"Translational and Structural Requirements of the Early Nodulin Gene enod40, a Short-Open Reading Frame-Containing RNA, for Elicitation of a Cell-Specific Growth Response in the Alfalfa Root Cortex". 

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Carolina Sousa,^{1, a} Christina Johansson,^{1, b} Celine Charon,¹ Hamid Manyani,¹ Christof  Sautter,² Adam Kondorosi,^{1, 3,*} and Martin Crespi¹

^* Corresponding author. Mailing address: Institut des Sciences Végétales, Centre National de la Recherche Scientifique, F-91198 Gif-sur-Yvette, France. Phone: 33-1-69823696. Fax: 33-1-69823695.
E-mail: Adam.Kondorosi@isv.cnrs-gif.fr.

^a Present address: Department of Microbiology and Parasitology, University of Seville, 41080 Seville, Spain.
^b Present address: Department of Molecular and Structural Biology, Aarhus University, DK-8000 Aarhus, Denmark. 

A diversity of mRNAs containing only short open reading frames (sORF-RNAs; encoding less than 30 amino acids) have been shown to be induced in growth and differentiation processes. The early nodulin gene enod40, coding for a 0.7-kb sORF-RNA, is expressed in the nodule primordium developing in the root cortex of leguminous plants after infection by symbiotic bacteria. Ballistic microtargeting of this gene into Medicago roots induced division of cortical cells. Translation of two sORFs (I and II, 13 and 27 amino acids, respectively) present in the conserved 5' and 3' regions of enod40 was required for this biological activity. These sORFs may be translated in roots via a reinitiation mechanism. In vitro translation products starting from the ATG of sORF I were detectable by mutating enod40 to yield peptides larger than 38 amino acids. Deletion of a Medicago truncatula enod40 region between the sORFs, spanninga predicted RNA structure, did not affect their translation butresulted in significantly decreased biological activity. Our datareveal a complex regulation of enod40 action, pointing to a role of sORF-encoded peptides and structured RNA signals in developmental processes involving sORF-RNAs.

1. "enod40, a Gene Expressed During Nodular Organogenesis, Codes for a Non-Translatable RNA Involved in Plant Growth".

2. "Nuclear Ribosomes and RNA-RNA Duplexes".

3. "Nuclear Polyanions as De-Repressors of Synthesis of Ribonucleic Acid".

4. "Mated Models of Gene Regulation in Eukaryotes".

5. "Selective Gene De-Repression by De-Repressor RNA".

6. "Nuclear RNA Species Activate DNA Transcription within Chromatin".

7. "Oncogenes as Molecular Targets within Active Chromatin".