongation, thus controlling plant growth and development. Part of the auxin signaling pathway depends on the fine tuned degradation of the Aux/IAA transcriptional repressors. Recent evidence indicates that Aux/IAA proteins play a role in fruit development in tomato (Solanum lycopersicum Mill.), a reference species for fleshy fruit development. We report here on the functional characterization of Sl-IAA17 during tomato fruit development. Silencing of Sl-IAA17 by RNAi strategy resulted in the production of bigger fruit than wild types. Histological analyses of fruit organ and tissues demonstrated that this phenotype was associated with a thicker pericarp, rather than larger locules and/or bigger number of seeds. Microscopy analysis demonstrated that the higher pericarp thickness in Sl-IAA17 RNAi fruits was not due to a larger number of cells, but to the the increase in cell size. Finally, we observed that the cell expansion in the transgenic fruits is tightly coupled with higher ploidy levels than in the wild type, suggesting a stimulation of the endoreduplication process. In conclusion, this work provides new insights about the function of Aux/IAA pathway in fleshy fruit development, especially on fruit size and cell size determination in tomato.

Revue:

Plant & Cell Physiology

Lien:

pcp.oxfordjournals.org/content/early/2014/09/16/pcp.pcu124.abstract