Download KNOX TRANSCRIPTION FACTORS IN MEDICAGO TRUNCATULA

Proceedings of the 57th Italian Society of Agricultural Genetics Annual Congress
Foggia, Italy – 16/19 September, 2013
ISBN 978-88-904570-3-6
Poster Communication Abstract – 3.18
KNOX TRANSCRIPTION FACTORS IN MEDICAGO TRUNCATULA
SYMBIOTIC NODULE ORGANOGENESIS
SCIARRA F.*, DI GIACOMO E.*, IANNELLI M.A.*, PENG J.**, CHEN R.**, PLET J.***,
FRUGIER F.***, FRUGIS G.*
*) Istituto di Biologia e Biotecnologia Agraria (IBBA), Operative Unit of Rome, Consiglio
Nazionale delle Ricerche (CNR), Via Salaria Km. 29,300, 00015 Monterotondo Scalo (Italy)
**) Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401 (US)
***) CNRS - Institut des Sciences du Végétal (ISV), 91198 Gif-sur-Yvette (France)
KNOX trascription factors, Medicago truncatula, nodule organogenesis, cytokinin signalling
Cytokinin signalling, mediated by the CRE1 receptor, plays a crucial role in symbiotic nodule
and lateral root formation in Medicago truncatula, a model for legume research (Gonzalez-Rizzo et
al., 2006; Plet et al., 2011). In seed plants, members of the KNOX homeodomain transcription
factor family control multiple hormonal pathways in the determination of cell fate and organ
formation at the shoot apical meristem, including cytokinin biosynthesis (Di Giacomo et al., 2013).
In M. truncatula, most KNOXs express in roots where rhizobia can induce symbiotic nodules
that develop through a persistent meristem.
Within the framework of a bilateral Scientific Cooperation between CNR (IT) and CNRS
(FR), we are investigating the role of KNOX genes in cytokinin-mediated symbiotic nodule
organogenesis in M. truncatula. Among several KNOXs (MtKNOXs) expressed in root (Di Giacomo
et al., 2008), we identified three cytokinin-regulated genes that may act downstream of the CRE1dependent cytokinin pathway. The three MtKNOX genes identified are homologous of the
Arabidopsis thaliana KNAT6 (MtKNOX7), KNAT-M (MtKNATM/FCL1) and KNAT3 (MtKNOX3).
Preliminary results suggested that MtKNOX3 and two additional MtKNOX3-like genes are
preferentially expressed in zone I and II of the symbiotic nodule, corresponding to nodule meristem
and prefixation zone. Functional studies involving the analysis of mutants and Agrobacterium
rhizogenes-mediated M. truncatula roots that misexpress MtKNOX genes have been carried out to
assess MtKNOXs role in cytokinin-mediated symbiotic nodule organogenesis.
Di Giacomo E, Sestili F, Iannelli MA, Testone G, Mariotti D, Frugis G (2008). Plant Mol Biol,
67:135-50
Di Giacomo E, Iannelli MA, Frugis G (2013). Plants 2:317-342
Gonzalez-Rizzo, S., Crespi, M., and Frugier, F. (2006). Plant Cell, 18:2680-2693
Plet J, Wasson A, Ariel F, Le Signor C, Baker D, Mathesius U, Crespi M, Frugier F (2011). Plant J
65:622-33