Viral‐mediated deletion of Mettl14 in Substantia nigra impaired mice motor function and locomotor activity. (A) Mettl14 deficiency was made by using loxp‐cre system, and the region from second exon to tenth exon would be deleted if Cre recombinase is existed. (B) Example of genotyping result. The PCR products by using 5’loxp‐F and 5’loxp‐R primers were separated by agar gel electrophoresis, and a 230 bp band will be detected if loxp sequence was inserted while 198 bp will be observed in wild type. We marked homozygote of the floxed Mettl14 gene as Mettl14(f/f) and heterozygote as Mettl14(f/+). (C) Experimental plan of the present study. One group of mice (Mettl14(f/f)Cre) was injected with lentivirus packaging the Cre recombinase (Lenti‐Cre) into SN region (AP: −3.4 mm, ML: ±1.25 mm, DV: −4.5 mm) to induce SN conditional Mettl14 deletion. The control group (Mettl14(f/f)Ctrl) received lentivirus without Cre recombinase (Lenti‐Ctrl). Five months later, the behavioural functions of mice were examined by rotarod test, pole test, open‐field test and elevated plus maze. Subsequently, mice brains were harvested. (D) Visual observation of mice. (E) A computer‐controlled rotarod apparatus with a rod (7 cm diameter) was set to accelerate from 0 to 40 revolutions per minute (rpm) for 30 sec and sustain 40 rpm for 5 min, and the time to fall was recorded (latency to fall). (F) Mice were placed on the bottom or top of the pole (40 cm length, at a 45‐degree angle to the ground), the time used from bottom to top (t1) or from top to bottom (t2) was recorded, and the sum of t1 and t2 was calculated as time in pole test. (G) An open‐field chamber with tetrahedral enclosing walls (total zone: diameter of 40 × 40 cm) was divided into three parts: border (green), periphery (red) and centre (blue). The time in border (H) and total distance in open‐field chamber zone (I) were calculated. (J) Mice were placed on the centre of elevated plus maze with an open arm (red, 40cm length) and a closed arm (green, 40cm length). Time in open arm (K) and total distance in total plus maze zone (L) were calculated. * P < .05, ** P < .01 and *** P < .001 vs Mettl14(f/f)Ctrl (n = 6)