Identification and evaluation of conserved miR164-targeted Aeluropus littoralis NAC genes in response to abiotic stress

MicroRNAs are a large class of small and non-coding RNAs that regulate gene expression by binding target mRNA, which leads to cleavage or translational inhibition. Plant miR164 family is highly conserved and is involved in the responses of plants to biotic stresses through the regulation of their target NAC genes. In the present study, 68 putative NAC domain-encoding genes (NACs) were identified in Aeluropus littoralis, a halophyte plant of family Poaceae. Among the AlNAC genes identified, 4 were predicted putative targets for regulation by miR164. The high conservation of miR164 recognition sites in AlNAC genes indicates the essential role of target sites in the normal function of these genes as transcription factors. Expression profile of AlNAC1L.1 candidate gene in response to salt and drought stresses and ABA phytohormone in leaf, stem and root tissues was analyzed by RT-qPCR. The results showed that AlNAC1L.1 gene down-regulated in all tissues at 6 hours after applying stresses. Among the treatments, 600 mM NaCl treatment reduced AlNAC1L.1 expression in leaf, stem and root tissues to about -217, -26 and -9 folds, respectively. Therefore, the AlNAC1L.1 which is ortholog of known Oryza miR164-targeted NAC gene OMTN6, may play negative regulatory role in response to salt, drought and ABA treatments. These results indicated that function of some NAC proteins might be conserved among species. Collectively, these findings provided a useful resource for further analysis of the interactions between NAC genes and their intricate regulation by miR164 in response to abiotic stresses.