Transcriptional and functional variation of NF-YC1 in

LUCIA MAZZIOTA, MAURICIO ALBERTO REYNOSOA, O. MARIO AGUILAR, FLAVIO ANTONIO BLANCO AND MARÍA EUGENIA ZANETTI

PLANT BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 vol. 15 p. 808 - 818

1435-8603

Phaseolus vulgaris (common bean) is an agronomical important legume crop native of America, where two centers of genetic diversification (GD) are recognized, one in Mesoamerica and the other in the South Andes. Mesoamerican bean accessions exhibit a preferential and more efficient nodulation with Rhizobium etli strains carrying the allele nodC type-á, which is predominant in soils of Mesoamerica. It was previously demonstrated that the host nuclear factor NF-YC1, which is involved in nodule formation and rhizobial infection, contributes to this preferential selection and enhance nodulation in the domesticated accession from Mesoamerica NAG12. Here, we show that both domesticated and wild Mesoamerican beans exhibited a higher nodulation performance with a nodC type-á than with a nodC type-ä strain. Transcripts of NF-YC1 significantly increased in roots of these accessions at 24 hours post-inoculation with the nodC type-á strain. On the other hand, accessions from the Andean GD center formed a higher number of nodules with a strain carrying the nodC type-ä, which is predominant in the Andean soils. However, NF-YC1 transcript levels exhibited significantly changes in Andean accessions upon inoculation with the nodC type-ä strain, at least at 24 hpi. RNA interference (RNAi) mediated gene silencing of NF-YC1 in the domesticated Andean accession Alubia showed that NF-YC1 or a close related member of this family is required for nodule formation and bacterial infection, in agreement with that observed in Mesoamerican common beans. Isolation and sequencing of the full length open reading frame of NF-YC1 from Alubia revealed that it was identical to the sequence previously identified in the Mesoamerican accession NAG12. Interestingly, overexpression of NF-YC1 had a negative impact on nodule formation in the Alubia accession, independently of the R. etli lineage. Our findings suggest that transcriptional and functional variation of NF-YC1 occurs among genetically diverse bean accessions, which might positively or negatively contribute to the fine-tuning mechanisms that regulate nodule formation in the common bean- R. etli symbiosis.