Family-Wide Survey of miR169s and NF-YAs and Their Expression Profiles Response to Abiotic Stress in Maize Roots

Previous studies have identified miR169/NF-YA modules are important regulators of plant development and stress responses. Currently, reported genome sequence data offers an opportunity for global characterization of miR169 and NF-YA genes, which may provide insights into the molecular mechanisms of the miR169/NF-YA modules in maize. In our study, fourteen NF-YA transcription factors with conserved domains were identified based on maize genome loci. The miR169 gene family has 18 members that generate 10 mature products, and 8 of these mature miR169 members could target 7 of 14 ZmNF-YA genes in maize. The seven ZmNF-YA proteins were localized to the nucleus while lacked transcriptional activity. We investigated the expression patterns of the zma-miR169 members and their targeted ZmNF-YA genes in maize roots treated by drought stress (polyethylene glycol, PEG), hormone stress (abscisic acid, ABA), and salt stress (NaCl). The zma-miR169 family members were downregulated in short term (0,48 h) and generally upregulated over the long term (15 days) in response to the three abiotic stress conditions. Most of the targeted ZmNF-YA genes exhibited a reverse correlation with zma-miR169 gene expression over both the short term and long term. Maize root elongation was promoted by PEG and ABA but repressed by NaCl over the long term. Apparently, ZmNF-YA14 expression perfectly matched the zma-miR169 expression and corresponded to root growth reversely.