Transcriptional and functional variation of NF-YC1 in genetically diverse accessions of Phaseolus vulgaris during the symbiotic association with Rhizobium etli

L. MAZZIOTTA, M. A. REYNOSO, O. M. AGUILAR, F. A. BLANCO & M. E. ZANETTI

PLANT BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012

1435-8603

Phaseolus vulgaris (common bean) is an agronomic important legume crop native toAmerica, where two centres of genetic diversification (GD) are recognised, one in Mesoamericaand the other in the south Andes. Mesoamerican bean accessions have preferentialand more efficient nodulation with Rhizobium etli strains carrying the allelenodC type-a, which is predominant in soils of Mesoamerica. It was previously demonstratedthat the host nuclear factor NF-YC1, which is involved in nodule formationand rhizobial infection, contributes to this preferential selection and enhances nodulationin the domesticated accession NAG12 from Mesoamerica. Here, we show thatboth domesticated and wild Mesoamerican beans exhibit higher nodulation performancewith a nodC type-a than with a nodC type-d strain. Transcripts of NF-YC1 significantlyincreased in roots of these accessions 24 h post-inoculation (hpi) with thenodC type-a strain. On the other hand, accessions from the Andean GD centre formeda higher number of nodules with a strain carrying the nodC type-d, which is predominantin Andean soils. However, NF-YC1 transcript levels did not exhibit significantchanges in Andean accessions upon inoculation with the nodC type-d strain, at least at24 hpi. RNA interference (RNAi)-mediated gene silencing of NF-YC1 in the domesticatedAndean accession Alubia showed that NF-YC1 or a closely related member ofthis family is required for nodule formation and bacterial infection, in agreementwith observations in Mesoamerican common beans. Isolation and sequencing of thefull-length ORF of NF-YC1 from Alubia revealed that it was identical to the sequencepreviously identified in the Mesoamerican accession NAG12. Interestingly, overexpressionof NF-YC1 had a negative impact on nodule formation in the Alubia accession,independently of the R. etli lineage. Our findings suggest that transcriptionaland functional variation of NF-YC1 occurs among genetically diverse bean accessions,which might positively or negatively contribute to the fine-tuning mechanisms thatregulate nodule formation in the common bean?R. etli symbiosis.