microRNA (miRNA) participates in various physiological and biochemical processes in plants by regulating corresponding target genes. NAC [NAM (no apical meristem), ATAF (Arabidopsis transcription activation factor) and CUC (cup-shaped cotyledon)] transcription factors, usually as the targets of miR164, play important roles in the regulation of plant development and responses to abiotic and biotic stresses. In a previous study, the target gene of tae-miR164 in wheat was sequenced through degradome sequencing. In this study, we isolated the full-length cDNA of the candidate target gene, which is a NAC transcription factor gene in the NAM subfamily, and designated it as TaNAC21/22 after bioinformatics analysis. The interaction between TaNAC21/22 and tae-miR164 was confirmed experimentally through co-transformation of both genes in tobacco leaves. Transcript accumulation of TaNAC21/22 and tae-miR164 showed contrasting divergent expression patterns in wheat response to Puccinia striiformis f. sp. tritici (Pst). TaNAC21/22 was confirmed to be located in the nucleus and could function as a transcriptional activator. Silencing of the individual gene showed that TaNAC21/22 negatively regulates resistance to stripe rust. These results indicate that the target of tae-miR164, a novel NAC transcription factor from the NAM subfamily of wheat, plays an important role in regulating the resistance of host plants to stripe rust.
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