Mass−metallicity relation (left panel) and star formation main sequence (right panel) of our galaxy sample (circles color-coded by SFR in the left panel and by gas-phase metallicity gradient in the right panel) in comparison with the distribution of SDSS galaxies and LVL galaxies. The solid or dashed lines represent the median trend or linear fit; the shaded regions indicate one and two standard deviations from the median trend. The metallicity is derived using N2S2Hα method (See Sect. 3.1 for details).