A Nuclear Factor Y Interacting Protein 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, FLAVIO ANTONIO BLANCO

PLANT PHYSIOLOGY.

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2014 vol. 164 p. 1430 - 1442

0032-0889

A C subunit of the heterotrimeric nuclear factor Y (NF-YC1) was shown to play a keyrole in nodule organogenesis and bacterial infection during the nitrogen fixing symbiosisestablished between Phaseolus vulgaris (common bean) and Rhizobium etli. In order toidentify other proteins involved in this process, we used the yeast two hybrid system toscreen for NF-YC1-interacting proteins. One of the positive clones encodes a member ofthe PAT1 subfamily of GRAS transcription factors. The protein, named SIN1, localizesboth to the nucleus and the cytoplasm, but in transgenic Nicotiana benthamiana cells,bimolecular fluorescence complementation suggested that the interaction with NF-YC1takes 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 usingRNA interference (RNAi) showed that the product of this gene is involved in lateral rootelongation. However, root-cell organization, density of lateral roots and the length of roothairs were not affected by SIN1 RNAi. In addition, the expression of the RNAi of SIN1led to a marked reduction in the number and size of nodules formed upon inoculationwith R. etli and affected the progression of infection threads towards the noduleprimordia. Expression of NF-YA1 and the G2/M transition cell cycle genes CycB andCDC2 was reduced in SIN1 RNAi roots. These data suggest that SIN1 plays a role inlateral root elongation and the establishment of root symbiosis in P. vulgaris.