Distribution of metallicity gradients as a function of the galaxy luminosity in V band with the respective uncertainties. The dashed blue lines represent the linear LSQ fit to the data and the blue shaded areas show the 95% confidence interval. In the legend boxes we report the slope value from the LSQ fits. On the y-axes, the left panel shows the metallicity gradients in units of the 2D SMA half-light radius, while on the right panel, they are in units of the physical radius. Dwarf galaxies that may have experienced a past merger event are marked with an open circle.