The NF-YC1 interacting protein SIN1, a member of the GRAS family, is required for nodule organogenesis, infection thread progression and lateral root growth

Marina Battaglia, Carolina Rípodas, Joaquín Clúa, Maël Baudin, O. Mario Aguilar, Andreas Niebel, María Eugenia Zanetti and Flavio Antonio Blanco

Résumé:

A C subunit of the heterotrimeric nuclear factor Y (NF-YC1) was shown to play a key role in nodule organogenesis and bacterial infection during the nitrogen fixing symbiosis established between Phaseolus vulgaris (common bean) and Rhizobium etli. In order to identify other proteins involved in this process, we used the yeast two hybrid system to screen for NF-YC1-interacting proteins. One of the positive clones encodes a member of the PAT1 subfamily of GRAS transcription factors. The protein, named SIN1, localizes both to the nucleus and the cytoplasm, but in transgenic Nicotiana benthamiana cells, bimolecular fluorescence complementarion suggested that the interaction with NF-YC1 takes place predominantly in the nucleus. SIN1 is expressed in aerial and root tissues, with higher levels in roots and nodules. Post-transcriptional gene silencing of SIN1 using RNA interference (RNAi) showed that the product of this gene is involved in lateral root elongation. However, root-cell organization, density of lateral roots and the length of root hairs were not affected by SIN1 RNAi. In addition, the expression of the RNAi of SIN1 led to a marked reduction in the number and size of nodules formed upon inoculation with R. etli and affected the progression of infection threads towards the nodule primordia. Expression of NF-YA1 and the G2/M transition cell cycle genes CycB and CDC2 was reduced in SIN1 RNAi roots. These data suggest that SIN1 plays a role in lateral root elongation and the establishment of root symbiosis in P. vulgaris.

Revue:

Plant Physiology

Lien:

www.plantphysiol.org/content/early/2014/01/14/pp.113.230896.short