I'm trying to characterise 3 genes presumably related to ammonium transport in Arabidopsis. At the beginning we thought this gene family facilitated NH4+ influx based on previous data from yeast experiments. Therefore we assumed that by losing the genes we should see an increased tolerance to MA (20 mM) in plant growth experiments. However, one of my mutant (now I call it mas1, stand for methyl ammonium sensitive1) showed an increase sensitivity to MA at 20 mM and the double mutant with with mas1 background (mas1xmas2 and mas1xmas3) showed additional sensitivity even at 5 mM MA. I measured the sensitivity by measuring the primary root length. For growth experiment I used plate with modified MS media containing low nitrate (0.05 mM) supplemented with 5 or 20 mM MA.

However I'm not really sure whether this happened as a direct result of MA getting into the cell or it's an indirect results of MA effect on other things. So, by understanding how MA affect growth I could see how my genes work in relation to MA treatments.